LS3 Heads
Staging Lane
Joined: Jun 2009
Posts: 70
Likes: 0
From: San Diego, CA
So what makes the LS3's intake and heads so much better? I see alot of people that do a head/intake mod go with the l92 heads and/or the l76 intake to go with it.
The LS3's and 92's are rectangular intake port heads. The LS3's have hollow stem intake valves ,the 92's don't. They flow good #s out of the box on the intake side, not so good on the exhaust. The LS3 intake is a great factory piece, kind of like the early LS6 compared to the LS1 intakes. You have to run a L76 or LS3 intake with the LS3 or 92 heads. The LS3 intake manifolds only draw back is that it was tuned to make peak power at around 6300 rpm. With the flow capability of these heads and a 400 cid plus engine this intake seems to be the limiting factor for making huge power.
These heads are a good upgrade if you want something different, they make good low end and great midrange power for a street driven car. Most of the builds that I've seen make over 400 lbft from off idle to the cams torque peak.
I'm building a 414 with these heads and a 76 intake. I had my heads ported by The Head Shop here in Houston. They got some great #s out of them they flow in the mid 300's from .500-.700 lift and 342 at .700. On the exhaust side they did even better mid 200's from .400-.600 and mid 250.s from .600-.700. These guys are great to work with.
The cam is most important factor with these heads and bigger is not better. These heads were not used on the LS7 for a reason. They don't like huge lifts and long duration cams. I'm having a custom cam ground for mine from FTI.
Good Luck with what ever you decide.
These heads are a good upgrade if you want something different, they make good low end and great midrange power for a street driven car. Most of the builds that I've seen make over 400 lbft from off idle to the cams torque peak.
I'm building a 414 with these heads and a 76 intake. I had my heads ported by The Head Shop here in Houston. They got some great #s out of them they flow in the mid 300's from .500-.700 lift and 342 at .700. On the exhaust side they did even better mid 200's from .400-.600 and mid 250.s from .600-.700. These guys are great to work with.
The cam is most important factor with these heads and bigger is not better. These heads were not used on the LS7 for a reason. They don't like huge lifts and long duration cams. I'm having a custom cam ground for mine from FTI.
Good Luck with what ever you decide.
I Just ordered my TSP LS3 heads, since this stuff is all still a little new, aftermarket heads/int not available. I'm going with a stock intake for now and like everyone else, wait for the LS3 FAST.
I had LS6 ported heads 90/92 FAST on my 408 but didn't my whp goal. I tore it all off and waiting for my new heads.
My current cam specs ar below and for now leaving it. May do a Cust Cam when I swap to the Fast.
I had LS6 ported heads 90/92 FAST on my 408 but didn't my whp goal. I tore it all off and waiting for my new heads.
My current cam specs ar below and for now leaving it. May do a Cust Cam when I swap to the Fast.
2009 gmpp catalog gives PNs for each set of heads. valves and springs are different. l92 springs are good to .530 or .560 (i think?) depending on which part of the catalog you look at.
I wouldn't run the stock springs on a performance build. Some vendors are installing the early model LS6 springs on them and calling that an upgrade.
The soild stock 92 valves are heavy. I bought a set of LS3 valves they are pretty nice. I would recommend PAC 1518's as performence spring.
The soild stock 92 valves are heavy. I bought a set of LS3 valves they are pretty nice. I would recommend PAC 1518's as performence spring.
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TECH Resident
Joined: Jul 2007
Posts: 844
Likes: 0
From: Florida
The LS3 has some foam between the inner and outer layer of plastic for NVH on the vettes. I think the map sensor mounts different. Do a search LG had some photos of the LS3 on this site. I don't know of any one doing a test of these manifolds against each other. They are basically the same. The 76 was on a Holden car the 3 the vette.
LG Comparo LS3 v. L76
@1lejohn - i agree. i got comp 921s since I'm running a healthy cam. but a spring upgrade is a must for any performance build.
@1lejohn - i agree. i got comp 921s since I'm running a healthy cam. but a spring upgrade is a must for any performance build.
Yeah I read that awhile back...I purchased a LS3 since the L76 isn't made anymore...I was just wondering if for some reason the L76 flowed better even though the LS3 intake is a newer design...Like does it have the same design problem as the LS2 intake being plastic "welded" toegether and air seeping out...etc....
Jeremy at fasterproms.net they were recomended by TSP, plus they are in FL so shipping is one day each way. Seems like they've got some decent #s. Time will tell, once I get my heads and on the dyno that will tell the story. They are also going to cut and lower the floor. At least I won't have to jump at the Fast when it comes out...
