Goblin

I've brought this up before, but I'm gonna bring it up again now that some stuff has changed. There's doesn't seem to be that much non-performance/non=WOT EGT or timing information around, so...


My brand new EGT probe (the old one burned itself to a cinder) is now mounted in my headers (stock engine, T-78 kit and etc.).

Idle I see about 600C, and cruise is 800C.

Which seems overly hot to me. A/F is reasonable, according to the O2 sensor (I know, I know. I'm waiting on a connector for my wideband...).

Increasing the idle timing to 28/20 degrees (from 18/10) drops about 50C off the temps.

For cruise, going to 42/32 (from 32/20) had the same effect.

How much advance is too much for idle or cruise? How hot is too hot?

Eric Michel

Those EGT values are fine, the only concern regarding EGT is under boost. I have seen up to 900C on my cruise EGT's, I have dual EGT's (one for each rotor) about 4" from the exhaust port. For some reason the front rotor has always run hotter on my car, and guess what, every time the motor pops it's always the front rotor, go figure. I have a wideband permenantly installed, I run 14's at idle and cruise. You can add fuel or screw up your timing to have a less efficient combustion (run rich) but why? If you run rich at idle and cruise your oil will be contaminated, your plugs will foul and carbon deposits will build up quickly in the motor. Under boost you need to run rich in order to cool the chamber and prevent pre-ignition but at idle and cruise that is not an issue. You want to have just enough fuel at idle and cruise to keep the engine from surging/hesitating.
Before you ask, I run high 11's (11.8-11.9) to low 12's (12.1-12.2) under boost, 11's for higher (14-17PSI) and 12's for low boost (10-12PSI). Under boost I like to see the EGT's stay below 920C on pump gas, 116 oct your cool up to 1000C. Keep in mind if your measuring after the turbo or further down the manifold you temps may be lower, for example if your measuring after the turbo you can subtract about 100C from the values I just mentioned.
This information is based on experience with my car and feedback from Chris and Ari at Rotary Performance (Garland TX), they indicated these values are what they normally see on properly tunned cars.
Yes rotaries run a lot hotter than a comparable 4cycle piston engine, that's just the way it is, deal with it. This is why I highly recomend a wet center turbo and synthetic oil.

Hope this what you were looking for,

Eric

RETed

What kinda EGT?
I've got a 60mm GReddy P/H unit right now, but it's mounted in the stock '87 FC turbo manifold.

480C idle
800C-820C cruise, closed-loop

I used to run a 52mm GReddy with the probe in the downpipe about 2" away from the turbo dischrage...
480C idle
780C-800Ccruise, closed loop



-Ted

Goblin

It's the GReddy guage, not the peak hold one, though, in an FD.

I guess before, when the car was still twins, the probe was in the DP (didn't want to deal with a tapped manifold), and the switch over to it being in the headers just makes it look so much hotter than it was, so I was freaking out. Combine that with the old probe (about three years, I guess) melting, and I figured something must be wrong.

Guess I'll pull some of that timing back out.


Thanks for the information, guys.

Ryde _Or_Die

You have stock headers on your car?

fast13b

Woah. I have the Greddy EGT gauge. At idle the needle just barely comes off the bottom. On the freeway it runs 450-600 ish. It used to run in the 850-1000 range with my old suck maps. At idle my timing is 0 to 2 before. I know it runs rich but geez... My O2 sensor reads around 900-1000 mV. If it gets too much below the low 800's the car won't run. It also runs like *** with the closed loop on... Strange popping noises from the motor. ???