Pi Head Swap: Worth The Effort?

I'll leave a longer reply later tonight when I get time.

But short answer? Yes.

They will probably add more than 15 hp because I think you will get more compression. PI heads on a non-PI bottom end usually make more power than a full PI engine. And since you already have them you might as well get them ported by a good company. They will make a night and day difference with a good stage 1 cam. If you upgrade the springs and go with a stage 2 cam then you will gain even more!

To add, if you take your time (if it isn't your DD and you can spare downtime), then why not just build a short block. You already have the block. The GT crank is good for probably like 700 or 800 hp. Tear that block down, get it machined, add some H-Beam rods and forged pistons with a good 9.0:1 - 9.5:1 compression ration (if planning to go FI) or like 10.5:1 - 11.0:1 (if staying NA). Then get the heads ported, add some aftermarket cams, and do the engine install. You may be looking at spending about $2500-$3000 but that engine will be rock solid and a beast.

sneaky98gt said:

I'll leave a longer reply later tonight when I get time.

But short answer? Yes.

Click to expand...

Alright, 2 days later, I finally get the time, haha.

I think you're going to see a good bit more than 10 horsepower. I think that the better heads, bump in compression, and (I'm assuming) tune afterwards, you'll see more like 20-25 on the tires. Basic bolt-on (CAI, exhaust, tune/timing adjuster), PI head-swap cars will make 260ish on the tires (amirite? @Winters98GT ). At the same time, I remember someone on here a WHILE ago had a 100% full bolt-on, PI cam/intake setup with NPI heads that made 225 on the tires. That's 35 rwhp. So I think you're selling yourself short on how much you'll pick up.

Granted my case is under boost, I picked up a TON of power simply by going to PI heads. My semi-old setup (blower, blower cams, NPI heads, intake, exhaust, tune) trapped a best of 112 mph in pretty decent weather. When that motor popped, I went to a full PI motor on the exact same components, and it went 118 mph in similar conditions. So even without the bump in compression, I picked up 6 mph in the 1/4 just from PI heads. That's a solid 60 rwhp.

And on top of all this, just how much do you think you could get if you sold the heads? I know in my area, you'd be pretty lucky to get $150 for them. I see complete top ends going for $250. For the cost of a head-changing kit, I'd definitely say go for it. Also, if you wanted to save a few more bucks, I've read many times now that you can re-use the head bolts at least one extra time. So you may could pass on the head-changing kit and just get the gaskets.

It depends how much you want to put in the engine, but if you just want to rebuild it throw some 4v rods and pistons in it. Makes 11.8-1 comp runs great off pump gas/e85(with tune).

My old car had stock cams. Perfectly fine on pump gas. You have to run really high timing to get one to knock. I have a race tune that will barely knock, and its like 26-27deg. at WOT. Stock timing on 96-98 cars are like 10-12 at WOT.

Ive built 5 of the 4v rod/piston with pi head engines. Its a very fun/cheap engine. Even more fun on a 125-50 shot!