Is piston slap something that every LS1 has or just some? I am pretty sure my car has it (dull knock/tick when cold, right?). My real questions are:

1.) What kind of damage is being caused?
2.) Is this damage avoided if the car is not actually driven until it is up to temp?
3.) What can the dealer do about it?
4.) Is it worth letting the dealer tear apart your motor and worrying about problems that they might cause?

Sorry so many questions, I am just getting a little concerned. I searched and found out what it is but could not find answers to these questions. The car is a 2002 z28 with about 4000 miles on it. The noise started at about 3500 miles.

Thanks in advance
Dustin

 

Ahhh the LS1 piston slap. Its great.

Theoretically damage CAN be caused, BUT there are people with 450 RWHP NA and have never had a problem linked to piston slap. The dealer wont do **** about it. They will just tell you "its normal". Well, its NOT normal, but like I said, nobody has had a problem with it yet, so who knows.

The piston slap as you might know is because of an overbore in the number 1 cylinder. Once the piston heats up, it expands and the sound goes away. Thats at least what ive heard.

 

I guess that is good too hear. I don't like my car sounding like **** every time I start it but I can deal with it. I am glad to hear that there have not been any reported problems with it. I didn't want my engine torn apart anyway, the car is breaking in great. I guess I won't even bother with a trip to the dealer then, unless someone else has a different opinion.
thank you
Dustin

 

It's like U 8 DUSST said, the dealer won't do squat, but..... you never know. I'm here in N Ca. also--where you located??

 

I'd also have to say that it's normal. My car currently has just over 9000km (~5500miles) and it's got a knock that it's had since the day I picked the car up from the dealership. It's especially worse first thing in the morning, but even during the day, if the car sits shut-off for a short period of time, when I start it back up, it'll knock (lightly) for a minute or so. To me, aside from just a piston slap sound, it also sounds a little like lifter noise --- but regardless, it's noisier than I'd expect a brand new engine to be. I think the whole reason is that they've increased all the clearances so that the engines can run hotter to burn off more emissions without seizing the motor --- it's still stupid though.

 

I am by no means an LS1 (or other) guru, but I am trying to learn more about LS1's.

A lot of hot rodders will build an engine "loose", and with forged pistons, they would slap until warm. This was considered normal. None of the engines I've built did that, but I assembled them to spec and didn't mess with loose tolerances.

I assume that the LS1 has hyperuetectic pistons, at best, but I don't know for sure.

Maybe these engines are built loose and that is one reason (besides killer heads, intake, ignition) they make sick power out of the box.

Scott

 

It is (unfortunately) normal due to the difference in material used between the piston and the cylinder sleeve. They heat at different rates, causing the slap till warmed up. Believe me, it doesn't compare to the piston slap that the old timers talk about from the 60's... that was way noisier.

Some people have had it (or extreme versions) fixed by a dealer - it has been found on numerous cars that one of the cylinders is overbored from the factory causing excessive noise. However, I won't trust a dealer to tear apart my engine unless necessary.

 

Is this a hollow sound? Mine sounds like just one piston or whatever. It reminds me of a clearanced race motor sound but only on one one cylinder. It sounds like a loose or full floating wrist pin on a older 283-350. If it is just one cylinder does that mean that mine is probably bored with one cylinder too large?

 

Yeah, it could be described that way.

 

You couldn't hear them because the engine itself was louder. Remember that you had to walk 15-20 feet away from the engine to carry on a conversation while it was running? The difference is that the newer engines have much, much, less background noise so any odd sound stands out like crazy. An LT1 has worse piston slap than any LS1 I have ever heard but the LS1 is so much quieter everywhere else that the noise is very noticeable. The thing with the LT1 was that every one of them did it below about 60F at about 2000 RPM and it sounds NASTY. It never did any damage in those engines, never did any damage in the older hot-rod engines. And so far, no one can prove that it does damage today on the newer engines.