thats funny because every motor i have seen has the dished pistons from the factory
Yes, that is true, and they should be ashamed of themselves for using these in the Marine version.
The fully dished piston was a product of the 70's when emmissions control became important for automotive.
The use was continued when the small chamber cylinder heads came along as to control C/R.
If not familiar with the Quench Effect (aka Squish Effect), you can find many articles on the Internet regarding the topic.
Many are related to automotive, but the principle nicely crosses over into the Marine environment.
However, the Quench dimension can be tightened up some for Marine use.
Here's a great article by Jeff Smith
Here's one by Charles Borrini. see section 3.0.12
Another by John Erb.
Here is an explanation of the differences between Detonation and Pre-Ignition of which the Q/E build plays a role in re; Detonation potential reduction.
And one that I cannot link you to, would be Dennis Moore, the author of; "Small Block Chevy Marine Performance".
In order to read what Dennis has to say, you'd need to get your hands on a copy of his book.
I'm personally no expert on the topic, but I've been involved with the SBC since the 60's. I have never used the full dished piston in any SBC that I have built.
It's simply the wrong piston to use, and if you have any concerns for detonation, this piston should be avoided for Marine use in particular!
It has to do with a more ideal LPCP (approx 14* ATDC) and detonation control.
We can't do this with the full dished piston when used underneath the wedge area of the SBC cylinder head.
It renders zero quench or squish effect.
All that having been said, marine engine builders will no doubt continue using the full dished piston in the SBC Marine Engine line.
It's cheap, and readily available!
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