Quote:
Originally Posted by 911monty
IMHO superchargers on a 986 stock motor is a losing proposition. One distinct problem is the high compression and lack of dome volume in the stock form. These engines want a cool dense air charge. A supercharger running high pressure looses efficiency by creating heat of compression aka adiabatic heat. This is a killer as the supercharger is simply heating the intake charge by beating from compression. Efficiency falls dramatically. To properly utilize a supercharger you want low compression around 8.5 to 1, flat top or dished pistons and large domes are desired. Reason being Theoretical volume. eg if you have a 2.5 liter engine (swept volume of the piston) and add 100 cc of dome volume (for illustration purposes) then you have now increased the theoretical displacement to a 3.1liter engine (2.5 L or 2500cc + 6 X 100cc.) This is because the supercharger fills the swept volume plus the dome volume. You can now use less boost pressure and increase adiabatic efficiency. You now enjoy the benefits of a theoretically larger engine, and a s the saying goes there is no replacement for displacement.
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Long story short... Superchargers are just terrible.
I have 32 thousandths of ring gap in my car. Why? cause superchargers are just terrible. I also run 8.9:1 compression; and I still have a locked distributer with 1* of boost retard for each PSI over 2#s.
That being said there is NO replacement for the noises the roots blower makes right behind your head. Its simply orgasmic.
If you wanna go fast check out turbo. Turbo is good. The noises it makes are cool if its your first turbo car.
ike84: Na, I've been too chicken to run the nitrous yet. I spun a bearing and had to pull the engine... again. Oh well I got 2000 miles on this rebuild so give me a few more months of enjoyment and I'll squeeze the giggle gas button and break it some more.
