4 ms·

It will take time for the computer in the car to detect the ethanol and switch to a high ethanol fuel map. In the mean time, the engine is going to run pretty

It will take time for the computer in the car to detect the ethanol and switch to a high ethanol fuel map. In the mean time, the engine is going to run pretty lean, since more ethanol is required than gasoline for the same volume of air. Running too lean usually causes the engine to buck and shake pretty badly. This, of course, assumes that the car is even capable of running higher ethanol blends. The performance benefits are mostly from turbocharged engines. Though, Chevy V8s can see solid torque gains over 4000 RPMs. Once you get into the E50+ blends, you should have seen a huge mileage reduction. 10-20% for E50 and 25+% on E85. There's so much less energy density in ethanol.

bluGill 4y ago
Unless your car has a turbocharger or other means to run a higher compression ratio and thus take advantage of the higher octane of ethanol fuel. I've seen this done in lab and garage settings (they typically don't retain the ability to run regular gasoline), but I'm not aware of any commercially available engine that does. Race settings similar things as well, but they are trying to get power not fuel efficiency and so you can't get a fair fuel efficiency measure.
- mywittyname 4y ago
  GM cars run separate tuning maps for E85 and E15 with an ethanol sensor to help the engine decide which to use. You're not going to see the insane power gains possible on E85 from the factory though because the E85 map needs to be conservative enough to no blow up if someone suddenly fills up with regular.
- lloeki 4y ago
  > I'm not aware of any commercially available engine that does Engines with knock sensors and advanced valve timing + phasing can do that. Source: mine does, stock '08 K20 engine, which has a very wide operational RPM range, so these things matter.
- bluedino 4y ago
  You'll get a solid 20-30lb/ft gain on a GM or Ford V8 with E85.
  - mrguyorama 4y ago
    That's such a small difference it could literally just be that it's a slightly richer setting because E85 needs a higher fuel ratio for Stoichiometric burning.
    - bluedino 4y ago
      That is not a small difference, and you can't get 30lb/ft by "richening things up"
bluedino 4y ago
> Though, Chevy V8s can see solid torque gains over 4000 RPMs. The gains will come in well before that

bluGill 4y ago

Unless your car has a turbocharger or other means to run a higher compression ratio and thus take advantage of the higher octane of ethanol fuel. I've seen this done in lab and garage settings (they typically don't retain the ability to run regular gasoline), but I'm not aware of any commercially available engine that does. Race settings similar things as well, but they are trying to get power not fuel efficiency and so you can't get a fair fuel efficiency measure.

mywittyname 4y ago
GM cars run separate tuning maps for E85 and E15 with an ethanol sensor to help the engine decide which to use. You're not going to see the insane power gains possible on E85 from the factory though because the E85 map needs to be conservative enough to no blow up if someone suddenly fills up with regular.
lloeki 4y ago
> I'm not aware of any commercially available engine that does Engines with knock sensors and advanced valve timing + phasing can do that. Source: mine does, stock '08 K20 engine, which has a very wide operational RPM range, so these things matter.
bluedino 4y ago
You'll get a solid 20-30lb/ft gain on a GM or Ford V8 with E85.
- mrguyorama 4y ago
  That's such a small difference it could literally just be that it's a slightly richer setting because E85 needs a higher fuel ratio for Stoichiometric burning.
  - bluedino 4y ago
    That is not a small difference, and you can't get 30lb/ft by "richening things up"

bluedino 4y ago

> Though, Chevy V8s can see solid torque gains over 4000 RPMs. The gains will come in well before that