I'm putting the Kooks TD system in within two weeks. 1/7/8 headers, Xpipe ( no cats). Before it even goes in I've replaced the kooks bullets (R300) with a pair of Billy Boats Bullets ( from their C7 Vette catback system). Hoping to mellow it a bit & round out the tone.
If you've got the time ... I'll give a full report when done.

 

I hate seeing those pictures.

 

It makes me cringe. We are all a 1/2 a pedal away from the same thing.
OP, Sorry that happened to you. It's a tough hit to take.
Bright side: you have a new build to look forward to.

 

Yeah. I have no f'in clue what happened. I've talked to a multitude of smart people who build motors for a living, and all have said faulty rods. SCAT of course says can't be the rods. If the motor was built wrong, I would have had issues in the first few hundred miles, hell, I hammered on it enough to get the rings seated etc. You would think that a stock ls6 block, opened up to 3.905", with a stock crank, would have been the weak link in a 750rwhp build. Like I said, the pistons are fine, no ring land issues, no signs of detonation on the crowns, no issues with the heads or the crank. So how do you get enough pressure to break a rod, and bend 2-3 others, but don't damage the cylinder liners or the crank? Up until it popped, I still had 38-40psi of oil pressure at idle, at at cruising rpm, in the 50-60 range. I don't get it, my wife certainly wasn't happy about it. My friends who were traveling with me back from LS FEST at 1am certainly didn't get it.

It just pissed me off, sorry to be blunt. I literally hand assembled this motor with the guidance and over-site from my machinist/engine builder. He showed me every measurement, I watched him torque the mains, I torque ever single rod bolt (ARP 2000s) to stretch and was spot on in the middle of the range with each. Measured the pistons out of the hole (0.005-0.007") but with a 0.051" gasket, I wasn't concerned.

I didn't beat on the car. Sure, every once and a while, I'd do the blast to 6000rpm in second or third gear, but it wasn't raced. The tune was conservative. 11.2-11.5 AFR's and 16 degrees of timing. Oh, the rod bearings also looked fine, so if it were detonation, the bearings would have shown signs of being hammered, but they didn't.

Who knows. It's broke, I'm having a new one built.

 

I know someone with some big boy headers that'll never get used, I'll get some specs if you want. If I remember they were stepped kooks with 3.5 collectors.

 

Yeah, get me some pics... let me know.

 

Ok I'll find out.

 

What cubic inch is the motor going to be?

 

My opinion is that you can't "over header" a procharged deal.

 

http://www.superchevy.com/features/0...cadillac-ctsv/


This CTS-V has Kooks 1-7/8 headers and a Magnaflow cat back. It was at 809 rwhp and we swapped the LS2 intake manifold for a FAST 92, and it lost boost but the hp went up to 864 rwhp. The owner took it to another shops dyno day and it made 900 rwhp on their DynoJet.
Bob

 

Their claim about pistons hitting the head...nonsense at only 5 thou unless you had a really thin gasket.

And if they were hitting the head there would be marks clearly visible on the pistons. ie there would be a clean area around the edge where contact was made cleaning away any carbon.

And hitting only on the rock of the piston at TDC, which Ive had before when some Wiseco's seemed to have been specced too loose....it would cause no harm to the rod itself anyway.

Although what caused the failure....at what seems should be the strongest part of the rod, I havent a clue.

 

I'm leaning towards 1 7/8 more and more, simply because I still want to drive this with the wife and kids from time to time, and don't want it to be an allout race car. So there's no point in putting on some 2" race headers with a massive ypipe, if it's going to go through a Magnaflow catback.

I honestly don't know either. Like I said, there's no sign of contact at all between the piston or the head, and I had stock GM mls gaskets which compress to 0.051". SCAT said it's either contact or hydrolock. Which if I hydrolocked the motor, enough to bend forged rods, don't you think I would have taken out a thin ls6 cylinder liner? I don't get it.

It's a 416 with a D1SC on it.

 

If I had to do it all over I would have gone 2" header with the 3.5" Ypipe on my 370. I picked up 80rwhp opening the cutout and dropped around 2psi or so.

 

Yep. And the sound difference between a 1 7/8 and 2" header isn't going to be noticible at all.

 

A true dual 3inch system I heard is good to 1200hp. Any truth in that I dont know

 

I would go ARH 1-7/8" headers and build a true dual over the axle set up.

 

The only problem with that is I don't own a welder, and have never welded. I really don't have anyone local either that I can take the car to and have them do it at a reasonable price.

I do have a 220 line in the garage, and a lift, so if there was someone who was willing to come over, and do something custom, I'd pay them for their time.

Anyone? Bueler?

 

in for results on the 416....

 

If you had a welder and a chop saw I would come over and help.

 

It's going to be a while, probably spring time at the earliest. Since I'm still running the D1SC, I'm expecting a bunch more torque down low, and a mild gain up top thanks to a better cam and bigger headers.