Felix C

Only have LS1 experience and you know how it easy it is to make power with most cam profiles.

New to the LS3 and remember when they first came out folks were not quite used to them and cam selection had to be carefully done to make good streetable average power increases. Huge ports, big valves, heavy valve train compared to the LS2 changed cam selection.

What to do or avoid when selecting a camshaft for an LS3?

No reverse grinds? Split? How much? overlap range? etc.

BODUKE

Give one of the sponsers a call hey can hook you up.

Felix C

In the old days of Ls1tech.com folks who have answered the question and not post "call as sponsor"

A.R. Shale Targa

iTrader: (2)

Kinda hard when you have given very little of the combo, car, or your intended purpose.

Tuskyz28

I 100 percent agree.

Felix C

I left it open for folks to explain their rationale

A.R. Shale Targa

iTrader: (2)

Perhaps change the thread title to build my car please.
LS3 has thirty more inches and a half point more compression.
Unlike the one heads at 70% e/I ratio the threes are 60% e/I.

KCS

iTrader: (20)

Bigger straw, shorter breath. Keep it conservative on the intake lobe.

Jason 98 TA

iTrader: (4)

The LS3 heads & intake are different for sure! In fact we use proprietary lobes on a lot of our ls3 stuff that has the p/v restrictions in mind. We even have camshafts that have made over 100hp gains from a stock L99! (vvt afm version of ls3)

We can help put together a package that will work great for you! Camshaft, springs, pushrods, gasket etc. We can even help mail order tune it if needed!

Give us a call so we can discuss your specific mods & goals. That's truly the best way to make sure we get you exactly the right combo!!

moeZ28

iTrader: (7)

Anything that works cam wise on LS1, works on L92/LS3 stuff as well. You don't need special cams. Although with the size of the intake valve, you may have to flycut for a cam that you may not have too on LS1 stuff. Don't drink the KoolAid on here about special cams.

1sick_eg

I think a lot of people go overboard on stock ls3 motors when it comes to duration. A lot of guys are making 480-500whp in the 220-230 range on the intake side, and 225-235 on the exhaust. You need a little more duration on the exhaust side due to the not so great flowing port.

I did go a little bigger on my cam, but I plan on throwing some heads on here soon. I didn't want to lose too much torque however because I plan on tracking the car. I went with a 232/238 .621/.603 113lsa cam(Cam motion core. Kip is great.) and put down 484/444 to the tires. Over 400wtq just over 2k rpms.

edit: car has 1 7/8 lth, 2.5" stock exhaust, adm intake.

Felix C

Well I read on speedtalk.com regarding the large valves and reversion being an issue so camshaft selection is more critical(less forgiving) than on the LS1.

I read the 10 camshaft comparo done by the mags by that is old news already.

Some basic things to do and some not to do. I mean as for as camshaft stuff. Not bolt-on. You know mild is X range of degress, moderate, aggressive, wild,etc.

I could read all the threads here and in the dyno and camaro/c6 section but that would take a year. There must be a distillation of information somewhere.

moeZ28

iTrader: (7)

My custom blower cam is 235/238 .619/.615 115+2 COMP LSL/LXL lobes
Makes around the same numbers with this blower cam as LS3 Camaros with a G6X3 cam make on my tuners dyno, and blower cams are typically softer than N/A cams.

But everyone will tell you that "there's no way a cam like this will do good with rectangle port heads, the duration doesn't have a big enough split, and the intake duration is too big." BS!!

moeZ28

iTrader: (7)

Stock LS6 heads
.200 .300 .400 .500 .550 .600
Int. 126 184 224 251 256 257
Exh. 108 143 163 176 180 183

Stock LS3 heads
Int. 156 226 276 310 324 332
Exh. 120 158 183 194 199 204

As you can see, the "weak" exhaust side of the LS3 heads matches LS6 heads peak flow at .400 lift...not exactly weak. People get too caught up in the ratio of intake flow/exhaust flow on the ls3 heads, and neglect that fact that they still outflow LS6 exhaust heads significantly.

LS6 head flow numbers taken from LS1tech Sticky thread
LS3 head flow numbers taken from Lingenfelter (Were more conservative than 3 others charts I saw)

Black_Phantom

That's what PatG had to say about LS3 Heads IIRC

Here's what the collective resources are showing so far:

The bigger L92 numbers for 400+ CID motors seem to favor an intake valve closing point of 50-52 degrees ABDC at .050" (just like a cathedral-port motor).

The L92 motors like around 4 degrees more ignition timing than cathedral port motors. If you're running less than 30 degrees of timing, you're probably leaving power on the table.

The L92 motors respond well to higher DCR as long as it does not limit total ignition timing (see above). Better to have full timing and lower DCR than high DCR and low ignition timing.

The 400+ CID L92s seem to be more exhaust sensitive. 1 7/8" headers seem to help more than on cathedral port motors.


The L92 402s don't seem to not like much more than 15 degrees of overlap at .050" (which baffles the hell out of me). Start making more overlap than 15 and they really start to get lazy down low.

I think with the large intake port, the airspeed must be pretty slow. This might explain why they're so overlap sensitive. This does not mean you have to run a wide LSA cam or a narrow one, you just have to hit the valve events that fit the critical criteria (IVC and overlap).

Dyno Junkie

I'm using an off the shelf CompCam in our LS3 Monaro.
231 239 .617" .624" 113.

Seems to work ok.