EGT - Normal Temp.?

[2369488]

Just bought an '86 930. It has an EGT (Engine Gas Temperature)gage which is wired to two sensors (one in each header). My question is what is the normal operating temperature of the exhaust gas and what is the red line for this temperature in a 930?

thanks,

Steve M.

[Jim2]

I've got a single fine probe located 1" from the flange on cyl 4, digital display in car. I've never been able to get my exhaust gas temp under mid 1600s during track use. On the street I would occasionally see 1600+.

Interestingly, after my efi conversion last year when I hooked up my second set of plugs the EGT dropped to 1590 on track. Other pelicans with twin plug noted the same.

Not sure if there is a red line per sa, but high 1600s or into 1700s is very high I'm told. This would typically indicate a problem with timing or mixture.

These are my findings, not gospel.

Jim

[Craig 930 RS]

I'd check the AFRs first.

[thechiller]

Interesting, does any one know how high exhaust temperature a 930 ca stand and over how long time?

I was testing my 930 today, but i had problems with high exhaust temperature.
In my car i have haltech ems, 3,2 cylinder heads, 3,2 plenum, efi, 964 turbo pistons and cylinders 3.3, a larger turbo that have air up to 600hp.

Car was running at 4000 rpm, boost around 0,8 bar. When running like this the exhaust temperature immediately vent up to over 900C (1700 F) i gave the engine more fuel and it dropped to 880 C (1600 F+) and would not go lower. I tried several times by more fuel (11/1), delay the ignition (8°), etc
Air temp after the intercooler was around 35C (95F)

But exhaust temperature wouldn't go lower, i think this is too high exhaust temperature.
I tried to give the engine so much fuel that it was flames out the end pipes.

What do you say, is this high exhaust temperature ok? what can be done to lower the exhaust temperature?



Cheers
Kjell Robert

[911st]

Barbecue!

[mooney265]

Ok, so I'll be the first to ask: "What is going on behind your car?"

1. A Fork Lift
2. 2 Batteries on the skids
3. A spare tire resting on the engine

I give up?????

[hobieboy]

I think ~1500degF is what most shoot for...

On the street, mine is usually around 1450degF, and it may hit low 1500degF. On track its still around mid 1500degF even after 30min on the track. 1700degF sounds high to me.

[DailyDriven'88]

Originally Posted by mooney265

Ok, so I'll be the first to ask: "What is going on behind your car?"

1. A Fork Lift
2. 2 Batteries on the skids
3. A spare tire resting on the engine

I give up?????

Keep weight on the rear end to prevent the car from coming off the dyno? I believe he did say 600hp.

[DonE]

While dyno'ing my motor on a dedicated engine dyno, we shot for 1675 for best performance at WOT, 12:1 AFR and correct timing. The tuner took NA motors to 1750 for best tune at WOT, etc, etc (these were 12.0:1 CR motors, 42 degrees timing, 12.0:1AFR, 8000 rpm).

[thechiller]

Hi

yes we used the fork lift to give more weight on the rear end, the car started to spin on the dyno when reaching 5500 rpm 300 kW (400 hp).

It was frustrating that the exhaust temperaturee became so high, I didn't dare to advance more to get take out more hp at high rpm. So we tired to run at 3000 rpm using variable load.
I did run the engine too hot and when cooling down on idle i got problem with the crank sensor that became overheated (sensor give signal to ems for spark, etc). New sensor is now ordered.
Next time i will remove the rear bumper and get some more large fans over and under the car's engine area. Now we only had a large fan in the front of the car.

I have never had a exhaust temperature senor on before and i wanted to control the temperaturee when converting to EFI. Sorry now that i didn't look after this temperature when i used CIS for reference.

1500 °F is wanted i agree, but on a air cooled 930 engine what is happening in the real life? what heat can the engine stand in short periods?

Crank sensor


Knock sensor





Cheers
Kjell Robert

[911st]

I am not an expert in EGT and hope you do not mind my two cents worth.

It seems ones temps are going to vary somewhat with the location of the probes, your AFR, timing, outside air temp, and intercooler efficiency. I do not know but I guess having a small turbo hot side might show up in extra heat but do not know if that is the case.

I think I have heard of temps in the range of 1600 to 1650 before but do not recall. If you know your AFR is correct and your timing is solid the resulting EGT I would think becomes your base line and is what it is.

Today with lead free race gas that allows wide band monitoring full time, EGT's become redundant to a degree thought they do add some additional info.

Your cat look great! How about more pictures and a pic of the motor?

[thechiller]

Originally Posted by 911st

I am not an expert in EGT and hope you do not mind my two cents worth.

It seems ones temps are going to vary somewhat with the location of the probes, your AFR, timing, outside air temp, and inter-cooler efficiency. I do not know but I guess having a small turbo hot side might show up in extra heat but do not know if that is the case.

Agree, that might of course be a reason to have high EGT. I know for sure that the turbo including the exhaust turbine is larger than original. It is even bigger than the K27 hyflow turbo from imagine auto that i had last year running on original setup and CIS (this turbo only lasted 3700 miles before starting to leak oil into the turbine). Turbo i use now is an hybrid type from turbonetics, but exhaust turbine is larger. It spins up quite fast already at 2000 rpm i got 0,6 bar boost (4. gear), since my spring is only 0,8 bar the waste-gate opens.

I will check the turbo model.

Thanks

Cheers
Kjell Robert

[911st]

I believe the turbine on a HF is from a K27-7200.

What are you using your car for?

I am an expert but if full boost by about 2200rpm that is very very early. If it is a street car that is probably ok. If it is a track car you are leaving efficiency and HP on the table. You may have a larger turbine wheel by your housing has to small of an AR. For a track turbo you want full boost after 3500RPM I believe.

A bit turbo with that small of a hot side I am surprised you do not see any boost creep and have a hard time holding .8 bar to red line in higher gears.

I have never thought about a smaller turbine w a larger AR housing v a larger wheel with a smaller housing AR. I think I like the later.

[911st]

Sorry, I am not an expert.