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Discussion Starter · #1 ·
Just picked up some from the local station a few days ago. I have one of the quickfuel testers that you mix water and ethanol in and it separates the water so you can get an idea of the percentage.

In the summer it checks dead on 85%. I just picked up some fuel, and the blend for this one is at 75% since it is colder.

What changes need to be made from different blends on the a/f or is it not really noticeable performance difference with no change?

Do I need to take out some extra timing since there is more gas in it?

Last year, the station had 85% all year so I didn't have to do anything!

Thanks
 

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Youll have to lean it out some since there is more gas than ethanol in the mix. The stoich point of the mixture will change which changes overall AFR. If your banking on cooling properties of the ethanol for intercooling I would pull some timing from it.

Regular E85 takes about 30-35% more fuel roughly than a leaded racegas to obtain the same AFR. The two stoich points are 14.7 for leaded racegas vs 9.8 for E85 respectively.
 

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Discussion Starter · #3 ·
Last time out the a/f was 10.7 (on the gas scale) and total timing going down track was 22deg. The car is non intercooled, so I am planning to run 20deg total and see what the a/f does.

On the street with a test hit, it seems the a/f was at 10.2, but it started spinning pretty quick so it may not have been a good reading.
 

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Discussion Starter · #5 ·
No timing marks on the plug straps, just looks like it is starting to get hot on the end. NGK's -9's. They were not fresh plugs with one pull, but were run for several passes. Color looked like a gas plug with a good bit of tan on the center porcilin, but not real dark. Little sooty on the threads.

Time before this the a/f was at 11.2 and the plugs were super clean with still not much timing mark, but I got a little nervous since I had had some gasket issues in the past so I fattened it up a little.
 

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I run 11.2-4:1 all summer in my DD S10 with a good 85% blend. In the winter when it drops to 70% my AFR will be right at 10.5-10.7, I will leave it like that for weeks if I am too busy to make a change to the tune. 20k miles a year in this slug no problems.

Dave runs his GTO on the same E85 tune with no troubles too, 11.5 at the leanest and 10.7 at the richest according to him. No troubles at 19psi for him, 4040lbs 142mph.
 

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Discussion Starter · #7 ·
I run 11.2-4:1 all summer in my DD S10 with a good 85% blend. In the winter when it drops to 70% my AFR will be right at 10.5-10.7, I will leave it like that for weeks if I am too busy to make a change to the tune. 20k miles a year in this slug no problems.

Dave runs his GTO on the same E85 tune with no troubles too, 11.5 at the leanest and 10.7 at the richest according to him. No troubles at 19psi for him, 4040lbs 142mph.
So you guys don't do anything to the timing?

Does the performance stay pretty consistant?
 

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No I keep the timing a little conservative because both of those vehicles are street cars. The GTO made 825 to the tires and I keep the timing below 18*. I am sure it would make power with more timing but we choose not to got there.
 

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Discussion Starter · #11 ·
Ok, took the car out this weekend. With the same jetting and timing, the a/f was at 10.2, so I started leaning it out some and did manage to get it to 10.4 when we ran out of time. So it looks like the blend change got it about a 1/2 point lower.
 

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Can you correct the difference in the blends by adding more gas or Ethanol?
 

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You can buy a drum of E98 and just add the amount of that to whatever is in your tank to bring it back to E85. Just don't fill your tank all the way up so you can fit in the E98 to bring it back in spec. They also sell real time purity gauges now that show you what's in your tank at all times. I'm not sure, but some may even be able to tie in the computer and adjust your tune automatically.
 

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Man ya'll run some fat a/f ratios! I run 12.8 a/f on one system, 12.3 a/f on two...and still slowly leaning that one out! I do run straight ethanol though.
 
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