Someone who sold me one of those pistons told me that the SD 455's single trough was for higher compression.
But Pontiac was adjusting the compression ratio (except for the 428s) by changing the size of the combustion chamber. So a few ccs via the trough design would have been minor.
What I am thinking is that the single trough was for higher compression, as in higher anti knock resistance with such, and hence was developed initially with a smaller chamber head, as part of the high performance Pontiac V-8 engine development during the Ram Air IV/LS-1, and hypothetically, a higher compression version of the SD 455.
Imagine such an engine, with the smaller chambers and the single trough.
What other engines ever used such a design.
Quote:
Originally Posted by johnta1
Doug, the stock design seemed to work good as far as I could tell.
The trough (no eyebrows) made a little more CR. The engine with a higher lift roller cam made good power. With the addition of the domed pistons really woke the engine up. (compression to 10.4 to 1)
If it had 12 to one it would have been a beast. But the chambers were too big probably to get that CR. Unless the head was milled of course.
(would have made a killer turbo engine back then  ) |