I have a Zeitronix EGT and I log EGT in EvoScan. I think sometimes too much info. might be a bad thing because I see my EGTs rising into the mid to upper 800s (celcius) at only 25-26 psi. I see others tuning set-ups like mine to 30 psi on pump and much higher on race gas, and I'm wondering how high people are letting their EGTs get.

I know that E85 is a miracle worker for EGTs, but does plain old race gas lower EGTs if you have a knock free tune? Or are EGTs kept in check due to running leaner and more advanced timing with race gas? Or are these 30+ psi tunes just pushing 1000+ celcius EGTs and somehow holding together because they are only run in short bursts?

Anyhow, I'm concerned about the EGTs getting too high, even if I show no knock or lean AFRs. Seems like if things get too hot, I'm risking damage to pistons or perhaps the turbo itself.

Thanks for any info or suggestions.

 

What are normal EGT temps? If my Evoscan is reading correctly, I consistently see 280 degrees fahrenheit but that doesn't seem right to me. Do Evos gather that data from the front or rear oxygen sensor?

 

There is no stock EGT sensor. You have to have an aftermarket set-up.

 

Anything above 1700 / 1750 F you should start to think about why your EGT's are so high. 1500-1650 F is pretty normal.

That being said, I would also keep an eye on your wideband to make sure your A/F's are good.



-Bink

 

you're thinking too much into it. Exhaust Gas Temperature usually will RISE if you have too much ignition RETARD. Not advance. This causes heat and you'll risk burning up your exhaust valves amongst other issues. If you aren't knocking you should advance your timing. Not only does it make more power but you'll notice cooler EGTs. Just remember since you are on E85 to watch for MBT as its possible to hit it w/out knock on this fuel at high rpms.

 

I'm seeing around 1625F (885C) at 7000-7250 rpm at 23-24 psi with AFR around 11.2 and 17 degrees of timing at that RPM. So that's not unusually high I guess? I'd like to push the boost harder because I don't have any knock issues, but if I do I think the EGTs are going to start pushing 1700F.

When running race gas, do EGTs stay lower? If so, why? Is it because the tune allows more timing, or does the fuel itself lower the EGTs?

I sure wish I had easier access to E85...

 

the only time I looked at egt's was when we got done with a run at Bonneville Salt Flats.


Temperature is essentially out the window, all we cared about was synchronous rise fall and consistency. It was a v8. temps got sort of high when we backed off the timing, but previous post was correct.

Here's the limit I've seen, you can't tune to knock to the point that you are pulling so much timing that it renders the combustion process ineffective. You just can't run that much boost for whatever fuel you're running when you get to that point.

EDIT:

Do you know how to read plugs?
There's so much to this I don't even know where to start.

 

EGT will also go up/down depending on AFR. 13-14.0 will be about the highest and then as it gets leaner it drops as there is insufficient BTU available to make any power or heat. Why people have had FPR lines blow off in the middle of a pull and the engine survives 16:1 @ 35psi. Typically halves the power as well.

Excessively rich will do the same thing (drop EGT) which is why it used to be used to "cure" knock. Since knock threshold is dependent on EGT to an extent (high is more knock prone) it becomes a crazy game of whats good and whats not. This leads to application being very important. Drag engines and turbos will survive 2000+F since they are doing it for 7-9 seconds but that would never work in road racing or rally. Normally 1400* is about the limit there, which is why the boost is lower and the AFRs are richer generally.

Meth injection will help drop EGTs as well as will some fuels. Diesel and E85 are naturally lower EGT fuels, though we cant burn diesel obviously. I would think that some racegas (maybe C16) would have some properties capable of lowering EGT to an extent but they almost always end up being exploited for what they can do and the EGTs are right back.

 

Wow...1400F max for the road course is really low! I think I'd have to run 20 psi or less to be that low on 93 octane. Ugh... My primary application is the road course (other than street driving on weekends).

 

On 93+Alky I see 1620 degrees on a 1/4 mi straight in which I enter in mid 2nd gear and start braking at 138-140. If I want to alter EGT, I cheat using shift points (6spd).