HPDE/TT guys running E85, mpg?
 

Trying to get an idea of how much E85 I'd use at my local track over a weekend, 5 sessions a day 15-20 minute sessions on a 1.8 mile track.

Typically 8 timed laps + cool down lap, last session of the day (if it's thinned out) they may give us 10/11/12 laps.

I can buy a 55 gallon drum of quality, guaranteed E85 fuel and have it at the track ready for me.......just not sure how much I'd actually use? And I'd prefer to use E85 at the track for the extra oomph and the lower temps.

Any idea? Our tanks are 13.5 gallons?

It'll depend on how much time you're on the throttle (more open tracks will use more gas), but I typically drain a full tank of 94 in a lapping day. That would be six or seven 15 minute sessions. With e85 running richer already, plus making more power, I would guesstimate you're going to need 30% more fuel per day on a similar track.

Assuming I would burn about 12 gallons of 94 on a tighter track, adding 30% is ~15.5 gallons per day. Even if I'm not super close, you're still well under 55 gallons in a weekend. Your mileage would have to be a 100% increase over mine to burn up close 55 gallons in a weekend.

I've emptied my tank many times here:

http://www.1addicts.com/forums/attac...2&d=1400550337

I haven't run any full days on the CTMP GP track, but I've gone through about half a tank in two 20 minute sessions:

http://www.corvetted.com/wp-content/...vation-map.gif

I've heard ~30% increased fuel consumption on E85 for NA cars, compared to 91/93.

I used to run E85 at the track but had to give it up when the aero was installed because of fuel starvation on long fast left handed sweepers. I would drive 50 miles to the track and carry 12 gallons of fuel. I could do 4-20 minute sessions and drive back home and be at less than 1/8 of a tank left including using the 12g I carried with me.

My car usually uses a little less than 1/4 tank E85 per 20 min session and on the way to the track it does 23-27mpg depending on the speed and traffic.

I'm aware, but I haven't had this car out on track yet.

Only MPG experience I have at my track is on an R6 and my last Miata, not really relevant to the BRZ.
@Jonsey do you have more details on your suspension/wheel/tire/aero setup?

Also, at what fuel level on the guage were you having issues?

Just trying to get as much info as I can first. I might see if anyone else locally runs it and see if they want to split a barrel, but not sure 28 gallons will get it done for the whole weekend.

Running Koni yellows and Swift Spec R springs, FT86 Front Splitter w/ race upgrade, DWL Type 1 rear diffuser, 235/35/17 ZII Star Specs, stock motor other than tune and running rear LCA and camber plates (well sorted now), I would get fuel starvation at just above 3/4 tank on 2 back to back fast left handed sweepers. I was no longer able to run a full session before getting fuel starvation so I went back to pump gas.

I average around ~4MPG...

One third of a tank per 20 minutes pushing hard

Yikes, that's bad! I didn't realize the cars were that sensitive to fuel starvation.

We could run the Miata on Rcomps down below the E mark and not get fuel starvation, but no super long sweepers at Hallett really either.

Yikes, that's bad! I didn't realize the cars were that sensitive to fuel starvation.

We could run the Miata on Rcomps down below the E mark and not get fuel starvation, but no super long sweepers at Hallett really either.

I don't think 28 gallons will be enough for the weekend, on the local tighter track that would barely be enough 94, add the extra consumption for e85 and you'll probably run out.

2 barrels between 3 people is probably the sweet spot for a tighter track.

Unfortuntely with E85 you are pushing the fueling system pretty hard and the tank is raised in the middle and the pickup is only on the bottom of the left part of the tank. PST has a chart showing some fuel pressure drops while running 93 at pretty full tank levels, the effect is just not as pronounced on gas. If you are familiar with MSR Cresson, the starvation happens after the horseshoe/boothill/tombstone complex and big bend when going ccw.

Thanks, good to know. I'll start asking around with the track guys.

Damn. The old E30s used to be like that (the hump that is), but there was a small pump that pushed fuel to the other side for the main pickup.

So really this car needs a surge tank............ugh.