I found two completly different 455 pistons on Competetion Components website.... WHATS UP WITH THIS???? Look at the difference in these two pistons... * This one says Bullet 455 .....The quench deck is DISHED. http://www.buyracingparts.com/piston...d-pistons.html * This one says #26700 ..... The quench deck is FLAT. (That's a good thing!) http://www.buyracingparts.com/piston...d-pistons.html They also have different weight and different rings... The flat deck #26700 with 22 cc dish is fully surrounded with a flat quench ring (360 degree quench). Looks like a very efficent design, and uses small low tension rings for an extra 15 hp. ANY OPINIONS?...and whats the purpose of these two different piston designs???
For some reason the links don't work, so I went to the other thread. Maybe I'm stating the obvious, but... It looks like one piston is already cut dished with valve reliefs cut. The other looks like a flat top with valve reliefs and a D-dish on one side. Looks about the 2 cc difference. Looks like the lower priced one has more potential for some quench action. I'd check the price difference on the rings, as well as types based on how you might run it. The weight difference is fairly irrelevant. Someone's suggesting a 15hp difference between a .187" and a .118" oil ring? What rpm is that @ ?
The Bullet piston is a 2618 alloy piston more suited for high rpm racing. The Autotec is a street/strip 4032 alloy piston that is more suited for low rpm cruising where quench is more important. OK So here is the story from talking with Autotec/Racetec and other piston manufactures at the PRI Trade Show. During the development time for the spherical dish piston at JE, they noticed that any piston head design, dish or trough that was symmetrical and centered about the piston pin line produced more power. Later it was taken a step further with the advent of the CNC billet piston by making a Center-of-gravity balanced piston. https://www.youtube.com/watch?v=t6xLKXGrkFk&feature=youtu.be Quench velocity is a function of squish distance, squish area and piston speed. A street engine operating mostly at low rpm relies on squish distance and area. Race engines as in NASCAR operating at 9000 rpm do not need a lot of squish area. Al Dicksen does our cylinder heads and I asked him about piston head design. He said that going to spherical dish in NASCAR engines saw a 30 hp increase. The Bullet piston has good balance and a strong alloy material for high rpm application. The Autotec has good quench characteristics along with an alloy that has good strength but allows a tighter piston to bore clearance. Better street piston. It is all about application.
If the autotec pistons were modified to a 2.00 compression height, would the strength or dynamics of the piston be degraded? Would be nice to use this piston with stock rods and minimize cutting the block deck, and intake surface.
If you talk to Scott he will custom order those pistons with different compression heights and dish sizes. I ordered mine with a 2.0 pin height
