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

[Jerry Krakauer]

Back in the late 60s, my first BSR built U20 used domed R16 pistons and a 
milled head for a compression ratio north of 12.5:1. (the second and current 
build is 11.7:1)The only street fuel it would run on guaranteed not to knock 
was Sunoco 260. If  I recall it was around 102 octane - around 95 - 96 by 
today's R+M/2 method. We sometimes used 100/145 av gas - (122.5 octane 
R+M/2). Due to the fact that it had no highway fuel taxes you could not 
legally just "fill it up" had to use 5 Gal containers, and most general 
aviation airport operators were in an industry that liked to follow the 
rules.

In the northeast Sunoco still has some stations that sell Sunoco Racing 
Fuel(formerly known as Cam 2) with an octane in the high 90s, but since it 
contains lead, again you can't just fill it up, must be purchased in 
containers, and the nozzles are still the older larger diameter so they 
won't fit a modern fuel neck.

Jerry Krakauer
SRL311 00099
----- Original Message ----- 
From: "Scott Ulrich" <scott8933 at socal.rr.com>
To: "datsun-roadsters: autox.team.net" <datsun-roadsters at autox.team.net>
Sent: Monday, September 21, 2009 12:06 PM
Subject: Re: [Roadsters] What is in todays fuel that makes everything gum 
up?


> 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?