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Is 8.7:1 low enough turbo 202?

Started by _rb3torana_ , Jun 11 2012 10:26 AM

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14 replies to this topic

#1 _rb3torana_

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Posted 11 June 2012 - 10:26 AM

Im wondering wether 8.7:1 comp will be low enough for what I want to do. My setup is 202 blue, duralite pistons, starfire rods arp bolts, stock blue head, aussiespeed manifold, 650hp holley modded for blow through, custom exhaust manifold, 50mm gate, gt3582r 0.82 turbo, powerglide 3500rpm stall. I want the setup to go around 115mph in a uc torana (times wont be great 13"tyres).
I know you get away with this much comp with an rb30 which Ive done before. But just would like to know wether it will be ok with a holden 6. Im figuring Ill have to run around 15psi to acheive my goal. Let me know on your thoughts. Cheers

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#2 _Bomber Watson_

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Posted 11 June 2012 - 10:32 AM

Should be fine mate. 15psi on 9:1 is a reasonable ballpark for a blow through setup.

Though Jason is going to chime in shortly and say you need 4:1, surely.......

Are you running an intercooler? Or water/meth?

Cheers.

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#3 _rb3torana_

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Posted 11 June 2012 - 11:24 AM

Yeah got an intercooler, I figured the comp should be ok, going by dynamic comp calcs etc, shit I even ran 10.2:1 and 16psi on 95ron in a blow thru sigma.... with 10 deg timing lol, went alot better with 7.7:1 and 22psi though. I just wasnt sure on 202 head designs etc wether they have a different detonation threshold. What sort of timing should I run at 15psi, I was thinking around 15 deg? Anyway heres some pics of the setup.

Posted Image

Cheers

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#4 Litre8

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Name:Howard
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Posted 11 June 2012 - 11:51 AM

With an intercooler I would think around 28 degress max timing as a ballpark.
With 6.8:1 I used to run 32 degrees at 20lbs boost with leaded super + water/methonal injection. Another big HP 202 used to run 30 degrees at close to 30lbs boost (again, water/methanol injection).
These were pre-intercooler draw through set ups.

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#5 _Drag lc_

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Posted 11 June 2012 - 02:13 PM

id think that would be fine,

mine will have 9.5 to1 hoping to not need more than 20psi boost.. ive got an alloy head aswell.. so i guess its not relavent to this..

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#6 _ljxu1torana_

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Posted 11 June 2012 - 03:33 PM

With an intercooler I would think around 28 degress max timing as a ballpark.
With 6.8:1 I used to run 32 degrees at 20lbs boost with leaded super + water/methonal injection. Another big HP 202 used to run 30 degrees at close to 30lbs boost (again, water/methanol injection).
These were pre-intercooler draw through set ups.

thanks litre 8 for making some sense here.this what i try to tell other members about c/r.in a turbo 6.other people will learn the hard and expensive way.thanks jason.

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#7 Litre8

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Posted 11 June 2012 - 04:24 PM

Running E85 might provide some detonation insurance too.

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#8 _Drag lc_

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Posted 11 June 2012 - 04:42 PM

Running E85 might provide some detonation insurance too.

it sure does from my experiance.........

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#9 _rb3torana_

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Posted 12 June 2012 - 07:25 AM

id think that would be fine,

mine will have 9.5 to1 hoping to not need more than 20psi boost.. ive got an alloy head aswell.. so i guess its not relavent to this..

How much comp and timing did the HR hand grenade have when it ran 114mph? I thought of E85 but just not that readily available yet where I am. Cheers

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#10 _ljxu1torana_

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Posted 12 June 2012 - 05:53 PM

How much comp and timing did the HR hand grenade have when it ran 114mph? I thought of E85 but just not that readily available yet where I am. Cheers

for a turbo 6 set up you need 7.5.1 cr.or even a bit lower.lower static compression ratio is always better than higher static compression ratio.if you want to run at least 114mph at the drags you will be building another motor really quickly with 8.5.1 or more c/r.thanks jason.

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#11 orangeLJ

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Posted 12 June 2012 - 06:01 PM

I think there are plenty of examples to the contrary....

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#12 _Drag lc_

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Posted 12 June 2012 - 08:05 PM

yeah mate im not sure now but it ended up with around 8 or 9 to 1 .. 33 deg

not sure what it has now prolly around 9 to 1 but it run 100mph to half track at a recent 1/8 mile drags a few weeks ago....pump gas 14psi boost..... the engine has had a few major refinements since the great race with dj.. and i must say i think its heading in the right direction pete is still trying to get a handle on the tune up...

but each to their own.....

Edited by Drag lc, 12 June 2012 - 08:07 PM.