Thread:

12.5 to 1 compression / 6-8 psi boost / on E-85.....doable?

So.....short of converting to alcohol, can 105 octane E-85 handle this high of an initial compression ratio AND a blower (8-71) setup for say, 6-8 psi of boost? Let's also say I would limit the total timing to 30 degrees. Jocko

(Of course the other alternative is a 200-250 shot of NOS, but I prefer blowers)

Originally Posted by gn7

jocko, like Hass said, Unchained is running upwards of 30# boost and a effective compression ratio in the nieghborhood of 35 to 1, and your closer to 18-19 with 8# boost. Mark is running a pretty wide LSA, and a fairly short duration compared to a roots deal. he does have a built in exhaust gas recycler that helps.

I think maxi is running a roots with less compression but more boost, but I think his effective ratio is still higher than your asking.

Thanks Bob. All this info now makes me more comfortable in throwing a blower on this new racer I bought. It's just hard to break old (somewhat conservative) build habits. Virtually all of my previous blown gas deals were built for longevity (ski race/lake racer style), being 461-468", 8.5-1 compression, fully studded, o-rings, Carillo rods, quality steel crank, 6 or 8-71 blower @ 12-18% over, on Av-Gas or 50-50 mix with pump gas. No complaints, these motors always made between 750-800 HP and would last for several seasons of lots of use per weekend. I've never deviated from this combination.
So.....I'm not ruling out nitrous, but I will be looking for a blower setup and then will modify my carbs for E-85. What's cool is the fact that 105 octane E-85 is literally sold at every gas station in Minnesota, Iowa and Wisconsin for under $3.00 gal. Thanks again guys, Jocko

This last summer we did...

10:1
14lbs w/8-71
400hp of nitrous

all on straight E85 with no intercooler, worked killer!!

High compression and E85 would be the only setup I would consider if for some odd reason I wanted to do something roots. That thing will be angry!.....and tons of fun! I wouldn't hesitate for a second with what you are planning on E85. Only reason you might rethink doing it would be to save yourself all the regret for not doing it sooner!

Andrew

Just curious are you guys talking E-85 out of the pump from the local BP or E-85 race fuel from a drum? Here in corn country E-85 is available everywhere, but I've heard from the pump its pretty inconsistent from tank to tank in terms of actual octane rating. This wouldn't matter to a flex fuel auto, but for the applications discussed above it certainly could.

Thanks,

Craig

Originally Posted by WETTE VETTE

Just curious are you guys talking E-85 out of the pump from the local BP or E-85 race fuel from a drum? Here in corn country E-85 is available everywhere, but I've heard from the pump its pretty inconsistent from tank to tank in terms of actual octane rating. This wouldn't matter to a flex fuel auto, but for the applications discussed above it certainly could.

Thanks,

Craig

out of the pump. I've heard of people talk about race E85, but never met anyone using it. The pump stuff isn't as inconsistent as people say, and most E85 guys aren't looking for a race fuel to run their full race engines right on the edge with. Most are avgas or 50/50 mix guys looking for a better option. If you can put pump E85 on the edge of disaster why wouldn't you just go to methanol? you would clearly be running an engine so over the top, that you might as well.

E85 out of the pump has the ability to do anything a lake hot rod guy could want. I would definitely ALWAYS run a wideband O2 for tuning anything (especially carbs) on E85, simply because there aren't as many people that are familiar with it, and it ensures you make the right changes needed to get it running right.

I would put money on it that the majority of engine failures on E85 are tune related, not E85 quality related.

Andrew

Originally Posted by MAXIMUS

So far I have not seen any major consistency problems for the pumps.

This is exactly the info I get from the people that ACTUALLY test the fuel. I always HEAR the inconsistency claims from people that hate on it, or just don't know much about it, because its definitely a common rumor.

That is pretty impressive. Now aside from the obvious like fuel delivery capacity and a carb re-tune what else needs to be converted so one can run e-85? Do the fuel pump seals need to be changes? How about braided fuel lines and an aluminum fuel tank? Are they compatable? Just like what I've heard about the fuel consistency I've also heard the corrosive nature of E-85 requires all of the above to be compatable which could add up quickly $$$ on a boat with 3 fuel pumps, two tanks and the plumbing / valving to make it work.

Thanks,

Craig