They do, and it does work.... most of the time. Keep in mind some things are made to keep the customer satisfied, and the others to keep the EPA satisfied. This and DOD are done to do both. Do WE think they are such great ideas? Weeeellll…. not usually….

 

I have thought about ls3 heads but I want to run nitrous with this new short block next season and in the future swap heads and go turbo

 

For a street car the ls6 head will make more torque and carry out to 7-7200 no problem. GM got away with it on the trucks because of VVT. If you were spinning to 8k+ and it was a 50/50 car then I'd understand the argument for ls3 heads but for a budget stroker street car? No way.

 

 

Everything he has said indicates this isn't a street car

 

Yep, hard to make the number when you can't breathe

 

 

2 inch without a doubt

 

I wasn't sure when they started but I knew they had been at it for a while, I just threw out a number, and I agree that they do very well.

And these aren't in light trucks, these are trucks that weigh around 7k and up that obviously produce plenty of low end and only on a 4" bore..

But can't run LS3 heads on a car that weighs less than half of those trucks or you'll lose too much low end, L O L

Sure, you may give up a couple of ft lbs on the low end, but I'm willing to bet the OP's car is going to have at least a 4k stall. The other part that's laughable is people recommending spending approx 3k more (high end cathedrals, big intake and TB) than a stock LS3 top end to make a couple of ft lbs more down low.. where your converter flashes right past

 

More torque where? All the dyno sheets I see show slight edge to cathedral ports under 3,500 rpm above that the LS3's take over...… Nobody I know that has a performance car/truck really gives a **** about losing a little torque down low if they gain from 3,500 to 7,000-8,000. We aren't talking tow trucks here lol

 

 

But some of these LS3 style heads are 270-280cc intake runners if ported. 255 cc heads seem big enough for a moderate stroker.

 

I really think GM went with the big *** LS3 ports to make power with the little LS3 cam and stay emissions friendly. Big cams leave a nastier carbon footprint print and in these politically correct times that's a big no-no for a smart company. That's just my opinion, no one else's but that occurred to me after a cylinder head master guru explained a new way (for me) to think about port size when making power.


Brett at Land Speed Cylinder Heads explained thinking about making good power in this general way and keeping good drive ability.

• Smaller CC port cylinder heads respond well to big cams
• Big CC port heads can work well with smaller cams

What I've seen in real life and online supports that idea.

For instance a fat port GMPP head with 250 cc runners can and have made 400+ whp with a dinky little GT2-3 cam with 207/220 .570/.578 lift 118 and drive very well.

Stock ~200 cc runner heads can also make 400+ whp with a fat cam like a MS3 /MS4 ~ . 239/242, .649"/.600", 111.5 LSA, 110 ICL. Not as drive ability friendly but makes power.


So a big cam & big runner can really make some high rpm power if the intake can flow the air and bottom end take the high rpm.

 

What I like about the LS3 is that the heads and intake manifold are as big as needed for up to about 600HP. So take one LS3, and cam it up to the power level you want...

 

There is a vast lack of basic knowledge about cylinder heads on this site...

 

 

defiantly ls3 heads and intake

 

I'm always up for learning more about cylinder heads. Please spell it out for me.

FWIW - Velocity is important, wouldn't argue otherwise. There are a lot of factors. LS3 heads are well proven. It's even possible to increase the flow in an LS3 cylinder head by reconfiguring the intake port with epoxy and selective porting to flow 375+cfm with a ~245 cc volume intake runner. Makes outstanding hp. It's also expensive.

 

The biggest difference between the 317 cathedral-port heads and the LS3 heads was the port shape and attending flow rates. The 317 offered peak intake flow numbers of 244 cfm, but the LS3 head peaked at a whopping 318 cfm! The LS3 head offered an additional 70 cfm over the stock 317 head!

So a ported stage 2 243 will flow 318 cfm also, maybe more, There would technically be no difference from the 243s to the lS3 except the 243s will have more street friendly TQ under 4000. Now you will all say you will port your LS3 heads and beat the ported 243s, well by the time you do all that just buy some AFRs or Trickflows and beat them all. Plus heads are not going to make your car unbeatable at the track, there are alot more pieces to the puzzle to make a fast car. Last time I checked nobody races CFM numbers or Dyno's.. This is a dumb debate, I bet there are a ton of 243 cars out there that will destroy LS3 engine and vice-versa.. Only thing anyone can do is build it and take it to the track.. Hell, I had a PAW 383 stroker that cost a total of 2500$ in a street car all steel, street tire, registered 68 Camaro and was putting tubbed out big blocks on the trailer in Palmdale. So build it the way you want and go race it, it really doesn't matter anyway due to the fact a LS2 cant compete with modern engines anymore anyways.

5.0 mustangs run 9s all day long with just a Blower and Tune, Hellcats run 9s, CTSv runs 9s and they all can be driven everyday in comfort..

 

We have another KingTalon in our midst....