Plenum & IH Pull

[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]

Originally Posted by A26B

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-...llation-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-s...n-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-s...n-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!!

[32valvZ]

Originally Posted by 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.

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]

Originally Posted by 32valvZ

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.

[32valvZ]

Originally Posted by 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.

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

[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..20191114_060235.jpg

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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..Attachment 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?