GrantB

My 70k mile heads/cam LS1 died yesterday, at a NARRA event at Sebring. I'm not sure on the cause. Initial symptoms were blowby and burning oil, followed by light rod knock. Oil level (overfilled), pressure and temperature were and are all normal. Peak oil temps (pre-cooler) were 285F (very briefly; I never usually take it over 265F) with 5w40 Redline. I guess I'll know more about the cause when I pull it.

My next motor will likely have an accusump, and maybe some oil restrictors in the pushrods. I'll also get the HPTuners cable that will log without a laptop, so I can log oil pressure and ensure there are no drops on track.

Anyways, who is known to make impeccably reliable setups? Katech? I've also heard good things about HK Racing Engines.

It seems like LSx motors are never known to be as reliable as some others' (Porsche, MKIV Supra, Viper, etc). I'm not sure if this is due to something inherent in the motor, or something more variable (I know some people, like Subdriver, reported insufficient bearing clearances in some of their engines).

Z06Fix

The LS6 has proven to be a very strong engine

Katech does awsome work. I have only heard good results out of their builds.

vette6aut0x

You just joined the long list of wet sumped LS engines that have fallen victim to the long sweeping turns of Sebring.

Lot's of denial out there about the reliabilty of the LS engines. All the builders say "we've never lost an engine", so why are there so many guys needing engines?

Both of the builders you mentioned have excellent track records.

Katech = pricey
HK = long lead time

You might try SpeedSouth. They are a forum vendor and I understand they're engines are built by Ron Sporl, noted marine racing engine builder.

imp zog

Having just pulled apart my stock LS6 from the '01 Z06, after 7 years of hard track use (30 - 40 days per season, 42K miles on it now), the engine was immaculate aside from some minor scoring in one cylinder, which honed right out. I used Mobil 1 5W30 or 10W30 religiously, and always put the +1 quart in for track events, but due to it being an '01 oil-burner, I never bothered removing any oil because it would disappear on the street anyway. Other than that, the *only* thing I ever did to that motor was put new spark plugs and wires on last spring. Still purring like a kitten, I decided to pick up a crate LS6 and swapped it out so that I could do the refresh before something major did happened.

AU N EGL

the most reliable LSx motors are UNOPENED create LS6s. Nothing more reliable then create LS6s.

Now, if you dont mind refeshing your motor once or twice a year, then YES a custom built LS motor can be great, but expensive.

GrantB

What does it matter if its opened or not? There are reported cases of insufficient bearing clearances on factory motors (e.g., look here).

What typically fails on higher-output LS motors?

GrantB

That would explain why I never had any issues on any other tracks, and my first trip to Sebring = boom. However, the car was on street tires. Peak lateral gees before throttle application didn't even hit 1.3.

I'm definitely going with an Accusump, HPTuners logging of KR and oil pressure, and regular oil analysis with my next motor.

Timz06

I ran my 01 z06 forever with no engine problems at all-including at Sebring.

I would go with a crate motor with an accusump. Most shop motors that go boom are drag racing motors, and don't stand up to road course use.

Tim

imp zog

I have also added an accusump with the new crate LS6. As for weakest links on the LS6, from what I have been told, if you are going to modify it, replace the chain with a Katech and upgrade the lifters.

AU N EGL

I know Subdriver and know of these failures as well.. When looking at the total numbers of LS engines produced, these are few and far between. Now if you look at LS3s in a race situation, then those numbers go up dramatically

Revving the engine too high with a weak valve line. over 6500 rpms and using Stainless steel valves, springs too weak or too strong and valve lifts above .600 cause valve failure.

Many guys who have put high lift cams in find challenges too.

you can build a bullet proof motor, Katech and HK out of Houston are some of the best. at what cost?

one can easily spend $10K - $12K or more on a race motor or buy 2 LS6 create motors for the same price.

What do you want your motor to do? That is always the big question


my LS6 with comp cam 224/224 581/581 112 cam has 24,000 had track miles. Yes I run an accusump, pull the heads each winter to check the valves and springs. ( comp 918 springs) 6750 redline, but keep it 6500 or under

GrantB

Ah, I should have added that I have AFR heads and a camshaft sized specifically for valvetrain durability (0.570"/0.578" lift, mild lobes). What typically fails on LS3s?

The heads are likely fine, so if I stuck with 5.7L I'm guessing a crate LS6 shortblock would be my best bet. Though the 7.0L Katech LS2-based shortblock is tempting...

GrantB

What kind of lap times were you running at Sebring, and on what sort of tires? Did you have an Accusump?

AU N EGL

LS3 first were the 2 piece valves, then the SS valves. both breaking. Oiling issues were also challenges in the LS3. IIRC oil pan change helped there too.

turns out the LS3 head chamber may be too big for road racing.

Light wt yet very very strong valve train is big factor into success.

Tony did a great job with the AFR heads.

Tony has some data on the LS2 and even an LS3 with AFR 205 heads and his Mammo cam, 224 / 228 518/588 114 with some rwtq great numbers.

Oh I know that Katech short block is very VERY tempting. so is a HKE 418 darton sleeved LS3 short block.

Only one thing better then MORE HORSE POWER, that is more and more seat time.

OKsweetrides

Here's some options:
1. crate LS6 + accusump
2. used LS1 + refresh + valvetrain + accusump

Trick is to do something with the oiling!! and if you do a heads/cam, do NOT skimp on valvetrain & chain.

GrantB

Or both! Thanks for the information. I was considering a LS3 crate motor until your last post.

I'm currently running a LS7 chain, and the valvetrain should be solid. At what point is a chain damper needed?

0Randy@DRM

Just about everytime the engine spins.

Randy

AU N EGL

know a forum member who road races and IIRC went though 3 or 4 LS3 create motors. all blew up do to valve train or oiling issues. GM did replace them all.

what is that old saying when you build a motor:

1. HP
2. budget
3. reliability

you can only have two of those three. Chose wisely

there are some great engine builder vendors here on the forum . I am sure anyone of them would love to build you a new motor.

Good Luck

davidfarmer

01-04' LS6. Keep it under 6900rpm and it will likely run a long time!

GrantB

Thanks, I was under the impression they were only needed for 7000+ RPMs.

bosco022

Tim Schwanke at Schwanke Racing Engines business' is mostly circle track and roadracing
LS Motors his carb'd LS1 in my road race stock car was the best road race motor I have had. He is building my Grand Am GT motor at a very fair price.