I have a 383 with 10.5 to 1 comp about 550 HP. I have been running av.gas 100. My question is is it worth it to change to E-85 or just stay with the Av. gas.

My answer is: it depends on what you want. Do you want to go quicker ? Try to be more consistent ? Save money on fuel cost ? Are you just bracket racing or trying to get more power to fit a certain class ? Or what ?

You would most likely need to get a new carb that would flow enough to use E-85. May also need a different fuel pump. All E-85 is not exactly the same from batch to batch or station to station, there can be variations with the ethanol content and water content.

My 2 cents: If you are just bracket racing, have easy access to buy the Avgas, are running consistent and winning rounds. Then I would just stay with the Avgas.

I ran Avgas for a long time in a big block chevy with 14:1 compression and won lots of rounds and races with no issue or damage to parts.

Just my opinion.. I've run AV gas and it worked well. I would not hesitate to switch to E85 with a good carburetor. It's easy to obtain in my area 24 hrs a day, AV gas isn't as easy. It's definitely cheaper then running AV gas once you have the carburetor and fuel system. The engine temperature is simpler to control and no cooling between rounds usually, It's proven to be consistent.

We ran pump E85 for a couple of years. Always tested it & it ranged from E70-E85. No issues with consistency between the blends & didn't change the tune-up.

I did change to VP X85, just to try & see if I was missing out on something. No change in performance & ran the same tune as the pump E. It was cheap enough back then just to buy 5 gal. pales; it was around $40.

The number one thing we found for consistency is to stage with the engine @ minimum 170*. We did no in between round cooling & very rarely used the electric fan. Our track is in Las Vegas & we mainly race mid-day.

I've been considering going back to X85 on our supercharged combo.

2BKING