COMBINING THE NPI AND P.I. MOTOR!

bottlefed97 · Jan 12, 2008

After a tiring search for a P.I. engine for my 97 GT, my dad and I finally decided to combine the two. We're using a NPI block, rods, pistons, crank, and a P.I. intake manifold. The heads are P.I.'s that have been shaved 10,000's. Since we're using the NPI pistons (which have less of a dish than P.I.) combined with the shaved P.I. heads, we figured that it would create more compression, therefore more power! What do you guys think? Thanks!

Matt

AaRoN · Jan 12, 2008

Yes. A pi swapped npi would have compression of 10.5:1 (correct me if I'm wrong here)

voidfinger · Jan 12, 2008

yea it should have 10.5:1 cr with the stock heads... but with shaved i wonder what it would be ? I'm thinking of doing this sometime too. it will sound awsome.

lethal2v · Jan 12, 2008

Sounds like you got yourself a good plan there.

Zwolaver21 · Jan 12, 2008

how many miles are on the npi block?

Jrgunn5150 · Jan 12, 2008

Well if I want to be a technical douche... It's 10.3: to 1, but with the .010 you shave, it will be higher yet. And it's the best option to build a N/A motor on a budget. Let me know if you need any help.

MustangMatt96GT · Jan 12, 2008

Well when shaving a Modular Head, you really have to be careful. Because of the timing chains not having enough tension and a few things like taht. I really think that shaving a head is a mistake.

Jrgunn5150 · Jan 12, 2008

.010 is half the thickness of a human hair.. The tensioners can take that up. It's guy's that wanna get all absurd and angle cut .080 off them that run into trouble. A .010 cut is pretty standard to clean up the surface.

bottlefed97 · Jan 13, 2008

Actually, I was wrong, it was a .030 shave. And the NPI block has around 70,000 miles on it, so it's not too bad. We're building this engine right now so we can get my car back on the road asap. This will hold me over while we build a badass N/A motor with ported heads, cams, rods, pistons, and the works. I'm to get at least 350 ponies

Jrgunn5150 · Jan 13, 2008

.030 is enough to cause concern, especially if using aftermarket cams. Check clearances carefully and degree the cams if using aftermarket. Why was the cut so heavy?

bottlefed97 · Jan 13, 2008

My dad wanted it to be .030. He has a 9 second Pinto and has been racing for over 35 years so I trust him lol. We're not going with any aftermarket cams though.

voidfinger · Jan 13, 2008

yea that seems kinda deep for a simple shave job. My brother who has a 9 second lx tried to get me to shave more off my heads but they usually don't get that the timeing is an issue.