 Engine Modified: What is the highest compression for 93 Octane?, engine mods, compression, 93 octane |
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| Stark 01 |
 Aug 28 2015, 10:54 AM
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#1
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Racing newbie  Group: Members Posts: 43 Joined: 26-May 14 From: Concord, NC Member No.: 17,404 Region Association: South East States  |
Hi everyone,
Those of you who have built up a Type IV 2.0 with higher compression, what is the safest compression ratio to use 93 octane pump gas? |
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| toolguy |
Aug 28 2015, 02:32 PM
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#2
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Senior Member Group: Members Posts: 1,268 Joined: 2-April 11 From: San Diego / El Cajon Member No.: 12,889 Region Association: Southern California 
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Forget about piston compression ratio. . which does not take into account ignition timing, cam design, cam / valve timing, lobe overlap and separation, all of which reduce maximum designed piston compression ratio. .
Take a compression reading and see where the motor actually is. . anything around 160-175 is still pump gas. 150 or lower is definitely regular gas. Modern engines can run lower octane, but remember they have ECU's with sensors and do all sorts of magic to get reliability and mileage on cheap gas. My 69 Z-28 had 220 psi , factory rated at 11:1 compression, and wanted 98 or better back in the good old white pump Chevron days. 9.5 : 1 should be good on premium gas these days. |
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Posts in this topic
Stark 01 Engine Modified: What is the highest compression for 93 Octane? Aug 28 2015, 10:54 AM
RoadGlue This question invokes a bunch of other questions. ... Aug 28 2015, 11:57 AM
Stark 01
This question invokes a bunch of other questions.... Aug 28 2015, 12:11 PM Dtjaden I'm running a 2056cc engine with a Web Cam #86... Aug 28 2015, 12:25 PM yeahmag I strongly disagree with the above. Go with the CR... Aug 28 2015, 06:06 PM Dave_Darling Yup, unless you are really significantly changing ... Aug 28 2015, 06:23 PM |
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