Ds2k1

Most pd blowers have a bypass so that under partial thottle or freeway use you will not see boost.

Banger

I have a TRD "roots" type SC in my v6 toyota tocoma.
It makes 6.5 lbs of boost max. It is a sealed ceramic bearing unit which means no oil piping or oil changes.

I does require premium gas, but did not require any
ECM mods or other "tuning", water injection or intercooler.

This was a direct bolt on unit, and the only add on was a "piggy back" fuel pressure regulator that bolted on to the OEM regulator.

I installed this unit when the truck had 5000 miles. It is still going strong at 60000 miles.

Very pleased with the flat tourque curve that these type of SC's produce. I know this isn't a engine that has a 9000 rpm redline, but it sure would be nice if someone could come up with a similar "bolt on" solution!

CrazyPhuD

Yep so I definately agree tuning is tuning, and you HAVE to get it right...but it will cost more $$$ than a centrifugal to do...

So the big concern with our engines at low RPM boost, is that most driving is done at low to mid rpms(unless your car is track only). As a result a centrifugal SC that generates boost only a high rpms puts less stress only the engine since it is under boost only a fraction of the time. An Engine that boosts at low RPMs will be under boost for the majority of its life. This will reduce reliabilty.....how much depends upon how good of a tuning job you do and how much boost you run. Remember you are going to be one of the first here which means you will run into more problems. Due to the high compression ratio and the way that our engine is designed(lightweight NA) it is less tolerant of boost.

My personal thought since you are the first to do this and you are building your own kit, if you are not prepared to spend the same amount of money that turbo people have, you may wish to reconsider doing this project. Not saying that you will speed that much money, but it is possible..... Not trying to discourage...I think it's a great project, just being cautious....

S2kRob

We'll see. I would only do it if I were doing it the right way.

And 5psi really shouldn't overly stress the engine that much. It'd be like driving the S2000 at 250 feet below sea level.

tomas

Kenne Bell makes a screw style sc called autorotor. Here is a paper that describes them compared to Lysholm.

http://www.kennebell.net/techinfo/ford-tec...ORvsLYSHOLM.pdf

The only thing about the autorotor is that it is kinda noisy... although most screws are.

BlueS2000Boy

[QUOTE]Originally posted by tomas
Kenne Bell makes a screw style sc called autorotor.

ultimate lurker

I believe you misunderstand - a PD supercharger setup does not boost at all times. As another poster mentioned, there is a bypass valve that recirculates air until full throttle (i.e. low vacuum) is reached. The bypass then closes (it can be adjusted) and boost is achieved. The effect is instantaneous.

So, you only boost when you mash it - most of the time you cruise just like a NA engine.

UL

[QUOTE]Originally posted by CrazyPhuD

So the big concern with our engines at low RPM boost, is that most driving is done at low to mid rpms(unless your car is track only).

CrazyPhuD

[QUOTE]Originally posted by ultimate lurker
I believe you misunderstand - a PD supercharger setup does not boost at all times.

S2000_Europe

[QUOTE]Originally posted by CrazyPhuD

ultimate lurker

No, the switch is vacuum dependent. As you near the point where you'd be at wide open throttle on an NA car, the manifold vacuum approaches zero. Somewhere near this point (depending on where you set it), the bypass valve closes and boost begins.

UL