Gen IV LS3 build elements

[PTAddict]

All an LS3 needs to make that kind of crank HP is a cam (and a mild cam at that). I had an LS3 in my previous car (71 Camaro), completely stock internally other than a 227/235 113 LSA Comp LSr cam. Headers too, of course. It made ~465 HP and 430 TQ at the rear wheels. It survived about 20 track days without a hiccup. It idled and drove almost like a stock late model Vette.

[Sieg]

Originally Posted by PTAddict

All an LS3 needs to make that kind of crank HP is a cam (and a mild cam at that). I had an LS3 in my previous car (71 Camaro), completely stock internally other than a 227/235 113 LSA Comp LSr cam. Headers too, of course. It made ~465 HP and 430 TQ at the rear wheels. It survived about 20 track days without a hiccup. It idled and drove almost like a stock late model Vette.

So 550 - 575 at the crank is a reasonably safe target?

What are the LS3's common stress related failures?

[71RS/SS396]

I would use the LS3 525 cam and springs, GM did tons of testing on that combo, it makes good power and is easy on the valvetrain. The question is... how good does the car handle that it's going in? The higher the grip level is the more time you need to spend on helping it keep oil where it belongs. A oilpan with good baffling (I'm a fan of the Autokraft pan), accusump, oil cooler, and good venting on the valve covers and valley through a catch can.

[Sieg]

Originally Posted by 71RS/SS396

I would use the LS3 525 cam and springs, GM did tons of testing on that combo, it makes good power and is easy on the valvetrain. The question is... how good does the car handle that it's going in? The higher the grip level is the more time you need to spend on helping it keep oil where it belongs. A oil pan with good baffling (I'm a fan of the Autokraft pan), accusump, oil cooler, and good venting on the valve covers and valley through a catch can.

Thanks Tim. Completely agree with the handling statement and will add brakes to that. With the new generation crate powerplants it's an uncomforting thought wondering what type of chassis' they may be going in.....and the fact that they could be coming at you on public roads in a manner similar to a Skud missile.

One the the better tracks near us (6 hours) is Thunderhill and T2 is an oil starver for sure. It's a pure 180*3rd gear radius that's probably damaged more than it's share of motors.

The GMPP LS3 525 motor is what I've been looking at as a decent target for the shop to improve on by addressing the oiling and venting issues along with insuring the motor gets adequate fuel, that should deliver a reliable cost effective package in my amature mind at least.

At what point does the Nodular Iron crankshaft/rods/pistons become a weak link in an LS?

[PTAddict]

Originally Posted by Sieg

At what point does the Nodular Iron crankshaft/rods/pistons become a weak link in an LS?

The bottom end parts in an LS3 are far more robust than in the production Gen 1 small blocks. I simply wouldn't worry about the bottom end at any normally aspirated power level. The failures I've seen on LS motors at the track almost all seem to be related to either oiling issues or valvetrain.

You do want to make sure you're using an ECU with correctly calibrated knock sensors (like the GM ECU, or a correctly calibrated Holley or AEM). LS3s are quite knock sensitive, especially on the crap gas we get here in Oregon. I dyno tuned a 2011 Camaro SS yesterday with stock cam, headers, cold air, and I couldn't get it to keep more than 19 degrees timing at WOT. And it still made 413 hp at the rear wheels!

Also if you're going to track it, overdo the cooling system as much as possible, especially in a 1st gen f-body, which has smaller core size than the 2nd gens. Ron Davis or C&R radiator, secondary oil cooler, tightly seal the high pressure area at the cowl. Also a 160 thermostat if you don't care much about the heater

[carbuff]

Originally Posted by 71RS/SS396

and good venting on the valve covers and valley through a catch can.

Tim,

Do you have a preferred catch can that you suggest/use? There are so many different styles, and as such, a lot of marketing hype for each...

[Jay Hilliard]

Bryan,

Petersen and DSE cans seem to be the ones used a lot.

[Sieg]

Thanks for the input gentlemen, very much appreciated.

What are the basics to improve valvetrain reliability?

[PTAddict]

Originally Posted by Sieg

What are the basics to improve valvetrain reliability?

No easy answer there. Every combination known to man has broken for somebody at some point, and you'll see even very highly regarded builders swearing by completely opposite strategies.

Basically, you see variations on two schools of thought. One school emphasizes valvetrain stability - minimize flexure, resonance and valve bounce through light weight hollow stem or titanium valves and beehive springs. That is also the factory GM approach. The other school goes for brute force - solid stainless valves and high pressure dual springs.

Katech, a highly regarded builder who does a lot of research for GM and built all of the Vette endurance racing engines for a number of years, goes for school #1, and they have lots of Spintron data to back it up.

Lingenfelter, on the other hand, goes for big dual Ferrara springs.

I myself think approach #1 makes the most sense from an engineering perspective, and its worked for me for 50ish track days over 10 years. But YMMV, and as I said there is no absolute 100% reliability on any motor used repeatedly to its limits.

BTW, no reason to replace stock rockers - they have very low "effective tip mass" and are reliable.

[carbuff]

Originally Posted by Jay Hilliard

Bryan,

Petersen and DSE cans seem to be the ones used a lot.

I wasn't aware that DSE sold one. After looking at the picture on their site, that sure looks like the Mike Norris can, which is the one I already have. Thanx...