51 replies to this topic

[Bargi]

I have some oem pistons which you can swap with me for your low comp ones

What pistons are you running if they're not low comp ones!

[speedster]

Please be advised that the CR advertised for Wiseco pistons is with a 1mm thick gasket.
A Z22se or Z22yh head gasket is not 1mm thick

How thick is it 2-20?

[2-20]

I read somewhere that they are :
Z22yh gasket 0.37mm
Z22se gasket 0.49mm
Z20net gasket 0.98mm

http://www.z22se.co....r-sc-use.18077/

So you have about 0.5 more CR than advertised . Do you have standard size pistons or overbored ?
It also influence slightly the static CR

[oakmere]

Lots of cam options here: http://www.verboom.n...dster/cams.html May need adjustable sprockets with the comp cams to get them timed in correctly.

[TheHood]

My Z22yh rods and pistons are definitely good for 7600, probably more if you count the couple of times I've buzzed them on track days You need 4032 alloy for after market pistons to allow a more OEM like bore clearance thus avoiding too much piston slap on a cold start up, problem is they cost £££££.

[Nev]

Have you considered whether the oil pump on the Z22 will cavitate the oil at those sort of revs? I expect Vocky or someone will know. Looks like a lot of new bits in that engine. Good luck.

[oakmere]

Don't think so but the oil pump gears can fall apart so you can upgrade to forged items. http://www.allecotec...products_id=118

Edited by oakmere, 24 April 2013 - 07:31 PM.

[alanoo]

Alanoo had the same issue an got low comp pistons by mistake. He skimmed the head by 1.4mm which is the max before you hit the oil restrictor.

http://www.z22se.co....r-project.6314/

Nop I got 10:1 pistons and skimmed 1.4mm
It's the bore that was wrong and fixed with a rebore.

Mine has seen 8600 rpm on multiple occasions (and I have datalogs proving it), but I was generally putting the limiter at 8200 rpm on track

[speedster]

Supercharger is starting to look very economical Just bolt it on and off I go. Head currently has turbo (Saab) cams.

[speedster]

Mine has seen 8600 rpm on multiple occasions (and I have datalogs proving it), but I was generally putting the limiter at 8200 rpm on track

Sweet! can you give me a quick intro to your engine build and mods

[speedster]

Keep the pistons if you have already fitted them and skim the head

Ok batman mulling it over.....looking at the engine..... ThIs suggestion is starting to make sense!
I need to skim off a millimetre, is that correct? Can I go further? Mill and a half?

[speedster]

Ok I need to pay attention. 1.4mm on the standard head. The SAAB head is cast differently and has thicker walls at the top of the combustion chambers but not sure if thicker all around.

Alanoo had the same issue an got low comp pistons by mistake. He skimmed the head by 1.4mm which is the max before you hit the oil restrictor.

http://www.z22se.co....r-project.6314/

Nop I got 10:1 pistons and skimmed 1.4mm
It's the bore that was wrong and fixed with a rebore.

Mine has seen 8600 rpm on multiple occasions (and I have datalogs proving it), but I was generally putting the limiter at 8200 rpm on track

[speedster]

Standard L61 bore (z22se). I see the Alfa Romeo 159 which uses a modified z22se engine has a compression ratio of 11.3:1

I read somewhere that they are :
Z22yh gasket 0.37mm
Z22se gasket 0.49mm
Z20net gasket 0.98mm

http://www.z22se.co....r-sc-use.18077/

So you have about 0.5 more CR than advertised . Do you have standard size pistons or overbored ?
It also influence slightly the static CR

[speedster]

Have you considered whether the oil pump on the Z22 will cavitate the oil at those sort of revs? I expect Vocky or someone will know. Looks like a lot of new bits in that engine. Good luck.

Thanks!

Lubrication!

Spoiler

[Boombang]

Does skimming so much off the head not have a detrimental affect on the squish?

[vocky]

Keep the pistons if you have already fitted them and skim the head

Ok batman mulling it over.....looking at the engine..... ThIs suggestion is starting to make sense!
I need to skim off a millimetre, is that correct? Can I go further? Mill and a half?

If you skim too much the chain tensioner cannot cope and you need to fit a manually adjustable chain adjuster.

I have had the GM Racing oil pump gears fitted to my car for several thousand miles and have had no oil pressure problems yet.

My new 2.5 engine has a set of one off JE pistons which give a CR of 11.5:1

[NickB787]

I have some oem pistons which you can swap with me for your low comp ones

What pistons are you running if they're not low comp ones!

seriously if you want standard you can have some which are in the shed, 30kish on them, just pay postage


you can always sell low comp pistons.....

[oakmere]

I have kept my std pistons. Good for 300 bhp so fine for N/A and no nasty piston slap! Don't think there is an issue with rpm up to 7800.

[siztenboots]

does the gmpt-e15 scale up to these rpm , I thought most high rpm had gone webcon ecu.

[speedster]

Does skimming so much off the head not have a detrimental affect on the squish?

it can but depends on what piston choice you made, afaik