forged engine noise
have the same "knock" from my mahle forged pistons, they have -2 cc valve reliefs.... i dont like the noise much but as long as its not setting off the knock sensors im happy.... 
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Joined: Mar 2009
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suggestion You're going to be spending a lot of money chasing a non-existant problem. The clearances on forged pistons are different than with normal pistons. They are built with looser tolerances due to expanding. So... the reason is sounds like a diesel on a cold start is due to the pistons being cold-The reason the sound goes away when it's warmed up is due to expansion from the heat. Thermal dynamic is neat. Williams saw a sucker, and they're going to get plenty of labor tearing your engine apart. Good luck.
This info is very useful for me
Thanks Again
I don't see how anyone here who hasn't heard the car in person can have a specific opinion of right or wrong. I have been around plenty of cars with forged internals and some that I knew had too much clearance. None of them have sounded quite this bad. Now before we go and boost this thing up more, wouldn't it be smarter to check it out before possibly completely destroying the engine?
I know that it is normal to hear a little piston slap when the engine is first started. Typically it goes away fast. With this one the noise is still audible when fully warm, just no where near as bad.
Nick
I know that it is normal to hear a little piston slap when the engine is first started. Typically it goes away fast. With this one the noise is still audible when fully warm, just no where near as bad.
Nick
There is a big difference between the sound going away when warmed up to not going away. If it was clearly stated in the original post it would have been easier for others in the thread to discern between the nature of forged pistons and a possible problem. Good luck.
Thread Starter
On The Tree
Joined: Jan 2008
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From: sc
I don't see how anyone here who hasn't heard the car in person can have a specific opinion of right or wrong. I have been around plenty of cars with forged internals and some that I knew had too much clearance. None of them have sounded quite this bad. Now before we go and boost this thing up more, wouldn't it be smarter to check it out before possibly completely destroying the engine?
I know that it is normal to hear a little piston slap when the engine is first started. Typically it goes away fast. With this one the noise is still audible when fully warm, just no where near as bad.
Nick
I know that it is normal to hear a little piston slap when the engine is first started. Typically it goes away fast. With this one the noise is still audible when fully warm, just no where near as bad.
Nick
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10 Second Club
Joined: Apr 2002
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From: Cincinnati, Ohio
I had my forged 427 originally built with JE pistons without offset pins, it sounded like a diesel and did not quiet even once it was warm. I would not drive a car that sounded like this so the pistons were replaced with Diamonds w/offset pins and it is quiet as a mouse even cold.
Thread Starter
On The Tree
Joined: Jan 2008
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From: sc
motor is out. they are checking clearances on the pistons and cylinder walls. looks like it may have been too much clearance and scared #1 and #3. won't know the whole story until next week. pictures to follow.
