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· Premium Member
5,665 Posts
70429scj said:
What octane will I need with this dynamic ratio?
This is a very, very vague question and sort of a loaded question as a result...there are so many variables, but generally speaking (going by D/C/R alone), you will need at least 92-94 octane.

Give us more info if you want a more accurate answer...


· Registered
2,672 Posts
Dynamic compression is calculated by....

the static compression built into the motor and the closing point of the intake lobe on the cam. Example: 13 to 1 compression and Crane's 308 adv. duration solid cam with a closing intake point of 80 degrees gives you a dynamic compression of 8.97. For that combo you're going to need 100 plus octane. Also, if the heads are aluminum or cast iron will effect the octane requirements as well as the quench action taking place in the chamber during combustion. Give us your engine combination to ballpark the estimation.
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