This "slow burn" thing has me wondering-is it unique to ERC fuel or typical of
all the higher octane stuff.Is there some spec or number published by the mfg.
that tells us what the burn rate is?Very interesting-never really thought about
it much before.
Tim Schoeny
ardunbill@webtv.net wrote:
> Very interesting and comprehensive presentation Dave, lots of good
> thoughts there, worth saving.
>
> The item about some degree of detonation in highly stressed
> blown/nitrous engines is a good point, undoubtedly true, and it must not
> become excessive or damage will result.
>
> Another interesting point is that the fuel octane must suit the
> compression ratio, the very high octane gases do not work well with low
> compression ratios. This was demonstrated at Bonneville a few years
> ago, when Marty Dickerson brought his Vincent out to run in Vintage
> Pushrod class, in exactly the same form as in '53 (probably most if not
> all the same parts!) when he took the AMA 1000cc Class C gas "naked" (no
> fairing) record at 147 mph. Class C at the time restricted you to 8 to
> 1 compression (this is real ancient history). Same bike, same man (and
> this is a lion of a man), now he has to use ERC spec gas at Bonneville,
> and the bike would only do a little over 125 mph. He told me it was the
> spec gas, the octane was too high for the compression ratio, it burned
> too slow, didn't push hard enough on the pistons. No matter how much he
> advanced the ignition timing, he couldn't get it to detonate audibly,
> which told him the tale. The old-timers, in the pre-data-collection
> days, tuned their bikes by advancing the timing until they got
> detonation, then backed off a tick.
>
> I'm going to send your paper to a few of my off-List friends. Cheers
> Bill
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