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We all know about forced in duction, I hope anyway. The low end power of the roots supercharger. The rediculous high end potential of tubocharging. Best of both worlds? Twincharge! But here's one more to consider, Mike's going to have fun with this one! It's not new, been used to boost performance for some time now, but not talked about much from the street perormance crowd. Compound boost! Supercharge the engine? Yes! Add a turbocharger? Yes! At the same time? Yes! Supercharge the engine, turbocharge the supercharger! That;s right! Increase the supercharger's inlet pressure! Tune the low end power to get off the line with the roots charger, where it does the best increase in power! As the roots type charger tends to drop off at the upper RPM's where a turbo shines. Hmmm. Boost the inlet side of the superchargeer? Makes for some interesting tuning challenges. Say you are getting 10 pounds boost from your supercharger. Boost the inlet to 7 pounds, 1/2 atmospheric pressure. Now you have 15 pounds of boost, theoretcally of course. But the real advantage is the expanded powerband! 10 pounds off the line, but when the turbo comes on, you get the 15 pounds! And that would carry through to beyond where the supercharger drops off! Also, since you don't have to overdrive the supercharger as much the engine RPM can be raised! Imagine the possibilities! Only problem I can think of with the Toyota superchargers is the flourine coating an the impellers. Spinneing the SC12 and SC14 over 11,500 RPM is said to melt the coating. How would boosting the inlet affect this? Is the melting of the flourine due to the heat produced by the increase in pressure or just an effect from increased RPM?

Another thing said about this is the parasitic losses from driving the supercarger. It's said that increasing the supercharger's RPM increases parasitic losses, so compounding should decrease the losses at higher boost levels as the RPM level remains lower per pound of boost. That's the claim anyway.

I'd be concerned about the high temperatures entering the blower. Chee has been talking to me about doing compound Turbos where one turbo feeds the inlet of a 2nd turbo.

I like the idea of a twin charger since our SC's use an electronic clutch. It must be great when the Turbo out boosts the SC and then the SC turns off. It would be like a quick shot of power just from the sudden reduction in parasitic losses!

I've seen compound turbos on competition pulling tractors. Inagine three stages of turbos boosting to 200+ psi on a diesel! Massive power! But only good for the short 100 yard pull. The temperature of the inlet is my main concern on the S/C setup though. Although, since low boost pressures are to be expected to boost the S/C, temps would probably be manageable. Water injection may be a way to control that problem. Set it up with a thermal control system. Second intercooler? Power gain vs weight gain is a consideration. Being different is a big consideration. But the concept is intrigueing nonetheless.

Wonderful !! you make me to great experience. I will do it same you.


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