E85 vs e98 fuel percent increase?
Thread Starter
Joined: May 2011
Posts: 8,483
Likes: 1,026
From: Wichita, KS
E85 vs e98 fuel percent increase? So i know its roughly 30-35% from gas to e85. Have the car dialed in on e85 now. Looking to switch to e98 to see if it helps my non-intercooled setup any. Anyone know roughly how much fuel to add on the map? Just looking for ball park.
I pick up good 5.5-6 mph from 10-16lbs or so... 16-20 i nose over pretty hard. IAT is 250 bybthe end of the run. Bud picked up quite a bit going from e85 to e98 on his hot air car.
Thanks.
I pick up good 5.5-6 mph from 10-16lbs or so... 16-20 i nose over pretty hard. IAT is 250 bybthe end of the run. Bud picked up quite a bit going from e85 to e98 on his hot air car.
Thanks.
Last edited by Forcefed86; May 29, 2022 at 09:09 AM.
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You would need a methanol safe fuel system, and flush the engine with gas afterwards. You can gain power, but may not be worth it for some.
Thread Starter
Joined: May 2011
Posts: 8,483
Likes: 1,026
From: Wichita, KS
I've now heard 5-15% lol. I have e98 at the pump a couple blocks from my house. Only reason I want to try is a bud picked up almost 200whp switching from C85 to E98 at our local pump. Same timing and boost. 1200ishwhp to almost 1400ish whp. IDK if C85 is that bad or what. He runs a gen4 mopar with twin bullseye 83s non-intercooled. Def don't expect that, but its almost no effort to test it for me personally. a 15% jump for me would be 90hp tho. that would be huge at my weight.
I don't have the fuel system for methanol and I drive to and from the track.
I don't have the fuel system for methanol and I drive to and from the track.
Last edited by Forcefed86; Jun 1, 2022 at 11:05 AM.
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I've now heard 5-15% lol. I have e98 at the pump a couple blocks from my house. Only reason I want to try is a bud picked up almost 200whp switching from C85 to E98 at our local pump. Same timing and boost. 1200ishwhp to almost 1400ish whp. IDK if C85 is that bad or what. He runs a gen4 mopar with twin bullseye 83s non-intercooled. Def don't expect that, but its almost no effort to test it for me personally. a 15% jump for me would be 90hp tho. that would be huge at my weight.
I don't have the fuel system for methanol and I drive to and from the track.
I don't have the fuel system for methanol and I drive to and from the track.
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Note: That was at 1000 hp fwiw
talk to mark sullens @ mark sullens e85 carburetors. the man probably knows more about e85 fueling than anyone else. and his knowledge is backed up by time on the dyno and at the track. he says that there is no power to be had running e98 over e85. and that e87 is optimum. the ethanol makes the power but needs the 13%-15% gasoline to light the ethanol off. and that the cheap 87 octane fuel blended with the ethanol in e85 works best for that purpose. anyone can learn alot from talking to mark.
talk to mark sullens @ mark sullens e85 carburetors. the man probably knows more about e85 fueling than anyone else. and his knowledge is backed up by time on the dyno and at the track. he says that there is no power to be had running e98 over e85. and that e87 is optimum. the ethanol makes the power but needs the 13%-15% gasoline to light the ethanol off. and that the cheap 87 octane fuel blended with the ethanol in e85 works best for that purpose. anyone can learn alot from talking to mark.
TECH Enthusiast
Joined: Sep 2019
Posts: 532
Likes: 630
talk to mark sullens @ mark sullens e85 carburetors. the man probably knows more about e85 fueling than anyone else. and his knowledge is backed up by time on the dyno and at the track. he says that there is no power to be had running e98 over e85. and that e87 is optimum. the ethanol makes the power but needs the 13%-15% gasoline to light the ethanol off. and that the cheap 87 octane fuel blended with the ethanol in e85 works best for that purpose. anyone can learn alot from talking to mark.
There may not be extra power to be made but the ethanol does not need gasoline to "light the ethanol off", what that bit of gasoline is doing is giving you a bit of oil to help lubricate your engine,
BTUs of heat produced x total gas molecules in the combusted material = cylinder pressure. Cylinder pressure + RPM = Horsepower. Add a small multiplier for increased efficiency due to running the most compression possible and you have your formula.
I’m factory ecu open loop with no flex fuel setup. When I change ethanol percentage I just change the stoich in the tune and my fueling is pretty much dead on.
For example I’m currently running 50 percent ethanol. I use this calculation to determine my stoich.
9 x (ethanol percentage) + 14.68 x (gas percentage) = stoich
So stoich for 50 percent ethanol is 11.84
When I switched from 70 percent to 50 percent to give my fuel system more room the stoich is all I changed and fueling fell right in place.
For example I’m currently running 50 percent ethanol. I use this calculation to determine my stoich.
9 x (ethanol percentage) + 14.68 x (gas percentage) = stoich
So stoich for 50 percent ethanol is 11.84
When I switched from 70 percent to 50 percent to give my fuel system more room the stoich is all I changed and fueling fell right in place.
Thread Starter
Joined: May 2011
Posts: 8,483
Likes: 1,026
From: Wichita, KS
My reasoning for trying it is simply because its down the street and doesn't take much of a tune change. If I pick up anything notable or the plugs read cooler its a win. I go to the same gas station to fill up on E85 as I would for the E98.
Im seeing 250* charge temps now @ 20lbs on twin 78/75s' (mild SBE 5.3). So having 10-15% more fuel in the cylinder to help cool it seems like a good idea. 8 heat range plugs are half way down the strap at 14-15*. Really didn't want the additional hassle of an intercooler or meth injection. No room on a model T and figure I *should* be able to hit a 8.50 cage cert at 2400lbs race weight without it. Setup is down 200hp from where it should be IMO.
Still working the bugs out here.
https://ls1tech.com/forums/conversio...-turbo-16.html
Last edited by Forcefed86; Jun 2, 2022 at 02:59 PM.
I agree and don't think E98 is magically going to fix my problems or give me 200hp. But I was there! back to back pulls... drain fill E98. Had to add a ton of fuel at like boost and timing. Im sure not saying e98 is worth a 15% power increase over E85. All i'm saying is for *some reason* his setup hated C85 drum fuel and did much better on E98. A switch to pump E85 may have net similar gains. Or maybe the C85 needed ALOT more timing than they had in it. Who knows. Most I know that have run both fuels, aren't hot air cars either.
Thread Starter
Joined: May 2011
Posts: 8,483
Likes: 1,026
From: Wichita, KS
There was another variable outside of the fuel change. C85 is virtually no different then pump E85, etc and it doesn't tune any differently either. The benefits all the fancy E85/E98 fuels have over pump E85 is consistency and safety in the form of higher octane/better base fuels that are used when mixed with the ethanol portion. I run One R in my TT Z06 not because it's going to make more power with my conservative tune up but because it's super consistent, clean, and has an octane level that SHOULD help keep things safer if something else decides to **** up.