The Twin screw supercharger is the best balance. They still draw parasitic losses, but they are still very efficient.
Plus they generate less heat than a roots.

I have different priorities, I like carbs & less wiring. I dont have a twin screw anymore Im going simple roots inefficient but can make it look old skool, I did consider turbo but prefer the instant torque. If I wanted efficient Id go efi twin charged but too much work for my simple scone.

Ok yea I see it's that expansion of gas that the centrifugal misses out on. Well it's gonna either be twin screw or a turbo I think. Leaning towards a twin screw I think. I would buy yours D but I'm still not %100 sure and funds aren't their yet!

Thanks Dave

Centrifugal SCs arent as good as twin screw superchargers in terms of torque and overall efficiency as the centrifugal need revs to get them going so mimick a turbo somewhat without using the exhaust. Roots and Twins screw Superchargers have strong usable torque characteristics so more suited to street duty where the sweet spot is much broader from lower down.

Yep I am aware of those centrifugal chargers too they would look shmick in an engine bay imo. Though I thought most of them were made for v8s that have more torque to get more out of them? Are there any smaller ones that would suit an a15?

uldQuote:Keep in mind that the most popular superchargers are high rpm, and are built like a turbo. This type is called a centrifugal supercharger. Like the old Paxtons and the modern racing bowers (Procharger and Vortech).

These have similar compressor efficiency to a turbo, so compare these to a turbo to find out how the Turbocharger makes more power. The turbo would win the race every time except where racing class rules give an artificial advantage to the supercharger.

Thankyou A14Force! That was the exact answer I was looking for as I knew there had to be more behind it! That makes so much sense too. Thanks for giving a detailed explanation. D, that's the next step is looking into what size turbo and plenum and runners etc for the setup. Cool video, amazing how well those 1200 and 1600 vw engines and a series engines work with turbos and superchargers!

Thanks guys problem solvered

A small turbo or bigger turbo can be the biggest decisive factor to Lag, I dont like Lag and carefully planning, knowledge and $ is required to avoid as much of it as possible with well designed manifolding and tuning. I do like both turbo and superchargers but prefer response which is easier and looks neater with a supercharger and single SU.

I like this vid on how quickly he tunes it to run cleaner, check out the classy engine stand he uses :) - very responsive for such an old low power usually NA donk.
http://www.youtube.com/watch?v=-xmPq6azfyU

Quote:

We are all happy that your so comfortable coming out like this bart.... finally. Lucky same sex marriage is allowed in nz now.

You're looking at it wrong.
It isn't the flowof the exhuast gases that spins the turbo. When an engine expels the spend gases, the combustion event can be only milliseconds ago. The (very hot) gasses which are exiting the engine and passing through the turbo are still expanding. So it is more the residual thermal expansion energy of the gasses which the turbo is recycling, rather than the exhaust gas flow. I refer to this energy as residualas the initial thermal expansion at the point of combustion is what pushes the piston down the bore to make the engine run in the first place.

The turbo is more efficient because it harnesses the otherwise wasted energy. (VS the belt driver blower's parasitic losses to drive)
The difference is that with their being no lag, the supercharger has the scope to generate substantial bottom end torque.

Horsepower sells cars,
TORQUE wins races.

Most folk here know all too well which camp I'm in.