Gen IV LS3 build elements

[Sieg]

So if a guy wanted to build a Gen IV LS3 starting with a late model Camaro salvage motor with a goal of high reliability 500-525 crank hp range or more if realistically obtainable. What modifications and critical components need to happen?

Motor could be subject to occasional or daily driving in town, a few 500-1000 mile road trips, and handle a few 'recreational' track days during the year.

Bottom end

Valve train

Oiling

Tunable EFI

Cooling/venting

Clutch

Machining tips/tricks

I ask because a friend just had a longtime local performance motor shop dropped in his lap. This shop had never done LS motors. Old school GM, Ford, Mopar V8's for drag racing, boats, sprint cars, and performance street cars was the focus.

The new owner knows they need to embrace the LS platform to survive and wants to get a Gen IV to analyze and experiment with.

I want to get him pointed in the right direction with solid fundamentals and advice from those with experience.

Thanks :thumbsup:

[rustomatic]

HP Tuners software for the stock PCM or the Holley hp/Dominator setups are probably the best place to start. There's some decent time learning right there--I might get to it myself in a few years, as I just stuck a Gen IV LS in my Falcon. Tons of power seems to come just from cam swaps and tuning in these motors, so there's a lot of homework to do right there.

I'll be keeping the VVT and cylinder deactivation stuff on mine (along with the DBW throttle), because I'm all about efficiency . . .

I'll look forward to any info dumps that happen here.:goggles:

[Flash68]

Scared me for a minute there Sieg...

[Sieg]

Tons of power seems to come just from cam swaps and tuning in these motors, so there's a lot of homework to do right there.

Yes there is. :thumbsup:

[Sieg]

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. :unibrow:

[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]

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]

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]

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]

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. :thumbsup:

What are the basics to improve valvetrain reliability?

[carbuff]

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...

[PTAddict]

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.

[Sieg]

Good answers.....Thank you. :thumbsup:

[Solid LT1]

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.

[Vega$69]

The GM Performance LS3/525 is a great motor as is. If looking for 550-575 crank there is no reason to start throwing away bottom end parts. With long tubes and good tuning you'll be likely at the 550 mark without changing a thing

Lots of guys run stock rotating assemblies up to 800 HP without any issues at all.

The GM hot cams are easy on the valve train with their relatively low .525 lift and longer durations.

[ErikLS2]

http://www.hotrod.com/how-to/engine/hrdp-1109-stock-gm-ls-engine-big-bang-theory/

[Sieg]

http://www.hotrod.com/how-to/engine/hrdp-1109-stock-gm-ls-engine-big-bang-theory/
Well that was interesting :confused59: :thumbsup:

[Che70velle]

Sieg, that article has been out for quite some time, and has changed many peoples minds of just how resilient the LS platform can actually be. I just read through it again, and I get a laugh out of the line that says "this 5.3 came to party" every time I read it. That little 4.8 was quite a conversation piece over on LS1Tech for a long time. Prolly still is...
We are closing in on 20 years of the LS being out (hard to believe)
It's a very strong performer, and for a guy looking for 500ish horsies, I wouldn't change anything in the bottom end, unless I was rebuilding it. You can buy forged pistons, for almost as cheap as the GM units, after rings and pins. Nothing wrong with the powdered metal rods at that power level. The stock crank is good to go also. As mentioned above, if your looking to build a race engine, that's different, but for a guy wanting 500ish horsies, to ride around with, get great fuel mileage, and be reliable as the day is long, throw a camshaft, springs, intake and headers at it and be done. I like the rocker arm trunnion upgrade also, but it's not necessary.
So when are you starting the conversion? :underchair:

[snichols28]

Cam and a tune will get you where you want to be. Definitely get rid of those valve springs, push rods and those rocker arm needle bearings.