Quote:
Originally Posted by oldskool
Here's a Pontiac 350 factory piston that was used to get a CP piston approved.
http://forums.maxperformanceinc.com/...8&postcount=77
As you can see, they're not EXACT duplicates. Main thing is that they are forged, & they are NHRA accepted & legal, for some Pontiac 350 engines. |
Correct, they do not need to be exact duplicates, however, they must maintain the specifications I mentioned in my previous post.
It appears that some engine builders may have some close friends in piston companies because I have taken apart engines that although they have the approved part number stamped,they do not meet the approved spec sheet.
I have found the following discrepancies in some of the Stock Eliminator engines I have torn apart:
- Ring grooves that are thinner than spec.
- Shorter distance from top of piston to top ring land that shown in spec.
- Deeper valve reliefs than spec.
- Smaller domes than spec.
- Smaller dish volumes than spec.
During a teardown, does NHRA assume the piston was built and approved in that configuration or the engine owner blames the piston company?
I assume since there are less intrusive teardowns and less piston removals, that many are taking the risk by doing so.