In Reply to: Re: Super or Turbo Charger kit. posted by Brock Fraser on February 25, 2000 at 00:15:38:
I designed and constructed the supercharger system for my 530i V8: ATI Procharger P600B with giant intercooler (38"x14"x3") and a $300 fuel management unit, running 8 psi of boost, resulting in an extra 127 HP.
If you would have some questions or need some information that could be helpfull on a sixcilinder, please email me.
Some advise: if you are talking about a stock 535i with 211 HP and a compression ratio of 10.5:1 you really don't want to run 7 psi of boost, especially not with low octane fuel and without an intercooler. Not a single supercharger manufacturer or dealer offers a kit with more than 6 psi of boost. For this application is
7 psi a risky business (detonation).
Why a screw type supercharger and not a centrifugal supercharger? This would be much easier to mount onto the engine and to hook up to the throttle body.
The only real advantage of a screw type supercharger is its linearity. Boost pressure raises in relation with engine rpm.
Even with 7 psi you will not obtain a power gain of 100-125 HP. No way with a basic kit without an intercooler. A realistic value with 6 psi would be 40-45 % more power, about 85-95 HP.
Material costs can be well below $2500 for a basic kit (supercharger, fuel pressure regulator, pulleys, belt, hoses, brackets). Basic kits from companies like ERT and Dinan start at $6000.
About the cooling fan: on my V8 I had a 1" long spacer made that went between the waterpump and the cooling fan clutch. This moved the fan 1" closer to the radiator and freed up more than enough space for the belt drive system. Maybe this will work on an inline 6 too?
Get a copy of "Maximum boost" by Corky Bell. An up to date book on turbochargers and also very informative for superchargers.