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Discussion Starter · #1 ·
Hello,
Got a question and need your advice, My turbo zcar has a n42 block with flat top pistons 20 over my crank has been turned 10 over also. I'm running a p90 head with a good size cam boost is about 6 psi what should i do to produce more power out of the motor without detination I am planning on intercooling. should I lower my compression with a hks head gasket. 2mm or 1mm I like the off boost power It allows me to get of the line pretty quick. I need advice on what to do .
Thank you once again
Ron
 

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Discussion Starter · #2 ·
<b>Got an HKS 2mm to sell you cheap</b>

They no longer make the HKS 2mm. Sells for about $155. Mine has been used once with stock head bolts, not ARP'd. Can reuse up to 5 times. Will sell for $90. I have cleaned it and sprayed a fresh coat of copper spray on it.
 

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Discussion Starter · #3 ·
<b>RE: Need help! Turbo z owners advice need. plea

A lower compression motor will allow you to generate more hp at the same dynamic compression as a high compression motor. It also allows you to run more boost. Also the HKS 1mm will not lower your compression, it is actually has .2mm less thickness than the stock head gasket, thereby ever-so-slightly increasing static compression. People talk about lag, my last motor was 8.1:1 and I had no problem getting too much power of the line.
 

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RE: Need help! Turbo z owners advice need. plea

Do you think my setup will generate problems down the line. any idea what my compression ratio might be. or should i go ahead and continue to add to the motor.
Thanks Again
 

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Discussion Starter · #5 ·
<b>RE: Need help! Turbo z owners advice need. plea

If you are using a P-90 on a stock configuration P-79 block with the flat-top pistons, your compression will be approximately 8.8:1. For the stock fuel management and considering you are turbocharged on pump gas, that is pretty high static compression. Typically, street turbo cars run in the neighborhood of 8:1 compression. My last motor was 8.1:1 and my new motor will be about 8.2:1. That is not to say you cannot go higher. I would definetly lower the compression down some before trying to raise the boost. Your main problem is detonation control when running higher compression on a pump gas turbo motor. The HKS 2mm will give you approximately 8.3:1 compression which gives you lower compression and still provides great off-boost response. Also, because you run the stock flat-top pistons(I assume) and high compression, you will be limited to 10-12psi of boost, if even, with intercooling. One plus is that you are running the P-90 head which has a huge squish area that is ideal for fighting detonation when turbocharging or on any motor. Ideally, you want a large squish area and a small combustion chamber. That is why alot of top Z motor builders choose to use a modified E-88 head. They weld up the recessed squish area to be similar to the P-90 and they already have the small combustion chamber of the E-88 head. Hope this helps, my recommendation is to lower compression if you want to run higher boost levels.
 
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