Quote:
Originally posted by Jake Raby
CHT is not impacted by octane..( I can show you on the dyno or any one of my cars).. The lower octane has a lower threshold for knock and does damage if detonation occurs. You can see the impact that octane has on the engine by monitoring the EGT and the threshold of detonation with varying fuel grades.
Many people do not understand that the same engine that runs good on 87 octane with lower CR, may run WORSE on 93!! When going up in octane the viscosity of the fuel changes and a jetting change is needed. The higher octane matched with lower CR almost always runs rich without a vast amount of timing to help burn it all BEFORE the exhaust valve opens..... thats why it impacts EGT so much..
Its ALL in the combo, and fuel is part of the combo that must be considered when designing the engine.
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You're assuming carburation when you talk about a jetting change, correct?
Aaron
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Silver 1998 Volvo S70 T5 <- Daily (Anja)
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