Roots/Twin screw heat soak?
 

Hello all,

I'm looking for some opinions from people who have raced with a roots(magnacharger) or twin screw (kb or whipple) superchargers. How fast did heat soak set in?

Hopefully, you'll get some more responses but also be sure to check out the build threads on Mayhem and Camaro XV aka Hellion. Mark and some of the other guys got very technical with the engine details and specifically cooling the engine. You might find some good info there.

I pay attention to all of marks post. He's a brilliant engineer. Ive seen all of his cars at optima... None of them appeared to drop off too bad due to heat soak...but his last 2 motors were build by Brian Thompson. To the best of my knowledge, Brian is one hell of a builder/tuner.

I'm just curious why you are asking about the "time it takes for heat soak to set in when raced" rather than what is a more efficient design or what Brand is more efficient or how you can improve heat soak say if you had a roots or twin screw.

Are you trying to buy a supercharger but not going to depending on the time it takes for it to set in?

Maybe there is a reason behind you specific question it but I think you want to know what is more efficient?

You may already know this but twin screws are superior for many reason in my opinion. It's a true compressor and by design, has a higher adiabatic efficiency. I don't believe even a tri lobe roots design are close to the efficiency on many levels as a twinscrew.

There's also water meth to keep charge temps cooler especially when spraying into the twin screw (never tried it on a roots)...it really seals the "gap" between the screws and lowers the compressed air pre discharge.

Simple. Real world experience. Mark runs a LS9 blower on his 427. A few years ago, a guy with a 99 magnacharged vette was ripping off impressive times at Optima. Everyone says twin screws are more efficient, but ....yeah never know. Again, looking for real world experience.

Fair enough fair enough !

Good points but it is a big chunk of aluminium on the top of the engine. Keeping under hood temp as low as possible is something to keep in mind.

Heat soak happens, IMHO, on any blower motor. I agree w Carmello above that twin screws are more efficient. KB advertises a 10 degree intake charge increase with their intercooler system, but you can always go bigger and less efficient and engineer more cooling into the system.

Temps and humidity on the specific day, how long your track sessions last (Optima at Spring Mountain is what, four laps / 2.5 miles a lap?) all factor into the equation.

What's the intended use?

The intended use would be street driving, good guys, and USCA events. I would also like to do random speed venture outings at Fontana.

With the type of power you'd be making with a PD blower, I wouldn't worry too much about heat soak. You're going to be making so much power under the curve that it'll more than make up for loss of power under heat soak. AND if the heat soak is something you are irritated of for lack of a better word, you can run water/meth injection. I think you should go ahead and get the blower if you're thinking about it. I doubt you'd be disappointed with the overall result regardless of the heat soak issue.