what compression is needed for 91 octane

[mopar3401987]

So I am living in San Diego and the highest octane at the gas stations is 91 my 73 340 has 10 to 1 compresstion I have been mixing race gas but I am really tired of paying 8.99 for a gallon of it I looking into maybe doing some head work to reduce this need for mixing gas . what compression ratio would I need to safely run 91 octane ?
Running out of the box air gap intake and rpm preformer eddy heads with a Hughes whiplash cam

 

[RustyRatRod]

You should be fine with that cam and the aluminum heads on 91.

 

[oldkimmer]

..............that's what I think also..........how much timing u running...............kim.........

 

[Abodybomber]

I live in Cali, feel the same way.(91 Cali pee water sucks...) However, that is too vague a combination, to recommend a clear answer. How about more info, on the combination? ( makes for a more concise response..) Let's, start there.....

 

[famous bob]

I live in Cali, feel the same way.(91 Cali pee water sucks...) However, that is too vague a combination, to recommend a clear answer. How about more info, on the combination? ( makes for a more concise response..) Let's, start there.....

agree w/ rrr and kimmer,I run alum. heads 10.3 c.r. on 91 oct, no problem. timing is everything!

 

[SRT_DSTRHOLC]

Around 8.6 dynamic compression, static means nothing if you have correct camshaft

 

[mopar3401987]

I am running 36 degrees total timing I have tried to run 91 in my car and I get spark knock so either my compression is higher then 10 to 1 or the gas I am buying is not 91 octane... I going to test my cylinder pressure to see what's up . does any one know what cylinder pressure I need to run 91?