I have a 94 Z28, currently needs an engine rebuild. My goal is to make about 450-500 HP N/A, then shoot nitrous on top. This will only be a weekend/track car, no daily driver. I'm currently considering a 383 stroker and direct port nitrous.

Now, I know E85 has a greater octane capability (105 approx. vs 93 for premium pump gas) and burns cooler. This would allow for a higher compression ratio, helping to offset the fact that it contains less energy than gasoline. I'm also aware of it's corrosive nature compared to gas, requiring the use of materials in the fuel system to prevent it from degrading (typically stainless steel). I'm toying with the idea of rebuilding my LT1 to run only on E85, but I'm no expert in this area and could find little information through searches on this.

Now, I live in Pekin, IL, and we have an ethanol plant right here in town. Ethanol/E85 is readily available at most pumps in my area and there is little worry about me having to find one. I know this is typically the problem for many people considering E85.

So aside from the fuel system being capable of handling E85, building the engine for a compression ratio that will work well with E85, and retuning the PCM for the different fuel, what other things should I consider? I know little about E85 and nitrous. What about the ignition system and spark plugs? Is there anyone that has done this yet? I'm pretty much looking at an entire teardown of the engine and rebuild from the ground up, so that won't be a problem. Cost is a factor, but if it would only be a few hundred dollars more to do this, I wouldn't have a problem with it. A few thousand would be different story.

I know there are many knowledgeable engine builders in this forum, many with alcohol fuel experience. Any information would be very helpful and appreciated!

 

Over on impalassforum.com there's a guy who posts about E85 in the PCM forum a lot. Not sure if he rebuilt the engine for E85 or just retuned.

 

I had my car dyno tuned for E85 - was good for almost 40 RWHP (was previously dyno tuned for 91 octane @ 444rwhp)
i also got a fuel pump, regulator, and injectors that are ethonal friendly (upto E100)
replaced ALL rubber (not very much - but there was some) w/ either stainless steel or teflon

the internals of the motor were treated and E100(or E85) resistant

and E85 is chealer than 91

 

Hmmm where could i get the components to make my z28 e85 ready id really like the idea of it being able to use flex fuel

 

Stoich for E85 is ~9.7, so you need ~1.5x the capacity in your fuel system as compared to gasoline. So, a bigger pump may needed along with bigger injectors, and of course reprogramming. While ethanol contains less energy than gas, you burn more of it. Ditto for methanol. This is primarily why there isn't a drop in power compared to gas. You will be able to raise your CR, and as you suggest the combo should ultimately produce more hp than a straight gas engine.

Gas ~125 BTU/g
Ethanol ~84 BTU/g
E85 ~90 BTU/g
90(14.7/9.7) = 136 BTU in the amount of E85 burned per mass of air at stoich compared to gas. Of course, the greater volume of E85 displaces some air, so the ultimate power output does not increase like you might think it should.

Of course, extensive tuning will be needed. Besides adjusting for more fuel, you will likely need more timing as E85 does not burn as fast as gas. You will not need a new ignition system for E85 per se, but more spark may be needed with the higher CR.

Rich

 

Reading material -

http://www.turbomustangs.com/smf/ind...?topic=47094.0

http://forums.nasioc.com/forums/showthread.php?t=803341

http://forums.nasioc.com/forums/show...=796466&page=2

http://www.gt-labs.net/e85conversion.html

http://200.14.206.180/dama/libreria/...roaire/GM1.pdf


Bottom line, why E85 is so interesting???

1) E100 (100% ethanol)can be run in motors with a compression ratio as high as 19.5:1. Really, 19.5! Determining the upper compression limits of E85 when used in a purpose built motor is not well known yet, but 14.5 doesn't seem outrageous.

http://www.hybridcars.com/blogs/hyvi...e-from-ethanol

Higher compression all by itself gives you (EDIT: See chart below) power increase for every 1 point in compression increase

http://www.popularhotrodding.com/tec...on_ratio_tech/

2. E85 has a much higher evaporative cooling power than gasoline so the intake air charge in the cylinder is significantly cooler that it is with a comparable mixture of gasoline --- that means higher VE.

3. E85 has an octane of 105!!!

4. E85 (ethanol) burns faster than gasoline but has a slightly longer ignition delay during the slow burn phase of combustion so the engine does not do as much negative work fighting rising cylinder pressures due to large ignition advances. The total ignition advance for E85 is almost identical to the ideal advance for gasoline so it should not cause the ECU problems when you mix them.

5. At proper mixture you actually are releasing more energy in the cylinder due to the higher quantity of fuel you can burn. (Ethanol can burn efficiently at much richer mixtures than gasoline can) That means about a 5% increase in energy release all by itself.

6. Peak combustion pressures are actually lower for ethanol than for gasoline but the cylinder pressures stay higher longer, so you have more (longer) crank angle that is usable by the engine. This lower peak cylinder pressure also helps with detonation control. With this characteristic, I think having a longer rod to stroke ratio, which will make the piston stall somewhat longer at TDC, will help.


EDIT - Here is something to look into that is happening later this week at the Engine Rebuilders Association Show in Indiana -

http://www.aera.org/expo2006.aspx

http://www.aera.org/docs/other/E85Rules.pdf

 

Just one correction to the above post: power does not increase by 5% per unit of CR. In the rnage we are talking, it's a couple of percent and with each incrase in CR, the gain in power decreases. This makes sense when you consider that going from 10:1 to 11:1 is a 10% increase in CR but 15:1 to 16:1 is just 7%, and so on.

Rich

 

Plus increased compression ratios also increase negative work on the crank thru pumping losses. The extra compression needs to counteract that pumping loss to get a net gain.

E85 is some cool stuff, ain't worth **** when it comes to milage but in terms of what you can do to make more power it's pretty cool.

Bret

 

Thanks for all the information. The more I think about it, the more I believe I'm going to end up building my LT1 for E85. I don't have to worry about emissions here and it's going to be a total rebuild. I might even be able to make more than my original goal of 450-500 HP N/A.

What about E85 and nitrous? I haven't seen a whole lot about it and I am sure it is going to be quite different from running nitrous and pump gas. The fuel to nitrous ratio is going to be different, of course. I plan on using a direct shot system, but would it be safe to shoot a 300 shot of nitrous with E85?

I know the upgrades and different materials needed for the fuel system, but would there need to be any special materials for the engine parts? Or can I just use standard parts and gaskets? If all I need to change is the fuel system parts and set it up for greater flow, I don't think this project will be too much of a problem.

 

I did some more digging and found the following from this article on the benifits of higher compression

http://www.popularhotrodding.com/tec...on_ratio_tech/

"... a high-compression cylinder produces better power and fuel economy. It is not just because the charge is squeezed harder and the resulting combustion pressure goes up, but also because the higher expansion ratio allows more energy to be extracted from the original high-pressure charge."

"Because the high compression cylinder makes its power much earlier on in the power stroke there are other implications we can take advantage of. The most obvious is that we can apply the earlier exhaust valve opening needed for higher rpm output without significantly impacting the engines low speed output. Using as much compression as circumstances will allow makes dual pattern cams work at their best."

"Rather than flogging through a lot of calculations, the quick reference chart has been made up. To use this chart locate your original CR on the horizontally top bar(Bold Blue text). Next, locate your new CR down the first column on the left side (Bold Green text). Where the two intersect is the gains that can be expected. For instance if the CR is raised from 9:1 to 12:1 we find the two values intersect at the box with 7.7 in it. This is the percentage increase (Black text)that can theoretically be had by raising the compression from a lower to a higher level.

..................Original CR
....................8:1__9:1_10:1_11:1_12:1_13:1_14:1_15:1
New CR..9:1__3.5
...........10:1__6.5__2.9
...........11:1__9.2__5.5___2.5
...........12:1_11.5__7.7___4.7__2.1
...........13:1_13.6__9.7___6.6__4.0__1.9
...........14:1_15.4_11.5___8.3__5.7__3.5__1.6
...........15:1_17.0_13.0___9.8__7.1__4.9__3.0__1.4
...........16:1_18.6_14.5__11.3__8.6__6.4__4.4__2.8__1.4

Hope it helps...