[Shotimes] RE: 10% Ethanol and A/F ratio

[Ron Porter]

As I understand, this is one of the key reasons that every engine built in
at least the last 15 years or so has the tuning to run on 87 octane, even
Z06 Vettes and Vipers. You don't know the quality of gas that you are
getting, and as you drive around the country, some place (like west Texas as
an example) only have 90 octane off the interstate. And every now & then
stories still come up about stations getting caught putting 87 in the higher
octane tanks.

I can understand if they bring out ethanol fuel with higher octane, but all
else being equal (like octane), alky blends can't perform better.

Ron Porter

-----Original Message-----
From: shotimes-admin@autox.team.net [mailto:shotimes-admin@autox.team.net]
On Behalf Of Rich Bruso
Sent: Wednesday, February 15, 2006 2:18 AM
To: ronporter@prodigy.net; SHOtimes@autox.team.net
Subject: Re: [Shotimes] RE: 10% Ethanol and A/F ratio

>Besides not believing that, I was trying to think "how" a
> car could be tuned to raise it's efficiency on alky
> rather than gas. Seems that any tuning tricks that would
> work for ethanol would also work for a gas engine.

   The tricks do work for gas engines.  180 proof Ethanol is roughly
equivalent to 110 octane gas.  In theory, if you use a good octane base fuel
for the 15% gas and don't allow for non-ethanol fuels, you can bump the
static compression ratio and maximum timing advances.
   One major problem: Joe Blow consumer, trying to run Mexican (I'm by the
border, it happens) 85-ish octane regular in a 12.5/1 CR motor.  So, I don't
picture production E85 motors to go for the gusto with static CRs.
   If you're building it yourself, and you have good sources for fuel, you
could gain back some of the ground lost by going to ethanol with a higher
static CR.  Of course, if E85 isn't your thing, that same static CR with
strait gasoline (at the appropriate octane level) gives even more power.
Just don't let the kids fill the tank with the cheap stuff.

-Rich Bruso
89 Black (Lola)
89 Silver (parts)
Sierra Vista, AZ
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