E85 spooling vs other fuels
- Thread starter Sydwyndr
- Start date
I think the short answer is that despite Gasoline having more energy, the additional amount of E85 burned (due to way less density) after surpassing Gasoline's energy deficiency equates to more energy in the exhaust overall.
Plus some can get more aggressive with timing curves, fueling curves, etc...
I'll add that unfortunately I have no anecdotal solid evidence for this as i changed too many other things at the time I switched mine. But afterward it seemed to have noticeably more pep, realized most before boost.
Plus some can get more aggressive with timing curves, fueling curves, etc...
I'll add that unfortunately I have no anecdotal solid evidence for this as i changed too many other things at the time I switched mine. But afterward it seemed to have noticeably more pep, realized most before boost.
Last edited:
Makes sense and what I have been reading with 30% more fuel entering the combustion chamber the end result is a larger volume of exhaust gases exiting the cylinder thus with more mass spins the turbine faster....
Let me preface that I haven't researched this and am thinking out loud: Cylinder pressure is what makes power. Cylinder pressure on the same Buick V6 is the same regardless of the fuel used. If E85 actually gave off more energy, even at 30% increased volume, then there would be more hp made at the same time, but that is not usually the case. I really think it's just from being able to increase timing, which in turn will increase dynamic compression and thus have higher cylinder pressure at lower load and rpm which is hard for a chassis dyno to capture. I'm fine being wrong.
Loaded question.. lots of ways to answer this .. The fuel in itself lends itself to producing more power per revolution .. the stoich for E85 is about 10:1 instead of about 15:1 for gasoline.
so technically you can shove 1.5 times more E85 in a fixed cylinder volume to get full combustion. E85 also carries oxygen ... So if you can shove more fuel in what happens at the cylinder level ? even with reduced BTU per lb of air of E85 compared to gasoline the added volume that you can put in the cylinder makes the over all BTU output higher than gasoline ( i.e. more HP per revolution )
It CAN create faster spool if you know how to take advantage of the fuel .. 10 years ago I would have never dared to run certain combinations on gasoline like we do today on E85 .. it
lets you get away with murder on the tunes , and also lets you really do things with the motor that just are not possible on fuel.
IF you have E85 available and are not running it on a TB .. you are really not doing the car justice.
So that would lead me to believe that in the exhaust mixture there is more leftover gases because of the added volume therefore more volume across the exhaust turbine will create a quicker spin simply because there is more leftover "stuff" after combustion to do the same job...
Flyin Brian
Member
- Joined
- Jun 18, 2011
Speaking of heat. I have noticed that when I accidentally ran my car very lean on E85 that my EGT's were approaching 1800 degrees and the turbo spooled faster and reached higher boost (no knock by the way). Seems like hotter EGT equals more exhaust volume thus more velocity in the pipes and faster spooling. While I have done this accidentally 2 times and try not to do it I suspect that some people that are pushing the envelope do it on purpose and enjoy the benefits. Just my theory and personal opinion.
Volume of exhaust gas has less to do with spool than exhaust pressure. IE cracked stock headers don't spool or make max boost well.
More BTU's equals more heat which also means more power. At the same hp level, I have a hard time believing that E85 spools better WITHOUT also adjusting the timing, or changing the tune altogether which breaks away from the OP question again. All else equal, does E85 spool faster?
Bingo! On a different tune, E85 will allow things that gas does not. This is where E85 works better. All else equal, E85 should work similar to gasoline as it's the exhaust system and the tune that determines spoolup properties.
E85 allows tunes to be pushed farther creating better results, but on the same timing and adjusting nothing but the fuel energy constant, I have a hard time believing that E85 will perform any differently than gas. Most people adjust the tune or change out the chip when converting to E85, with a different tune, and then make judgements about the spool of E85 vs gas. Compare an edgy race gas tune to an E85 tune, identical EGT's, and I predict spool would be very similar.
Great discussion here guys.
Great discussion here guys.
I like that thinking and must agree it makes sense to me.....
Eric Stage I
TurboTweak Guy
- Joined
- May 25, 2001
Yes. IMO its exhaust mass. Ethanol is denser to begin with, then we shove in 30% more than with gasoline. I see significantly faster spool with E85 with the same timing as a gas tune, and colder EGT's (roughly 100* colder).
On top of that, then you can still add more timing to bring the torque up, which helps even more.
Eric
Noe that raises some interesting points... i thought abt 2 things..
1. If EGT temps with E85 are lower than gasoline then that would mean the expansion rate is lower thus less velocity and shldnt spin the turbin faster.
2. If it takes 30% more e85 to do the same job then with all being equal in the cylinder that has to displace 30% less oxygen, i kmow e85 contains oxygen.
I like this thread as it is food for thought....
I know some TSO cars are definately faster with e85 and i might be cuz more timing and cooler EGTs..
Last edited:
And i wld tend to agree with that since adding 30% more of something with something far denser than oxygen alone would result in a denser exhaust discharge. Based on all the discussion that would almost certainly have to be why the spool would be quicker
to answer accurately If your just gonna run E85 and not switch anything to optimize it ... I have to ask .. why bother doing a half ass job ?
If you optimize for E85 .. then yes it will OUT SPOOL fuel
Back ur statement up with facts... optimize how??? Inguiring minds want to know
TT/Ameasap
The White Blur
- Joined
- Jan 31, 2002
I ran 92 MPH @18psi in the 1/8th three times with 93/alky just to see where the car was at.
Next week I swapped to E85 and changes were stretch IC and a couple degrees of timing. I ran 95.4MPH in the 1/8 same boost three times. Both were SD chips.
I didnt really notice a difference in spool until I started playing with a leaner AFR mixture. The AFR mixture as stated above..You can get away with murder. I ran as lean as 13AFR on gas scale with no KR in 1-2. Car ran extremely faster, but I wasnt comfortable being that lean.
Theres my anecdotal evidence.
Out of time. I will explain my theory later........Yelling (Yes Dear)
Next week I swapped to E85 and changes were stretch IC and a couple degrees of timing. I ran 95.4MPH in the 1/8 same boost three times. Both were SD chips.
I didnt really notice a difference in spool until I started playing with a leaner AFR mixture. The AFR mixture as stated above..You can get away with murder. I ran as lean as 13AFR on gas scale with no KR in 1-2. Car ran extremely faster, but I wasnt comfortable being that lean.
Theres my anecdotal evidence.
Out of time. I will explain my theory later........Yelling (Yes Dear)
Similar threads
