E85 tuning notes

[PeteyTurbo]

I run the same type of timing..With a good afr it refuses to knock above 5000rpms..But before that I keep it minimal just because my car spikes a bit.

Originally Posted by JohnBradley

you can run between 16 and 17:1 cruise on E85 without misfire and run 40* of timing at cruise.

Timing maps will generally look the same at peak boost as a pumpgas map (with more boost to makeup for it), run lower timing numbers to about 5500, ramp harder to 6k and then about 10 more degrees to 8k on a stock turbo...samples would look something like this:



This was for an ETS 57 trim on E85 with stock MAF, Stock cams, 3.5" FMIC, pipes, and 28psi. It made 440whp and like 351 torque on a dynojet that always seems to read low torque (maybe rpm sync?)

[andrewzaragoza]

Originally Posted by JohnBradley

you can run between 16 and 17:1 cruise on E85 without misfire and run 40* of timing at cruise.

with a closed loop afr of 16-17 that should help a lot with fuel economy. e85 is really amazing. time to save and switch.

[JohnBradley]

I forgot to add on the timing, thats without adding in for the EGR dynamic advance tables that we messed with earlier in the year. Stock timing those can add up to 5-6* all on their own in most cruise ranges.

Yeah like rick james said...its a helluva drug

[Tek3Evo]

wow 16-17:1. is that really that safe, that's awesome. what type of EGTs will we see running that lean.

[mrfred]

Originally Posted by Tek3Evo

wow 16-17:1. is that really that safe, that's awesome. what type of EGTs will we see running that lean.

E85 burns much cooler than straight gasoline, and on the lean side of stoich, EGTs will drop (stoich is the point of maximum EGT during cruise).

[Tek3Evo]

So we are really only concerned with knock and misfire from the lean condition during cruise. Great info.

[fixem2]

Anyone figure out the EGR Advance tables on the 96530006?

[andrewzaragoza]

whats the advantage of modifying the egr advance tables?

[mrfred]

Originally Posted by andrewzaragoza

whats the advantage of modifying the egr advance tables?

So far, I haven't seen any changes in performance when tinkering with it.

[JohnBradley]

No there isnt any performance gain, its only working in closed loop when the EGR is functioning from what we learned I thought? Maybe I misunderstood that point back when it first came to light. The advantage is that it adds timing during cruise automatically to help keep the ethanol firing off.

[mrfred]

A few notes:

Fuel economy on my second tank of E85 was 15 mpg which is only a 25% reduction in mileage compared to the 33% higher fuel requirement to hold stoich with E85 compared to gasoline. My third tank is looking to be 15+ mpg. Strange but good.

I've been doing power tuning for the last week now. AFRs are now ~11.8:1 across the rpm range. I'm still in the early stages of tuning, so I'm just working on optimizing timing with my gasoline boost curve. I started by ramping up the timing starting from 5500 rpm. I've been able to add 4 deg of timing at 7000 rpm and still no knock at all. I've picked up an average of about 15 whp at 7000 rpm, but it seems that my last change of +1 deg more timing from 6000-7000 rpm made little or no effect on power in this rpm range. The more I mess with E85, the more I get the feeling that its possible to hit MBT with no knock. I'll post up some logs and timing maps tomorrow.

[PATRICK B.]

I'm soaking this all up like a sponge......nice thread thanks guys

We are getting an e85 station real close to home so i'm thinking of making the switch when it opens in th enext few months

[denver]

Just so Im clear mrfred, you are referring to a/f with e85 on the gas scale? Or have you rescaled your WB for e85?

[razorlab]

Originally Posted by mrfred

I've been able to add 4 deg of timing at 7000 rpm and still no knock at all. I've picked up an average of about 15 whp at 7000 rpm, but it seems that my last change of +1 deg more timing from 6000-7000 rpm made little or no effect on power in this rpm range. The more I mess with E85, the more I get the feeling that its possible to hit MBT with no knock. I'll post up some logs and timing maps tomorrow.

I would imagine you gained more than 15whp from 4* more timing or you have already passed MBT.

I've found, depending on the setup, you can indeed find and pass MBT without knock.

This isn't our fathers pump gas.

[mrfred]

Originally Posted by razorlab

I would imagine you gained more than 15whp from 4* more timing or you have already passed MBT.

I've found, depending on the setup, you can indeed find and pass MBT without knock.

This isn't our fathers pump gas.

I'm beginning to question the value of pushing the AFR up to 12:1 because of this. My guess is that leaner AFRs will promote a faster burn, and it seems that the stuff already burns fast, perhaps making it too fast to make good use of the combustion event. I need to do some reading, but my feel right now is that a little richer might slow the burn and perhaps distribute the combustion event over a wider range of crank angle. This may have to be balanced against the apparent possibility of a rich misfire.

BTW, I got 15.7 mpg on my last tank with standard closed loop 14.7:1. I'm really interested in reenabling my closed loop adjustable AFR patch to see if I can get 16.5 mpg or better.