So I have a 436 LSX with stock LS3 heads and intake my question is if it worth it to run a stock LS7 set of heads and intake vs a worked over set of LS3 heads and intake. What are the gains if any?

I am currently running a baby cam 230/242 600/605 on a 113, it runs out of steam at 5400 rpm's, made 461rwhp and 490rwtq thru a 4L80E in my Datsun 240Z.

I need to purchase a cam no matter what but before I do I need to decide what heads and intake combo to run, which is the best investment.

Thanks
Mike

 

The million dollar ? Is how much do you really want to spend and what are your goals.

 

Ported Ls3 heads are good 4 well over 750+ FWHP n/a but if you would like 2 just spend some cash feel free.

 

Well you have to take into account that the ls7 intake manifold is also superior to the ls3. If you go sticking a stock ls3 manifold on some worked over ls3 heads I can't imagine you making more power than an all stock ls7 top end.

There are other things to consider as well. Such as the factory ls7 heads tendancy to consume valve guides.

Each setup has its pros and cons. If you just want to make the number then the ls7 setup would probably come out on top.

 

But @ the cost of buying new heads Vs having Ls3 heads ported. He stated stock L$7 heads vs ported Ls3 heads. Most ported Ls3's heads would kill a stock set of L$7 heads they tend to die out around .650 lift where as ported Ls3 (Mine are good well past .700 lift. Cool part about it is he already has the heads. Yes the L$7 heads are better but can he get what's wanted with what he has? Yes 550-600rwhp without going out his way buying New heads, intake, rocker arms .....etc.

 

Thread from my files:

Dyno'd the street engine for my 4th gen Firebird earlier this week.

427ci LS3 (4.070 x 4.100), 11.5:1 - prepped by HKE and myself
LS3 heads done by AirFlow Development (Dennis Wheet)
Holley Hi Ram also done by AFD, 102mm NW TB.
Cam Motion solid roller,The cam is 256/265 .754/.747" 108 ICL 112 LSA I believe. Port work is nothing too crazy, just a standard deal.
Jesel/Morel valvetrain
Kooks 2" primary headers. (Tiny 3" collector, being changed)
Moroso vacuum pump (8-9"~ of vac, being fixed and increasing to 16"~)
Bigstuff 3 COP
740 fwhp @ 7200 rpm
Has another 30hp+ in it easily, dynoing again in a few weeks after some minor fixes. Not bad for a OEM head/block deal.

 

From 2007 head porting and cams have come along way since then for Ls3 headed combinations.

L92 head 427 makes 700HP n/a!
We just finished tuning a 427 LQ9 motor with HTM modified heads and sheet metal intake and HTM custom hyd roller cam on the engine dyno..... it finished with a very reasonable idle for the cam that was in it (257/264-114 .664/.644") and made 701 flywheel hp, 579 tq. With a L-76 intake (modified to fit our heads) it made 660 hp, 599 tq. It should make more tq with a cam geared to the L-76 manifold's RPM range.
Brian
HiTech Motorsport

 

Interesting....... very interesting thread.

 

If you like these T here's what I would like from my 408 just without the high compression and race gas. I think my stock ported heads can support this much. So Y go out my way spending a crazy amount of $ when what some of us have can work.... That old saying still holds true: Some people just like Buying a name. When what they got usually will work


6.0 LQ9 Iron truck block (4.03 bore)
4" stroke Callies DS crank
6.125 Lunati I-Beam rods
15:1 diamond pistons
LXR Ls7 4.0 bore head (out of the box) 2.125 Ti/1.600 ss valves
370/250 cfm @ .800 lift
Victory Ti retainers and locks
Pac 1325 valve springs 250/750 pressure
Crower SS 1.8 shaft rockers
Bullet solid roller 278/290 @ .050 .818/.819 lift 112 LSA
Morel Ultra Pro .903 lifters
Smith Brothers 7/16 .165 wall pushrods
LXR 4500 Ls7 cncd intake
Ken Jones 1120cfm Alcohol Dominator
HVH 2" spacer
Stefs oil pan
Dailey external oil pump
Star vacuum pump
Pro Header 1 7/8 x 2 x 2 1/8 with 3 1/2 merge collector

Tune was 26 degrees of timing with 184/184 jets and 5671A-9 plugs .025 gap

Started on a Superflow and finished on a DTS dyno. According the Superflow the DTS is 5% lower. Between time constraints and a **** load of problems is the reason why I had to finish on a DTS. Had to break up the dyno sessions in two days, because of work schedule. First was on a Thursday it made 821 @ 7800, 621tq @ 6100. Came back the following Tuesday and was down 16hp, because of the weather so kept the tune the same. Went from -10 to -9 plugs, bumped up the vacuum 4 Ibs, and turned down the oil pressure and gained another 16hp. There's several things I didn't get to try which IMO would have picked it up another 10hp to 20hp. I'm assuming it would have been low 860s to high 870s on the Superflow dyno, weather pending. Either way this is the second motor I've ever built and still have a lot to learn. Just can't wait to get it on the blacktop dyno to see were I'm really at. Figured I would share.

 

LilJon,
damn dude. alot of power from that motor.^5

 

Well, I busted the bank on the short block build so the budget is tight for now. I don't want to throw away money just to have to make changes again. The cam has got to go, too small but when choosing a cam I need to know what heads to use, LS3 or LS7.

I know of a guy in Ft. Worth who sells the ls3 heads in 3 different stages dependant on needs and build, can't remember his name or shop....brain fart! I like the idea of not replacing the heads just having them worked over. They are already milled .030 and have Brian Tooley double roller springs, new guides and a valve jog from Kim Barr's shop.

 

I am staying hyd. roller cam too, trying to make good power and keep it simple. The 240Z is a street driven pump gas friendly ride that I drive everywhere to play on the streets and track too.

 

Who go cut the cam ? A opinion from them will be very valuable in my book....

 

Geoff Skinner at EPS, he spec'd the original cam for my LS2 build, we just threw it in this motor for a base but it's way too small.

 

I agree with you that the ported LS3 heads would outflow the un-touched LS7 heads. Like i said though, that ls3 intake manifold is a major bottle neck and i am doubtful that the ported LS3s with the LS3 intake would make any more power than the un-touched LS7s with the better flowing LS7 intake.

That being said, if the OP is on a budget then the LS3 path is a no brainer. Lots of good CNC programs out there for the LS3 heads.

 

Sticking with the LS3 milled heads, going to need to have them ported, etc.. Anyone recommend someone in the Dallas/Ft. Worth area? Under a grand hopefully...lol

 

Frankenstein Racing heads they did mine I used the stage1 you could go larger being that you have a larger engine.

Frankenstein's NEWLY Designed LS3 Heads!!!
We just finished up our new port designs for the Stock Gm L92/LS3. We have three versions. The first is a stock valve port program, Second is a 2.180/1.600 valve, and last there there's the big bore option with 2.200/1.600.

Stage 1 flows 388/244

Stage 2 flows 401/255

Stage 3 flows 410/262




BTW: about the intake doesn't flow Vic Jr or Super Vic........Holley High Ram anymore ?"s

 

Cost was $1200 to do my heads bare and returned bare. There right outside of Dallas:-)

 

I strongly agree. I'm running a 370ci with approximately the same cam you running....... cubes eat duration!! I personally think that's why you came up unhappy with your combo. I said it before and I'll say it again the CAM is so so CRITICAL with these rectangular port heads. The reason I say that is due to the intake/exhaust ratio. The more air the heads get in the more they need to exhale if thst make any sense to you. That's why I think people come up very happy or dissatisfied with their setups. Instead of worry about the heads so much cause the LS3/LS7 are both decent budget heads I would be paying someone to really do my cam selection over.......

 

New cam on order from Geoff @EPS. How long of a turn around for the Frankenstein heads?