I ran 1500 street and strip miles in a 12.2 C.R. Chevy Big Block on LL100
aviation fuel back in '85. Never had a problem with the engine. Exhaust
odor was very irritating to eyes and smelled alot different than pump gas
does. You'd catch a whiff when you stopped at a stop sign and the wake of
air behind the car rushed up beside it. Left bluish haze on bumper above
both tailpipes. It was used as a cheap alternative to racing fuel. The
reason this engine was probably fine on the stuff was that the carb (Holley
800 DP) was tuned specifically for it by a locally renowned racing engine
tuner who knew what to make different knowing that I planned to use LL100.
He'd done it before and knew what to look out for. I've heard that LL100
needs to be run richer to avoid burning pistons. Back in '85 the volatility
was not a problem even though I used a mechanical pump and the engine needed
fed enough fuel to make 450 hp or more. Nowadays even pump gas is so
volatile that if temp is a little unseasonable my daily drivers with
mechanical pumps bog out after a few seconds of WOT. Maybe LL100 is even
worse now, I don't know.
BTW, I don't recommend anyone run 12.2 C.R. on street anyhow. It was what I
had to work with at time, but I'd never build an engine that way to drive on
street alot now.
Mike
> You don't want to use avgas in an automobile engine. Especially
> one driven
> on the street. One, the vapor point is different. It is designed for an
> engine that is run at low rpm, and at a constant rpm at that. Auto engines
> need easy starting at all temps, high vapor point to prevent
> vapor lock, and
> an auto engine varies rpm over a much wider range and runs at higher rpm.
> It needs to burn quickly enough at high rpm, yet have high anti-knock
> capabilities. Aircraft engines turn a steady 2400 rpm, rev slowly and have
> maybe 8.5:1 compression. Avgas is designed to run clean in these
> conditions.
> It can't operate properly in auto engines with compression ratios
> exceeding
> 11:1 and running 3x the rpm. Plus, in aviation engines the a/f mixture is
> adjustable. Avgas has a different specific gravity and will not meter the
> same in auto fuel systems.
> Plus 100/130 avgas is LEADED.
> Want high perf auto fuel? Buy it.
> And I deal with 800 hp racing engines. You will make more power, more
> reliably in an auto engine with mogas.
> Now, the 80 octane IS mogas, but it is also leaded, and your aircraft must
> be certificated to be run on such.
> Plainly stated, avgas is not designed to be run in auto engines.
>
> A few cents saved on fuel can cost many dollars in engine repair later.
>
>
> Jon
> STL MO
>
>
This archive was generated by hypermail 2b29 : Mon Mar 01 2004 - 00:34:03 EST