I've seen several E85 threads in the last few days pop up, but all speak about using a carb. My 305 TBI will likely get replaced in the not too distant future, and I've still been debating between staying TBI or going to a carb. (It will probably get upgraded to a 350) Can you make TBI work with E85 as well?

E85 is corrosive. would require replacement of fuel system with parts that can handle that. Other than the higher octane that E85 affords what are the advantages?

The biggest advantage to E85 is that it doesn't cost $4.15 a gallon right now. It would also be sort of cool, since I'm surrounded by farmland in IL, to say that I'm supporting local farmers and such. Not sure there's a performance advantage to it, thats a debate that would be far above my head. I'm just curious right now as to if there is a TBI system available that would accommodate it.

search E85 on this forum and corvetteforum. I think the advantage is supports higher compression and or higher boost.

yeah, I've seen some of that stuff, but still haven't seen anything applied to TBI yet, its all applied to carbs, and I think I saw maybe one TPI thread.

I think carbs have same issues with corrosiveness. something tells me the E85 crowd is using their cars as drag racers only. to convert our cars may cost a more than it is worth. Granted gas is over $4. I too am in corn country and they sell E85 central WI. Will check out price this weekend.

Yeah, carbs do, but I've read that while a bit expensive (around $750-800) you can buy a carb that is E85 ready. I'm beginning to assume that such a system does not exist for TBI, especially if its only the drag racing crowd interested in running that fuel.

E85 has the advantage of being a higher octane fuel, but it has a lower energy density on a per mass basis. This means having to run more fuel (volume) for each unit of air through the engine = more capacity required out of the injectors/pump. I haven't run any calcs, but I'd assume, on a stock engine, that the stock injectors and stock fuel pump can handle the additional requirements.

As far as getting more performance out of the LO3, I can only speculate, but I doubt it will happen with a 9.3:1 compression ratio. If you run E85 you'll have to mess with the injector constant (BPW constant), change the AFR, up the fuel pressure, or remap the VE/PE tables; there are many ways to tackle it, but it will most likely require a combo of a few of them. You'll be able to run more timing because of the increase in octane, but, once again, it may not make any more power. Last I checked (a while ago) people were concerned with the ethanol eating rubber gaskets, but some I've found some people have been having luck with the existing fuel components.

Check with Synapsis and five7kid who have both done conversions and next time do a search rather than saying "I don't know" back and forth for 6 replies lol

I'm not looking to modify the L03 I have. As I said, the L03 is gonna need retired before long, and I'm looking at what motor will find its way between the fenders. God knows if I even look at my current motor wrong, it'll simply dissolve.

As for the "I don't knows" I'm trying to steer this thread away from being another E85 debate. I can certainly PM guys who have used it or modded their cars for the pro's and con's on that, or i can search other threads. I'm just trying to keep the TBI specific question on the table, as I haven't seen it addressed before.

I think it's definitely do-able. You'll have to make quite a few changes in the ECM tune because stoichiometric AFR for gasoline is 14.7:1 while E85 I think would be around 9.75:1 so you need a much richer mix, and everything in the ECM concerning that needs to be increased (BPC, AE, Hiway mode, etc.). You'll also need a lot more fuel flow which most likely means bigger injectors or higher fuel pressure.

As far as prices go, unless the E85 price is much much cheaper than gasoline it isn't worth it IMHO. Your gas mileage will go down quite a bit using E85 so you'll just be filling up more often for a slightly lower price.

Running E85 on a TBI system is straight forward. Should replace the injectors with larger ones, or increase the fuel pressure. E85 requires more fuel then gasoline. This is why there are E85 carb's available. The internal passages need to be enlarged.

It is then a matter of changing the AFR values in the calibration. Along with increasing the AE PW's. Look for a post by SR-71 on the DIY_PROM board. He put together and posted a spread sheet to do the AFR calulations.

The spark advance requirements won't change much. Ethanol burns faster then gasoline. But the latent heat of vaporization is higher with ethanol, so that slows it back down. But does allow it to pack a denser charge.

If you build an engine specifically for E85 then go high compression. This is where E85 shines. Starting at 11:1 through 20:1 has been used for a SI compressions ratio.

RBob.

Thanks guys, sounds like its actually not too bad. It'd actually be really cool to have a streetable motor that made reasonable power on E85.

My first post on this site.

I was told that FlexTek has a kit that is universal for TBI, TPI, and MPI.

I have also been looking and doing research on converting to E85 and everything that I see has to do with the injector pulsing for a longer period of time allowing more fuel to go to the engine. My 305 TBI already runs rich due to me upping my pressure regulator so I have been running 1/4 tanks for 3 weeks (Hope I do screw things up).

I have upgraded to stainless fuel lines but have done nothing about the O rings or anything else on the car. After watching a video clip on youtube they were showing a tahoe that has run 105000 miles on E85 90% of the time and the hoses did not get brittle,O rings were still good, and they have seen no more that average wear I may not do anything else until I decide to go full time.

E85 is also a 105 octane that delivers more horses and torque

I've ran tanks of half E85 a few times in a few different vehicles with no issues. I ran a couple tanks of it through my TBI 4.3 liter truck and it never bothered it. Just keep some gas in there with it; make E60 out of it.

at a dollar less than gasoline, E85 (which can get up to 30% less mileage due to tune and only having 80% of the energy that gasoline has) may not even be cost effective. if you get 30% less mileage, you come out losing money using E85, you'd have to bring that to closer to 20% or so to start saving anything worthwhile. I am pretty sure you wont really pull ahead without tuning for E85 specifically.

use a hotter themostat ????

Isn't E85 more directed toward fuel independence and environmental concerns?

Here where I live in Illinois it's a little over a dollar cheaper for E85, I just put 4 gallons in my 1989 TA. I'm sure that will change with demand for it growing because of higher gasoline prices and the recent flooding here in the corn producing states.

yep,, wish we had it here i'd mix

Given the money required to adapt your fuel system and retune for a different fuel mixture, plus the loss of fuel economy, the lower cost per gallon for E85 will not really be worth it.

E85 has high performance advantages only(ie forced induction). 100 octane. good article in HOT ROD this month on carb tuning.

anyone know the stoich A/F? 100% Methanol I think was 7.5/1 or close.

Ethanol is 9:1 so E85 is about 9.75:1

Well, gas is at $4.35 for 87 in Chicago, and E85 is $2.99

Everything I have read states that E85 is what you WANT to use when it's $0.45 less than gas, the mileage makes it break even with regular, after that it's money in your pocket......

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