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Discussion Starter · #1 ·
I'm forging a block atm and I want to keep the comp ratio as close to stock as poss so it's still responsive off boost

I'm looking at CP Pistons and they vary from 9.0:1 to 8.5:1 to even lower I've seen some CP Pistons 87mm with a 9.0:1 cr I've been advised to run a 1.5mm head gasket is this a good combo

Searching using tapatalk is shite and don't bring anything up
 

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I have 9.0:1 CP pistons and 1.2 mm head gasket I think. The response off boost is fine but to be honest I drive in a way that I am never far off boost.



Having a good map is the main thing to help with quick response and spool up
 

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Discussion Starter · #3 · (Edited)
Cheers fella what size Pistons are you running ?

I've been calculating what cr Pistons I need for 87mm Pistons using possibly 1.3mm HG and cp are reluctant to give me the piston dome cc which is all I need to calculate... I've tried explains this and no answer so I may go for Mahle or wossner Pistons instead
 

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Cheers fella what size Pistons are you running ?

I've been calculating what cr Pistons I need for 87mm Pistons using possibly 1.3mm HG and cp are reluctant to give me the piston dome cc which is all I need to calculate... I've tried explains this and no answer so I may go for Mahle or wossner Pistons instead

I think there's a lot more to compression ratios than just the spec of the pistons like how many times your block has been decked how many times your head has been skimmed. Are you building the engine your self?
 

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Discussion Starter · #6 ·
I think there's a lot more to compression ratios than just the spec of the pistons like how many times your block has been decked how many times your head has been skimmed. Are you building the engine your self?

Yes there is you need the thickness of head gasket, piston diameter, HG diameter ,stroke, head combustion cc, piston dome cc etc etc I have all required info except for piston dome cc which CP won't disclose
 

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Discussion Starter · #8 ·
I have 86.5mm pistons. Only .5 bore in case I have an unfortunate incident and need to bore out again.

Fair do unfortunately the block I bought needs 87mm Pistons and its touch and go if it will get the gouge out from the piston melting... Luckily enough there's a engineer near me who can reline the bore so we'll see
 
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