JerryTX

Sorry, couldn't trim the video due to an error in the timestamp on the file, last two minutes are all that matter. Back story:
- Nobody else was in ST2
- I'm running with AI/CMC
- Friday no start problem meant no practice Friday
- Still feeling out the car as I just got LG Monoball suspension, LG G2 coilovers, and T1 Hardbar AP front brakes
- Started at the back because no brakes during practice meant working on the car during qualifying.

So this was essentially time for me to just drive and shake out the new setup, and pray I had brakes! I was trying to gingerly make my way through the pack and not mess up anybody else's race. Touched the rev limiter for 1/2 second and boom! Stock LS2 dry sumped, not torn down yet but guessing a dropped valve? Sounded like shrapnel hit both shock towers and I knew it was time to get off the track. Corner workers said fire was coming out from under the car when it first happened, I was thankful it didn't ignite in the dry grass. I was ready to unbuckle and bolt if needed.

MarkDFW

That sucks! Sorry to hear about your car. Hope you are able to get it fixed and make it out to ECR in a couple weeks.

wallyman424

Your car got pissed because you let all those mustangs pass you

if fire was shooting out the bottom then you likely have a hole in the block. Thrown rod would be more likely to me. How many miles/seasons/races were on that motor?

JerryTX

True true! I was trying to be nice and not mess up their fun.. didn't expect them to come back on track so fast after skidding off, lol! I definitely windowed the block, maybe on both sides. I can only guess the motor has >10K miles on it, half of which were on track; history was sketchy. Mark I should be there, dropped of the used LS3 yesterday at LG.

Maynor29

lmao!

05C6GAC

I thought the Dry Sump was suspose to fix that????

WBHighwind

Odd situation all around in my mind. Glad you got the car home safely! Hope you find out what exactly caused this. Im the one with the yellow 944.

Maynor29

Doesn't look like an oiling problem so far. Something else failed mechanically.

JerryTX

Preliminary autopsy reveals the wrist pin was yanked out of the bottom of the piston. No external block damage, but the ARE dry sump pan has a huge hole in it. I'll try and post up a pic..

wallyman424

unfortunate.

sabastian458

what were the engine mods and rev limit you were running?

JerryTX

Stock longblock, 6700 or 6800rpm rev limit based on the factory tach. Going to dyno the new combo and put a big honkin shift light in the center of the dash 200rpm before my designated shift RPM.

taken19

Sucks to lose a motor, I lost my LS2 back in March from a timing chain break...

Hope the damage is minimal and the repair bill doesn't hurt too bad. Hope it all works out for you.

sothpaw2

What chain did you go with on the rebuild? I thought the LS2 chain was better than LS6!

taken19

Actually, I had a Katech C5R chain in the motor at the time. After some research, it may have been the ASP under drive pulley that caused it all. Jason Katech spoke with me personally about it and said the ASP acts less like a damper and more like a harmonic inducer on downshifts. The ASP works works well for the drag strip guys but not so much for road race guys - who knew...

The rebuild? Car got a whole new LS3 dry sump. This motor will see a cam sometime next year and will most certainly have a C5R chain with an ATI pulley. Live and learn!

Sean

Gering

l98tpi

What is the deal with all the LS 2, 3, and 7 failures? Is it cheap China metal the manufacturers are purchasing to manufacture or just poor CAD designs? And, it is not only these engines with issue. I see a lot more issues with heavy duty truck engines as well. All the C6 engine failures keep me wondering whether to step up or not. Yes, GM may warranty most failures, but that is only for 5yrs. 07's and some 08's are just about out of warranty. And I really don't think one should be thinking warranty when using under racing conditions, but you would expect an engine built for a Vette to be engineered to handle the abuse. I have beat the hell out of my L98 bottom end and it is still pump'n hard with around 107K miles. Yeah it could let go at anytime, but it's not likely and the cost would not be much more than $5K to replace. Hopefully there is an answer for you LS guys in the near future besides having to upgrade to high dollar aftermarket heads and cranks and wrist pins and pistons and so on.

Zip Corvettes

He was racing, an engine that had over 5k racing miles on it. Race track and street are different. I have seen many old 350's retire early in a race. That is what comes with racing, lots of engine failures when you are pushing items to the brink. You do not know what calibration was in there and what role that had to play also. I think the new GM stuff is great. Had all the HPDE's been around when the C4's were new you would have seen allot of blown up Tuned Port engines.

JerryTX

Thanks!

Ya I'm not gonna get too upset, stuff happens. I'm thankful I'm in a class that dictates a power level and that I can use an OEM longblock to hit that number. Its not like a bunch of forged this and ported that and balanced and blue printed parts got mangled and the custom bits are out the window. The craigslist longblock I picked up has a small cam in it, wasn't buying it for the cam but the deal was too good so I jumped on it, otherwise Id be dropping in a 100% stock LS3 with a dry sump.

Shaka

Interesting stuff. I'd like to know more about 'Harmonic Inducing'.
As with all engineering, there are compromises. I suppose in reversal or de- acceleration modes, there are damper designs that transfer vibration to the crankshaft which is acceptable in dragster applications maybe. The are constant load aircraft damper applications absorbed by propeller hubs and gearboxes.

A stick shift car and poor downshifts can induce some pretty complicated vibration orders.

The vibration or what I like to call a torsional vibration damper is part of a system that includes bending modes of the crankshaft also, The damper tuning engineer is worth his weight in gold especially on the LS engines it seems.

I did some work on Subaru and Porsche damper issues in aircraft applications years ago. 3 cylinder, 6 and 12s have extremely complicated resonance modes and some rpms are critical.

Packard built a better Merlin than Rolls Royce because of their knowledge of V12 crankshaft damping since 1908. A 3.8 Jag L6 was good, a 4.2 was bad. Today's technology would have fixed both engines easily.

V8s have unique shakes especially 90' V8s as in Chevy engines compared to flat or 180' crankshafts of V8 Ferraris.

The vibration damper has two or three major components. A mass part for absorbing the energy of primary and secondary shakes, limiting their migration or propagation which is directly attached to the crankshaft and one or two energy dissipating elements that handle lessor harmonic frequency orders which include non crankshaft initiation. The use of polymers, rubber, fluid and even clutches are employed with varying degrees of success.

Automatics have torque converters which help a lot.

A single cam has its own issues especially in the case of push rod V8s. That cam twists thru one or two degrees with some awful reverse torque pulses that are transferred thru the chain to the crankshaft and damper. A rubber belt would cure some failures I'm sure, the main reason for rubber timing belts, not cost.
Two 'in block' cams would reduce loads also and inncrease the length of the chain. Shorter pushrods and on plane geometry can only help matters with this set up. 8000 rpm red line???

Most of the in car videos on this forum show really awful downshifts. This is probably 90% of LS engine failures. Popping that clutch and accelerating that huge mass beyond design envelope can only cause harm. There are lunatics out there who will not learn to shift gears properly because of their total lack of knowledge or respect for machines.

Crankshaft Torsional Dampers wear out. They work hard. Replace damper and valve springs every 30 hours of hard racing. Log it if you can. Engine over heating and contaminants will further reduce TBOs. The titanium bolt that holds the damper on is part of the system and the low modulus requires replacement at least as many times as you replace the damper.

Did you ever take your chain apart as suggested? I'm curious as to the type of wear on the link shafts. I have a theory.