Ported top end: Port Match or bolt it on...

[LGAFF]

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]

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]

Originally Posted by LGAFF

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]

Originally Posted by Schrade

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 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).

[XfireZ51]

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]

Originally Posted by XfireZ51

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]

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]

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...

[Paul Workman]

Originally Posted by LGAFF

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]

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