Hi Bill,
I suspect that if you run the same gas blown and unblown and if it is
"safe" detonation-wise in the blown engine, it will be the wrong fuel for
the unblown engine. Probably will be too slow a burn rate. This, to a large
degree, depends on the compression ratio on the unblown engine......if it
is around 15 (or so):1 the same gas might be OK. To illustrate this, I have
learned that if we had run the next higher octane rated ERC gas instead of
110K in Bill's unblown BBC last summer, we probably would not have hurt the
valves, rings and heads. The EGTs would likely have been in the ballpark too.
I really don't think that it is smart to run a blown engine with gas that
is correct for an unblown engine. It would probably not have pistons and
rod bearings left afterwards.
What might be helpful is if ECTA ran ERC fuel so the tune-up could be the
same (with altitude changes) at B-ville. Kind of fits with the "use one
fuel premise".
Skip (I had a long and enlightening discussion with Rick Gold of ERC on
this subject just yesterday)
At 12:16 PM 3/3/02 -0500, you wrote:
>Hi Folks, if you don't mind could we kick this topic around a little, it
>does matter to me and is "my business" because I plan to run my Ardun
>blown or unblown in the future on gas only.
>
>I am aware that a variety of approved spec gases have been available at
>Bonneville for years, and they seem to have various characteristics. In
>a race gas I imagine we want a certain octane and a good power, with no
>harmful detonation under the conditions of use. Note I said "harmful"
>because there is slight detonation that causes no harm, and severe
>detonation that breaks parts.
>
>
>I have heard rumors that there is sometimes confusion about what gas to
>use, from the selection available, and if people choose wrongly, they
>may wind up with detonation damage in highly stressed engines.
>
>Now it comes that VP gas will be available at ECTA, which is not a bad
>thing because honest records should be set with one definite approved
>fuel. I don't know if more than one spec VP gas will be offered at
>ECTA, but I am of the opinion that ONLY ONE should be offered, and the
>same gas should be offered from now on, to simplify tuning and engine
>prep for everybody who uses gas.
>
>I don't know if NASCAR permits more than one spec gas at their meets,
>but I think it would be best if they did.
>
>At the historic Isle of Man T.T. motorcycle races, the great tradition
>was that one fuel only would be supplied to all competitors, for many
>years it was 100 octane premium pump gas (petrol they preferred to call
>it), but it may be some spec race gas today, if so, everybody uses the
>same gas.
>
>I personally dislike the idea of a "guessing game" about choosing which
>of a range of options will work best in my engine based on what I
>"think" the fuel rep is trying to tell me and how I must tune for it.
>
>The thoughts of those experienced in dealing with this issue at
>Bonneville or elsewhere will be appreciated. Come on lads, don't ignore
>this now!! Cheers Ardun Bill
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