Plenum & IH Pull

[32valvZ]

Took my last drive yesterday ahead of some bad weather today. Figured Id finally break down and pull the plenum and injector housings to send off to Pete for porting. Everything went ok except a couple of broken hard vacuum lines.... AND I found the map sensor rubber hose ends are pretty well cashed out. Not sure if I can just use a rubber line for that or not... In the mean time I pulled the coils and starter (replaced in 2016 by p.o.) for some valley cleaning. Also pulled the alternator and I think Im going to replace it with one of Jerrys units. Also going to send my FPR out to Phil for a rebuild while its all apart.

Any general suggestions are welcome

Just a shot of before and after cleaning..

[32valvZ]

Had another thought.... the injectors were replaced in 2016. Do I need to replace the o rings again?

[Jagdpanzer]

If not damaged, clean them up and use again.


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[billschroeder5842]

Had another thought.... the injectors were replaced in 2016. Do I need to replace the o rings again?

You are probably OK, but if it were me, I'd put new O rings. My OCD would not let me re use them as they are cheap and easy; everything is apart any way.

[Ccmano]

Had another thought.... the injectors were replaced in 2016. Do I need to replace the o rings again?

No! Unless you damage them. As long as they’re soft there is no issue.
H
:cheers:

[32valvZ]

No! Unless you damage them. As long as they’re soft there is no issue.
H
:cheers:

Yea, they feel soft and there was almost no dirt or soot on the tips of the injectors. Thanks Hans!

[32valvZ]

Somethin' else just came to mind... will I need any changes to the prom due to the porting that Pete is doing? :confused:

[Ccmano]

Somethin' else just came to mind... will I need any changes to the prom due to the porting that Pete is doing? :confused:

The stock eprom runs rich to begin with. So it’s not absolutely necessary. However. If you want to max the power gain a Haibeck chip tune for those mods is great. Better yet a custom tune will extract the maximum out of the mods.
H
:cheers:

[A26B]

Had another thought.... the injectors were replaced in 2016. Do I need to replace the o rings again?

As stated in other answers, just make sure none of them are cut, lube with motor oil & reuse.

However, new injector sets do not come with the o-rings for the lower seal on the primary injectors, used on 90~92 models. There are 8 o-rings and they are located in a recess groove in the injector housing. Who knows whether these were replaced when new injectors were installed. See it here https://www.jerrysgaskets.com/lower-primary-injector-seal-installation-guide/

I imagine we probably provide most of these o-rings, which makes them easier to identify. Buna-N is black & Viton is brown. If you see a black o-ring inside the primary injector hole, in the Injector Housing, it is most likely Buna-N. We recommend replacement of the Buna-N o-rings with Viton o-rings for use with ethanol blended gasoline. The PN is 10067600-V. Here's the link https://www.jerrysgaskets.com/seal-set-fuel-injector-lower-primary-viton-90-92-7-5d8/

The remaining o-ring seals in the engine fuel system are in the Fuel Feed & Return Block and on the fuel pipes between the Fuel Rails & Regulator. For one set of Viton o-rings, use PN 14104675-9V, https://www.jerrysgaskets.com/seal-set-fuel-pipes-to-rails-regulator-viton-90-95-7-5d8/

[32valvZ]

The stock eprom runs rich to begin with. So it’s not absolutely necessary. However. If you want to max the power gain a Haibeck chip tune for those mods is great. Better yet a custom tune will extract the maximum out of the mods.
H
:cheers:

Prom isnt stock exactly... its already been re calibrated for headers and exhaust by Mark... so will I need to send it back to him again?

[wutanec]

I am doing the same thing at the moment for the first time! Mine is not even near as clean as yours though. Makes me quite embarassed actually haha.

[32valvZ]

As stated in other answers, just make sure none of them are cut, lube with motor oil & reuse.

However, new injector sets do not come with the o-rings for the lower seal on the primary injectors, used on 90~92 models. There are 8 o-rings and they are located in a recess groove in the injector housing. Who knows whether these were replaced when new injectors were installed. See it here https://www.jerrysgaskets.com/lower-primary-injector-seal-installation-guide/

I imagine we probably provide most of these o-rings, which makes them easier to identify. Buna-N is black & Viton is brown. If you see a black o-ring inside the primary injector hole, in the Injector Housing, it is most likely Buna-N. We recommend replacement of the Buna-N o-rings with Viton o-rings for use with ethanol blended gasoline. The PN is 10067600-V. Here's the link https://www.jerrysgaskets.com/seal-set-fuel-injector-lower-primary-viton-90-92-7-5d8/

The remaining o-ring seals in the engine fuel system are in the Fuel Feed & Return Block and on the fuel pipes between the Fuel Rails & Regulator. For one set of Viton o-rings, use PN 14104675-9V, https://www.jerrysgaskets.com/seal-set-fuel-pipes-to-rails-regulator-viton-90-95-7-5d8/

Thank you Jerry. I have a full cart and will be placing my order today or tomorrow... Sure is nice having you for an almost one stop shop!! :handshak:

[32valvZ]

I am doing the same thing at the moment for the first time! Mine is not even near as clean as yours though. Makes me quite embarassed actually haha.

Well, to be fair, mine was cleaned up in 2016 by the previous owner during a starter and injector procedure. So my clean up this time around was fairly easy.

[RussMcB]

Prom isnt stock exactly... its already been re calibrated for headers and exhaust by Mark... so will I need to send it back to him again?If it were me I'd wait until you can put it all back together, take it to a local chassis dyno and have them record AFR. Then you can see if the tune needs tweaking. The AFR recording will tell Marc pretty much exactly what needs to be changed. Conversely, if you send it to him now, he'll just be able to give it a Best Guess tune, which might be fine but not optimal.

[Paul Workman]

Porting the top end netted me about 70-75 rwhp gain. That is pretty significant - too much to NOT have (Marc) re-calibrate the chip. With that much more air, the last thing you want it to be too LEAN at WOT! And, that said, passing that LT5 through a dyno session with a tuner like Marc or Pete or Dominic is how to wring out the full porting potential.

I can tell you from experience, you'll love it! That motor will behave like a different car. In retrospect, knowing what we know now (and seeing the plenum of the gen-III LT5 that never was), why did Lotus go so conservative in the first place is a valid question.:confused:

[32valvZ]

Porting the top end netted me about 70-75 rwhp gain. That is pretty significant - too much to NOT have (Marc) re-calibrate the chip. With that much more air, the last thing you want it to be too LEAN at WOT! And, that said, passing that LT5 through a dyno session with a tuner like Marc or Pete or Dominic is how to wring out the full porting potential.

I can tell you from experience, you'll love it! That motor will behave like a different car. In retrospect, knowing what we know now (and seeing the plenum of the gen-III LT5 that never was), why did Lotus go so conservative in the first place is a valid question.:confused:

Dang 70-75 hp is great! Thats with head porting also right? Im just doing the plenum and IH's. I emailed Marc about the PROM re cal, and he said if the porting is done correctly and well done, I can expect 30-35 hp gains.

Unfortunately, I dont have a tuner very close to me. Ill look into getting it on a dyno, but I dont have anyone close to me.

Would I be able to get the AFR info from a Snap On 2500 scanner? I have one with cartridges.

[Ccmano]

Tuning is not as simple as getting an AFR reading. An AFR reading at idle is almost meaningless. In a nut shell there are two important aspects to tuning. For our cars there is open loop tuning and closed loop tuning. Closed loop tuning addresses fuel mixture in every parameter of every day driving except wide open throttle. It’s complex and requires data logging the driving of a car over hundreds of miles/conditions and doing multiple adjustments of the VE table, amongst other things. It’s probably the most overlooked aspect of performance tuning.

What most people understand as “tuning” is actually open loop tuning or wide open throttle tuning. This is where AFR comes in, because with wide open throttle the system goes into open loop and operates purely off the chip settings not the sensors (sort of). This is done on the Dyno or open road. Run at WOT and watch the AFR readings. The idea being to stay around 13/1 AFR through most of the RPM range all the way to redline. This is also where we see those max hp numbers we all talk about after a “tune”. Tuners will tune the AFR to max HP which may be +/- 13/1 AFR.

Engines that are only tuned to AFR and HP in open loop may actually be considerably out of tune in every other aspect of driving.

As I said that’s “in a nut shell” there is lot more to it and it varies even more with more modern engines and electronic control systems. Best to let the pros do it.
H
:cheers:

[32valvZ]

Ill have to go with Marcs recalibration at this point. When he did the re cal for the headers and exhaust, there was noticeable improvement. I trust it will be the same in this case.

[jss06c6]

Are you port matching the primaries on the heads as well? If not, your gains will be limited since the primary intake port on the head will be much smaller than your freshly ported Injector Housing primary runner.. see pic atrached..11052

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[32valvZ]

[QUOTE=jss06c6;302775]Are you port matching the primaries on the heads as well? If not, your gains will be limited since the primary intake port on the head will be much smaller than your freshly ported Injector Housing primary runner.. see pic atrached..11052


No, I'm not doing the heads. What you say makes sense. How "limited" will I be? Ive heard/read my gains would be anywhere from 20-35 hp Im guessing Pauls gains of 70-75 hp was because he had his heads ported as well?

[Paul Workman]

[QUOTE=jss06c6;302775] Im guessing Pauls gains of 70-75 hp was because he had his heads ported as well?

Below are two Dynojet "before and after" my porting and then final tuning by Marc Haibeck, prior to some later minor improvements to the IH/Head junction.

I don't have a Dyno graph of my motor with only top end* porting. I wish I did**. Instead, I have to derive an estimate of rwhp by subtracting the known gain achieved by others after the heads too were ported (that being between 25-35 rwhp) to approximate what my top end only porting was.

The Dyno graphs show the before (stock) peak starting point, and peak after that establishes the full porting (and cam phasing) improvement - the bulk of improvements up to that time: starting at 336 avg rwhp and ending with 432 rwhp with HEAD porting included. So, est. of "400" rwhp before porting the heads is reasonably accurate, in my estimation.

Dyno graphs and HP numbers and estimates are popular for most - salesmen especially. But, where rubber meets the road means more to me than HP bragging rights, and actual force at the wheels, i.e., TORQUE over the entire rpm range, or POWER UNDER THE CURVE gives a better indication of the worth of any modifications - to me, anyway.

*TOP END included the plenum and IH brought out to 36mm, and later 37.5mm

** Port matching into the heads was a lot more than just matching the junction diameters only.

Instead, I took to heart the recommendations of many knowledgeable people and good ol' physics and extended the port matching in the heads from the IH junction tapering all the way down to the valve bosses (to achieve a taper that was no more than ~ 2% (think of a the velocity stack design on a Webber single bore carburetor)

Unfortunately, I didn't dyno the motor before proceeding to finish porting the heads too, because the "seat of the pants" improvement after finishing the heads was very disappointing, compared to the improvement over the top-end only achievement. And, based on experience and study witnessed by others too with even minor improvements to porting, I'm certain doing the long taper has significant benefit over merely grinding the opening of the smaller runner to match and little more. And too, I suspect the longer taper mitigates (somewhat) any anticipated gains from pulling the heads to complete the tunnels. (I'll put it this way: Given the same circumsances as I had at the time, I don't think bothering to port the heads justifies the trouble or expense UNLESS the heads have to come off for some other mod or reason [my reason was a burnt valve]).

[jss06c6]

[QUOTE=jss06c6;302775]Are you port matching the primaries on the heads as well? If not, your gains will be limited since the primary intake port on the head will be much smaller than your freshly ported Injector Housing primary runner.. see pic atrached..11052


No, I'm not doing the heads. What you say makes sense. How "limited" will I be? Ive heard/read my gains would be anywhere from 20-35 hp Im guessing Pauls gains of 70-75 hp was because he had his heads ported as well?Paul, thanks for the detailed summary!

From a fluid mechanics perspective, sharp upsets, especially when fluid flow direction is such that a sharp reduction in diameter is encountered, causes significant turbulence and reduces laminar flow velocity (volume reduction). So, having a beautifully ported plenum and injector housing will deliver reduced volume by presenting the fluid stream with a sharp restriction like the stock primary runner on the head.

Gasses can be compressed, so a smooth reduction in crossection, especially when extended over a reasonable distance, allows most of the fluid volume (air) to "get through". The fluid is moving at a higher velocity..

I've not done a top end port without port matching the heads, so I can't provide actual hp/tq numbers or cfm data. I do know that my experience before and after top end port with port matched primaries, headers and tune yields a consistent 50 rwhp on our Mustang Dyno. Headers and tune deliver about 20 rwhp, port another 30 rwhp. This is with stock DM Flywheel as well as stock diff ratio.

Using 15% loss, that would be 24 crank hp for headers and tune and another 35 crank hp for top end port and tune. Total engine hp gain 59 hp.11214

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[Ccmano]

If I remember correctly,LGAFF, one of the long time members had several ZR-1s and did porting with and without port matching to the heads. He found the difference to be negligible. +-~5hp or something like that. Let’s see if he chimes in on the one.
H
:cheers:

[32valvZ]

Well, Im sure there are a few ponies left on the table by not port matching the heads... It does make sense that necking down a passageway will interrupt flow of fluid or air... similar to exhaust.... BUT, Im pretty happy with the results of only the plenum and IH's. Give me some time... Ill catch up!!:p

[Paul Workman]

[/ATTACH]If I remember correctly,LGAFF, one of the long time members had several ZR-1s and did porting with and without port matching to the heads. He found the difference to be negligible. +-~5hp or something like that. Let’s see if he chimes in on the one.
H
:cheers:

Yes, I'm aware. But, what exactly did his "port matching" amount to? Was it just the expedient removal of the sharp angle and reduction, tapering only 1/4 to 1/2" as is so often seen (even in factory port matching)? Or, does he have data on the long (laminar-flow) porting? It would be very interesting to see.

This is a conceptual picture of a carbide porting tool I sent to a tool and die maker (10 years ago) that would facilitate the rapid porting matching of the head with respect to something closer to ideal laminar flow. The idea was to not only expedite the porting process, but to also mitigate the chance of breaching into either the coolant or oil areas. (But, since I had already completely ported my heads by that time, the couple hundred bucks for a tool no longer needed (by me) ended my pursuit of the bit. And, too, there was the question of being able to secure/position and power the bit if the head was not first removed from the motor - a step unnecessary if only doing a "top-end" port job.)

[Paul Workman]

And, another diagram derived via trial and (expensive!) errors!:p (in case anyone is interested...)

[Paul Workman]

AND....

One more, as long as we're on the subject of porting (yes?), supporting the LONG TAPER theory, one of the examples is this set of Webber VELOCITY STACKS mounted on single throat carbs. Check it out. :)