Ported top end: Port Match or bolt it on... [Archive]

Schrade

03-22-2014, 10:51 PM

Don't know much about airflow dynamics, but I do know ALL the good questions ...

With such a difference in bore from IH to head, is it possible that instead of a smooth taper, from IH to head, that you induce vortices in the air column, which would accommodate better flow? Such as with angular FURROWS.

Like the Coriolis Effect - Think of the how the juice and chunky jam goes away through a SMALLER hole, when you pull the trigger in the 'library' every morning. http://t3.gstatic.com/images?q=tbn:ANd9GcRW_8fDrH-c6BkglH7-LzGY2YP8DGYbsQyy_gMhgn39iOwsHHXw27cvfJI

Or how the water drains in the sink even. It DOES want to spiral out to accommodate the restriction...

( I think GM even tried to mimic this with their VORTEC induction )

Perhaps 'furrowing' at the juncture, that could later be opened for full matching?

Or perhaps 'dimpling' in the juncture (think of a golf ball aerodyne).

If furrowing, would there be the appropriate angle in the column? That would be determined by differences in bore of each player? EDIT: Or determined by bore difference x some linear gradient ( = angle / length of furrows). I think airflow through the juncture AS IS, would have some nasty eddies fighting against the flow...?

Anything that would maintain some semblance of lamination in the flow.

Definitely intriguing. I come up with good stuff huh! http://www.zr1.net/forum/images/icons/icon14.gif

Still thinkin' on this too here...

Schrade

03-22-2014, 11:07 PM

Paul Workman

03-23-2014, 11:36 AM

Some people have asked about port matching the heads to the intake....obvious solution is the taper the IH runner, but if you plan on port matching in the future, you might go ahead and open it up to 36mm from the get go.....

if so this is what a 36+MM IH look like when mated to a stock head...to me its not that bad...not optimal; but I am guessing you are still picking up over a tapered runner:

http://i134.photobucket.com/albums/q115/lgaff/DSCN5668.jpg (http://s134.photobucket.com/user/lgaff/media/DSCN5668.jpg.html)

NOT according to most of my sources RE porting. Air has mass, and therefore inertia. So, leaving a ridge perpendicular to the air flow will direct the flow colliding with that ridge to run perpendicular to the flow direction, resulting in a "standing wave" of pressure at the mouth of the narrower runner. The net result impedance will off-set some or all of the net gain porting the IH afforded, or even (worse) be more of an impedance than if nothing at all was done. AND, to make matters worse, such a lip will result in some pulse reversion - also working against your efforts.

So, some (any transition) tapering is better than none. Multiple sources on the topic of porting seem to focus on 4º (approx 14.3:1) taper (or less) is required to avoid the practical issues of reversion and restriction.

Going from 36mm to 32.5 mm (at the valve guide boss of my 90 heads) at 4º is ≈ 2". However, it is 2.85" from the IH to the valve guide boss (again on my 90). So, I went the whole 2.85" just for a bit more thickness to avoid a coolant/oil incursion problems as I did my (initial plenum/IH only) head port matching with the heads in place.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/IH7Large.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/IH7Large.jpg.html)

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/IH8Large.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/IH8Large.jpg.html)

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/IH9Large.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/IH9Large.jpg.html)

Wow! I wish I had dyno'ed the result then so I'd have a clearer picture of what the net gain was after I later finished the head porting. But the "ol' seat of the pants" gauge said the lion's share of the net 432 rwhp came from the top end alone.

As you know, the head material is easier to cut than the IH. So, it took under 2 hours per hole to do the initial head runners. (BTW, I pulled the secondaries at that time and applied the same taper to all the head runners while I had the IHs off). And, an added benefit was to reduce the amount of cutting when I later finished porting the heads; eventual full porting was considered too when I initially tapered the head port match.

Paul Workman

03-23-2014, 11:58 AM

Furrowing. (which could be leveled when full porting is done).

http://www.zr1.net/forum/attachment.php?attachmentid=3306&stc=1&d=1395540220

In fact, when full head port matching is done, would SOME degree of angular furrowing STILL be in order?

I asked long ago here, if the injector bosses were specifically designed, with flow dynamics in mind - Dunn's or Burmal's mind, that is???

HMMMmmmmmmm..........................

As I understand it, the rounded edges of a velocity stack (for example) helps establish a laminar flow of air as it enters the runner. The Webber stacks (pictured) show that "curl" at the mouth of the stacks (that I think you're alluding to). Such a transition would not be required in Lee's case because laminar flow has already been established in the preceding runner length. So after the flow is established, then tapering is how flowing to a smaller cross section is accomplished (also visible in this example).

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/velocitystacks_zps255babf6.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/velocitystacks_zps255babf6.jpg.html)

As for the OE injector bosses, they're massive bastards! Removing them as much as possible (see Lees' pic) is part of the increased flow the stock LT5 craves so much!

LGAFF

03-23-2014, 12:06 PM

A 90 I did last year was 36mm, not port matched and it picked up 37hp on the same dyno....so no real ill effects...

And that was without a tune

Schrade

03-23-2014, 03:35 PM

Been reading (so more Q's at best) :mrgreen:

'Furrowing' is out (except maybe SHORT 45' channels, cut into head inlet, but only instead of NOTHING, such as to prevent the 'standing wave', that PW refers to below).

Furrowing (or channels) would be better serving for solids (bullet rifling, i. e.), or liquids. Gases have plasticity, so dimples WOULD be in order - HIGH order indeed, for variations in bore, and even then, only in absence of taper...

THoughts???

----------------------------------------------------

NOT according to most of my sources RE porting. Air has mass, and therefore inertia. So, leaving a ridge perpendicular to the air flow will direct the flow colliding with that ridge to run perpendicular to the flow direction, resulting in a "standing wave" These are the nasty eddies I was wondering about.
-----------------------------------------

of pressure at the mouth of the narrower runner. The net result impedance will off-set some or all of the net gain porting the IH afforded, or even (worse) be more of an impedance Which one are you thinking it is? I don't see how it (leaving a ridge) could offset ALL of the gain from porting, but this is interesting here...
------------------------------

than if nothing at all was done. AND, to make matters worse, such a lip will result in some pulse reversion - also working against your efforts.

So, some (any transition) tapering is better than none. Multiple sources on the topic of porting seem to focus on 4º (approx 14.3:1) taper (or less)That's the 'linear gradient' that I was guessing about.

------------------------------- is required to avoid the practical issues of reversion and restriction.

Going from 36mm to 32.5 mm (at the valve guide boss of my 90 heads) at 4º is ≈ 2". However, it is 2.85" from the IH to the valve guide boss (again on my 90). So, I went the whole 2.85" just for a bit more thickness to avoid a coolant/oil incursion problems as I did my (initial plenum/IH only) head port matching with the heads in place.

Wow! I wish I had dyno'ed the result then so I'd have a clearer picture of what the net gain was after I later finished the head porting. Ok, now this is real interesting here PW (actually answers Q's I posted below, before re-reading). Did you do any math on paper for this porting? Or did you just 'open it up', and take what it gave ya'? Is anyone on the boards in water or airflow engineering, that can do math for flow dynamics? Any computer programs available that do it for ya?
------------------------------

But the "ol' seat of the pants" gauge said the lion's share of the net 432 rwhp came from the top end alone.

As you know, the head material is easier to cut than the IH. So, it took under 2 hours per hole to do the initial head runners. (BTW, I pulled the secondaries at that time and applied the same taper to all the head runners while I had the IHs off). And, an added benefit was to reduce the amount of cutting when I later finished porting the heads; eventual full porting was considered too when I initially tapered the head port match.LeeG; did you do other work on the '90, from which you got additional 37HP??? If you didn't, your result SEEMS to conflict with what I was guessing, and with what Paul was saying...

Just to be sure here tho', you ported IH's, and didn't touch head ports at all? And put it together, like your first snappic above post #1???

A 90 I did last year was 36mm, not port matched and it picked up 37hp on the same dyno....so no real ill effects...

And that was without a tune

---------------------------------------------------------------

When you port heads too, do you HAVE TO do valvework? Do heads HAVE TO come out, to have tapered portwork done to them???

Has anyone done a partial port of IH's, WITH ONLY A TAPER?

What's the diameter of the plenum ports (once they're channeled to individual ports)?

Where is the bottleneck on the intake on a stock '90? Are dimensions in FSM? Now that I got the OBX's with 2"+ pipes, + 3" PE pipes, and no resonator restriction, where's MY next flowjam???????????????????

Schrade

03-23-2014, 03:48 PM

As I understand it, the rounded edges of a velocity stack (for example) helps establish a laminar flow of air as it enters the runner. The Webber stacks (pictured) show that "curl" at the mouth of the stacks (that I think you're alluding to). Such a transition would not be required in Lee's case because laminar flow has already been established in the preceding runner (IH???) length. So after the flow is established, then tapering is how flowing to a smaller cross section is accomplished (also visible in this example).

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/velocitystacks_zps255babf6.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/velocitystacks_zps255babf6.jpg.html)

As for the OE injector bosses, they're massive bastards! Removing them as much as possible (see Lees' pic) is part of the increased flow the stock LT5 craves so much!

I'm not following ya' here Paul...

If he DOESN'T taper the head port inlets, then his laminar flow STOPS at the head inlet ridge - doesn't it?

LGAFF

03-23-2014, 04:11 PM

The 90 only had ported intake and 63MM TB....I ported the airhorn, etc....doubt that mattered much.

No change in exhaust, or headers

Schrade

03-23-2014, 09:14 PM

The 90 only had ported intake and 63MM TB....I ported the airhorn, etc....doubt that mattered much.

No change in exhaust, or headers

Ok - so you got 37 additional HP - on a dyno, WITH a sharp ridge...
So, leaving a ridge perpendicular to the air flow will direct the flow colliding with that ridge to run perpendicular to the flow direction, resulting in a "standing wave"

I'm kinda' baffled on that - Paul? Chime in here?

What's the chance now Lee, that you can cut some 45' channels on that mill - even some short grooves - into the head port inlets, to break up that 'standing wave' (that I can well imagine that exists) ??? I just bet that would be 7 - 10 more HP on the dyno...

And even if you had only taper-ported the IH's, from plenum juncture, to head, would you have then gotten 37 more HP? OR MORE??? I bet so.

I sure wish some others 'in the know' would ring in on this...........

Has anyone else done plenum + IH portwork ON OTHERWISE STOCK MOTOR, and done a dyno?

Any links on LT5 portwork, with IN-DEPTH details?

Paul Workman

03-24-2014, 05:21 AM

The 90 only had ported intake and 63MM TB....I ported the airhorn, etc....doubt that mattered much.

No change in exhaust, or headers

Well.... Now I'm confused:confused: (something new). I thought you were asking a question regarding optimizing the transition from 36mm to 33ish, and not a hp prediction (which I wouldn't have ventured to comment on).

Anyway, only 37 hp gain WITH a 63mm TB and ported air horn seems low. For example, this graph shows Dom's car when it was stock except for the plenum and IHs were at ≈ 36mm. I snap gauged the (GVD?) heads he had on it and they were tapered almost exactly as I described mine were. At the time, Dom's car is showing about 395 rwhp(!) - and you'd have to ask him, but I believe that was with the stock 58mm TB then too.

http://i185.photobucket.com/albums/x220/6PPC_bucket/Dyno%20graphs/AzzuroFinalDynowithstockheadsandcams.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/Dyno%20graphs/AzzuroFinalDynowithstockheadsandcams.jpg.html)

So, if you were to optimize your scenario (w/o port matching), it would be interesting to compare. And, IF(?) yours comes up short, well at least you know where to start looking for more hp, I recon!

Paul Workman

03-24-2014, 06:25 AM

I'm kinda' baffled on that - Paul? Chime in here?

To visualize flow (gas or liquid) hold a table knife under a stream of water from a faucet with the blade vertical (edge on) to the stream. Then turn the blade 90º so the stream hits the flat side and observe the reaction.

The water splatters in all directions, perpendicular (more or less) to the stream. Gas does the same thing, but imagine now the stream is contained in a tube. Suddenly, the tube diameter changes. That portion of the stream flowing along the tube wall suddenly is displaced by the wall of the smaller tube. The air splatters in the only direction it can, and that is toward the center of the tube causing the air to compress, and due to momentum, the pressure measured at the narrowing is higher than the pressure before or after the narrowing. Pressure plotted vertically on a graph comparing pressure to length, the plot would look like a wave that would peak at or near the point of restriction. The wave remains stationary (standing wave) as long as flow continues in the same direction, and it is this pressure wave that impedes flow - sort of like when traffic flowing in one direction in two lanes and suddenly one lane is closed off.

Far as calculating taper goes: simple trig
Far as port size goes, serendipity and catastrophe play as big a part of the current "state of the art". I would recommend picking a goal and researching what is necessary to reach that goal.

Any links on LT5 portwork, with IN-DEPTH details?

The nuances of porting vary, but the specifics are generally held 'close to the chest'. I know that guys like Marc and Pete and Bob G (me!) have considerable time and money invested in what they know, and that knowledge is a marketable thing that I wouldn't expect would be divulged freely.

LGAFF

03-24-2014, 07:38 AM

Paul Workman

03-24-2014, 11:50 AM

Paul a 37rwhp gain on an untuned car is absolutely not low......this car also had stock exhaust manifolds.....392 at the rear wheel.

Dominics car was port matched well into the runner, with 63mmtb and well tuned.

From Haibecks website:
5.Top end porting. About +35 hp ’90-’92. About 20 hp ’93-’95.
*This would be tuned with port match and 63mm

Apples n Oranges....

You said:
"Some people have asked about port matching the heads to the intake....obvious solution is the taper the IH runner, but if you plan on port matching in the future, you might go ahead and open it up to 36mm from the get go.....

if so this is what a 36+MM IH look like when mated to a stock head...to me its not that bad...not optimal; but I am guessing you are still picking up over a tapered runner:"

Forgive me, Lee, but guess I read this as more of a question than a statement. Mebby not? Anyway, sorry for the confusion.

I posted Dominic's results as an example* of what can be accomplished (≈395 rwhp) with top end porting and a well port-matched head (read: min 4º taper his GVD heads had).

(Below) was my bone stock dyno run, averaging 337 rwhp (cutoff early due to a lean condition developing - due to a couple weak injectors, as it later turned out.)

http://i185.photobucket.com/albums/x220/6PPC_bucket/Dyno%20graphs/Basecase-DynoZR-19-20-08LargeMedium.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/Dyno%20graphs/Basecase-DynoZR-19-20-08LargeMedium.jpg.html)

I've no idea what Dom's stock #s were, but using my stock #s and comparing it to his "ALL-IN" results, the net is a 395-337 = 58 rwhp increase WITH port matching and tune.

But it is what it is (not impugning ya at all!). So if you got 37* hp w/o port matching the heads and little else (particulars of the test not withstanding) I guess the question is, how would it compare with everything sans port matching compare to Dom's 395 hp example with port matching? All but port matching being equal, I'm supposing the value of port matching the heads would be somewhere between your 37 and Dom's 58 hp net gain, me thinks.;) But, I guess your point is matching 33.6 to 36mm or a net of 2.4 mm lip doesn't matter much in the context of over-all top end porting - and maybe you're right. But if, as you say, you got 392 wheel hp w/ stock exhaust and no port matching, comparing to Dom's 395 "ALL-IN"... somethin ain't addin up, doanchaknow.:icon_scra

*Note: Results taken with a grain of salt as some ambiguity % exists due to unknowns relating to exactly what the circumstances are/were with regard to mod specs and environmental conditions at the time of the dyno run.

mike100

03-24-2014, 11:54 AM

I ported mine before I had headers and I think it was only good for 20 rwhp or so and about the same torque as a stock car with a cat-back. This was all over 5000 rpm so really not the big seat-of-the-pants kick like you wish all mods had, but still, it seemed to run better on the freeway than it previously did. I did port down into the heads on the primary to smooth out the ridge and port mismatch.

I think Paul's experience with the porting gain was because he already had headers and supporting mods when he went with a full aggressive porting and secondary removal...So probably there was a nice big step that he could feel.

now to finish this story, I finally got long tube headers (2" primaries) and a proper x-pipe on the cat-back and boy oh boy did that wake it up! Was it because the headers help the mid range torque (they do-and you feel it), or was it because the top end porting done the previous year was finally able to contribute to the big gain because the bottle neck in the exhaust was finally taken car of? Probably in my case the top end port helped the header mod to feel so significant. One might also mention that if you kind of do mods in incremental steps, you get used to the power and it isn't the same as spending all the money at once and getting a 100hp gain.

I gave a ride in my car to a guy with a stocker and he said he thought it really pulled massively and wants to mod similarly. Probably time to get back to the dyno if I don't end up selling the car first.

mike100

03-24-2014, 12:07 PM

No reason to make the task difficult. Just mark the port circle with the gasket, test fit the IH, and grind it. All the time was spent masking it off, stuffing oil soaked towels in the port, vacuuming and making sure the valve was closed on the port being worked on (turned engine with tool on crankshaft).

http://i29.photobucket.com/albums/c265/mschrameck/Cars/makingamess.jpg~original

I didn't go the full 36MM, so I didn't have to taper 2" down. This hole took 10-15 minutes to do, it was the extra prep that takes the time. I did all 8 in about 5-6 hours.
http://i29.photobucket.com/albums/c265/mschrameck/Cars/port_match_1.jpg~original

Schrade

03-24-2014, 07:10 PM

Paul - thanks, but what's baffling isn't what a standing wave could be. When I said I don't know flow dynamics, I was trying to be a little modest here...

What's baffling is that LeeG dyno'ed 37+ HP increase, with NO flow enhancement at the head, at the IH-to-head interface. You even said you thought possible that NO gain could be the scenario:
The net result impedance will off-set some or all of the net gain porting the IH afforded, or even (worse) be more of an impedance than if nothing at all was done.

and I'm with ya' on that. But Lee's dyno don't lie.

So, given that 'nasty eddies', or a 'standing wave' (call it what you want) DOES exist, where the IH is opened to 36mm, and the head inlet is NOT touched, but remains at 32.5mm, with only the factory bevel cut in, then even some furrows / vanes / channels cut into the head inlet, would CERTAINLY break the eddies (or standing wave), SUBSTANTIALLY, and boost HP 7 - 10, maybe 12HP +++, OVER WHAT HE DID GET... RIGHT???

Or even more efficient than furrows / vanes / channels, would be dimples - like the golf ball aerodyne that I referred to, which would enhance airflow lamination, vs. turbulence (eddies, standing waves, etc.).

No one into fluid dynamics here? Anyone can just 'open up the holes' blindly, and hope for the best...

:confused: :confused: :confused:

To visualize flow (gas or liquid) hold a table knife under a stream of water from a faucet with the blade vertical (edge on) to the stream. Then turn the blade 90º so the stream hits the flat side and observe the reaction.

The water splatters in all directions, perpendicular (more or less) to the stream. Gas does the same thing, but imagine now the stream is contained in a tube. Suddenly, the tube diameter changes. That portion of the stream flowing along the tube wall suddenly is displaced by the wall of the smaller tube. The air splatters in the only direction it can, and that is toward the center of the tube causing the air to compress, and due to momentum, the pressure measured at the narrowing is higher than the pressure before or after the narrowing. Pressure plotted vertically on a graph comparing pressure to length, the plot would look like a wave that would peak at or near the point of restriction. The wave remains stationary (standing wave) as long as flow continues in the same direction, and it is this pressure wave that impedes flow - sort of like when traffic flowing in one direction in two lanes and suddenly one lane is closed off.

Far as calculating taper goes: simple trig
Far as port size goes, serendipity and catastrophe play as big a part of the current "state of the art". I would recommend picking a goal and researching what is necessary to reach that goal.

The nuances of porting vary, but the specifics are generally held 'close to the chest'. I know that guys like Marc and Pete and Bob G (me!) have considerable time and money invested in what they know, and that knowledge is a marketable thing that I wouldn't expect would be divulged freely.

mike100

03-24-2014, 11:39 PM

Nobody is blindly just hogging out ports. It has been proven out many times before and Paul's taper specification has been tried and proven on may applications and is a good rule-of-thumb.

the golf ball aerodynamic reference is valid- it is recommended to leave intake ports a tad rough and not polished. I think the reason that gains are possible even on such mis-matched ports is because these engines are way under ported and starving for air. certainly square edges are undesirable, but the LT5 defies convention- certainly compared to a 350 chevy.

XfireZ51

03-25-2014, 12:20 AM

Just to clarify, the 398# was with stock heads and cams not the ported GVD heads which went on when I upgraded the intake cams. When I did port the IHs and plenum, I also did a port match BUT only of the primary runner since the secondary was already ~ 36mm. I left the ridge also in the secondary runner and tapered the primaries about 2" below the deck. The secondary throttle shafts were also still in the heads.
The 398# was using a 63mm TB, full exhaust including MFlow resonator and muffs. Finally, at the time the camshafts were "as is" which we later found out were not timed optimally. So those were the conditions for the dyno run.

LGAFF

03-25-2014, 12:39 AM

Dominic I remember your port matched heads.....you damn near did a full port job while they were on the car: you went deep!LOL

Schrade

03-25-2014, 01:23 AM

Alright - I guess it's not cheap to do such extensive testing as I'm asking here...

What IS ... ABOUT the max HP / TQ numbers available for a motor, STOCK, with only airflow mods?

Paul Workman

03-25-2014, 04:19 AM

Dominic I remember your port matched heads.....you damn near did a full port job while they were on the car: you went deep!LOL

Exactly! I remember that too - is why I guessed Dom was using the GVD heads.

As it happens, I snap gauged a primary and secondary runner on those GVD heads, and I wish I had recorded the #s, but what struck me was they were nearly Identical to what I ended up with (while leaving the heads ON); tapered from ≈36.x at the inlet to ≈ 33.x mm (32.5 = my stock#) at the choke point entering the bowl area (read: not much cutting and perhaps only sanding in that spot marked by the valve guide boss.)

Paul Workman

03-25-2014, 04:24 AM

Alright - I guess it's not cheap to do such extensive testing as I'm asking here...

What IS ... ABOUT the max HP / TQ numbers available for a motor, STOCK, with only airflow mods?

Marc Haibeck's (http://zr1specialist.com/HAT%20Web/products/major%20engine%20upgrades.htm) web page has the options delineated about as well as anybody.

My WOT rear wheel torque (below) measured stock and after the 508 hp mods were done, which were essentially ALL air flow related fully ported (except for stock TB & air horn), headers, x pipe. And, a big part is the tune and cam timing (see my signature).

http://i185.photobucket.com/albums/x220/6PPC_bucket/Dyno%20graphs/Dynographs_zps723fdad7.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/Dyno%20graphs/Dynographs_zps723fdad7.jpg.html)

XfireZ51

03-25-2014, 08:34 AM

I never got near the bowl area. The 36mm was at the top and tapered from there. I did the surgical masking off thing and had foam stuffed down the runner.
I was using a double fluted burr so as to not cut too deeply w each pass. The primaries were the ones I concentrated on. Just touched the secondaries to eliminate any edge in th transition, otherwise nothing there. I think it was Marc that had recommended a taper that had a 36mm sitting in the opening and a 35mm ball would sit completely into the runner flush w the opening.

Paul Workman

03-25-2014, 09:08 AM

I never got near the bowl area. The 36mm was at the top and tapered from there. I did thewhatgical masking off thing and had foam stuffed down the runner.
I was using a double fluted burr so as to not cut too deeply w each pass. The primaries were the ones I concentrated on. Just touched the secondaries to eliminate any edge in th transition, otherwise nothing there. I think it was Marc that had recommended a taper that had a 36mm sitting in the opening and a 35mm ball would sit completely into the runner flush w the opening.

Yep! Only difference was I did cut the secondary port to match. & of course the bowels were untouched (initially ported (i.e., port matched) with heads on as well - heads didn't get the "FULL MONTE" - including the bowls and valve job - until I had to repair the exhaust valve anyway).

I removed the throttle plates, but the TB is stock, whereas your TB is ported and you left the throttle plates and rods in place (tied open). So, I'm guessing the two offset each other, and therefore extrapolate to mine from your dyno results measured at that time.

Anyway, porting science is very interesting, far as the nuances of what works and and what sometimes doesn't do what was expected. My last Dynojet run showed 432 rwhp. Since then, I modeled some flow number scenarios for upping the TB to 63.x mm and got 6 hp predicted gain, which is more or less confirmed by Marc's empirical experience. In addition, I want to go with the Dynamax 17228s(?)/NPP mufflers (Sharp transitions rub my flow sensibilities the wrong way. The MFs go sharply from 3" inlet down to about 2.5"). I don't know if the combination of the two can get to 450 rwhp on stock cams w/o going to an electric water pump, but it would be sweet! (Would you be interested in playing with my tune as a project, once those two items are accomplished??)

Pete

03-25-2014, 01:07 PM

Lee, picking up 30-50 HP is nothing new been doing it for almost 15 years.

On the port matching of course it would be nice to match/taper the head to the ported IH's remember we have N/A motors the piston sucks in the air where as a turbo/SC pushes air.

Pete

LGAFF

03-25-2014, 02:09 PM

Paul Workman

03-25-2014, 06:54 PM

I Agree nothing new, point is.. despite not port matching gains were comparable or better to that of a tapered runner match to the stock port....in other words not port matching to the stock head does not set you back...

Really, Lee???

Just to clarify... You're saying there's no difference in flow between a 36mm IH feeding ≈ 33 mm port matched head vs. one that is not, right? Ya wanna bet a steak dinner on that compadre??;)

LGAFF

03-25-2014, 09:49 PM

LGAFF

03-25-2014, 09:51 PM

Original Post:

Some people have asked about port matching the heads to the intake....obvious solution is the taper the IH runner, but if you plan on port matching in the future, you might go ahead and open it up to 36mm from the get go.....

if so this is what a 36+MM IH look like when mated to a stock head...to me its not that bad...not optimal; but I am guessing you are still picking up over a tapered runner:

cvette98pacecar

03-25-2014, 10:12 PM

Port Match it Lee, You will regret your decision if you don't when the engine is complete.

LGAFF

03-25-2014, 10:17 PM

Come on guys.....

I am not talking about my car...I am talking about when someone sends out an intake to have it ported and does not have the skill to port match their own heads. Do they go 36mm all the way down or port the top part of the IH and then neck it down to 32mm at the bottom of the IH.

My 92 is port matched...and thats port match just slightly into the head 391rwhp...no tune

my 90 is fully ported into the head...... 441rwhp...thats untuned, small exhaust, stock tb, and I did not play games with dyno....take the air filter off to gain 5 more hp. etc.

I regret ever even posting this thread.......

USAZR1

03-25-2014, 11:09 PM

XfireZ51

03-25-2014, 11:21 PM

Schrade

03-26-2014, 02:04 AM

Locobob

03-26-2014, 02:13 AM

I prefer to taper to about 34mm even if the heads might be done later. Reason for this is mainly port skew i.e. the intake and head ports rarely line up just right. By leaving a little material to work with on the injector housings I have a better chance at getting a perfect port match when doing the heads.

-=Jeff=-

03-26-2014, 09:18 AM

Option 1)Port to 36mm to bottom of IH, no port match, head primary stays at 32mm
Option 2)Port top of IH to 36mm and taper to 32mm
Option 3)Port to 36mm port match head 36mm primary

I think there may be people that struggle with this if they want to port, but

1) aren't comfortable doing it
2) are on a limited budget to do this
3) are afraid if they screw up the head on the car this porting joib just got real expensive

I have not ported, have I thought about it. Absolutely. Am I motivated? not really, I have an extra set of IHs (the originals and if I did them or had them done, I think I would start with porting like Locobob suggested and taper to 34mm on the bottom, then leave the heads alone and see how that works for me.

But I am really not in any rush to do that

Lee, I think the info is good.. THANKS

Schrade

03-26-2014, 11:22 AM

Paul read the post:

This is what I am trying to say:

Option 1)Port to 36mm to bottom of IH, no port match, head primary stays at 32mm
Option 2)Port top of IH to 36mm and taper to 32mm
Option 3)Port to 36mm port match head 36mm primary

What I am saying is.....Option 1 is as good or better than Option2 and option 1 is not that substantially different that option 3.

Conclusion: Even if you are not port matching, I would still open it up to 36mm.....its as good as the taper and depending on the car as good as some produce with a port match. Plus if you decide to port match later...its ready

What I am not saying:
*My porting is great or better because a guy got 37 rwhp
*Point is someone did not port match yet got results similiar to port matching
* That porting a runner 2 inches in would not produce better results; **** if you port the thing down the runner thats alittle more than most people would do port matching.

Holy **** this is my last tech post everybody wants to turn this thing into a pissing match

That goes against logic there MrG...

Sorry you choose to not post further on it tho' (I don't see where anyone ELSE was trying to make a 'pissing contest' out of the DISCUSSION), but I hope someone else will try to explain this, without getting upset, what seems to go against logic.

Fortunately, NO one knows it all, and EVERYone still can learn a thing or 2, IF THEY WANT:

... and a little wisdom while I'm at it here.

I'm into learning, and learning how my Z works (or is supposed to work anyway ;) ). That might be evident when you see how I break stuff down, shoot snappics, post them and write stuff out, clean, and re-assemble (front fascia, Cruise Module, TPS testing, etc.). Kinda' like Dynomite's 'Solutions' (http://www.zr1.net/forum/showthread.php?t=16778) threads... Good stuff there Cliff :thumbsup:

Knowledge is good.

Reading tech posts is good info too. When opposing posts show up and get resolved, that's another tech tidbit that you can add to FSM info. IF they get resolved, that is...

The Bible says in Proverbs that "Iron sharpens iron". When done right, both edges are sharper. When done right, you're gonna' get heat, and sparks, but both edges get sharpened - IF DONE RIGHT. When 2 Bible scholars debate doctrine, using other Bible verses as reference, both know MORE. They might not agree, but each knows MORE.

But if you just bang together a couple of edges, both edges just get dinged up (and iron 'dings' actually integrate into the iron's molecular structure, BELOW THE SURFACE). You stop sharpening them, they just get rusty. You have to start over again, clean off the rust, sharpen out the ding, and then go deeper even, to get below the dinged molecular latticework.

When 2 Z experts debate tech info, CORRECTLY, I know more. And there IS a bible for each year's Z...

If I remember correctly, some forum bosses had a difference of opinion about BG '13. The thread just got wiped. No resolution (and that dinged molecular latticework is still there).

Maybe let US decide who's right, and who's wrong. And who can admit it. THAT takes a REAL man.

This time, same outcome. No one learned anything about the Z. Too bad... Maybe try it again, and do it RIGHT.

Then we all know the Z better...

WISE old sage OUT.......................................

ed.:
I don't see a 'Site Feedback' sub-forum, so I posted here. Hope it ain't out of order (or no nerves are touched).

batchman

03-26-2014, 12:33 PM

Do they go 36mm all the way down or port the top part of the IH and then neck it down to 32mm at the bottom of the IH.

Option 2)Port top of IH to 36mm and taper to 32mm

Sincerely hoping this thread has not scared Lee off, I have a question.

My racing rules limit me to going 1" into the head ports, intake or exhaust. On the other hand if I'm going to crack open the thing (or the wallet), I want to make sure I don't leave anything on the table. After all, this is war racing.

To my eye, choices appear to be A) porting IH with <=4deg taper to match the stock head or B) porting to the extent that <=4deg taper can happen within the top inch of the head.

Looking at the implements of destruction I honestly didn't think one could taper like "A" in the IH. On the other hand I figured using the 1" into the head would be the way to make sure the ports register properly between the IH and the head.

If I think between the lines a little bit it sounds like Lee's answer to my dilemma would be let the head ridge stay, but knowing myself I'd take that to mean stick with tapering in the IH.

Maybe the truth lies in the middle, taper the IH from 36 to 33 then use the last mm in that top inch of the head to be sure to align the ports?

I am still on the fence about the secondaries. Once in a while I need to leave the car with a mechanic and knowing human nature that's a great time to keep the power key in the pocket so to speak. It sounds like there's nothing to be gained there at the head other than simplification, which I do confess I like a lot...

Thanks,
- Jeff

Schrade

03-26-2014, 01:30 PM

Jeff (batch); would you clarify / equate please your 'A', and 'B', to Leeg's options - either Option 1), or Option 2), or Option 3)???

And which Option are you favoring here? (Never mind your race regs, for the moment here).

Your 'A', looks like LeeG's Option 2), but I'd like to be clear here on what we're saying...

Sincerely hoping this thread has not scared Lee off, I have a question.

My racing rules limit me to going 1" into the head ports, intake or exhaust. On the other hand if I'm going to crack open the thing (or the wallet), I want to make sure I don't leave anything on the table. After all, this is war racing.

To my eye, choices appear to be A) porting IH with <=4deg taper to match the stock head or B) porting to the extent that <=4deg taper can happen within the top inch of the head.

Looking at the implements of destruction I honestly didn't think one could taper like "A" in the IH. On the other hand I figured using the 1" into the head would be the way to make sure the ports register properly between the IH and the head.

If I think between the lines a little bit it sounds like Lee's answer to my dilemma would be let the head ridge stay, but knowing myself I'd take that to mean stick with tapering in the IH.

Maybe the truth lies in the middle, taper the IH from 36 to 33 then use the last mm in that top inch of the head to be sure to align the ports?

I am still on the fence about the secondaries. Once in a while I need to leave the car with a mechanic and knowing human nature that's a great time to keep the power key in the pocket so to speak. It sounds like there's nothing to be gained there at the head other than simplification, which I do confess I like a lot...

Thanks,
- Jeff

LGAFF

03-26-2014, 02:24 PM

Just facts not speculation:

*Marc Haibeck's website posts the average gain of his tune, 63mm, porting, port match to 36mm was 35hp. I think the dyno sheet listed shows a 33rwhp gain on a car with stock manifolds and Corsa

*So the prior statement that 37rwhp was low...not sure were that comes from...no dyno sheets were shown

http://zr1specialist.com/HAT%20Web/products/top%20end%20porting.htm (http://zr1specialist.com/HAT%20Web/products/top%20end%20porting.htm)

*Car intake I did with essentallly the same mods as Marc had, except no tune or port match..it did 37rwhp......if someone wants to see the dyno sheet search my last name in forum it will show.....same dyno same car... (again this is not some claim about my porting, point is the port match was not done and # was still in the 30s for an increase)

*When I port matched my car and Dominic did it at the same time, I recall Marc saying it was worth another 5 or so(I hate to quote other people, but it was clear port matching did not pick up another 20hp+)...and we are talking about a port match, not porting 3" down the runner....thats more than a port match, thats a ported runner....be real

*My 92 is port matched just into the top(1 inch tops, maybe not even), nothing near what Dominic did, although I wish I did, but the car put down 391 with no tune and ran 12.42 @ 117.5mph with cheap tires and a 1800 rpm launch(I am not a pro driver what can I say(This car has headers)...(this is to answer someone's question about a track car)

Again this is about a person wants to know if they have to port match a 36mm or should it be tapered from the top of the IH to the bottom to match the stock head. That was my intention for the discussion.....if you are going to spend $1K-$2800 why not go to the 36mm.....leave the door open for future mods....opening up the last few inches on the port is what takes the longest......so why pay twice????

Bringing up comparison cars with headers or full cyl head porting is not; as was said here Apples to Apples. The comparisons I made were on actual dyno results....

So if someone wants to port an intake and have it taper to a port match on a stock head and have it well outperform a 36mm ported intake; lets see it......By the claims here it should be about 50hp+ rwhp on a car with no headers....step up! Heck lets see 50+ rwhp on a 36mm with port match and no headers.

Paul Workman

03-26-2014, 02:39 PM

Jeff (batch); would you clarify / equate please your 'A', and 'B', to Leeg's options - either Option 1), or Option 2), or Option 3)???

And which Option are you favoring here? (Never mind your race regs, for the moment here).

Your 'A', looks like LeeG's Option 2), but I'd like to be clear here on what we're saying...

It took me a while and lots of re-reading and intuitive unraveling (along with overcoming personal prejudices), and I'm essentially OK with everything Lee said. In fact, we're in "violent agreement" (with these caveats):

Dyno results for several LT5s with very similar mods, for various reasons, produce a range of hp results that exceeds that typical for the particular (port matching the head) hp gain. Its sort of like trying to measure an inch within a stick a yard long.

Therefore 'it is beyond the bounds of accepted scientific process' (there's a mouthful;)) to predict the absolute outcome of a test conducted under one set of variables based on results derived from a different test where some or all of the variables are independent or uncontrolled.

In short, the change in hp between porting matching the head to the same ported IH 36mm (primary side only) vs. not matching the head to the 36mm IH falls inside the range (in Lee's considerable experience) for LT5s that have been port matched, and therefore irrelevant compared to the relatively wide range of hp results for all LT5s w/ head port matching (primary side).

Now, THAT SAID, on and individual basis, Lee is NOT saying hp would not be improved at least some amount when the head is later port matched to the IH.

So, if you send a plenum and IH to Lee for 36mm PNP, but don't want to DIY port match your heads, chances are your LT5 hp will still fall within the established range of LT5s performance that have had the heads port matched.

How-some-ever, there also is some future "low hanging fruit" hp available when the head ports are matched to the IHs. (I don't believe I'm speaking out of school if I tell you that part of the reason Marc's 500 hp upgrade is now up to 510 is in part due to some changes in porting.) And, when you consider spending several 100s of $$ to have a TB opened up to 63mm, then a couple hours or so using a burr and a die grinder is pretty cheap for nearly the same amount of improvement.

:cheers:

EDIT: Ah, Lee, your post beat me to "what you said".

Paul Workman

03-26-2014, 02:53 PM

*So the prior statement that 37rwhp was low...not sure were that comes from...no dyno sheets were shown

Lee, I think that was essentially my initial position. I apologize for misunderstanding; taking 37 hp out of the context of the full top end pnp, short of full porting of the heads. Only using my stock 337 and Dom's 395* the net is 58 for "a top end upgrade", but of course that also includes the tuning, headers, etc, etc, etc, (i.e., the "full Monte"). So, taken by itself, 37 hp gain for the pnp plenum/IHs, is very respectable. So, please forgive me. My bad.:o

mike100

03-26-2014, 03:46 PM

I would have guessed that port matching would have been worth more than 15% of a top end port (5 extra hp). If you think about the head port itself being the real restriction once you open up the plenum, just up-sizing the plenum gains what it gains and further improvements would have to be more internal the the cylinder head.

Still, I thought it was worth my time while the thing was taken apart to blend out the stupid core shift bevel and blend it to my I/H. I didn't go too deep- it was about a 35mm hole at most.

LGAFF

03-26-2014, 05:09 PM

Locobob

03-26-2014, 05:32 PM

I think everyone needs to remember that dynos are a tuning tool. Comparing one dyno test to the next, even if its run on the same dyno, is fraught with problems. Variations of 5-10hp are common with even the same car on the same dyno with back to back tests. You'd have to do an awful lot of tests to establish a meaningful trend when you are talking about the kind of subtle changes that result in 5-10hp. I don't see how anything could be gained airflow wise by a sudden change from 36 to 32mm - except that you may expose some area that was previously shrouded do to port misalignment. This is why I go 34mm at the base of the IH primarys, its enough to capture the port skew area but leaves material to work with if the heads end up being ported some day.

LGAFF

03-26-2014, 06:51 PM

When you measure the primary runner mating surface on the head and if you include the bevelled portion of the opening it measures 33-33.5MM.

On the other hand a stock IH at the bottom of the runner can be as small as 30.3-30.5mm but most are 31-31.5. (90-92) IH

Schrade

03-26-2014, 07:17 PM

Glad you decided to re-join the DISCUSSION. If MY posts were what made you call the exchange a 'PISSING MATCH', sorry.

-------------------------------------
"if anyone wants to see dyno sheets..."

hmm... I didn't see anyone asking for proof of anything.

OTOH, I am EXTREMELY interested in exceptions to rules.

In this case, the exception is your result:

(and it doesn't need re-wording; I understand the syntax COMPLETELY).

Option 1)Port to 36mm to bottom of IH, no port match, head primary stays at 32mm
Option 2)Port top of IH to 36mm and taper to 32mm
Option 3)Port to 36mm port match head 36mm primary

What I am saying is.....Option 1 is as good or better than Option2 and option 1The RULE (NOT your exception to the rule, Mr. G, but the RULE) is laminar flow into a cylinder (no, NOT the combustion chamber) beats turbulent flow into a cylinder, EVERY TIME, all factors being equal.

If in the LT5 case, there's some waveform resonance that overcomes the abrupt bore diameter change from 36mm, to 32mm (inclusive of the bevel in the head inlet), I'm listening. And I have a pretty GOOD grasp of String Theory, and String Harmonics, so fear not going over my head.

USAZR1

03-26-2014, 07:23 PM

Port match might be worth ten on some, those with headers, etc maybe more...there is alot fo variables on hp from car to car.....

Cam timing

Variances in compression...some due to the above...

Its strange some stock LT-5s test out at 335-some even say 350 rear wheel stock...while other show 310-315...its all over the place. Dyno variances come into play...but its seems there are some really good stocker engines out there...

Cam timing would be my first guess as to why some LT5's make more power. IIRC,Paul Smith's Admiral Blue made over 385rwhp,stock.

What kind of ballpark hp numbers would I see by just porting the plenum & injector housings on our 94 with stock header cats? If you could only do one mod,what would you do; headers or ported plenum & IH's?

LGAFF

03-26-2014, 08:43 PM

Results speak for themselves......I would also note Mr. Haibeck sells his porting as a bolt on...maybe he can weigh in.....again, I am not proclaiming it to be superior, just that the 36mm will flow as well as a runner that tapers down to a stock head port......

*37 rear wheel upmatched....
*Marcs average is 35
*Locobobs average is about the same and he tapers to 34

I am not an engineer, but obviously what works, works, alot of things in play here, the angle of the entry into the heads, size of runner, air speed, etc.....Peter Brock was laughed at for his Daytona Coupe design, was told it did not conform to the "rules".....guess who was right.

Theory and practical application can produce two different results...show me proof of a dramtic difference in hp and I will agree....

again, broken rcord, someone go out and port an intake to the stock head port and show the improvement of 45 or 50 rwhp.....we can talk all day about theories, but someone show a result!

Glad you decided to re-join the DISCUSSION. If MY posts were what made you call the exchange a 'PISSING MATCH', sorry.

-------------------------------------
"if anyone wants to see dyno sheets..."

hmm... I didn't see anyone asking for proof of anything.

OTOH, I am EXTREMELY interested in exceptions to rules.

In this case, the exception is your result:

(and it doesn't need re-wording; I understand the syntax COMPLETELY).

The RULE (NOT your exception to the rule, Mr. G, but the RULE) is laminar flow into a cylinder (no, NOT the combustion chamber) beats turbulent flow into a cylinder, EVERY TIME, all factors being equal.

If in the LT5 case, there's some waveform resonance that overcomes the abrupt bore diameter change from 36mm, to 32mm (inclusive of the bevel in the head inlet), I'm listening. And I have a pretty GOOD grasp of String Theory, and String Harmonics, so fear not going over my head.

mike100

03-26-2014, 09:08 PM

...
If you could only do one mod,what would you do; headers or ported plenum & IH's?

Yes, that one mod.

I think my factory catalysts may have been a little plugged up because seat-of-the-pants wise, I liked the headers the most (and I'm still running cats). But like I described before- I had ported the top end previously so I can't really comment on what just headers alone would feel like. If one had to compromise because of emissions inspection, it would be interesting to slap a 93-95 set of catted manifolds to see what improvement you could get over the early units.

Quite honestly, I pretty much assume everybody has a chip too...if nothing else to fix the power key default and to make the fans come on sooner.

ZZZZZR1

03-26-2014, 09:24 PM

Lee,

You seem to be jack of all trades!

Porting

Cams

Engine building

Have you dyno'd anything?

Before / after?

How many cars have you worked on!

Great stuff!

:cheers:

David

Schrade

03-26-2014, 09:58 PM

Results speak for themselves......I would also note Mr. Haibeck sells his porting as a bolt on...maybe he can weigh in.....again, I am not proclaiming it to be superior, just that the 36mm will flow as well as a runner that tapers down to a stock head port......

*37 rear wheel upmatched....
*Marcs average is 35
*Locobobs average is about the same and he tapers to 34

I am not an engineer, but obviously what works, works, alot of things in play here, the angle of the entry into the heads, size of runner, air speed, etc.....Peter Brock was laughed at for his Daytona Coupe design, was told it did not conform to the "rules".....guess who was right.

Theory and practical application can produce two different results...show me proof of a dramtic difference in hp and I will agree....

again, broken rcord, someone go out and port an intake to the stock head port and show the improvement of 45 or 50 rwhp.....we can talk all day about theories, but someone show a result!

I'm pretty sure that the cut in those heads - on that '90, is pretty generous - perhaps to halfway between 36 and 32? Maybe 34?. And I'm bettin' that however 'deep' they are, that they're always cut @ 45'.

You didn't happen to mic the cut, or angle it, did you there Lee?

And still glad that you decided to re-join discussion there..............

Now if we could get F/B from others???

LGAFF

03-26-2014, 11:42 PM

This is the old school porting that my 92 came with....the DRM ported intake was 34-35mm(primary) and necked down to stock at the IH. This was done with Extrude hone; Dyno test of an Extrude Hone in Vette Magazine(Dec 1997) showed a peak power increase of 18rwhp; more under the curve(20+ at 5K) but 18 peak. Car was untuned with and exhaust

The DRM package came with more..tune and 63mm TB...mine also had headers.....

DRM 500/415
1990-92 ZR-1 Corvette
(50-state legal E.O.# D-323-2)
415 horsepower/390 ft-lbs.
350 cubic inches
Ported plenum and injector housings
K&N air filter
Modified air filter lid
63mm throttle body
Custom computer calibration

LGAFF

03-27-2014, 12:13 AM

This was the Doug Rippie plenum extrude honed with 35mm ball....some ports were larger and alomost the entire top of the ball was hidden

http://i134.photobucket.com/albums/q115/lgaff/DSC02361.jpg (http://s134.photobucket.com/user/lgaff/media/DSC02361.jpg.html)

http://i134.photobucket.com/albums/q115/lgaff/DSC02364.jpg (http://s134.photobucket.com/user/lgaff/media/DSC02364.jpg.html)

Narrowed to stock

Paul Workman

03-27-2014, 07:15 AM

Dom said he went with the GVD heads he already had rather than risk perforating the head runners. That decision makes a lot of sense, financially. Before I finished porting and relieving my heads, it ended up costing me just over $137/hp gained to go from about 395 (using Dom's numbers for top end pnp) to 432 ≈ 37 hp gain. (almost $2000 of that was the cost of my "education", and I have one of my original 90 heads sitting right here beside me as I type this.)

This explains why the "seat of the pants" meter felt like doing the full Monte on the heads was somewhat anticlimactic: 2/3 of my total wheel HP came from the plenum/IH/<4º taper almost 3" into both ports of the head/SW headers/SW X-pipe/tune.

For the same money I spent DIY, I could have had "Magic Marc" or Pete's CNC heads AND cams; sans all the fun I had learning where the thin spots are and how to fix 'em later.:o

Whatever dyno Lee is using...I want to do my next tune on that one!:D

rkreigh

03-27-2014, 08:33 AM

great stuff Lee, don't get discouraged.

I'm reminded of an "accident" back in my C3 days a buddy of mine put a square port intake on an oval port head on a big block chevy

worse port mismatch in the world with a HUGE ridge of the oval ports not lining up with the square port intake

made a ton more power and picked up 30 hp becuase the square port intake was so much better flowing and he got better mix from the air fuel turbulence I would have thought it would be horrible, but it worked.

sure the mismatch induced huge turbulence and was far less than optimal, but it worked

so he port matched to try it out . couldn't really get all that close due to the casting limitations and it really didn't do too much

then he "rounded" the edge of the head port so it's not such a sharp ridge

it again helped. so things that "shouldn't work" often do.

it's all about finding the flow choke point, optimizing flow "velocity and quality" and getting the air fuel mixture to be as homogenous (well mixed) to burn as much as possible. a lot of folks were shocked this year at engine masters when the "little ford modular" built by Jon Kasse pulled 720 hp ouf of a long stroke small bore coyote motor. tuned for top end it pulled over 800 *(albeit with a much less desireable "average torq" which is the numbers we should be focused on)

the lt5 has some pretty small ports in the heads. a very well ported LT5 head flows around 350 cfm which is about where a modern stock LS3 head flows

the big doggie LS7 has HUGE ports and flows 370+ out of the box.

Back to the LT5, Todd has shown me about the upper limit that the LT5 castings do with a max effort port and cam to flow enough for over 700 HP. I'm not really sure what the "upper limit" in CFM is for the LT5 head, Pete probably knows more than most on the best head porting

what we really need is a billet head for the LT5 with the MY95 port or updated head design

maybe we can talk graham and nelson racing into doing it together

it would be amazing to build a "modern LT5"

looking at what Mercury marine did would be a good start to see how they updated their cyl head and manifold port designs. they might be interested too, who knows

great discussion, let's keep it going

Paul Workman

03-27-2014, 09:36 AM

Sincerely hoping this thread has not scared Lee off, I have a question.

My racing rules limit me to going 1" into the head ports, intake or exhaust. On the other hand if I'm going to crack open the thing (or the wallet), I want to make sure I don't leave anything on the table. After all, this is war racing.

To my eye, choices appear to be A) porting IH with <=4deg taper to match the stock head or B) porting to the extent that <=4deg taper can happen within the top inch of the head.

Looking at the implements of destruction I honestly didn't think one could taper like "A" in the IH. On the other hand I figured using the 1" into the head would be the way to make sure the ports register properly between the IH and the head.

If I think between the lines a little bit it sounds like Lee's answer to my dilemma would be let the head ridge stay, but knowing myself I'd take that to mean stick with tapering in the IH.

Maybe the truth lies in the middle, taper the IH from 36 to 33 then use the last mm in that top inch of the head to be sure to align the ports?

I am still on the fence about the secondaries. Once in a while I need to leave the car with a mechanic and knowing human nature that's a great time to keep the power key in the pocket so to speak. It sounds like there's nothing to be gained there at the head other than simplification, which I do confess I like a lot...

Thanks,
- Jeff

For what it's worth, like Mike 100, I found tapering (from 36+mm) down the length of the head runners (<4º) to be easy enough while the heads were on the motor, and still be quite safe if done right*. I did both primary and secondary runners, making them identical, all said and done, and it took less than 90 minutes avg, start to finish per port. My top end, (36+mm for plenum and IHs) including that long matching taper into the head, was total DIY without doing anything I would consider anything risky.

Even at ≈ 390-400 wheel hp, the reward is it turns the Z into another animal - even before installing an aluminum FW for a bit more ZAP (especially in the first couple gears!)

Having BTDT, I see no reason to shy away from maxing out the top end P&P by complementing it with porting the heads at the same time.

Schrade

03-27-2014, 10:46 AM

I venture that turbulence in a carburetted induction motor is a little different that turbulence in a fuel injected motor...

Was there no bevelling in the OEM heads already?

great stuff Lee, don't get discouraged.

I'm reminded of an "accident" back in my C3 days a buddy of mine put a square port intake on an oval port head on a big block chevy

worse port mismatch in the world with a HUGE ridge of the oval ports not lining up with the square port intake

made a ton more power and picked up 30 hp becuase the square port intake was so much better flowing and he got better mix from the air fuel turbulence I would have thought it would be horrible, but it worked.

sure the mismatch induced huge turbulence and was far less than optimal, but it worked

so he port matched to try it out . couldn't really get all that close due to the casting limitations and it really didn't do too much

then he "rounded" the edge of the head port so it's not such a sharp ridge

it again helped. so things that "shouldn't work" often do.

it's all about finding the flow choke point, optimizing flow "velocity and quality" and getting the air fuel mixture to be as homogenous (well mixed) to burn as much as possible. a lot of folks were shocked this year at engine masters when the "little ford modular" built by Jon Kasse pulled 720 hp ouf of a long stroke small bore coyote motor. tuned for top end it pulled over 800 *(albeit with a much less desireable "average torq" which is the numbers we should be focused on)

the lt5 has some pretty small ports in the heads. a very well ported LT5 head flows around 350 cfm which is about where a modern stock LS3 head flows

the big doggie LS7 has HUGE ports and flows 370+ out of the box.

Back to the LT5, Todd has shown me about the upper limit that the LT5 castings do with a max effort port and cam to flow enough for over 700 HP. I'm not really sure what the "upper limit" in CFM is for the LT5 head, Pete probably knows more than most on the best head porting

what we really need is a billet head for the LT5 with the MY95 port or updated head design

maybe we can talk graham and nelson racing into doing it together

it would be amazing to build a "modern LT5"

looking at what Mercury marine did would be a good start to see how they updated their cyl head and manifold port designs. they might be interested too, who knows

great discussion, let's keep it going

rkreigh

03-27-2014, 01:58 PM

yes for sure carbed and FI motors respond a bit different. the port was beveled until it was enlarged to try and match it, and then it was sharp again so it was "re rounded"

the injectors are above the port, so it's at least similar

the best thing for me is experimenting and learning what theories are proven or prove false

kenny duttweiler said it best, "give the engine what it wants and needs for best power"

that guy has "disproven" a bunch of "theories" just like Jon Kasse

ALZR1

03-27-2014, 03:41 PM

[QUOTE=rkreigh;198869]yes for sure carbed and FI motors respond a bit different. the port was beveled until it was enlarged to try and match it, and then it was sharp again so it was "re rounded"

the injectors are above the port, so it's at least similar

the best thing for me is experimenting and learning what theories are proven or prove false

kenny duttweiler said it best, "give the engine what it wants and needs for best power"

that guy has "disproven" a bunch of "theories" just like Jon Kasse[/QUOTE ]

Sorry going off topic,do you Remember his Grand National.

AL.

rkreigh

03-28-2014, 07:47 AM

sure do. I just sold my turbo buick this year after owning it since 1987

gave that car away. a 10 sec ride for 8k

Paul Workman

03-28-2014, 10:41 AM

[QUOTE=rkreigh;198869]

the best thing for me is experimenting and learning what theories are proven or prove false

AL.

A-men!

(AND, we seem to have a high % of Z drivers up here that aren't afraid to get some aluminum splinters in their fingers!!:))

LGAFF

03-28-2014, 11:04 AM

My takeaway from this is that textbook theory rules all, I mean with solid engineering and following the rules why test things in the real world.....right, right?

http://www.youtube.com/watch?v=9h5twfENvgg

Oh, but that could not have really happened, I mean they followed all the rules!

LGAFF

03-28-2014, 11:09 AM

But I am sure that was a fluke....

http://www.youtube.com/watch?v=tUt-JVuiNEA

oh

LGAFF

03-28-2014, 11:25 AM

This is a good article to read on the new Boss 302 intake....

A few points to take away:

*Flow bench results vs on the car are two different things....
*Real world testing is critical
*Trying things out of the normal is an essential....

http://www.mustangandfords.com/car-reviews/m5lp-1108-2011-ford-mustang-302/

Schrade

03-28-2014, 12:09 PM

the injectors are above the port, so it's at least similar

If the injectors are blowing fuel DIRECTLY into the 'nasty eddies / standing wave', created by the ridge, at the abrupt 36mm-to-32mm juncture, then maybe fuel atomization is increased, over and above the 'normal' level of atomization.

Whereas, if the IH port was tapered, with no turbulence, but total laminar flow, that might explain this exception...

???

O2's MIGHT show this as reduced HC's...

Ideas? Opinions?

XfireZ51

03-28-2014, 02:22 PM

OTOH Chuck you could end up w reversion causing fuel
to drop out of suspension and a loss of velocity. I think about the flaps on the wing of a plane. What happens when it is lowered into the airflow?
So would I port IH and Plenum while not port matching the heads? Sure. Still worth some power. Does it flow better than port matching? You'll need to prove that to me.

LGAFF

03-28-2014, 02:43 PM

*Again important to define port matching:

*port matching to 36mm
*port matching to 31.5mm=33mm(with bevell), which means a much smaller runner tapering from 36-31mm

Schrade

03-28-2014, 03:57 PM

*Again important to define port matching:

*port matching to 36mm
*port matching to 31.5mm=33mm(with bevell), which means a much smaller runner tapering from 36-31mm
Understood.

(neither of these is "bolt it on...", as you refer in the title - right?

OTOH Chuck you could end up w reversion causing fuel
to drop out of suspension and a loss of velocity. I think about the flaps on the wing of a plane. What happens when it is lowered into the airflow?
So would I port IH and Plenum while not port matching the heads? Sure. Still worth some power. Does it flow better than port matching? You'll need to prove that to me.
Fuel dropping out of suspension [vaporization]? I can't see how that could happen, with gasoline vapor pressure (tendency to go from liquid phase, to gaseous phase) as high as it already is. Although of course, it's possible - but it seems IMprobable to me here...

I'm not sure I'm seeing the aileron application here Dom. Lower the flaps, and the NET effect is lift - higher pressure. The lowered flaps BLOCK flow, sort of, when lowered, depending of course on degree of lowering. And higher pressure retards vaporization.

I think with angled furrows, or channels, cut into the 32mm opening, you'd get some spots of LOWER pressure in some spots, as well as higher pressure spots (created by the flaps). And LOWER pressure INCREASES vapor pressure.

...and these angled channels would induce a SINGLE vortical flow...............