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As some know I run the N-42 head. After researcing for a week now, I have found that the head is not too good for turbocharging applications. The chambers have a recessed squish are by 2mm or .080". If you look at the chamber on the P-79 or P-90 you will notice the squish are is just about even with the bottom of the head. This forces air/gas into the combustion chamber on the up stroke of the piston. It makes for a better combustion and creates good swirl for a more homogeneous mix and burn. I have sent my head to be shaved .060" which will give me about 9.2:1 for my new turbo motor. For $400, rebello racing would weld up the squish are, blend the chambers(heart shaped) and mill the head back flat. Unfortunately, I have to build the motor by this weekend. Anyway, the hot ticket for a detonation free head is to use the E-88 and have the chambers welded in the squish area. You will have small chambers, but if you use the dished piston L-28 you should be able to retain a decent streetable compression. Rebello says they have a street motor surviving at 11:1 with no pinging. FYI.
 

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Discussion Starter · #2 ·
<b>RE: Combustion chambers!</b>

We have been wondering why you were using that head for your application...

The P90 has been proven to be pretty much the **** for turbo applications. I've been running a slightly shaved P90 with factory flat-tops for a while and love it (est. 9 - 9.2:1 CR). Excellent response and good pwr. I even run NOS with it with no prob.

I would caution anyone in using the E-88 as they tend to be more prone to cracking (due to age, material or something), and you are going to spend $400+ for welding, $40 for milling it flat again and $250 to $400 to put 280z valves in it. And i really doubt that it would make that much more pwr than a properly set up stock P90 head. $ would probably make significantly more hp put twards I/C, bigger turbo, and fuel management.

Rcr X


240z turbo wrote:
-------------------------------
As some know I run the N-42 head. After researcing for a week now, I have found that the head is not too good for turbocharging applications. The chambers have a recessed squish are by 2mm or .080". If you look at the chamber on the P-79 or P-90 you will notice the squish are is just about even with the bottom of the head. This forces air/gas into the combustion chamber on the up stroke of the piston. It makes for a better combustion and creates good swirl for a more homogeneous mix and burn. I have sent my head to be shaved .060" which will give me about 9.2:1 for my new turbo motor. For $400, rebello racing would weld up the squish are, blend the chambers(heart shaped) and mill the head back flat. Unfortunately, I have to build the motor by this weekend. Anyway, the hot ticket for a detonation free head is to use the E-88 and have the chambers welded in the squish area. You will have small chambers, but if you use the dished piston L-28 you should be able to retain a decent streetable compression. Rebello says they have a street motor surviving at 11:1 with no pinging. FYI.
 
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