Why does E85 fuel run cooler and make more power? | Fuel Tips-Page 2| Grassroots Motorsports forum |

Pete. (l33t FS) GRM+ Memberand MegaDork
9/16/21 12:24 p.m.

RichardSIA said:

Then add in the fact that an engine requires 30% to 40% more E85 than traditional pump fuel to make combustion

And that it will destroy older fuel systems.
I have nothing compatible with fermented corn syrup.

How old?

The fuel system in my '72 Ford was ethanol friendly.

frenchyd UltimaDork
9/16/21 12:44 p.m.

Pete. (l33t FS) said:
RichardSIA said:

Then add in the fact that an engine requires 30% to 40% more E85 than traditional pump fuel to make combustion

And that it will destroy older fuel systems.
I have nothing compatible with fermented corn syrup.

How old?

The fuel system in my '72 Ford was ethanol friendly.

My 1953 MGTD can be easily modified to run on E85. Probably a lot faster than you can hook up a lap top and change what's needed to run E85. ( I'm guessing )

z31maniac MegaDork
9/16/21 1:06 p.m.

frenchyd said:
In reply to z31maniac :

I'm sorry I'm old and have a limited knowledge /interest in the latest greatest.
   I picked the numbers I did because if you have the latest/greatest the tech is already there and all you need to do is hire it done.
   Most of the people who read this are grass roots kind of guys. They buy what they can afford to lose if it blows up, or is otherwise destroyed in a racing accident.
   That means cheap and cheap gets you old/ obsolete. Now you can follow the herd and on a good event wind up in mid herd. Or you can use the Gray matter and find the overlooked underappreciated. And maybe do better.

Totatally understand that. Just keep in mind, 70s Jag V12 knowledge doesn't really translate to relatively modern engines.

For example, the BRZ/GR86 engine I'm referencing went on sale in late 2012, meaning it was designed and tested for a few years before that.........so it's already nearly a 15-year old engine.

frenchyd UltimaDork
9/16/21 1:59 p.m.

z31maniac said:
frenchyd said:
In reply to z31maniac :

I'm sorry I'm old and have a limited knowledge /interest in the latest greatest.
   I picked the numbers I did because if you have the latest/greatest the tech is already there and all you need to do is hire it done.
   Most of the people who read this are grass roots kind of guys. They buy what they can afford to lose if it blows up, or is otherwise destroyed in a racing accident.
   That means cheap and cheap gets you old/ obsolete. Now you can follow the herd and on a good event wind up in mid herd. Or you can use the Gray matter and find the overlooked underappreciated. And maybe do better.


Totatally understand that. Just keep in mind, 70s Jag V12 knowledge doesn't really translate to relatively modern engines.

For example, the BRZ/GR86 engine I'm referencing went on sale in late 2012, meaning it was designed and tested for a few years before that.........so it's already nearly a 15-year old engine.

Would you be surprised that the stock compression on a 1981 V12 was 12.5-1?
That in 5 liter form that V12 made 502 horsepower in 1966 designed to run on the 83 octane pump gas the French had?
4 valve heads originated with the Peugeot of 1916? Turbo charging originated in the 1930's

Why am I so focused on Vintage ? Because I'm like most of you. I hate to lose to the newest, latest, expensive thing.
That's a game none of us want to play. But we like to race, go fast, test our skills.
Autocrossing will always be dominated by the newest. So Will SCCA, NASA, and most other racing.
Vintage racing freezes technology. You can compete for decades on a tiny budget. Every other decade a fresh set of rings, maybe a valve job? No more the trick of the week. Plus no contact racing!!! This Ford Falcon was bought for pocket change. Raced with the Trans Am boys and does remarkably well. You don't need the last word in vintage racing to have fun.

z31maniac MegaDork
9/16/21 2:36 p.m.

In reply to frenchyd :

Ugh, the US and Europe use different measurements for Octane. What's 97 in the EU is roughly 91 here. And no, I don't believe any engine was ever designed to run on the US equivalent of 75 octane. You don't even see if that low at high altitude. I can't even find anything that shows it was ever produced.

My apologies, I'm just making myself look like a jerk.

Pete. (l33t FS) GRM+ Memberand MegaDork
9/16/21 3:59 p.m.

In reply to z31maniac :

Ladas were designed to run on something like 67 octane. Maybe 76. It's a really low number.

Model Ts, and anything with a Ricardo designed flathead chamber (used as late as the 50s in the Ford flathead six) were designed to run on basically anything flammable, down to kerosene.

frenchyd UltimaDork
9/16/21 6:12 p.m.

In reply to z31maniac :

No problem. yes American V12's after 1981 had 11.5-1 compression and the rest of the world got 12.5-1 compression. Timing was pulled back from 38degrees to 17 degrees. So if you use a 100+ octane fuel like E85 you can advance the timing to normal. Free horsepower! Lots of it!
Before that the compression on V12's was 7.8-1 !!!

Now add some cams with more than 3/8ths of an inch lift and some duration. The engine might come ALIVE. The local cam grinder ( who does mainly pulling tractors ) will do that sort of work for modest money.
I'm sure there are other cars where a modest amount of work will give a major improvement. Benz, BMW, older Caddy's Buick?

drbradb1
6/20/24 12:14 p.m.

Interesting thread. I have a question some on here may be able to answer. I have a 1988 chev Caprice. It was stripped of puter controls way back. A 350 h.p. 350 c.i. chevy is in it now running vortec heads. I saw a post that a carb can be jetted approximately 20% richer to run E85. MSD dizzy and 6AL box. Runs very nicely now and been using ethanol free gas. Few years back was running an edelbrock carb and took it off to rebuild. There were deposits in the fuel bowls and a mechanic said it was from the "corn" in the gas I was using at the time. So now I am reading that with E85 I can run lower temps (running now at 200 F) and 20% more power. Is it just changing the carb jets and/or metering rods (possibly advance the timing like recurve the dizzy)or are there other factors to consider.?I have an A/f guage so I can check that too.

Andy Hollis
6/21/24 6:56 a.m.

drbradb1 said:
Interesting thread. I have a question some on here may be able to answer. I have a 1988 chev Caprice. It was stripped of puter controls way back. A 350 h.p. 350 c.i. chevy is in it now running vortec heads. I saw a post that a carb can be jetted approximately 20% richer to run E85. MSD dizzy and 6AL box. Runs very nicely now and been using ethanol free gas. Few years back was running an edelbrock carb and took it off to rebuild. There were deposits in the fuel bowls and a mechanic said it was from the "corn" in the gas I was using at the time. So now I am reading that with E85 I can run lower temps (running now at 200 F) and 20% more power. Is it just changing the carb jets and/or metering rods (possibly advance the timing like recurve the dizzy)or are there other factors to consider.?I have an A/f guage so I can check that too.

20% richer may not be enough, depending on the E85 % where you live...and for that time of year (less E% during colder months).

On the One Lap CRX, we run 40% richer for true E85. And less for lower percentages.

But...it's also not linear across the MAP load tables. WOT needs more richening than does part throttle. Not a problem for EFI because part-throttle runs closed loop and there is enough range to fix it dynamically. But carbs? That could be trickier...or just run rich all the time at part throttle.

And yeah, if you want to take advantage of the higher effective octane rating, and you are not yet at MBT via iginition timing, you'll want to alter you're ignition settings, too.