Thanks for all the input. I was originally planning my build around the Trick Flow rectangular port head announced at last years SEMA (supposed to ship in March of 2011)show or hoping that Airflow Research would come out with something to fit. It's starting to look like my best bet is to go ahead and get Richard to work his magic on a set of L92/LS3 factory castings.

I would revert to a cathedral port but I've already made substantial changes to my Maggie's lower manifold including port matching the L92s.

 

I'd really like to see some pics of your new build.

 

Not very good at posting pictures, but I'll give it a shot later this week.

This wasn't a planned build at all and I would like some educated guesses on what caused the failure. I Started hearing a clicking noise in the front of the engine. At first I thought it was the accessory drive so I pulled the belt but the clicking continued. Removed the front cover to discover a shattered LS3 timing tensioner. Didn't think I had jumped time or any piston to valve contact but decided to pull the cam and look at it. Cam showed extreme scoring (for 5000 miles)on most all of the lobes. Pulled heads to check lifters. Multiple lifters (LS7)showed flat spots, although none seemed to be seized. Bottom end only had 30k so I was going to vat and reassemble stock bottom end. Discovered either #1 or #2 piston had a 1.5-2 inch chunk broken out of the second ringland. Based on the carbon buildup inside the crack it had clearly been running this way for a while. Oil in crankcase was filthy at less than 500 miles.

 

Thats an interesting set of broken stuff....

 

You're telling me. When the machine shop called and said I was going to need pistons because of a broken ringland I assumed it was the top ringland from detonation even though the tune was way rich. Imagine my surprise to find the top ringlands in perfect shape and a chunk broken out of the second ringland.

 

I find it hard to believe all of those things are isolated incidents. I dont know how to tie them all together though...manufacturing defect in the piston caused it to fail and see metal fillings through the oil system causing the lifter rollers to stick and the cam bearing surfaces to wear much faster and the timing chain broke from the uneven application from the worn cylinder? Talk about a long shot...what timing chain was it?

 

LS2 timing chain and it didn't break, just the tensioner disintegrated.

So which came first the chicken (broke ringland) or the egg (broke tensioner)?

Clearly there were lubrication issues, but were they caused by debris from the tensioner, the broken piston, or something else I may have missed completely?

 

I am going to say the piston because metal fillings are a lot more abrasive than plastic filings....or do you have the spring type tensioner instead of the wedge type?

 

Stupid NEWB mistake - I didn't replace the spring type with the wedge when I did the DOD delete.

 

I know i dont have a FI engine but i dont have anything special in my setup other than Patriot Extremes. 15-18k on my top end for a total of 34-37k on my short block...i spun mine to 6800 atleast 6-8k of its life and i never had a problem with my valvetrain. Ive had a few 7k pulls that was a little scary considering i didnt know how the lifters would react


Im with skeet though, the LS3 valves would be a great upgrade but i dont know the "hp/tq" gain over just a valve swap.


Sorry to see that you had problems with your motor but i honestly doubt the tensioner caused your problem considering i know a few people that have been 6500-6900 rpm with their tensioner broken and no issues.