Chip Louie wrote: Hi Peter, Actually increasing the octane level is used to delay the onset of detonation or predetonation of fuel in the combustion chamber. Increasing the octane number of gasoline ideally should not delay flame propagation in the combustion chamber, only the point of uncontrolled detonation. Modern combustion chamber designs and materials are much more tolerant of high compression than the older, say 1995 and earlier designs. Almost all high performance combustion chamber/piston designs are capable of between 1-1.5 points higher compression ratio for a given octane number than these older CC designs were capable of suppressing the onset of pre/detonation.
I know something about engine management software. I taught Aaron Neumann (one of the principals of the highly regarded company Neuspeed and APS the distribution arm), how to modify the engine management programs in Bosch FI systems over 14 years ago. Even way back then there was already a fall back for low octane fuel in the engine management programs. This subroutine has propagated to even the lowest level of automobile engine sold in the USA due to emissions warranties here in the states. ------------------------------------------------------------------------ ------------------ Hi Chip, I can only speak from 60s hot rods, I bring the newer stuff to a local mechanic. You are correct, the term I used was combustion but it is detonation. Newer designs are much more sophisticated than the older engines I am familiar. The ones I worked on had only hardware and not even electronic ignition, they used a funny thing called points back then. :-) If I try running regular in my 69 Camaro RS SS, it runs like crap. Hi Test is fine but still I use octane booster. Samd with my motorcycle, requires 91 octane min. 87 works but the engine is a bit nosiers and with only 2 cylinders I would rather spend a few cents more on gas than several hundred on repairs. Peter K * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
