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Old 10-11-2012, 02:49 PM
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Originally Posted by 57Chevy3100 View Post
So will the motor run better on higher octane with the lower squish or dose that not have anything to do with it?
Yes, Vizard has stated that power goes up the tighter the squish is, up to the point of piston/head interference of course. It makes sense, because like I stated above, the squishing (or "jetting") of the fuel/air mixture across the chamber homogenizes the mixture and eliminates rich and lean pockets just as the spark plug fires. The thing that you want to do when maximizing this effect is to provide the largest flat area on the piston crown that is possible. Stock-type Chevy pistons and other pistons that I have seen in the aftermarket have only a very thin band of material around the perimeter of the crown that comes up close to the head and are cut into a shallow dish from there toward the center of the crown, so you have very little area to generate squish. Take a look at the Keith Black hypereutectic pistons. Even with a large dish, they have a generous flat area on the crown to mate up with the underside of the head and generate squish. Here's a 22cc dish design from KB. On the left side of the photo, you'll see a very large flat area on the crown.
KB Pistons for Automotive Applications
This design will provide maximum squish from a dished piston. Of course, a genuine flat top will work best, one where the crown of the piston is absolutely flat with no cut for a shallow dish.
KB Pistons for Automotive Applications
This type piston will work very well also....
Sealed Power L2256F40 Speed-Pro Powerforged SB-Chevy Pistons
This is the type of piston that I will not use....there is no squish pad on the crown....
Sealed Power L2323F30 Speed-Pro Powerforged Oldsmobile Pistons
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