[Allch Chcar]

Topsoil erosion? Right. Lets keep running 100% gasoline because farming contributes to erosion.

The better fuel economy with half Ethanol/Gasoline blends has been noted a couple times by individuals. I don't know the exact reasoning. I can only suggest that the compression is favorable at lower blends. Gasoline has a lower ideal compression ratio so it only makes sense that less compression is better with gasoline.

On the topic of fuel efficiency. I'm having no progress finding authentic improvements or information on higher compression for anything but performance or turbo projects. When you compare E83 to G90 you'll gain approximately 5% from just switching over to Ethanol intensive blends due to the knock resistance and cooling effect etc. But that is only on a modern OBDII compliant vehicle, First Gen or Second Generation. Eg. The OBDII mandate began in 96 with Ford they had EEC-III modified slightly to become EEC-IV. The gains were marginal even though OBDII are technically superior in design. In 2001 or so Ford starting implementing GenII or EEC-V which was noticeably better. The biggest gain for ethanol is still on an extremely high compression, beyond Gasoline NA compression ratios or Turbos. With Ethanol that could mean 14:1 on an economy cam. Racers run 16:1 on Methanol/alky but on longer duration cams that bleed off more compression, on Ethanol you're looking at 15:1. The difference is a racing cam with 40* degrees of overlap will lose 8% of it's Dynamic Compression ratio. If Ethanol's max ideal compression was something like 13.7 or so a 15:1 race engine would be just fine at 40* of overlap. A factory cam with about 20 degrees(Geo Metro came with 18) of overlap would be safer at 14:1 because it will lose 4% of it's dynamic compression approximately. With a turbo if you double the air pressure in the manifold for 15lbs of boost your 10:1 Static compression ratio becomes 20:1 before you factor in volumetric efficiency. 90% is a good starting point for Max RPM. With that you get a dynamic compression from a 14:1 Static CR with 90% VE and 96% effective compression, 12.096:1 at full throttle opening.

Now you're going to have to help me out with this one. Unless there is a major jump in energy efficiency from 9.5:1 to 14:1 Static CR that increases fuel efficiency 45% higher you're not going to see equal fuel economy. The only people I've seen running E85 have been getting almost EPA figures. Which we know is not as high as a certain vehicle and engine can get on the road. Also an engine that gets 45% higher energy efficiency is generating 45% more Power from a given amount of fuel. So we know that even if this was true the load decreases with power and fuel efficiency goes down. The only solution I found was of cutting the engine displacement to raise the load and increase the effective fuel efficiency. But to really get good fuel economy you need tall gearing and high load at cruise. Most engines are low load at cruise to allow for more available power during acceleration. The only way to increase available power is to increase compression which is not as effective with gasoline beyond 10:1, upshift or shorten gearing while upshifting is temporary it does cut down economy and gearing can be worked around with wider or more gearing, or go turbo which besides even worse fuel efficiency per unit of power a turbo is generally worse for gasoline than any other option due to the Static CR drops too far below the Ideal Compression for even gasoline.