deciding on heads.....
Jul 14, 2010 | 10:21 AM
#21
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12 Second Truck Club
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From: Cypress, TX
just spoke with Matt @ Texas speed. Very knowledgeable on their products. Now i have to decide if i want a 5.3 or ls6 head. Thanks again Matt, hopeullt be orderin them in a few months!!
Jul 14, 2010 | 11:38 AM
#23
On his LS1 short-block and that cam, we can't get all the way to 59cc without flycutting pistons....but the extra cubes of the LS1 and flat-top pistons don't require 59cc to get the compression that high either.
Jul 14, 2010 | 02:03 PM
#24
Corrected:
I had "stage 3" heads on my stock LS1 and the valves just don't have the room to breath with such small bore. My heads flowed 330CFM on the intake (on a flow bench with the intake bolted on), but my friend had the EXACT same setup with cleaned up (just smoothed casting flash and such) stock heads and got a few more HP than I did (I got 400rwhp, he got 405rwhp). We both had the same LT headers, same cam (TR224/224 112LSA), both T56, both 3.73 gears, both had true duals, etc...
I'd say the Stage 2.5s would be as large as I would go.
I had "stage 3" heads on my stock LS1 and the valves just don't have the room to breath with such small bore. My heads flowed 330CFM on the intake (on a flow bench with the intake bolted on), but my friend had the EXACT same setup with cleaned up (just smoothed casting flash and such) stock heads and got a few more HP than I did (I got 400rwhp, he got 405rwhp). We both had the same LT headers, same cam (TR224/224 112LSA), both T56, both 3.73 gears, both had true duals, etc...
I'd say the Stage 2.5s would be as large as I would go.
Last edited by 2001CamaroGuy; Jul 14, 2010 at 02:18 PM.
Jul 14, 2010 | 02:07 PM
#25
I'm surprise nobody else has asked this..... but what size engine are you putting these on? Because you name says 4.8 and I see nothing indicating anything bigger, I'm guessing these are for a 4.8.
If so:
I would stay away from the "stage 3" heads for your setup. They will flow WORSE than a smaller valved head due to valve shrouding in the bore.
I had "stage 3" heads on my stock LS1 and the valves just don't have the room to breath with such small bore. My heads flowed 330CFM on the intake (on a flow bench with the intake bolted on), but my friend had the EXACT same setup with cleaned up (just smoothed casting flash and such) stock heads and got a few more HP than I did (I got 400rwhp, he got 405rwhp). We both had the same LT headers, same cam (TR224/224 112LSA), both T56, both 3.73 gears, both had true duals, etc...
I'd say at most with the stage 2.5 head. Remember a 4.8 is a small bore and stroke so you don't need, nor can you use, huge heads. A good set of stage 2 heads will take a 5.7 till 7K and 450+ rwhp so unless you plan to spin to 1000000000000000000RPM, your 4.8 will be just fine. :p
The big thing will be getting more compression and a cleaned up port flow rather than bigger valves (with a small engine at reasonable RPMs).
If so:
I would stay away from the "stage 3" heads for your setup. They will flow WORSE than a smaller valved head due to valve shrouding in the bore.
I had "stage 3" heads on my stock LS1 and the valves just don't have the room to breath with such small bore. My heads flowed 330CFM on the intake (on a flow bench with the intake bolted on), but my friend had the EXACT same setup with cleaned up (just smoothed casting flash and such) stock heads and got a few more HP than I did (I got 400rwhp, he got 405rwhp). We both had the same LT headers, same cam (TR224/224 112LSA), both T56, both 3.73 gears, both had true duals, etc...
I'd say at most with the stage 2.5 head. Remember a 4.8 is a small bore and stroke so you don't need, nor can you use, huge heads. A good set of stage 2 heads will take a 5.7 till 7K and 450+ rwhp so unless you plan to spin to 1000000000000000000RPM, your 4.8 will be just fine. :p
The big thing will be getting more compression and a cleaned up port flow rather than bigger valves (with a small engine at reasonable RPMs).
Jul 14, 2010 | 02:17 PM
#26
Jul 14, 2010 | 03:42 PM
#27
The problem is that there is no standard for what a Stage is on a head...our Stage 2 Cathedral port heads have 2.02"/1.57" valves...but a competitor's might have 2.05"/1.60".
But I'd agree the 2.08" valves in an LS1/LS6 casting are shrouded a bit much for a 3.90" or smaller bore!
But I'd agree the 2.08" valves in an LS1/LS6 casting are shrouded a bit much for a 3.90" or smaller bore!
Jul 14, 2010 | 04:17 PM
#28
Here's what I have to say about PRC heads...
https://www.performancetrucks.net/fo...d.php?t=456408
And that's with no tuning.
https://www.performancetrucks.net/fo...d.php?t=456408
And that's with no tuning.
Jul 14, 2010 | 04:22 PM
#29
Your thread is one of the reasons I decided to pick up a set for my LQ4, damn good bang for the buck.
Matt everyone seems to be hung up on peak flow numbers, can you post up some tips for people in the market for heads to figure out what is best. There is a lot of voodoo about flow numbers that i think people have no idea about the different ways to skew them.
Matt everyone seems to be hung up on peak flow numbers, can you post up some tips for people in the market for heads to figure out what is best. There is a lot of voodoo about flow numbers that i think people have no idea about the different ways to skew them.
Jul 14, 2010 | 06:11 PM
#30
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12 Second Truck Club
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From: Cypress, TX
Your thread is one of the reasons I decided to pick up a set for my LQ4, damn good bang for the buck.
Matt everyone seems to be hung up on peak flow numbers, can you post up some tips for people in the market for heads to figure out what is best. There is a lot of voodoo about flow numbers that i think people have no idea about the different ways to skew them.
Matt everyone seems to be hung up on peak flow numbers, can you post up some tips for people in the market for heads to figure out what is best. There is a lot of voodoo about flow numbers that i think people have no idea about the different ways to skew them.
