PRC 5.3 vs PRC LS6 heads
02-26-2008, 12:06 AM
#1
PRC 5.3 vs PRC LS6 heads Just finished reading a bunch of good information thanks to the search feature, however (given that I'm working on getting a better understanding of how a head swap will help me make more power) I thought I should post this to see if I could get some more precise feedback.
Here's the situation: See mods below. I have all of the goodies and it's time for a head swap. I would like for my car to have reliable street manners and good power under the curve. A good power goal would be around 430 rwhp (I'm currently making 390 rwhp and 388 rwtq). Ultimately I'd like to find a set of heads to compliment my cam and other mods. My only future plans are to throw on a 100 - 125 shot of N20 and a 9" rear end.
I've done a good bit of research and I'm very comfortable with the quality and price of the ported PRC heads, however I can't seem to decide between the Stage 2.5 5.3L heads and the Stage 2.5 LS6 heads. It looks like the LS6 heads have marginally better flow numbers, while the 5.3 would significantly increase the compression of the motor, thus making good top end power (as well as plenty of torque down low). Given my criteria, which of these two would you recommend for my setup? Should I have TSP mill the heads too?
Sorry for asking a bunch of questions, however I'm (slowly) learning all of this. Thanks!
Here's the situation: See mods below. I have all of the goodies and it's time for a head swap. I would like for my car to have reliable street manners and good power under the curve. A good power goal would be around 430 rwhp (I'm currently making 390 rwhp and 388 rwtq). Ultimately I'd like to find a set of heads to compliment my cam and other mods. My only future plans are to throw on a 100 - 125 shot of N20 and a 9" rear end.
I've done a good bit of research and I'm very comfortable with the quality and price of the ported PRC heads, however I can't seem to decide between the Stage 2.5 5.3L heads and the Stage 2.5 LS6 heads. It looks like the LS6 heads have marginally better flow numbers, while the 5.3 would significantly increase the compression of the motor, thus making good top end power (as well as plenty of torque down low). Given my criteria, which of these two would you recommend for my setup? Should I have TSP mill the heads too?
Sorry for asking a bunch of questions, however I'm (slowly) learning all of this. Thanks!
02-26-2008, 01:14 AM
#4
Just make sure to check your PTV
Trending Topics
02-26-2008, 04:04 AM
#8
11 Second Club
iTrader: (3)
Join Date: Sep 2007
Location: Brooklyn Center, MN
Posts: 792
Likes: 0
Received 0 Likes
on
0 Posts
Same here too. I'm debating whether I should go with the 5.3 or LS6 heads with my Trak cam. Starting to lean towards a 59cc LS6 Stage II for higher compression ratio and better flow. Anyone have any ideas for this setup?
02-26-2008, 10:21 PM
#13
Thanks guys...great feedback so far. It looks like both the 5.3 heads and the LS6 heads are tried and true and put down solid numbers. Based on the flow numbers, the Stage 2.5 LS6 heads flow slightly better than the Stage 2.5 5.3 heads. Given that I'm looking to increase compression (hence building low to mid range torque), it sounds like I would be best suited with the 5.3 heads. The 5.3s should also nicely compliment my relatively mild cam.
I think where I'm getting confused is when you throw "milling" into the mix. By milling the heads, it helps increase compression even more, hence increasing the velocity of movement of air through the heads (please correct me if I'm wrong on this). Can you guys give me a simple explanation as to how this is accomplished?
I apologize for all of the questions. I'm completely dumb to a lot of this stuff, however I'm learning more and more each day.
I think where I'm getting confused is when you throw "milling" into the mix. By milling the heads, it helps increase compression even more, hence increasing the velocity of movement of air through the heads (please correct me if I'm wrong on this). Can you guys give me a simple explanation as to how this is accomplished?
I apologize for all of the questions. I'm completely dumb to a lot of this stuff, however I'm learning more and more each day.
02-26-2008, 10:27 PM
#14
I would go with the 59cc LS6 & here is why...
For a long time I WOULD HAVE voted for the 5.3 heads on a street car. Mainly for what all you read about with their smaller runners & higher compression making more torque & power "under the curve". This is true to a degree. Now since then I have had some LONG talks with major head porters. The keys are runner design, runner volume, flow, velocity, & how they all work together. With stock cubes, you don't want to just start hogging out the intake and exhaust runners because the velocity will probably slow down even though you'll have great flow numbers! Typically with the bigger runners you lose some velocity which will affect your bottom end and part-throttle response. There seems to be a fine line of flow vs. velocity & good porters know this. Runner shape and the cross section of the port is more important (to a certain point) than just runner volume. A well designed smaller runner can flow better than a larger runner. Now all that being said, volume alone does not always dictate velocity. As long as the cross section is not too big, and has the proper shape, you won't lose velocity... Lets look at LS1 heads, LS6 heads & aftermarket heads.
LS1 head ~ 205cc runner & flows ~ 230cfm
LS6 head ~ 215cc runner & flows ~ 260cfm
A.M head ~ 205cc runner & flows ~300cfm
LS6 head has larger runners & flows more than a LS1 head. OK, based on the above info you prob. think it gives up a lot of velocity & low end b/c of the hogged out runners. Not the case... I makes MORE power b/c it is a better "design" & still keeps the velocity up. How can the aftermarket heads have a smaller runners & flow more??? B/C they are a MUCH better design than the LS6
There is a lot more to it than all this but I wanted to point out a few key points. I am sure I missed a lot & others can fill in the gaps.
"I think where I'm getting confused is when you throw "milling" into the mix. By milling the heads, it helps increase compression even more, hence increasing the velocity of movement of air through the heads (please correct me if I'm wrong on this). Can you guys give me a simple explanation as to how this is accomplished?"
No, by milling the heads you ^ compression which = more torque/power.
For a long time I WOULD HAVE voted for the 5.3 heads on a street car. Mainly for what all you read about with their smaller runners & higher compression making more torque & power "under the curve". This is true to a degree. Now since then I have had some LONG talks with major head porters. The keys are runner design, runner volume, flow, velocity, & how they all work together. With stock cubes, you don't want to just start hogging out the intake and exhaust runners because the velocity will probably slow down even though you'll have great flow numbers! Typically with the bigger runners you lose some velocity which will affect your bottom end and part-throttle response. There seems to be a fine line of flow vs. velocity & good porters know this. Runner shape and the cross section of the port is more important (to a certain point) than just runner volume. A well designed smaller runner can flow better than a larger runner. Now all that being said, volume alone does not always dictate velocity. As long as the cross section is not too big, and has the proper shape, you won't lose velocity... Lets look at LS1 heads, LS6 heads & aftermarket heads.
LS1 head ~ 205cc runner & flows ~ 230cfm
LS6 head ~ 215cc runner & flows ~ 260cfm
A.M head ~ 205cc runner & flows ~300cfm
LS6 head has larger runners & flows more than a LS1 head. OK, based on the above info you prob. think it gives up a lot of velocity & low end b/c of the hogged out runners. Not the case... I makes MORE power b/c it is a better "design" & still keeps the velocity up. How can the aftermarket heads have a smaller runners & flow more??? B/C they are a MUCH better design than the LS6
There is a lot more to it than all this but I wanted to point out a few key points. I am sure I missed a lot & others can fill in the gaps.
"I think where I'm getting confused is when you throw "milling" into the mix. By milling the heads, it helps increase compression even more, hence increasing the velocity of movement of air through the heads (please correct me if I'm wrong on this). Can you guys give me a simple explanation as to how this is accomplished?"
No, by milling the heads you ^ compression which = more torque/power.
Last edited by cdoggy81; 02-26-2008 at 10:33 PM.
02-27-2008, 09:06 AM
#16
LS6 heads will be fine with the MS4 as long as they aren't past stage 1. Past that and you'll also be looking at flycutting the pistons.
Now, if flycutting the pistons is no big deal, then I would mill down the PRC 5.3 stage 2.5 heads over the LS6 heads.
02-27-2008, 09:12 AM
#17
TSP PRC 5.3 Stage 2.5's - 220 Runner
208 @ .300
257 @ .400
290 @ .500
317 @ .600
$1,209
TSP PRC LS6 Stage 2.5 - 230 Runner
209 @ .300
258 @ .400
295 @ .500
316 @ .600
$1,699
TEA 5.3 Stage 2.5 - 220 Runner
207 @ .300
252 @ .400
290 @ .500
317 @ .600
$1,699
TEA LS6 Stage 2 - 230 Runner
219 @ .300
271 @ .400
308 @ .500
320 @ . 600
$1699
208 @ .300
257 @ .400
290 @ .500
317 @ .600
$1,209
TSP PRC LS6 Stage 2.5 - 230 Runner
209 @ .300
258 @ .400
295 @ .500
316 @ .600
$1,699
TEA 5.3 Stage 2.5 - 220 Runner
207 @ .300
252 @ .400
290 @ .500
317 @ .600
$1,699
TEA LS6 Stage 2 - 230 Runner
219 @ .300
271 @ .400
308 @ .500
320 @ . 600
$1699
Last edited by Gun5; 02-27-2008 at 10:06 AM.
02-27-2008, 10:00 AM
#19
This is generally the best advice on here. If you have the MS4, you won't be able to do the 5.3 stage 2.5 heads without flycutting the pistons. The MS3 will be fine with them, but the MS4 you will have to flycut.
LS6 heads will be fine with the MS4 as long as they aren't past stage 1. Past that and you'll also be looking at flycutting the pistons.
Now, if flycutting the pistons is no big deal, then I would mill down the PRC 5.3 stage 2.5 heads over the LS6 heads.
LS6 heads will be fine with the MS4 as long as they aren't past stage 1. Past that and you'll also be looking at flycutting the pistons.
Now, if flycutting the pistons is no big deal, then I would mill down the PRC 5.3 stage 2.5 heads over the LS6 heads.
02-27-2008, 10:12 AM
#20
TECH Fanatic
iTrader: (4)
Join Date: Dec 2003
Location: Phila, Pennsyltucky
Posts: 1,520
Likes: 0
Received 0 Likes
on
0 Posts
I have the 5.3s and a 230 cam. I didnt have to flycutt with the. 40 gasket but i didnt have enough room to mill. I would recondmend the 5.3s with that cam. The cam is similiar to mine and I'm 450+. Ls6 heads would be better in my opinion with a larger cam, milling and flycutting. So keep it simple and just bolton 5.3s and use a smaller gasket.
Last edited by STRIPSTAR; 02-27-2008 at 10:19 AM.