I was reading up on these a little bit. Is there any lag to a centrifugal supercharger like on a turbocharger. I know it runs off of the crankshaft so i wouldnt think it does but i figure theres got to be a reason why so many people choose roots and twin screws over these.

 

well with a centri you wont make boost till you get past 3k rpms


easy fix thow just get 4.10's

 

Yes, there is lag w/ the centrifigual. BOost is dependant on rpms w/ those type. Think of it this way, they are a belt driven turbo. Turbos are driven off of exhaust velocity.

 

Yeah they start making boost around 3k, its kinda good because it wouldn't affect your gas mileage as much. And it pulls and pulls to red line. Its kinda quiet though, thats the only thing I dont like as much. I LOVE the whine from the roots type. The roots type gives you a **** load of low end, but the centrifugal makes more powre up top.

 

An S Trim Vortech is just as loud as a Roots. Most people end up with the quiet cut blades of the SQ Trim (vortechs anyway) and this ends up being very quiet. If you do a youtube search on the s trims you can definitely hear them =)

E.

 

While boost threshold is in higher rpm on a centri, there is no lag. Lag is the amount of time it takes from when you push the gas petal till you see boost & can only be measured above boost threshold (which on alot of centri's is around 3k). Turbo's lag because the impeller isn't at the desired speed due to little exhaust gasses to spin the turbo to higher rpm so no boost is available before the throttle plate when it opens, the centri on the other hand is spinning at a constant rpm so when the throttle plate opens, there is positive pressure there (again providing above boost threshold).
So no, no lag.

Centrifugals will effect fuel economy more than the roots because it compresses air internally in the scroll, the roots just moves air where it can be compressed in the intake (which is why it's called a blower). because of this, you can use a bypass on a roots to equalize pressure to where it can freewheel at cruise/idle. It takes hp from the crank when you're compressing air, which is why there isn't a big hit with the roots s/c while at cruise. Centrifugals will still be compressing air below 3k so there will be a constant drag on the engine lowering fuel economy a small bit. Twin-screws are the same way as the centrifugal because they compress air internally aswell.

The reason people will generally pick twin-screws & roots over centrifugal is because of the instant power at almost any rpm. It's like comparing a turbo 4 cylinder car to a n/a v8, you will probably get more power with the turbo 4 cylinder, but the v8 will feel faster because it sets you back in the seat harder when you hit the throttle vs a kind of rolling into the power feeling. Roots and twin-screw cars are more fun to drive imo, I honestly love when someone comes & asks for a roots kit because of the testing it out afterwards drive.
It more or less comes down to whether you want to be the faster person or look/feel like you're the faster person. Most of the people i build turbo/sc kits prefer the feel of a positive displacement supercharged (roots/twin-screw) car over centrifugal/turbo, but they don't produce as much peak power.

 

^^^nice info got me by surprise, so a centrifugal s/c will lower your gas mileage more than a roots type??? interesting. Well it also makes sense though, I mean the s/c is still connected by a belt to the engine so yeah it woudl drag power from the engine just like a twin screw.

 

nice, I didnt know that. Ill look it up.

 

Yes there is lag to it, I have 410 gears in my car aswell and you can still feel the lag..

 

^^^ yeah thats what i thought, you really start to feel the pull at like 3k right??