xph

So I am a bit of a noob here, might not have the right info or even be asking the right question... but bought a car with a LS2 (6.0) bottom end, with SCAT rods, and JE -5cc Pistons... The car has stock LS3 heads with LS3 intake and 90mm TB. Currently has stock exhaust manifolds, but will get Long Tubes this winter... The car is for track and autocross use..

Its currently running an LS7 cam (with the 1.6 rockers I think but am not positive), not sure on the valve springs, but it does have the sodium filled intake valves.

I also think the heads were decked to raise compression but I am not sure.

Car is currently tuned and dynos around 450hp but leaves me thinking there should be more power.

I am looking for a good CAM to work with the heads, and sort of assume I will need to replace the valve springs at the same time (engine has over 10K miles since it was built)

ideally I would like to make sure I have decent torque down low for off corner action, and a nice wide power band for racing, its ok / desirable to have more torque / HP at high RPMS to help manage wheel spin, but right now there is defiantly an "on cam" feeling as I get above 4500 rpm.

Thanks

HINSON Motorsports

Sounds like you got a pretty good setup to work with. The "on cam" feeling you refer to north of 4500 is really because the LS7 cam starts to shine at that point. Hopefully the LS3 heads were decked in order to increase the compression ratio otherwise you are loosing some power due to a pretty descent drop in compression. I am very familiar with this setup on LS2s and have done a lot of work with LS2 bottom end and LS3 top end. I think you are leaving a little power on the table throughout from not having headers and the cam choice not being ideal for what you use the car for. I would like to work with you on getting you a cam to make the power int he places you need it so the car performs better in the driving conditions it sees. Hit me up in an email and Ill work on some stuff for you.

chris@hinsonmotorsports.com

06vzssthunder

I would say that's making good power for the setup you have.

xph

it could be all there is for this motor, but I just have to wonder if a stock cam is really maxing out the potential...

It seems I need to really figure out my rocker ratio (for some reason I think its 1.6).. that should help me determine the correct lift.

Ideally Id like to be able to over-rev to about 7000-7200 max which is what makes me think I will need better springs (haven't gotten any float yet but I think I still have the stock or nearly stock rev limit.

Ideally I would like to see the torque curve more even, I guess I will probably drop the long tubes on the car, and get a good dyno plot of where I am at now before I move forward... I was just wondering if there was sort of a standard cam for these hybrid motor builds.

MuhThugga

What car is this engine in?

Depending on the exhaust manifolds being used, you can see a 20 horsepower gain switching to long tubes.

xph

Car is a 99 Firebird; has the stock LS3 exhaust manifold on it. The car made 430 rwhp on the dyno with the LS7 cam... so the tuner liked to call it 480 bs er flywheel horse power... not sure my T50 / 10 bolt is really 50 hp worth of loss, but I drive RW HP... So long tubes, and a bit better cam, which gives me a touch more torque and broader power band... and maybe some springs and a higher rev limit, I would be hoping to get closer to 450 rwhp...

Also I would say the power is pretty smooth, but not quite as "crisp" as some of the higher hp ls1 cars I have been in.. I am guessing that's a bit of compression and or cam that I am feeling.

MuhThugga

With long tubes, a 227/235 Lunati cam, and .030 milled LS3 heads, and stock LS3 intake, my LS2 GTO put down 470/410 at the wheels.

You are a bit of a different animal with 68cc chambers and -5cc pistons, though. You will definitely need stronger valve springs with an aftermarket camshaft.

xph

so it looks like I have standard stock height heads, and a stock stroke, with those I am right at 10:1 compression... seems like a conservative build, I don't think I should be at the dyno numbers I am; they seem a bit "rounded up" to me. have to wait for another dyno day...

I suppose I could also just pick up a 4" stroke crank, and that would raise my compression some and add almost 40 cubes... it would certainly help with my torque as well.

4LUX

I will be following, building the same motor. LS2 block, lunati 4" stroker crank with 6.125 lunati forged rods. Still trying to figure out which pistons to buy to work with a set of CNC'ed LS3 heads with lunati gold valve springs and stock intake and TB bored to 95mm.Want to stay at about 10.5 compression. Still need to dial in the cam, want to be in that 450-475 rwhp window.

low2001gmc

iTrader: (148)

Good numbers, similar to my set up of lq9 with milled .030 ls3 heads and lunati cam, except mine 232 238.

low2001gmc

iTrader: (148)

Dont need stroker for 450-475 rwhp. Easily attainable with Ls2, milled .030 Ls3 heads, and for 6.0 or 6 2 recommend only porting exhausts. Advanced Inductions has that as option. Save stroker and fully cnc head money for some else.

4LUX

The CNC heads from Pace are only $100 per head more and have free shipping. So it works out to only $100 total difference. I was thinking of not stroking and running stock pistons, forged rods (I have a hook up at SCAT that will build .944 floating pin rods) and the stock crank. But my buddy that is helping me is pushing for the stroker.

xph

For my application I would like a more broad torque curve, so the stroker is of interest; I already have the 6.125 rods, but would need new pistons and the crank... with bearings and such I am probably 2k to add the stroker...

I have untouched LS3 heads, and seem to be getting pretty good power (90mm throttle body, stock MAF, SLP intake lid) but like most people with these square port heads, I am just a bit off on the torque.. and need some "over rev" room as well so a set of valve springs are in order.

The main reason for the thread is just that the "cam" experts seem to not be in love with these rectangle port heads, and most of what I see says the flow characteristics are great at higher velocities (ie larger displacement and or higher revs) but aren't that great for the lower velocities, where I am hoping to have a flatter torque curve. looking to make sure the car has some decent power down in the 2-3k rpm range.

My engine was patterned after this thread on ls2.com

http://www.ls2.com/forums/showthread...-in-an-LS1-car

here is a nice power recipie with dyno graph for a 403 stroker with the LS3 heads on LS1GTO

http://www.ls1gto.com/forums/showthread.php?t=387867

that last one claims 11.5:1 compression, which I would think would have issues with pump gas, even premium, using a cam "241/252 6**/6** 112LSA" 506hp 456tq, (dyno didn't really go low enough to asses the torque below 4K.)

MuhThugga

Thanks.

I forgot to mention that my pistons did require flycutting.

low2001gmc

iTrader: (148)

My Lq9 pistons arent flycut

MX6.0

+1

Here's what I made with an EPS 222/230 .591/.608 114+4, 25% pulley, stock LS3 heads, NO milling, stock gaskets, 1-7/8" LT's. I don't know if it's the cam I'm running or what, but it seems to have a bit more torque than most I've seen. Blue line is with terrible 1.5" shorties and cats. Red line is after I built the 1-7/8" longtubes and catless duals.

I'm really curious as to how much milling the heads .030 (and maybe .040 gaskets) would gain.

xph

here is a very similar thread from nearly two years ago...

https://ls1tech.com/forums/generatio...76-intake.html




So seems to me I might be able to raise my compression a bit, maybe 10:1 is a bit conservative... that Patrick G Cam seems to be pretty popular with the road race crowd, all of em seem to be within a degree or two. And taking the dynos with a grain of salt, most seem to be getting in the 450-470 rwhp range when tuned... seems exactly like what I am looking for, and possible without a stroker....

Just long tubes, cam, springs and tune.. and maybe some porting on the exhaust..

The problem is (and reason for this thread) is I have no way to judge the results of a 241/232 vs a 223/231 short of buying them both and spending some time on the dyno... I was hoping to glean some insight from the board.

low2001gmc

iTrader: (148)

Good numbers. If Ls2 or Lq9, milling .015 and .040 gaskets will put you right at 11:1 cr. Definite boost in hp and torque. I wouldnt mill .030 just in case in future you decide to go bigger on cam, ptv issues will be minimized.

low2001gmc

iTrader: (148)

So seems to me I might be able to raise my compression a bit, maybe 10:1 is a bit conservative... that Patrick G Cam seems to be pretty popular with the road race crowd, all of em seem to be within a degree or two. And taking the dynos with a grain of salt, most seem to be getting in the 450-470 rwhp range when tuned... seems exactly like what I am looking for, and possible without a stroker....

Just long tubes, cam, springs and tune.. and maybe some porting on the exhaust..

The problem is (and reason for this thread) is I have no way to judge the results of a 241/232 vs a 223/231 short of buying them both and spending some time on the dyno... I was hoping to glean some insight from the board.[/QUOTE]

If heads arent milled, i would mill .015 and run .040 gaskets to raise compression approx .8 and boost hp and torque. Since wanting to do both track and autocross, and autocross benefitting from torque, either the pat g 223 231 or eps 222 230 cam with lower duration will be ideal whole still making good power. I would go with eps 222 230 as its cam lobes are easier on springs and ive seen just as good or better dyno numbers from it

xph

thanks low2001, really seems to fit with the other information I have been reading... I guess the ls3 heads really like the compression, so I am defiantly leaving something on the table there.

What sort of LSA would you run; 114 with a couple of degrees of advance? Car will be around 2600 lbs race weight. or should I go a bit lower on the LSA?