There is a thread over on performancetrucks on guys running 25-30% e85 and the rest 93 octane. What do you guys think about this and who all has done it? Is there any cons to doing this? I know that you need the fuel system for it which I beleive I have (dual 255's and 80's) and I have my own tuning software so adding to the ve table won't be to difficult to keep the AFRs in line.

So big question is who is mixing it and who thinks it's a good or bad idea?

 

You can mix it, you just have to make sure your ethanol content is the same, or the lambda will change much like it does from winter to summer blends.

I have customers that take E98 and mix it with C16 to make their own E80ish blend.

Nothing wrong with mixing, the anti knock qualities will be less than that of true E85 but it will extend your fuel system further.

Mix away, just test each batch for consistency.

 

Mix it, Ive read that the antiknock effect of anything over E50 is pretty much the same anyway

 

I used to do it when I was running dry nitrous, trapping in the 140's. If your VE table is good I used to just adjust the injector size instaed of the VE table to adjust the fueling up and down.

 

I used to mix it in my dsm with 91. It was good for 35 psi on that without knock. The problem, like said above, is the inconsistency of the blend. I was always having to adjust the tune to compensate for it. I got lazy just one time and broke a ring land.

 

what about if you tune for just 93 but add, say a half tank of e85. would that still protect more against detonation/knock than straight 93. Im not looking for more power, just more protection against detonation

 

You would end up lean. Speaking from a dsm standpoint, I had to add 13% more fuel with the e85 blend to achieve the same afr had I used straight pump gas. Ballpark, straight e85 uses around 23% more fuel per the same afr.

 

why not just run straight e85 ?

 

e85 is 15% reg. petroleum base gas octane unknown but honestly i seen it higher like in the 90's really its labeled that for alcohol tax exemption but mixing more just dilutes it as it seems that's what you want to do but then remember that reg. gas has 10% or so ethanol they say less but i ya we know its not less ethanol is there diluter to make them more $ long story short diluting 93 will hurt your mpg and no gains not even in the pocket if not used in a performance app just my tired late night thought lol

 

It takes a bad *** fuel system to power a 700-900 rwhp E85 car. If you cut it down, to say E30-E50, your fuel system doesnt need to be as robust, because you are talking about 10% more fuel needed, as opposed to 30% more needed. You get 80% of the gain of E85 with only 20%-40% more fuel system.

 

i agree just wasn't sure if it was for a dd or race setup i run e85 and what i had to spend on the pump bigger an lines injectors sometimes i think damn why but at 3.50 a gallon compared to $15 for 112 forget about c16

 

Agreed! Big initial cost but I think it pays for itself pretty fast.

 

a guy at works mate has two tunes, one for e85 and one for our 98 octane pump fuel, went for a spin in it the other night as a passenger, that thing flew and wasn't overly worked although a decent cam and head work but nothing major in the way of fuel system or other mods, anyway he had a gauge that told him the E85 mixture level, it would go from E85-83 and back to 85, didn't get lower or higher than 83-85 mixture, but he also mixes 98 in when he can't get E85 with no real problems except his petrol tune isn't 100% as it was rushed but tuned properly he said he'd have no problems.

only thing i noticed was a slight smell as the windows were down cause it was a nice night, but upgraded heavier duty teflon lines would help stop this yeh?

 

ya I upgraded to teflon it's not as easy to bend (kinks very easy) but assembly is easy and it does keep the smell in the line and not airraiding out

 

I run 25% e85 and 93 in my truck. Seems to work very well. I can run more timing and no KR then with 93. I did add about 6% to my fuel tables in my tune, but 6% could have been easily added with the trims and no tune changes. I get no KR with 9.2:1 comp and 15psi running 19* of timing. Truck just "feels" a lot better on it.

 

most definitely any boost or high compression app running more than straight 93 will help performance (less knock more timing)

 

With 255's and 80's I'd do 750-775rwhp on 2 pumps is all, after that you chance leaning it out. The 80's with enough pressure and either 3 pumps(or 2 with a BAP) will do 850+ rwhp, thats thru an auto. You can use the stock rails too at this level as we've proven in several setups. Just do e85, won't have to worry about mixing it and trying to make sure you get your mix right.