PRC 5.3 vs PRC LS6 heads
go with the 5.3's smaller runner and similar numbers for a bit cheaper.. use the .40 gasket and your CR will be a round 11.1 thats what Matt from TPS told me.. throw a good cam and intake on it your looking at 440-450 easy street able as hell 
Really...? I talked to Matt @ TSP and he didn't recommend milling the heads and adding the .40 cometics for PTV clearance reasons. I'm just going to mill them .20 and use the GM gaskets for better PTV clearance.
Subscribing.
Man I am glad you posted this thread. I am going to do a cam swap soon with the TR230 reverse split cam. Since I have the engine apart....whats another 1200 or so dollars right?
Whats the stock compression on a LS1? Whats the thickness of a stock head gasket? Predator Z said I wouldn't have any PTV problems with the 5.3 2.5 head(thats the one he thinks I should go with and I do to)I have a full Felpro gasket set I got for free so I really don't want to buy head gaskets. Would having the heads cut some up the compression and still be safe with PTV? I guess I just need to call TSP.
Good thread. I would like to see TSP post in this thread to help us decided which head is best for each setup.
Man I am glad you posted this thread. I am going to do a cam swap soon with the TR230 reverse split cam. Since I have the engine apart....whats another 1200 or so dollars right?
Whats the stock compression on a LS1? Whats the thickness of a stock head gasket? Predator Z said I wouldn't have any PTV problems with the 5.3 2.5 head(thats the one he thinks I should go with and I do to)I have a full Felpro gasket set I got for free so I really don't want to buy head gaskets. Would having the heads cut some up the compression and still be safe with PTV? I guess I just need to call TSP.
Good thread. I would like to see TSP post in this thread to help us decided which head is best for each setup.
if i have a Futral f14 232 234 .598 .600 lift and i want to bump the compression a bit but not fly cut the pistons should i go with the milled stage 2.5 ls6's or the ported stage 2.5 5.3's?
sorry for the hijack
sorry for the hijack
PRC 5.3 stg2.5 with MS3 and fast 90/90 setup made 472rwhp through mosier 9" and 4.10's
MS3 has proven itself many times, buddy has MS3 with fast 90 setup stock 241 heads made 448rwhp
MS4 doesnt make power till 14,000rpm
I would take MS3/PRC 5.3's over any setup for a stock cube motor.
Forged up bottom end with billet, stud the heads, add cometics then dual stage 250shot, now were talking.
setup makes bout 720rwhp
MS3 has proven itself many times, buddy has MS3 with fast 90 setup stock 241 heads made 448rwhp
MS4 doesnt make power till 14,000rpm
I would take MS3/PRC 5.3's over any setup for a stock cube motor.
Forged up bottom end with billet, stud the heads, add cometics then dual stage 250shot, now were talking.
setup makes bout 720rwhp
Last edited by PIMP_2; May 17, 2008 at 06:30 PM.
PRC 5.3 stg2.5 with MS3 and fast 90/90 setup made 472rwhp through mosier 9" and 4.10's
MS3 has proven itself many times, buddy has MS3 with fast 90 setup stock 241 heads made 448rwhp
MS4 doesnt make power till 14,000rpm
I would take MS3/PRC 5.3's over any setup for a stock cube motor.
Forged up bottom end with billet, stud the heads, add cometics then dual stage 250shot, now were talking.
setup makes bout 720rwhp
MS3 has proven itself many times, buddy has MS3 with fast 90 setup stock 241 heads made 448rwhp
MS4 doesnt make power till 14,000rpm
I would take MS3/PRC 5.3's over any setup for a stock cube motor.
Forged up bottom end with billet, stud the heads, add cometics then dual stage 250shot, now were talking.
setup makes bout 720rwhp
sorry, didnt mean to highjack. This thread did just help me though on deciding which heads to go with my MS3.
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From: Charlotte, NC
LOL if thats the case, the MS3 doesn't make power till 18,000rpm. Its one of the laziest low end cams out.
MS4 has quite a bit for low end with the same if not more top end. They wouldn't revise the cam and make it worse than a previous version.
MS4 has quite a bit for low end with the same if not more top end. They wouldn't revise the cam and make it worse than a previous version.
i have the ms3 and 2.5 5.3 heads from TSP, with the typhoon aluminum intake, with headers and full catback, and had mcracing tune it, it came out with 412RWHP and 359RWTQ...they said they couldn't get anymroe power out of it, i HOPE my clutch was slipping on the dyno!! It was a bit on the street when you got on it good....do you think it would have on a dyno?
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.
(https://ls1tech.com/forums/advanced-engineering-tech/111207-ls1-head-combustion-chamber-cc-volume-vs-cr.html)
Bore x stroke (in)
3.90 x 3.62 (99 x 92 mm)
Stock LS1 head
66.67cc = 10.1 CR
Camshaft duration (@.050 in)
200 degree intake / 203 degree exhaust
Camshaft lift (in):
.500 intake / .500 exhaust
Valve size (in):
2.00 intake / 1.55 exhaust
GM Stock gaskit
GM MLS Head Gaskets 5.7/6.0 Compressed Thickness .058 (Each)
GM MLS Head Gaskets 6.0/6.2 Compressed Thickness .055 (Each)
Can be found in down the page
(http://www.speedinc.com/catagory.cfm...in%20/%20Heads)
(correct me if im wrong)
Abby
I made 460 rwhp with the stage 1 ls6 heads and an ms3 cam. Without a fast intake. One of the heads was defective and broke(tsp says it was a bad batch). So I'm either going to get another set of stage 1 ls6's or 2.5 5.3's.
What ever happened with this thread?
What ever happened with this thread?
im in the same boat also cuz im running a X1 230/227 cam. and i hear these cams work well with 5.3 heads. but i was always under the impression that the LS6 heads made more power. i remember seeing old stoker setups where it was all LS6 heads making sick power.
my brothers '01 Z06 with his stock 243 heads and that X1 cam made 422rwhp. Just FYI