My c5z is currently cam only with some bolt ons puts down 430hp looking to add a good bang for the buck head and have heard great things about texas speed. What numbers are people making with these heads n/a?....btw I'm interested in the 5.3 stage 2.5 or ls6 stage 2.5...

 

Search LS1tech.com in the dyno results section. I personally wouldn't add heads to a cam only Z unless they were a great head such as AFR or TFS. Your stock heads flow pretty well. With the 5.3L heads you might not see much of a gain at all, but your compression will go up. Be careful with the 2.5's as you may have to flycut to fit ur cam. Adding PRC heads will cost you anywhere from 1100-1400 plus labor for 20rwhp at the most.

 

 

I gained 30rwhp going from stock ls1 heads to unmilled PRC stage2.5 5.3, made 426/386 with my sleeper cam(218/230 116)...agree with the above that you'll probably only see a 10-15hp gain though unless you go with something like their 215cc

 

Your car's 243 heads are pretty good as they are. I wouldn't trade them for a set of 5.3 heads. The main benefit you'd see is from a bump in the CR - smaller chambers. A well ported set of 243's milled to raise the CR is a better choice using GM castings.

Just my $.02

 

Do not swap a premium head for a lesser head. Spend the money of getting proper work done to your 243's (VJ and milling) or opt for some TFS 215's.

 

Thanks for the replies guys...I'm really surprised that nobody has had great results with the 5.3 head...their flow numbers are pretty decent....anyone know how the tsp ls6 prc2.5 heads compare to the trick flows? Forgot to mention my cr is already at 11.1 and my pistons are mahle and already have a relief

 

I gained 30 RWHP going to TSP Stage 2.5 heads, also unmilled.

 

did you go with the 5.3 or ls6 heads? what did you upgrade from 243? 241?

 

I got the 5.3 heads. I had 241 heads on the car before the head swap.

 

Alright I have first hand experience with these heads and a slew of other go fast goodies

My 2000 FRC has:

TSP 233-239 .595/.604 112 LS
PRC stage 2.5 heads , with the .650 lift springs
1 3/4 LG long tubes
Off road 3" X pipe
Corsa Pace car with tiger shark tips cat back
25% underdrive pulley
FAST 92mm intake
LS3 92mm Throttle body
VaraRam b2 CAI
VR bellows
HP tuners MAF tune

On a Mustang Dynanometer) that according to all research I have done on the internet produce numbers range from 7% to 13% lower than dynojet numbers) I put down, 435rwhp and 386RWTQ but I think they are low
with the loss compaired to the more popular dynojet here is a list of compairable gains.

@7% gain: 465.45rwhp 413.02 rwtq (realistic)
@8% gain: 469.8rwhp 420.74rwtq (realistic)
@10% gain: 478.5rwhp 424.6rwtq (starting to get absurd)
@11% gain: 482.85rwhp 428.46rwtq (absurd)
@12% gain: 487.2rwhp 432.32rwtq (absurd)
@13% gain: 491.55rwhp 436.18rwtq (absurd)

May 29th I will be hitting up a dynojet, so I will post my results and we will all see where I stand.

They are better than the stock LS6 heads but not as good as the 215's or other $2,000.00 plus heads. they bump cr up to 10:75.1

For the Money they are great heads. they flow 312cfm @.600 intake Now would I do it differently if I were ate the begining...Duh I would have bought a supercharger. I would also go for a set of TEA ported LS6 heads.

Thinking about a 50hp shot of the old school HP..maybe a 100hp shot, But I think I am getting gready,, my car weighs 3096 without driver.

Final .02 cents, if all you have the cash for are the PRC heads then get them, port your LS6 heads and then sell the PRC's to off set the cost, this way you are still driving her.

 

A Dyno is a Dyno nothing more than a tuning device, let the track tell you how bad@ss your car is!

Mario

 

i hear this a million times a day which it is correct to an extent... i have already ran my car down the track a bunch i know what she runs i have stock heads and am looking to upgrade... obviously i dont want to spend for a trick flow and be forced to buy rockers for them if the tsp heads perform the same... ultimately the bottle will help me get the times i want but 99 percent of the driving i do is off bottle so i am focusing just as much on n/a power.. i would like to see my car make mid 400's on the motor without a fast which will give me more mph and help some on my e.t.s..... dead cafe please post up new numbers when you hit the dynojet...thanx!

 

stage 2.5 5.3 heads or ls6 heads?

 

There is no if, the two aren't comparable. There are tons of guys running the PRC 5.3 heads with large cams making 430-440rwhp and 390tq, its about the norm unless its the shop selling them advertising a number. The norm for TFS heads are 450-470 depending on how matched the setup is and how large the cam is.

I personally run some older PRC 5.3 heads and made 457rwhp but thats with all the premium bolt ons and a cam matched to my setup. Its definitely not the norm. The heads on my car came with it so I just kept them, if I was spending money I wouldn't even consider downgrading my heads from 243's to 5.3's.

 

TFS 215s will give you much more torque down low and in the mid range over the ported LS6 heads. Up top, the TFS heads will better the ported LS6 heads by about 10rwhp. I chose the stg 1 LS6 heads and through LG streets, I'm making near 480rwhp SAE. If you're looking for unmatched performance down low and in the mid range, go TFS 215s. Up top there isnt a seat of the pants difference between ported LS6 heads and TFS 215s. The choice is up to you and your wallet.

 

FWIW I have as much faith in dyno #'s as I do in metorologists getting the correct weather forecast for the next 24 hrs.

Shops tinker with calibration etc to attract customers and garner bragging rights.

See lots of posts claiming 450+ to the wheels and run high 11's when they should be low 11's. This is why guys say take it to the track! And it makes a lot of sense.

 

480rwhp with PRC LS6 heads on a 346?

 

 

If you dont mind me asking, do you have any time slips from the track.

With that power level you *should* be high 10's in the 1/4.