What's the difference between race gas and E85?

[BoostedDrummer]

Hey guys,

I've been seeing alot of YouTube videos from 1320 and others showing cars running E85 gas and from what I've read, it has a higher Octane rating and is a little cheaper than 93 octane gas. When I get home from deployment and pick my car up, it should be racing season by then, and I'm wondering if I should (or even can) run E85 or just run race gas that they sell at the raceway (VP Racing fuels: Unleaded 101, 113, 110 Octane, C-12, C-16, and Methanol). Will I be safe to run the race gas or would I have to upgrade the fuel tank, lines, and pump? I don't even know the difference between all the race gas types lol.

I never run the Omni on anything less than 93 Octane. It has a Walbro 255, +40s, stock tank. Lots of mods, heres a pic with mods/power/good looks :P

[Keito]

You'll need a specific tune for E85(appx. 20% more fuel to run it)
Race gas you don't
I run race gas in my GLHT and I've run it in my SRT-4, I usually use 110
The only downfall to race gas is it will degrade the 02 sensor quicker than 93- (most race gas is leaded)

[Ondonti]

You'll need a specific tune for E85(appx. 20% more fuel to run it)
Race gas you don't
I run race gas in my GLHT and I've run it in my SRT-4, I usually use 110
The only downfall to race gas is it will degrade the 02 sensor quicker than 93- (most race gas is leaded)

The fuel requirements are much higher then that with true E85.

E85 vs race gas is down to things like.

1. availability
2. cost vs the minimum race fuel that is good enough for you
3. Ability to tune for E85
4. Fuel system capacity (to flow 30%+ more fuel if needed).
5. Ignition system (harder to light off a high fuel vs air mix).

[BadAssPerformance]

6. E85 typically needs upgraded fuel components for durability
7. E85 systems should be flushed out regularly
8. E85 is not typically 85%, it can be variable from pumps so you either have to tune for worst case, add a flex fuel sensor, or buy it out of a can
9. E85 absorbs moisture so more problems/inconsistencies if fuel sits
10. ....

I've only ready up some on E85 so far and there are several concerns.

As with any performance question it comes down to what are your goals with the car?

[BoostedDrummer]

Thanks for the replies guys,

As of right now, the car is back at FWD getting a more aggressive cam and tune for 26psi. I will also be buying M&H slicks from Cindy when I get the car back and hopefully, with the tune and new cam, make around 350fwhp. My goal is to be in the 10's and be able to stand with Reeves, Brian, Mike, Rob, Gary, and JT. I've been dying to go to SDAC to meet these guys to soak up any and all information and wish Gus was still around so I could meet him as well. My DREAM however, is to have the Omni in the 9's, but thats a ways off

[BadAssPerformance]

Sounds like a fun goal and you have a good head start! Would love to hang out at SDAC! Until then, soak up the info here

[BoostedDrummer]

Lol I intend to, so long as I don't deploy again when SDAC comes around lol. So to get back on topic, what would be ideal for running at the track? Does a certain fuel have more "pop" to it than 93, like gets more ponies than pump? And I assume 110 and 113 are around what I should run with high boost and a single cam?

[contraption22]

8. E85 is not typically 85%, it can be variable from pumps so you either have to tune for worst case, add a flex fuel sensor, or buy it out of a can

This seems like one of the bigger issues to me. E85 can be "up to 85% ethanol". Could be much less. There is no guarantee of consistency. This could throw of your tune dangerously.

OE Flex Fuel vehicles have the capability to monitor the ethanol content and adjust fuel and ignition events to compensate for variations.

[glhs727]

what about using a mix, say 20% e85 mixed with 80% 91 octane? has anyone done that? They just open a gas station sorta close by that sells e85 for $2.89 gallon. Been thinking about running it in one of my cars.

[contraption22]

what about using a mix, say 20% e85 mixed with 80% 91 octane? has anyone done that? They just open a gas station sorta close by that sells e85 for $2.89 gallon. Been thinking about running it in one of my cars.

I tried for about 10 seconds to figure out the math as to what your ethanol content would be assuming the E85 was truly 85% ethanol... but my head hurt, so I stopped.

Edit: Assuming E85 is 85% ethanol and 91 octane is 10% ethanol, that would roughly be 35% ethanol.

[86TSiGuy]

Math time Yay!

So it breaks down like this;
E10 (Most pump gas in states, all 87 & 89 pump gas in Ontario) has a blended (R+M)/2 octane rating equal to it's listed pump octane AFTER the ethanol is added.
= 91 oct
= 97.1% of the fuel efficiency of pure gas

E85 has a misreported octane rating of 105, when its actual (R+M)/2 value is 95. To make that even less appealing that's based on 83% ethanol content and ASTM 5798 specifies anything between 51-83% ethanol is E85. So you could be getting a dramatically lower octane value from a diluted mix.
= 95 oct
= 75.93% of pure gas economy

So a mixture of 20% E85 (optimistic 83% purity) and 80% 91 pump (E10);
= 91.8 oct
= 92.86% of pure gas fuel economy or 95.64% of the fuel economy you get out of straight 91 E10.

What isn't shown in the octane rating is that ethanol has a very low latent heat of evaporation, meaning it will absorb heat out of the intake charge faster and to greater capacity than gasoline alone. The added cooling means an ever so slightly denser air charge and additional detonation resistance.

I agree though, in anything but a track car you need an ethanol sensor to make good use of the stuff.