E85 mix with 87 octane

[GMTECH12002]

Is there a nifty calculation to figure out approximate octane when mixing e85 with 87octane? Also i am reading on the forums that only about 80:20 is a safe mix without fuel upgrades, is that the safe limit?

 

[Rafs-T-Type]

You should read some of the stickies in the E85 forum. As far as an octane calculator some simple math will get you there. For a 80/20 mix assuming E85 is 105 octane you would take (105x80%) + (87*20%) = 101.4 octane.

If you meant 80 percent 87 octane it would be (87x80%) + (105x20%)= 90.6 octane

 

[GMTECH12002]

Thanks for that formula that will help me, so is 20% e85 with 80% gas the safest maximum mix with a stock fuel system and stock engine

 

[Rafs-T-Type]

No engine is safe with the stock fuel pump even with straight 87 - which you should never use to begin with. You should be filling up with the best octane available at the pump - 91 or 93. Also you will max out your injectors real fast when you start dipping in to E85. If you don't have anything monitoring what's going on with your car - such as a scanmaster or powerlogger you shouldn't be messing with anything. If you have no way to monitor or check for engine knock and you start turning up the boost you will probably blow your engine or at least the head gaskets. If you have no way to monitor or check for engine knock and you start turning up the boost you will probably blow your engine or at least the head gaskets. Yes I know I put that sentence twice. I want to make sure it settles in.

 

[GMTECH12002]

Ok. Where to start??? Hmmm, first thanks for your input, I appreciate your
Concern for my head gaskets and engine, however I am not stupid, I know what knock and detonation are, I do know how to use the proper 93 fuel, but I also know I can mix some e85 in with gasoline and get a little better fuel to run in my car, now as I plainly ask, is 20% e85 safe or not, if not then sounds like there are a lot of members here that need to read this post, Warning Warning Warning. Back in about 93 or 95 I tuned an 87 gn into the 12's without a knock gauge or scan master or wide band o2, so let's skip past the really newbie stuff and assume that if I lean the engine out I will know it, and am willing to pay the consequences

 

[Rafs-T-Type]

Not with the stock fuel pump.

 

[GMTECH12002]

Ok so I throw a walboro 340 in then I can consider adding 20%e85 or do I need an adjustable regulator also?

 

[phil_jordan]

You'd actually need both....

 

[GMTECH12002]

I was just ready some old posts a it occurred to me that I can be an ass, so for all of you that help on this forum and put up with asses like, thanks

 

[turbo nasty]

IMO mixing the 2 fuels isnt worth it as the burns rates and BSFC numbers are different. If you are looking for more octane then get 93 and alky, racegas or setup your fuel system for E85 as mentioned.
Bottom line ...you have a turbo car that will pop headgaskets and hammer rod bearing that being either or both together.
So dont screw around with mixing.
Back in the day I use dto try and mix Toluene and then race gas with 93 to get high boost.....what I wound up with was a cluster f$%# mix and sometimes it would work and asometimes not.
And when you hear ...pling pling...clank clank...boom then well...... You found the limit and now its expensive.
Best bang for the buck for a 11.00 ish or slower car that cuts 1.7 or worse 60' foots is alky and 93 and its gets street driven...not track star.. garage whore ....trailer queen...lol

Good luck