Higher EGTs after installing IGN-1A coils - Still Okay?
 

I've done some searching but I haven't really found anything yet that seemed to give me the answer I'm looking for.

I recently installed the IGN-1A coils and noticed that my EGTs seem to be higher than previously. I'm still working on my tuning and am currently only boosting to ~7.5psi since I'm learning as I go here. I need to get out and log some actual data, but in general this is what I'm seeing:

------------------------Front EGT------Rear EGT--------AFR
At idle--------------------850------------900-----------12.1
Cruising ~80mph------1450-----------1550--------12.5-13.0

Do you guys think the cruising EGTs are too high? I would suspect that they are...

As I said before, I am running the IGN-1A coils. The rest of the applicable mods are as follows:
Garrett T04Z turbo
850/1680 injectors
NGK R7420 plugs, 10.5 heat range

Since my AFR's seem to be acceptable while cruising, is it a timing issue? Do I need to pull some timing out of the IGL settings, IGT settings, both, or ???

Any suggestions are greatly appreciated.

-Brian

Idle and cruise EGT are not important.
You have to think in terms of heat vs. temp, and mass flow of the hot gases.

Low mass flow at idle and cruise means high temps are easily dissipated.

It's not a concern for the life of the turbo?

What is the timing running at while you're cruising at 80? It's running fat. That, combined with conservative timing, will create high EGT.

I believe it's about 32-35 degrees on both the leading and trailing if I'm reading my maps correctly. Admittedly, I'm still learning this part of the tuning process, and I am not real confident in my abilities. Unfortunately the weather here is too crappy right now to get her out of the garage to log some data so I can look at it while its actually cruising. With any luck, it will warm up by the weekend and I'll get some logs to post.

It was a beautiful day in Colorado today so I got her out and went for a spin and logged some data. AFR on average (cruising at 80mph) was around 13.2-13.6.

Front EGT was ~1350-1400
Rear EGT was ~1480-1520
IGL & IGT was 35-37 degrees (no split in vacuum)

I've attached my log from the cruise data @ 80mph as well as a 3rd gear pull while boosting 0.5bar.

Any good advice is very much appreciated.

Regards,

Brian

https://www.rx7club.com/attachment.p...1&d=1367028984

Steady state cruising looks ok to me. I don't see any obvious signs of knock activity. You already listed your exhaust temperatures. Are they too hot? If it's not knocking, who's to say whether they are too hot or not? We don't know what the manifold and turbo can hold up to over time. I would still lean it into the 14's at least under cruising.

https://www.rx7club.com/attachment.p...1&d=1367028984

In your log of boosting in 3rd gear, you can see the engine initially going to a richer mixture, especially in the more knock-prone areas. That's helping suppress a rise in exhaust temps. Once AFR makes leans out, and rpms increase, your exhaust temps rise. This is expected behavior. Knock reading looks fine.


The normal approaches and tradeoffs apply here. Advance timing and you might lower the exhaust temps, at the risk of knock. Richen the mixture and you might lower the exhaust temps, at the risk of wasting fuel, losing engine output, and possibly increasing carbon deposits.

Thanks arghx, that makes me feel a little better. I think I'll play with the timing a little and see if it brings the temps down any while keeping an eye on knock.

I have been searching all morning and I can't find any information on the max temp for the Garrett T04Z anywhere. Does anyone know where I can find that info? I can't find any information at all on Garrett's site for the T04Z.