Since I couldn't leave well enough alone with my daily driver (2000 WS6), I decided it was time to add some ported heads. After talking with Jason@PRC, I decided his stage 2.5 cyl heads were the best choice in terms of a hp/$$ standpoint. The fact that I was getting brand new, GM heads were definitely a huge selling point. Plus, I have seen quite a few guys put down very impressive numbers with them.

My heads showed up last week and arrived in great shape. They were boxed very well with more than enough packing material to prevent any shipping damage. Along with the heads, I also recieved a black folder with my invoice, flow #s from PRCs bench, and a business card from Jason@PRC. I have dealt with quite a few cylinder head porters/companies over the last 5 years and this was one the nicer packets to be included.

Once out of the box, I flowed them on our SF1020 bench at Thunder to get a comparison between the two benches.

Here are the flow #s:

* SF1020 bench
* 3.900" bore
* Radiused entry on intake side
* Exhaust port flowed open

Intake Exhaust
.050 36.1 30.0
.100 70.0 57.2
.150 103.9 83.6
.200 139.1 110.4
.250 168.3 130.0
.300 198.0 150.1
.350 222.9 165.3
.400 244.4 177.3
.450 262.1 194.1
.500 276.7 202.2
.550 288.4 208.5
.600 298.8 213.3
.650 304.7 216.9
.700 278.4 220.1

Overall, I was very pleased with the #s! I flowed two ports on each head and none varied more than 2cfm!

The CNC work and hand-finishing looked very nice. I can't wait to get these installed in the next week, hopefully as soon as this weekend!

Here are some pics: PRC 2.5 cylinder head pics

My current setup consists of:

2000 WS6 6-speed (130k miles, original shortblock )

- Whisper lid
- TR ported TB
- LS6 intake
- ASP pulley
- stock manifolds/cats
- Hooker catback
- TR CheaTR camshaft
- Crane dual valvesprings/TR 7.400" pushrods
- Spec stg 3 clutch/steel flywheel
- stock rear/3.42s

Last dyno was 362rwhp/358rwtq. The only change will be the PRC stage 2.5 heads! I hoping to see close to 395rwhp with the stock manifolds/cats! I really don't think this will be too much of a problem. I'm going to re-baseline the car to limit as many variables as possible. I know my poor motor is tired, but we'll see how she does. My low oil light comes on once every 1000 miles.

Once the heads are installed, I have set of Pacesetter longtubes to go on the car, along with 4:10s.

Big thanks to Jason@PRC for all his help. Customer service has been second to none and he was very patient with all the questions I had for him. Thanks Jason!

If everything works out well with them, Thunder should have these heads on the webpage within the next couple of weeks. Stay tuned for that!

Jason

 

Those are pretty strong numbers for being on a 1020 bench with no pipe and for only 1530 bucks. Hopefully you pick up some decent power.

Nate

 

Thanks Nate! On top of that, Thunder's bench has always read slightly lower than others. As I mentioned above, for the hp/$$ standpoint, these are hard to beat!

Jason

 

When can we expect dyno or track times?

nate

 

Dyno #s might come as early as this weekend. Track times probably won't come until sometime in early November. I just have to see when I can get some time to install them with school/work.

 

WOW! Those look great!

Nice flow numbers as well. What size valves are in the heads?

John

 

Thanks John! 2.04"/1.585" valve size on the 2.5s.

 

Do those valves fit in the stock valve seats or did PRC have to change them out?

 

Stock seats!

 

I'm glad to see that you received your heads! I know you will be very pleased with the results. We work very hard to ensure the best and most consistent flow numbers on the market. The bang-for-the-buck for cylinder heads cannot be beat! You're going to have a major sleeper with these heads and your CheaTR camshaft!

Definitely keep us posted on dyno numbers and track results!

Trevor
Texas Speed & Performance

 

I've been waiting to see how you liked these heads Jason. I am really looking forward to your dyno numbers!

 

Thanks for all the kind words Jason! We've even done some additional updates to the heads after that set was built! I know you'll be very happy with the results!!

 

Not to bash AT all, but why do his look better then mine did?(LOL, not 3rd grade sounding) there are still voids in the chamber, but that is normal due to casting shift, but the CNC work and hand finishing seem to be more concentric and consistent....I know you guys have made good products and like everyone are constantly improving. Just wanting to know if I missed out on something by getting a slightly older set from a friend.
Either way, they look awesome, I dig the logo. Definitely gonna do something on a dyno.

 

Is it just me or did they flow a little low? They didnt even surpass the 300 mark at .600. The exhaust seemed a little low also. I was thinking they would least be around 220 or so at .600.

 

What the biggest cam you could get before you have to fly cut the pistons?

 

The exhaust was flowed without a pipe.A pipe will add 15 numbers or so.

 

Well what about the intake? They still seem low. I didnt even think think about that on the exhaust.

 

The intake's not bad at all on Thunder's bench, Jason told me some of the really popular small runner heads don't go but 290 on their bench.

We're testing This head right now with a MS3 & a 2.02 valve combo

 

The flow #s are very impressive on our bench, which is quite conservative compared to most. For the what these heads cost and you get NEW GM cylinder heads, it's hard to beat them.

Jason

 

I'm VERY interested in seeing the results of this!