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compression ratio vs. octane?

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Old 08-25-2008, 11:10 PM
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compression ratio vs. octane?
whats the highest compression ratio I can safely run with 110 octane race gas on the LT1? and the same with 112?
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Old 08-26-2008, 02:40 AM
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Some people on here are running 13:1 on 93 so id say "safely" 15:1? Just a shot in the dark really, im sure someone is much more knowledgeable then me on the topic.
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Old 08-26-2008, 05:19 AM
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You need to calculate the dynamic CR, not the static CR, to determine the octane requirement.
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Old 08-26-2008, 10:11 AM
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13.1/14.1 but really get a calc. you need to be exact.
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Old 08-26-2008, 10:32 AM
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why you need to max it out for
just run like 14:1 and tune it on 112
Mine is 13.7 and I tune it on 112 unleaded and it runs very safe
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Old 08-26-2008, 07:39 PM
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Originally Posted by Injuneer
You need to calculate the dynamic CR, not the static CR, to determine the octane requirement.


Im running 12.1:1 compression on 93 octane on the street in Southern Mississippi/Eastern Lousiana, heat in traffic with the AC blasting with no problem its all in the DCR and Ed Wrights tuning wizardry...
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Old 08-26-2008, 10:45 PM
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Originally Posted by rock1501
why you need to max it out for
just run like 14:1 and tune it on 112
Mine is 13.7 and I tune it on 112 unleaded and it runs very safe
I'm not trying to max it out, just kind of get an idea where the limit is so I can stay a little below it to be safe. Thanks though.
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Old 08-27-2008, 10:02 AM
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Originally Posted by Injuneer
You need to calculate the dynamic CR, not the static CR, to determine the octane requirement.

too many people get caught up discussing scr...
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Old 08-27-2008, 10:19 AM
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Exactly. SCR is only what people normally just throw out there when talking about compression. DCR is where it's at. I don't know what's safe for that much octane but use about 9:1 DCR as your maximum for 93 octane.
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Old 08-27-2008, 07:26 PM
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Originally Posted by rock1501
why you need to max it out for
just run like 14:1 and tune it on 112
Mine is 13.7 and I tune it on 112 unleaded and it runs very safe
What brand of 112 unleaded do you use?
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Old 08-27-2008, 10:37 PM
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not 100% sure but I think my local track carries sunoco. and how car I calculate dcr?
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Old 08-28-2008, 01:00 AM
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Originally Posted by Injuneer
What brand of 112 unleaded do you use?

http://www.proracingfuels.com/Product_MARK4.html
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Old 08-28-2008, 10:58 AM
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Originally Posted by rock1501
nice stuff. what's it cost you in Canada?
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Old 08-28-2008, 11:12 AM
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Originally Posted by SS MPSTR
nice stuff. what's it cost you in Canada?
Its not cheap
about 65 bucks for a 5 gallon container
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Old 08-28-2008, 01:43 PM
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Originally Posted by rock1501
Its not cheap
about 65 bucks for a 5 gallon container
VP 109 is the same here.
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