Gen IV LS3 build elements

[Flash68]

Scared me for a minute there Sieg...

[Sieg]

Originally Posted by Flash68

Scared me for a minute there Sieg...

The offer was made to use Norwood as the recipient.......but I haven't seen an engine cover that looks better to me than my Gen 1 SBC motor and everyone knows I don't have the talent to handle any more horsepower.

I did find him a really nice C10 shortwide today that would be a good donor/shop truck.

[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.

[Solid LT1]

Originally Posted by Sieg

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

What are the LS3's common stress related failures?

Throw the connecting rods away, forged pistons, some valve train components and mods to oiling system passages. I haven't built a lot of LS motors but, my friends machine shop has, including his sons kick ass KOH off road buggy engine. If your going drag racing, it's one thing but, if you plan on hitting a road course for 20 minute lapping sessions and extended high RPM running, cooling systems upgrades would come into play in my book.

When building my GS Vette LS3 I went with Mahle pistons, Manley forged rods (lighter than the GM powder metal crap rods) hand ported the heads, changed valves for hollow stem stainless stuff (but the OEM LS3 intakes are pretty nice and light) I drilled the plastic lifter guides for better oil drain back, used better lifters, pushrods, valve springs, and most importantly looked at all the poorly intersecting holes in the oil passages of the block/oil pan and ported/smoothed the transitions as I anticipate extended high RPM operation of my build. You won't find the deficiencies of the LS oiling system in a drag racing environment but, take that same modified motor to a track and you will. After all I went through on the LS build, I think I should have just called up Donvon Engineering and ordered an aluminum GEN1 block. In my opinion the oiling system of an LS motor isn't as good of a set up as a GEN1.