I think I want to mill my P90 head for my N/A turbo How Much?

[big-phil]

I went to the head shop where I bought my N47, and they said for $50 they would mill my P90. My compression now is 170 across all 6 cylinders. I want to mill the P90 so that I'm in the 160-170 area. A stock turbo is about 140psi?? right? Does anyone know how much I need to have them take off?

 

Also my cam towers in the N47 has shims and the P90 does not. Should I put the shims in the P90 after milling? The N47 feels awsome but I'm looking for more FLOW:burnout:

[73ZCAR]

Phil,

 

Why do you want to mill the P-90?

 

If it's straight you should leave it alone.

 

from what is listed in your sig. it looks to me like you need;

 

Bigger Injectors.

 

Stand alone fuel management.

 

An intecooler without those plastic thingies on the sides.

 

A Bigger Turbo.

 

BIG EXHAUST.

 

In that order.

 

Then you will need forged pistons for the short block you will be building for that tasty head.

 

Just my .02

 

Mike.

[big-phil]

I just thought since its running good with the N47 and its compression, that milling the P90 to get the same or close to the same compression would flow better than the N47 and have the same feel off boost with the higher compression. Plus the money for the stand alone is not in the cards. I have some supra 440 injectors but can't use them with out a stand alone system so I was going to sell them to try to get a better intercooler.

[Yokohama]

Just get the Maxima N47 and take out the exhaust liners, or you can keep them in. The Maxima head has the same chamber shape as the P90, except that it is smaller in size.

What do you want for the injectors? trade?

[big-phil]

Just get the Maxima N47 and take out the exhaust liners' date=' or you can keep them in. The Maxima head has the same chamber shape as the P90, except that it is smaller in size.

What do you want for the injectors? trade?[/quote']

what do you have to trade?

[boardkid280z]

Well, the P90 and dished pistons have lower compression (7.?:1 - ) and have a lower pressure on compression test. 140ish instead of 170ish. The P90 on Flattop pistons instead of dished will raise compression (8.5:1 or so) and I believe it will also raise the pressure during a compression test, so I wouldn't worry too much about shaving the P90. That might even be a bad way to go. Just my interpretation - I have done some thinking about this myself since I am doing the same thing soon. P90 head on flattop pistons. With turbo.

[big-phil]

so does a 78 N/A block have flat top pistons?

[TimZ]

so does a 78 N/A block have flat top pistons?

no - they are dished

[big-phil]

so if they are dished and that will get me 7.?to1 don't I want to take a little off the P90? What is the compression ration of a stock turbo? and what are you guy close to or over 300HP C/R??

I want to set it up to have a good TURBO C/R

[Thumper]

When you mill a head you RAISE compression. Also if you mill the head more than .020" then you will need to put spacers under your cam towers or have an adjustable cam gear.

[big-phil]

yes the n/a head I have now has spacers. I want to drop the head off tomorrow at the head shop. If the guy knows the stock turbo motors c/r he says he can figure out and mill it at what ever c/r I want. I don't want to be as high as I am now (I don't think?) But I want to be a little higher than a stock turbo. I have read and heard from guys that say the stock turbo c/r feels a little doggie off boost.