01BlueCobraVert

For a 97 Pi swapped car what is a good RPM range? Should I stop before 6000 or what? I do not want to overly abuse my stock bottom end. I have LT's, every bolton-on except electric water pump. Thanks

04BlueGT

First, I'm no expert.

With the PI swap, the Comp Cams 262AH or 270AH should work fine. The 270 has a range of 1800-5800 rpm. That is about perfect for PI motors, and I'd think it would be fine for yours too.

2000GT4.6

There has been some discussion on this, and I think people are making a big mistake thinking that they should be shifting at peak horsepower.

You need to shift not only when the car is making the most power at the top of the RPM band (in the lower gear) but also depending on where it will place you in the next gear. I had a shop telling me I needed to shift my car at like 5500 RPM back when it was at full boltons, because it made peak horsepower there. But that also placed me 500 RPM back in the RPM band in the next gear, and I would slip out of the powerband, making the car slower.

In 99.99 percent of cases you need to shift a PI 4.6 around 6000 RPM (non built engine). This should result in keeping the car in the powerband for the majority (if not all) of each gear.

01BlueCobraVert

I was looking into Houston Performance ground cams. I was told .531 lift and 292 total duration. Is taht a good cam.I know nothing about cams and little of the specific numbers.
I saw a lot having trouble w/ the 270's and stock pistons.

2000GT4.6

if it was me, espcially with a PI swapped NPI motor, I would be going with a company like VT. They have enough experence to direct you to a proper cam setup.

I was under the impression that you want to keep the lift at .500 for a NPI engine though, and it only has to get worse with a PI swap done. Whatever you do, make sure you double check PTV clearance before turning over the engine.

SNORX302

Yeah non pi motors have different pistons than pi motors resulting in closer ptv (piston to valve) clearance. The valvesrpings in the pi heads should be good for .550 lift on intake and exhaust, but with more duration and higher lift, those pistons are destined for contact.

01BlueCobraVert

So .531 lift is probably good. Maybe that is the cutoff point????