450NP .040 Pistons

[Cndeh]

I was wondering if these pistons are good to be reused in a Turbo engine? I did a search online and I cant see any references stating they are good for a Turbo engine. What I am dealing with is an A code engine what has been converted into a GN clone. The engine was rebuilt at some point and all the Turbo parts were added by a previous owner. After disassembly it doesn't look like the engine has seen many miles.

Here are some pictures:






Any and all advice will be greatly appreciated.

 

[MAK507]

They look perfectly fine to me. I had 40 overbore. Maybe get the cylinders checked to make sure they’re to spec? You wouldn’t be able to bore the motor anymore than 40. Anything over that could lead to cracking the motor.


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[earlbrown]

It depends. If you GN clone is turbocharged, those are ashtrays.

If your clone is appearance only, they're possibly still ashtrays.

There's a reason they're $18....

 

[SCOOBY DOO]

Google search has them coming up cast aluminum.

 

[Cndeh]

They look perfectly fine to me. I had 40 overbore. Maybe get the cylinders checked to make sure they’re to spec? You wouldn’t be able to bore the motor anymore than 40. Anything over that could lead to cracking the motor.


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Thanks for the feedback, I agree the piston looks to be in good shape. I am just not sure they are meant for a turbo engine. Now that the engine is completely disassembled I am going to check it for spec when the gauges I order arrive tomorrow.

 

[Cndeh]

Thank you sir, ashtray it is. The car had all the Turbo parts put on. It does have the proper crank and cam, I am going to measure the block and then decide what to do based on that.

 

[Cndeh]

Google search has them coming up cast aluminum.

Thanks, like the previous poster said they are going to become ashtrays.

 

[Jerryl]

Don't know about these pistons, but the stock pistons are cast.
Sure . . They have "featues" and will only hold up to 600 WHP or something like that. Just saying that not all cast pistons are build equal.

 

[earlbrown]

I am just not sure they are meant for a turbo engine.

It is NOT meant for a turbo engine. Period. That is a cast replacement piston for a N/A 3.8 that makes 20hp per hole. It is not by any means designed for any kind of performance.


And on a side note if the 'builder' claims the engine internals were 'upgraded to turbo parts', I don't think I'd trust any of the other parts to be upgraded.

 

[Cndeh]

It is NOT meant for a turbo engine. Period. That is a cast replacement piston for a N/A 3.8 that makes 20hp per hole. It is not by any means designed for any kind of performance.


And on a side note if the 'builder' claims the engine internals were 'upgraded to turbo parts', I don't think I'd trust any of the other parts to be upgraded.

I believe you 100%. I was told the piston were change here in the Dominican Republic but the engine was originally rebuilt in the States before the car entered the country. Dominican mechanics are shady so I was very suspect of the pistons. I have checked the crank and it is for a Turbo, has the rolled fillets. The cam is 25517480, I found an article around here stating that was correct for a Turbo.

I am waiting on a bore gauge and a set of micrometers to measure the block, crank and bearing to see where I go. If the block is with spec then I will start ordering all new parts to rebuild it, if its not then I will look to import an engine from the states.

 

[earlbrown]

Ahhhhh, now it's making more sense. Keep in mind, a turbo crank has rolled fillets on the rods and mains. A N/A crank does have them on the mains. When you inspected the crank, make sure to look at the rods. They both have the same casting numbers.

Right now you really can't tell much until you get your mics and bore gauges. That will tell you if the block needs to have some love before it can be put back into service.

 

[SCOOBY DOO]

Any other numbers on the end of the cam to help identify it? Looked at a few different cam companies with that number...but no luck so far.

 

[Cndeh]

Any other numbers on the end of the cam to help identify it? Looked at a few different cam companies with that number...but no luck so far.

No, there are no numbers stamped on the end of the cam. I was just going off a post I read here stating it was for a Turbo.

https://www.turbobuick.com/threads/factory-cam-25517480.309821/

The full markings on the cam are 1.5 CWC C1 D1 255174801 E

That's all I can find for now, if I come across anything else I will let ya know.

 

[SCOOBY DOO]

From that post Richard says it's a stock 86-87 cam...presumably for our turbo engines.