E85 Gasoline

Tyler · Post by **Tyler** » Tue Dec 18, 2007 2:09 am

would it even be worth it to tune it or would it cost more than you would eventually save?

JmBurton · Post by **JmBurton** » Tue Dec 18, 2007 3:01 am

LowePerf;85307 wrote:Yes, cheaper but you'll use about 30% more. Stoich for gasoline is 14.7 but E85 stoich is about 9.7 A/F. So you need more fuel to get the same power. The real advantage would come from increase compression ratio so you could take advantage of E85's 105 octane rating.

^^

MyfodoSi · Post by **MyfodoSi** » Tue Dec 18, 2007 3:51 am

Phate;85303 wrote:We were just interested in running it in our dailies cuz its cheaper. Still need to tune it?

Hold on, you get like 45 miles to the gallon, and you're worried about cheap gas?

Spork · Post by **Spork** » Tue Dec 18, 2007 3:58 am

so, can anyone point me to what the power difference is between tuning on 93 and converting the car to E85? you said that its rated at 105octane, but when tuned does it perform like running 105, or is it just safer for high comp like running 105?

Phate · Post by **Phate** » Tue Dec 18, 2007 4:15 am

MyfodoSi;85741 wrote:Hold on, you get like 45 miles to the gallon, and you're worried about cheap gas?

Haha. This will be for the white car thats parked in your driveway.

LowePerf · Post by **LowePerf** » Tue Dec 18, 2007 5:41 am

Spork;85743 wrote:so, can anyone point me to what the power difference is between tuning on 93 and converting the car to E85? you said that its rated at 105octane, but when tuned does it perform like running 105, or is it just safer for high comp like running 105?

Technically you will see no difference in power output by increasing octane in any vehicle if it's not needed. There is also the possibility to actually lose power from doing this. There are exceptions to the rule of course.

Running an 8:1 compression engine on 93 will not produce anymore power than running it on 87, but step the compression up to 9 or 9.5:1 and then you might start seeing some increase in power, but only if the spark timing is increased as well.
Different fuels have different burn rates. a higher octane fuel usually burns slower than a lower octane fuel, given the same BTU value, both fuels should produce the same power output but the output of an engine is only dependent on the pressure this burn can put on the piston to turn the crankshaft and it must be applied at the right time.

Triggering ignition at 30° before TDC with a fast burning (low octane) fuel will increase pressure in the chamber before the piston reaches the top and it will have to fight this pressure to get there and most of the fuel will be used up before it reaches the "magic" 14° ATDC that is generally accepted as the point that you want maximum cylinder pressure. On the other hand triggering ignition at 10° BTDC in a slow burning fuel (high octane) will decrease the losses of the piston fighting increased cylinder pressure from combustion but might burn slow enough that the piston actually runs away from the burning mixture (the piston would be going down the cylinder faster than combustion pressure can rise). As you can see correct timing depends on a lot of variables including RPM, fuel burn rate, combustion chamber design, ect ect ect...

In engineering terms, what your looking for is whats called Mass Fraction Burned or CA50. CA50 is crank angle for 50% burn this is the point at which 50% of the fuel has burned in the combustion chamber and should be timed to occur at the correct time to put maximum pressure on the piston top. There are many variables involved, and this is why timing tables should always be worked out on the dyno with the fuel that you intend to run the vehicle on.

This is just a very short version of what's involved in setting ignition timing in comparison to different fuels and I'm getting tired so I'll leave it at this for now.
-John

Spork · Post by **Spork** » Tue Dec 18, 2007 5:47 am

well, im building at least a 11:7:1 comp motor, and I'm just wondering if converting to E85 will benefit me much over running 93 octane... my ultimate goal is to build an even higher comp n/a "race" motor, but I already pretty much assume i will have to run at least E85 in that

RyanA · Post by **RyanA** » Tue Dec 18, 2007 11:39 am

If you ALWAYS run E85, you can run very high compression. Only problem is, if you ever get caught where they don't have E85, you are out of luck.

As for having to "retro fit" a vehicle to run E85, here's a site that has some useful information. Be sure to click "my mechanic told me....." to see the internals of an engine that was not intended for E85. Everything looks great.

http://www.rune85.com/

Phate · Post by **Phate** » Tue Dec 18, 2007 1:14 pm

RyanA;85789 wrote:If you ALWAYS run E85, you can run very high compression. Only problem is, if you ever get caught where they don't have E85, you are out of luck.[/url]

I dont think this is going to be a problem. Theres a lot of vehicles out on the roads now that use this flexfuel.

RyanA · Post by **RyanA** » Tue Dec 18, 2007 1:52 pm

I have bad news for you if you think this is true. I will tell you right now, there is NO E85 within 50 miles of me. Going west, you could probably drive 100 miles before you find it. Nearest place to me is Jefferson City.

Also, unless you want to make power, I think E85 is a joke, imho. Around here, if you are lucky, E85 may be 10 cents cheaper a gallon. The way I figure it, to simply BREAK EVEN, you would need to have gas be 66% or cheaper than what regular fuel costs. Ten cents is only about 3 percent cheaper than what regular fuel costs right now so you are actually losing money if you buy it over regular fuel. I don't know about pricing in STL but around here, it's a joke. If they want us to buy it, they need to start giving us a reason to.

BTW, here's a list of where you can buy E85 in Missouri: http://e85vehicles.com/e85-missouri.htm The closest place to me is Gravois Mills and they actually charge MORE for E85 than regular gas. This place is also in the middle of nowhere...