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how much compression i need 11.54 or 12?

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Old 04-22-2006, 01:00 PM
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Default how much compression i need 11.54 or 12?

i will be running a 402 with -2cc diamond pistons i calculated the compression and with the GM 0.056" head gasket i will get 11.54 compression with the 0.040" fel-pro i will get 12 compression. i will use the TSP Giant cam : 248/254 0.622"/0.614" 112lsa 110icl. what compression is adequate and streetable with this cam? i can use up to 98 octane unleaded fuel.

thanks for help.
Old 04-22-2006, 01:42 PM
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The bigger the cam, the more compression your gunna want to help tame it. Not to mention, more compression equals more power. If you don't mind using 98 octane, I'd shoot for at least 12, but possibally 12:5.
Old 04-22-2006, 01:50 PM
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i will shoot then for 12 compression. what about the heat? will the motor be hotter with more compression?

thanks.
Old 04-22-2006, 02:00 PM
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yeap, it will raise the DCR as well. Be careful running that much compression in our Summer heat.
I would keep the DCR at 8.5 max unless this is a drag only car on cooler nights.
Old 04-22-2006, 03:01 PM
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i'm going to use a Griffin radiator that can support 600 hp so i would guess that i'm safe to go to 12 compression, what do you think PREDATOR-Z?
Old 04-22-2006, 03:31 PM
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With 98 octane, 12 to 1 should be a joke. Not to sure about you guys's heat, but the south gets pretty damn rough and people go 12 and over all the time on 93.
Old 04-22-2006, 04:03 PM
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I'm not sure, but I know Saudi Arabia uses a different system of octane ratings than we do. Their "premium" grade is around 95, but when measured under our system, it's the equivalent of our 91 octane. If you're not sure on this, make sure and verify that before deciding. 12:1 is ok with our 93 octane, but you're close to the limit even with a big cam like that. You probably won't be able to run much timing advance without running into pinging and detonation.

Jason
Old 04-22-2006, 04:56 PM
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I would think you can run 12:1 with a qualty 98 octane gasoline. Reducing the quench by using a thinner headgasket will also aid in making power. With a .040" headgasket, I'd make sure that the pistons aren't out of the hole...at all.
Old 04-22-2006, 08:55 PM
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the heads are hand ported AFR 205 heads with 2.055"/1.60" valves. the -2cc diamond pistons are around 0.006 out of the hole. TSP told me that i won't have PV problems with the TSP Giant cam even with a 0.040" head gasket.
Old 04-22-2006, 09:12 PM
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Its their cam and they should know but I would check to be sure.
If you have a true 98 octane compression under 13.0 should work fine.
That is some good gas.
How much is it per gallon?
Old 04-22-2006, 11:07 PM
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we have 90, 95 and 98 octane unleaded fuels. the 90 fuel is for 60 fils per liter or about 20 cents per liter or $ 0.75 per gallon. the 95 fuel is 65 fils per liter or about 22 cents per liter or $0.83 per gallon. the 98 fuel is for 90 fils per liter or 30 cents per liter or $1.13 per gallon.

Last edited by Abdullah; 04-22-2006 at 11:28 PM.
Old 04-22-2006, 11:18 PM
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I have a feeling the South doesn't get nearly as hot as those guys get. I work with poeple that spend alot of time in the UAE, Qatar and Kuwait and I've heard it's pretty bad when you're looking to find shade under a camel (not meant in any dispareging way)

I'm not sure about the humidity though...I think our South might have them there.




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