where should it be around?tuned

 

12 on wideband tuned for gas seems to be the majic number.

 

So what would be getting too lean? I see 12.4-12.5 when it's cooler out with E85, is that a problem?

 

When you lose power or melt valves.

 

when your wot??

 

you would have to try pretty hard to melt valves using e-85.
I have seen EGT around 680C at WOT at 12/1 A/F
I have seen EGT around 720C at WOT at 12.9 A/F

I am truly amazed at low EGT from E85. I read EGT drops about 200C from gas. I wouldnt have believed it with out seeing it myself. I would say it runs 100-150C cooler than gas.

low EGT = happy engine

 

Your probe is likely a high mass, slow reacting probe.

Try another probe because I do not believe yours is accurate or you have it in an area downstream that is cooler than an inch or so from the exhaust port.

We have tons of datalogs of EGT and know that exceeding 900*C is not very difficult and it does not take an extremely lean mixture to achieve it.

 

Its TRE fast acting probe (zeitronics) . its in the middle of longest runner of evo 10 mani. reads about 75 lower than typical install ( 2 inch from head). direct back to back switch from 93 to e85 yielded ~125 cooler EGT. if you are getting same EGT as gas one of us is doing something wrong. if its me than I have higher power to look forward to.

also just some part throttle observations. tune lean for gas mileage. same car same setup.
93 octane cruised at 750c. 16.5 A/F
E85 cruises at 640C. 18 A/F

I am have always tuned with EGT. very helpful in my experience.

 

This is a current model probe from zeitronix. I do not believe what you are using is the same probe.

We can easily see 850-900*c with this probe on E85

[IMG][/IMG]

 

so in the 12's lol kinda went off topic

 

It depends on Ethanol content as to how lean u can get away with... More Ethanol content the leaner you can run it. I try to shoot for around 12.0 to mid 12s with the E85 we get around here. Some have to run it 12.0 to higher 11s... But if I try and run the E85 we get in this area in the mid 11s then I cant get away from false knock as it will knock like mad on a stock ECU until i lean it out some "12.0-12.5" and then it picks up quite a bit of power and will accept timing advance! I have tuned MANY MANY EVOs from AEM to stock ECU setups. I have been tuning with E85 for id say the better part of a year day in and day out on my car and others.... and you basically just have to go off what the car is telling you as theres really no set in stone answer here. But 12.0 i would say is the middle of the road. I hope this helps some...

 

I've seen the same type of spread from gas on multiple cars and Mike has seen the same on our Time Attack Subaru. Which also has 4 EGT's, one per runner now so we should be getting even better data.

E85 produces lower EGT's, I've seen it for over a year with E85 in multiple uses (track, street, drag)

I can imagine if I just had data from one shop car that just recently switched to E85, it might be biased one way or the other.

- Bryan

 

Unlike some others, we actually have datalogs proving our information to back up our fingers at the keyboard.

We have data from multiple Evo's supporting our information, as always.

We are also aware that 94AWDCoupe runs 10's AFR which is why his EGT is so cold.

 

I'm on a gt35r stock block on 1000cc injectors on 26psi on e85, it leans out to 12.6 sometimes and it seems pretty happy with no knock at all.... its all in your tuner man...

 

That's my limited experience as well. When I was briefly on about 60% ethanol (read from my eth content gauge), I ran the same fuel and timing maps as my 74% ethanol tune, and the car was quite happy with the mid 11's AFR that the greater amount of gasoline caused. No knock, great power.


94AWDCoupe's post indicatesthe EGTs were obtained with AFRs of either 12.0:1 or 12.9:1.