e-85 equivilent to 104 octane?

[Bigwhite11]

e-85 is great! It practically cleans your fuel system as you use it. I ran it in my 4-wheeler for about a year before I sold it and it ran great and the carb was PERFECTLY clean when I pulled it to re-jet it when I sold it. No varnish build up or anything. I was sold on it from then on!

[ChevyTech77]

Suuuurrrre it does.......

[MikeNH]

I don't know that I'd run E-85 in something not rated for it but I liked how it made the truck run and after the move (E85 seems widely available in MI) I plan to run it as much as possible. Better power is always a plus and I won't be paying for gas.

[RyanbabZ71]

Also right now the estimate price difference (worst case) for next spring (april/may) is around 63 cents less than regular. Speedway around here just started putting in pumps. I have 3 choices all within a few miles of each other

[Bigwhite11]

Why do you think people use it for racing applications? It lets you increase timing and compression far beyond the limitations set by regular pump gas. It's just facts and there's lots of reading out there and plenty of support.

 

I'm not trying to be rude, but seriously if you google it you can spend days reading about it.

[Wires]

Why do you think people use it for racing applications? It lets you increase timing and compression far beyond the limitations set by regular pump gas. It's just facts and there's lots of reading out there and plenty of support.

 

I'm not trying to be rude, but seriously if you google it you can spend days reading about it.

 

 

They ONLY use it in boost applications (supercharger/turbos) so they can crank up the boost and not have the engine fly apart (or super high compression engines).

 

More timing doesn't = more fuel. In the ideal world, you'd fire the plug at TDC (Top Dead Center), and the mixture would instantly light, and push the piston down. The reality of it is it takes a finite period of time. And when you run at part throttle, it's a lower compression ratio, so it takes even more time = more advance.

 

The timing advance is used to fire the plug early so that by the time the piston is swinging by TDC, the full explosion pushes the piston down and you get maximum power.

 

Too much advance, and it slows the piston (acts like a brake since the gas is expanding on the up stroke). Way to much advance, and you get the full bang on the upstroke, and a hole in the piston. Too little advance and it's expanding on the down stroke, and you waste the energy to heat the water jacket.

 

There is an optimum advance for each engine design so that the mixture is fully consumed around 10 degrees after TDC.

 

All E85 does is raise the effective octane. The only way you can get more power out of an engine with E85 vs dino fuel is by increasing the compression ratio, either with boost, or high compression pistons. The higher octane will prevent pre-ignition on the upstroke, before the optimum ignition point is reached. Neither case is relevant on a stock engine though.

 

It's a very common mis-conception that more octane = more power. I deal with guys everyday that think that tossing 110 octane in their engine will net more power. 99% of the time, it tends to burn less volatile, and they lose some power.

 

E85 has around 25% less energy per unit, and will give you 25% less power/MPG over regular fuel. I'd like to see someone dyno the 6.2L on E85 and get 403 HP. I think GM pulled smoke out of their a$$ with that one.

[00Silverado4x4]

To Wires:

 

I understand what you are saying but if you look at GMs hp/tq numbers that are rating engines higher on e85 (newest engines, mine not included.) Curious as to how they can do that?! It is my understanding of these engine that they can maintain at least the same hp/tq numbers between the two fuels by pumping in more fuel (especially true since we all know e85 is less powerful.) This explains the mpg loss? These are not my facts only what I've read & found on websites & this forum & no insult to you. However I would ask for you to take a look. Happy reading!

 

http://archives.media.gm.com/us/gmc/en/product_services/r_cars/r_c_sierra/10index.html

[Wires]

To Wires:

 

I understand what you are saying but if you look at GMs hp/tq numbers that are rating engines higher on e85 (newest engines, mine not included.) Curious as to how they can do that?! It is my understanding of these engine that they can maintain at least the same hp/tq numbers between the two fuels by pumping in more fuel (especially true since we all know e85 is less powerful.) This explains the mpg loss? These are not my facts only what I've read & found on websites & this forum & no insult to you. However I would ask for you to take a look. Happy reading!

 

http://archives.medi...ra/10index.html

 

 

Interesting read. One note from that is they spec the max HP on gas at a lower RPM than E85. Sort of seems like they "massage" the specs so that you put E85 in there. <insert conspiracy theory here> Probably gov't kickbacks to push E85 <end of conspiracy theory> Just for sh*ts and giggles, I checked the magnacharger site, and they post the 5.3L making max power at 5500RPM, yet GM is listing 5200 or 5300.....

 

At the end of the day, I really don't see how spending 25% more on fuel (when gas is already overpriced) makes any sense to anyone. Especially since E85 requires a crap load of fossil fuels to be burnt to refine it so it can be used in an engine. Might as well just burn fossil fuels and flip the bird to "the man". ;)

[kstruckcountry]

This ^^

[MikeNH]

I have a graph from GM of hp/tq on E85 vs gas, I'll post it when I get home.