Best replacement engine for 2003 Z06
 

It would seem that my 2003 Z06 sucked a valve and destroyed the engine (pending complete tear down) I am anticipating a replacement. I would be interested in exploring the options to the GM crate motor and would like some thoughts on the best source for a turn key replacement for the LS6 405 hp engine that might give me better performance and much better reliability. This engine failed with less than 27,000 miles and zero abuse, so its definitely a defect.

broken valve spring?

has happened to a few people which is why "change the valve springs" is said religiously on here to all new owners. when i bought my z the springs were changed within days of ownership

you have three options really, well, 4 i suppose

1. buy one of the last ls1 crate motor and instal a z06 cam and 243 heads making a stock ls6. all the NOS ls1's left and the late design which are more or less ls6 bottom ends

2. buy an ls3 and change over required items to use it

3. buy a built motor from a known good shop. this option is great if you want a race motor but may not go 200k miles if that's what you're after

4. sources a used ls6 engine with good leakdown numbers

Im waiting to see right now if it looks like a valve spring, but Im pretty sure thats the issue. My problem is compounded by living in Hawaii, where its difficult to get anything shipped and there is not a good parts market here at all. I dont have the time or really the expertise to do this swap myself. What are your thoughts on the GM LS6 crate motor? Have they resolved the valve spring and valve issues on the new engines?

I believe they resolved the valvespring issue at the end of the LS6 production run (2004 Z06s and 2004/2005 CTS-Vs), which should put the LS6 crate engine in good shape regarding valvesprings. GMPP would be the most positive way of verifying this.

Also, for me this would be a perfect excuse for a bigger, badder beast under the hood :yesnod: the cost difference between the two would be minimal, if anything

If mine were to go I would go with an LS3, so much potential for big hp with that engine with just a cam swap and LT's. Id probably try to find a low mile one out of a wrecked camaro or c6. If money was tighter I'd just get a low mile ls6 shortblock. Sorry to hear about your engine, I swapped out the springs in mine just after I got it, very glad I did.

I too broke a spring and ate a valve on the way to work back in April. That was at 35mph less than a mile from home when it died in the road. My situation was that I needed to get it back up and running as quick as possible which meant going the crate motor route from Jeggs. They had the LS3 480hp engine ready to ship. I tried looking for an LS6 crate but no luck so I took the LS3 and did not look back. It is a very good engine and takes a really good tuner to get it to run right. The cam they used has a lot of detractors all over because its not big enough, or makes the most power or cannot get it to run. Again if you have a tuner that knows what they are doing you can get it to run and idle. I love the lope it has and how the car shakes. Plus I now have an LS3 with a cam and a warranty from GM since I had a shop install it. Pics of the destruction and the new can be seen on Speed Secrets in Monroe WA facebook page. I hope I did not violate some rule by saying that.

Charlie, which island are you on? I live out in Kapolei and have a complete LS6 top end plus new springs that can be put on the heads from when I did my build. If you can fins a short block we could work out a deal for the other stuff if it would work for you.

you can fix any year ls6 with a $65 spring kit

by 2004 they began using the new manufacturer and what's now called the ls2 spring. very very few reported breaking. no more than any other engine

the problem is the ls6 crate is unavailable and no known new stock exists

if there are any GM dealers in hawaii you're already ahead of the game because you can buy either an ls1 or ls3 {my choice} at MSRP or should be able to i would think.

the other thing to consider is resale. motor swaps don't usually add value to the car unless it's some high end race motor you spend over 10k on or it's an improved factory engine. an ls3 would be desirable to many buyers since it's a stock engine that will go for a lot of miles AND it's a stronger engine than the ls6

ls3 all day long