pi heads conversion + which cams

[chevyboy_z28]

ive got a 98 gt with stock internals and was wondering what options i have as far as cams if i convert to pi heads. I know there are several options for pi headed cars, but in converting to pi heads i raise the compression of my npi motor to 10:1. now with bigger cams in pi heads, on a npi shortblock will i have ptv clearance issues?

basically what im dealing with is this, stock npi shortblock+ patriot stgII heads (ie600 lift springs), + which cams? all the comp cams for pi heads have .550 lift, and the ones i was looking at getting (xe278ah), i was told that i would definately have ptv issues, with having a npi shortblock?

 

[stangman]

vt stage 1 cams pretty much anything larger & yu're going to have ot have valve reliefs cut in your pistons

 

[CobraM23]

VT stage II NA cams here. No PTV problems either.

 

[chevyboy_z28]

what kinda gains are to be had with the stock npi heads and a decent set of cams? will the vt stg1s work with npi heads?

 

[Skidzz]

I've got comp 262's and they are great. No PTV contact and they added around 20 rwhp on top of the gains from the pi swap. But, if you are going to do it, get cam gears with it and have them degreed in for even more gains. That's something I didn't do, and it kept me from hitting my goal of 275 rwhp.

 

[Skidzz]

what kinda gains are to be had with the stock npi heads and a decent set of cams? will the vt stg1s work with npi heads?

20-30 rwhp gains, depending on the grind. I don't think VT even makes a cam for NPI's, but comp does. My advice would be not to even change the heads. Get the PI intake and an adaptor, and then get some comp 268's for the NPI heads. You can even buy them from VT's web site for $565 right now, but you might find them cheaper somewhere else. That way, you will still put down probably over 250 rwhp and you will keep the compression low, so you get still run on regular gas and get a blower later on, not to mention you'll save a lot of $$$

 

[chevyboy_z28]

would it be worth it to go with the crower spring kit offered on the vt site, or are the comp srings (best seller list) good enough. ie the crower springs come with retainers, and are allegedly good up to .660 lift. i know thats prolly overkill for me right now, but there only $60 more than the comps?...i know the vt stg1 ones dont require a spring upgrade, but ide rather be safe than sorry (i dont cut corners to save a lil cash)

 

[four six]

VT stage 1 or 2

I love the sound of stg 2

 

[chevyboy_z28]

yea i like the sound of the stage2s also, and i think theyd work well with my current mods if i had ported pi's and a strong shortblock.