This week I was at Speed Inc. getting my PRC stage 1.5's installed on my 2002 Z28, M6. During the install they also put an ASP pulley on the car and installed some SLP frame connectors. The car was then dyno tuned.

Other mods to the car are a TR220-114 cam, SLP headers with cats, SLP 2OTL exhaust, whisper lid, Bauer ported throttle body and a Fast Toys Ram Air kit.

Posted below are the results for before and after dyno runs. HP1 and TQ1 is the TR220 cam, SLP headers, lid and ported TB. HP2 and TQ2 has the PRC stage 1.5 heads and ASP pulley added. All runs are dyno tuned. All runs have the SLP cats installed.

HP1 TQ1 HP2 TQ2
3000 195 335 205 355
3500 225 335 235 350
4000 265 350 280 370
4500 300 350 320 375
5000 330 358 365 381
5500 355 340 385 370
6000 360 315 394 340
6500 n/a n/a 380 310

max 360 358 394 381

I gained 34 rwhp and 23 rwtq with the PRC heads and ASP pulley install.

The heads are PRC stage 1.5 heads. They are 5.3's milled to a 61CC. The heads were hand finished and have the 2.04 intake valve installed and a 1.575 stock exhuast valve. Flow intake runner numbers are as shown:

.100 75
.200 140
.300 200
.350 225
.400 245
.450 260
.500 280
.550 295
.600 305

Intake runner is approximately 218 CC according to PRC.

Some comments:
The car feels stronger all over. Notably in two spots; low end torque is increased so the car pulls off the line harder and above 3500 rpm it feels like the hand of God is shoving the car forward. I'm very pleased with this combination. I think its a great overall street car. No surging, bucking or any other nasty habbits. Fires right up, idles nice at 900 rpm and can also spin the tires at 50 mph. I'm pretty happy with a 400 hp, emissions compliant street car.

I can probably get another 10 HP out of the car if I removed the cats; however I really don't want the extra noise and stink, so I've elected to leave the cats on.

The SLP subframes really make the car feel much stiffer. These are also a great mod.

The surprise in all this is that the car got a crazy 29 mpg on the five hour trip home. This is through Chicago traffic, interstate cruising and two lane highway through southern Indiana!

Thanks:
Thanks to Larry and his crew at Speed Inc for the great install and taking such good care of my baby.
Thanks to Trevor at TSP for the great heads at a resonable price.
I buy from our sponsors because they are great for our hobby, they once again proved it to me.

What to do next???

 

How much valve train noise do you have over stock? Does it sound like a sewing machine under the hood? How about a sound clip please?

 

i didn't think their stage 1 heads came with valves that big on the intake or exhaust side? my 2.5's came with 2.02 and 1.575's.

 

nevermind, i bet you are talking about their LS6 heads. i am running their 5.3L heads.

 

nice numbers from a baby size cam

 

It's got some of the sewing machine noise around 2000 rpm. With the fast ramp rates of the TR cams you're going to have that. It's not annoying or very loud. You know what the sound is and go on.

The heads are PRC 5.3 stage 1.5 heads. I bought them almost two years ago when the PRC's first came out. At that time they did offer the stage 1.5's with the 2.04 intake valve. My understanding is that they don't offer that valve in the 1.5 head now.

I'm thinking of a FAST 90 / NW90 combination next. Maybe with Vengance or Mamo/AFS porting...still researching this one.

 

Very impressive. Some one was talking the other day about heads and small cam combos putting people in the 11's. sounds like you just might be there now.