View Full Version : What octane 9.5:1 comp?
miike
04-29-2013, 02:53 PM
Iron heads, forged internals 502.
Thanks
BUIZILLA
04-29-2013, 02:55 PM
minimum of 93...
Carb motor? Premium 93 or whatever you can get. Programable efi? You can probably run less octane.
miike
04-29-2013, 04:05 PM
Carb, no anti knock sensors
joseph m. hahnl
04-29-2013, 07:13 PM
Depends when the intake valve closes.
http://classicinlines.com/CompressionRatio.asp
Not recommended
Regular 87-89
Supreme 89-91
Premium 91-93
Race Only
below 7.0
7.0-7.7
7.7.0-8.4
8.4-9.1
above 9.1
The ideal DCR range for a performance motor on pump gas is 7.5 to 8.5
roadtrip se
04-29-2013, 10:19 PM
Running 93 with 10 to 1 on a MEFI3 system. Might be worth looking into aftermarket EFI...
pipnit
04-30-2013, 01:28 PM
with those heads I would guess 93 or higher as people mention. Spend some $$$ on some aluminum heads and you can go a lot lower. I'm at 9.5:1 and run 87 octane with AFR heads and no problems what so ever. 87 is all I can find at the docks around me. At least it's not ethanol gas...
tmdog
05-01-2013, 10:08 AM
9.7:1 with AFR alum. heads, 93 octane only.
miike
05-01-2013, 10:39 AM
Sounds like I want 93 then...
Don't want aluminum heads, I run salt with no FWC
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