GT Motorsports: 370Z Supercharger system development

Buddy Revell

Question: On the various 350Z forced induction systems, why was there such a wide variation in peak hp numbers from roots SCs, centrifugal SCs, and TT kits even when at similar boost levels?

kdoske

has nothing to do with the car but the different FI options. They all create boost differently. Roots having boost the quickest, then Centrifugal SC, then TT. Sometimes Centrifugal SC and TT produce boost at around the same time though.

Buddy Revell

But if boost is boost, then they should all have similar peak numbers at the same boost level on the same engine, right?

kdoske

I definitely don't know all the reasons why boost doesn't actually translate that way but I do know that TT is the efficient boost option. It is essentially free energy because it is using the actually exhaust of the engine to spin the turbine. The only problem is you have to wait for the exhaust pressure to build for the TT to spool. SC on the other hand uses engine HP because the turbine is spun by the engines belt system which, while creates boost, also takes HP to do. Typically the main benefit of SC over TT is earlier boost times. The disadvantages is that you will typically not have as high gains from SC then you would a TT. Main reason being is becuase the engine itself it working harder just to spin SC.

Like i said above, sometimes Centrifugal SC and TT produce boost at around the same time though.

roplusbee

With those thoughts in mind, the Centrifugal SC setup should cost less than the Roots SC and TT setups. Especially if the "spool time" is relatively similar on the Centrifugal SC and the TT setups. I would say Roots SCs have a different application (like as close to direct response as possible) as compaired to the other 2 options. I could be off in left field, but that is not how the ball bounces though. I have seen a few Mustang guys get Roots SC systems with everything necessary to make a beast for a few grand. Although their suspension setup sux big time (barring the latest models).

I have stayed away from SCs because I have always run higher revving 4-bangers and I do my best to stay in the sweet spot (in boost) so that I maintain that instant throw-you-back-in-the-seat response. I guess having a 6 cylinder is lilke having a jack of all trades kind of deal.

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Minicobra1

This is caused by the friction and drag from the supercharger and belt, some have more then others which will result in HP loss to the rear wheels.

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