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Old 04-24-2013, 10:08 PM   #1
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Max Compression Ratio w/ 91 octane

So I was looking at which compression ratio I want to go with. The block is iron. I can do 11:1 compression ratio no problem an below. I've been told 11:1 is too much for 91 octane and I've been told that it is fine. What is the ideal CR for 91?
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Old 04-24-2013, 10:17 PM   #2
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So I was looking at which compression ratio I want to go with. The block is iron. I can do 11:1 compression ratio no problem an below. I've been told 11:1 is too much for 91 octane and I've been told that it is fine. What is the ideal CR for 91?
Depends on the ignition timing, ( aka spark advance ) and cylinder head temperature.
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Old 04-24-2013, 10:42 PM   #3
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Why not run 93?
Or are you unable to get it in your area
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Old 04-24-2013, 11:21 PM   #4
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All depends on the tune.
WAY too many variables to give an answer to this question.

I could make 14:1 compression run on pump gas if need be....
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Old 04-25-2013, 01:10 AM   #5
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Quote:
Originally Posted by jhobbins
Why not run 93?
Or are you unable to get it in your area
Nope, we don't have 93.
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Old 04-25-2013, 01:13 AM   #6
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Nope, we don't have 93.
I'm sure some place has it. Most pumps are 91 max in my town too but there is always one that has 93
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Old 04-25-2013, 01:46 AM   #7
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https://foursquare.com/touch/v/rebel...64a5204ada21e3

How far are you from here? They have 100 octane you could mix with 91 or just run straight if you can afford it.
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Old 04-25-2013, 02:02 AM   #8
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Quote:
Originally Posted by jhobbins
https://foursquare.com/touch/v/rebel...64a5204ada21e3

How far are you from here? They have 100 octane you could mix with 91 or just run straight if you can afford it.
There is a rebel around the corner from my house with 100 octane, but this is going to be my DD so I dont want to go above 91 or 93
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