Abnormal EGT

[cactus2929]

Hello, I've been having a concern over the last 2-3weeks that has left me still without an answer.

I'm turbochaged(with Begi RRFPR and AFM tuning) and recently installed a Greddy EGT gauge to my setup with the EGT sensor in turbo manifold 2" from cylinder 6.
When the car has warmed up, at idle my EGT is 500C-600C(AFR at idle is 14.5).
At partial throttle(not boosting) my EGT goes up to 700C-750C, then I ease up off the gas. MY AFR's at partial throttle are between 13-14.5, nothing lean.
I heard that anything over 800C will start melting stuff, so I havent boosted the car since I put in the EGT gauge.
I use 90 octane gas, so I put in a bottle of octane booster but no improvement in EGT.

Please help me solve this problem guys.

[np75]

It is rather useless trying to get make sense out of EGT readings by themselves. EGT does not relate directly enough with AF ratio to be a real good tuning tool by itself. You can't say that this temperature equates to this AF ratio on all engines. The following link has some good info about EGT.

http://www.sdsefi.com/techegt.htm

With that said, the temps you are seeing don't look abnormal to me. My car ( not an E30) makes roughly comparable temps. Yours is slightly higher than mine at part throttle cruise, and I would have liked to get them higher untill I got a wide band oxygen sensor and realised that I was at 14-15:1. At idle on my car the temp usually drops off the gauge, I think that this is due to the very small volume of exhaust gas created (compared to under load) having it's temp sapped away by the piston, valve, combustion chamber, port, etc. If you have a wideband O2 sensor I would follow that rather than the EGT(but do keep an eye on it).

I would not expect that octane booster would have much of an effect on your EGT readings, not sure what your going for there.

[cactus2929]

It is rather useless trying to get make sense out of EGT readings by themselves. EGT does not relate directly enough with AF ratio to be a real good tuning tool by itself. You can't say that this temperature equates to this AF ratio on all engines. The following link has some good info about EGT.

http://www.sdsefi.com/techegt.htm

With that said, the temps you are seeing don't look abnormal to me. My car ( not an E30) makes roughly comparable temps. Yours is slightly higher than mine at part throttle cruise, and I would have liked to get them higher untill I got a wide band oxygen sensor and realised that I was at 14-15:1. At idle on my car the temp usually drops off the gauge, I think that this is due to the very small volume of exhaust gas created (compared to under load) having it's temp sapped away by the piston, valve, combustion chamber, port, etc. If you have a wideband O2 sensor I would follow that rather than the EGT(but do keep an eye on it).

I would not expect that octane booster would have much of an effect on your EGT readings, not sure what your going for there.

Thanks for your reply and the link.
After getting your sugesstion, and a couple others from E30tech.com I've decided to recalibrate my AFR gauge(again) and install a new EGT gauge to rule out instrument error.

I was advised that a bad tank of low octane gas could be a cause of my problem, that was why I added the octane boster.

The red zone on my Greddy EGT gauge starts at 900C, do you think it's safe to drive the car between 800-900C for any brief period like 5 mins?

Thanks so far.