[Roadsters] What is in todays fuel that makes everything gum up?

[Scott Ulrich]

Good to know. I remember from my street racing days that some of the people
*said *they were using avgas to fill up because you could get higher
octane. But as with everything else Street Racing related, I knew that 90%
of it was probably just big talk.

There were (maybe still are?) some gas stations around that sell "racing
fuel" - which was something like 105 or 110 octane. But again this may have
been just a marketing thing: regular fuel with some off-the-shelf additive
in it. The only people I ever saw filling up with it were Valley-Rednecks in
their jacked-up (or slammed) trucks. Certainly nobody that actually had a
ultra-high compression or forced induction - just a lot of forced-attitude.

When I worked for a guy who raced for real, in IT-S class, we just used
regular pump gas. But then those were theoretically stock engines. (How the
RX-7 guys got away with their gigantic extra ports while still passing
inspection, we never exactly knew. Hey, sure - every street rotary goes
blaaat-blaaat-blaaat when it idles..)

Other, higher-up classes certainly must have been using "real" racing gas
though. So I suppose that could be an option, if its stable and you know
where to get it. Also a good excuse to up the compression to 11:1 to take
advantage of the extra octane you're putting in. Again I'd differ to the
list - anyone know the scoop on the various forms of "racing" fuel?




On Mon, Sep 21, 2009 at 7:39 AM, Jim Gammon <gtpjimgammon at yahoo.com> wrote:

> Actually, Avgas (typically 100 LL) is a completely different thing. It is
> not a straight distillate, but a reprocessed "alkylate". The specification
> ASTM D910 requires it to have virtually no gum content, because aircraft
> often sit long periods between flights.
>
> JimG
>
> --- On *Mon, 9/21/09, Scott Ulrich <scott8933 at socal.rr.com>* wrote:
>
>
> From: Scott Ulrich <scott8933 at socal.rr.com>
> Subject: Re: [Roadsters] What is in todays fuel that makes everything gum
> up?
> To: "datsun-roadsters: autox.team.net" <datsun-roadsters at autox.team.net>
> Date: Monday, September 21, 2009, 1:24 AM
>
> My quick and dirty research also turned up Stabil the popular solution.
> Option (2): using AV gas which is said to be guaranteed for a certain
> length
> of time before degrading. I'm sure a pilot on this list could give the
> specs
> on that, though I've also heard its not as easy as it used to be to buy gas
> at the airport.
>
>
> On Sun, Sep 20, 2009 at 9:37 PM, Jim Gammon <gtpjimgammon at yahoo.com<http://us.mc511.mail.yahoo.com/mc/compose?to=gtpjimgammon@yahoo.com>>
> wrote:
>
> > Stabil ought to give you 6 months anyhow
> >
> > JimG