Rotrex Supercharger

[bottlecapE30]

I had a thought to get my car a little more grunt i would work out a supercharger. I found that lowendesign has a Rotrex set up but i can't figure out for the life of me how this thing spins the impeller fast enough to make boost the pully is on a shaft that gos stright to the impeller... i must be missing somthing. also has anyone here tryed the kit?

[kam-325i]

It could be that the design of the compressor is very efficient, and does not need any gearing.....But dont forget, a s/charger is "on boost" all the time, right from tickover....

[bottlecapE30]

i'm pretty new to forced induction but what difference does it make if i have boost as soon as i turn it over wouldn't a turbo do the same

[Turbo-Brown]

The compressor wheel's not driven straight from the pulley, there's an epicyclic gear train inside the supercharger which speeds up the impellor!

You won't get boost off idle with one of those either, they work in much the same way as a turbo in that they can't pump much air at low speeds.

If you want boost from idle, you need a positive displacement charger!

[chip-3door]

Rotrex's are fantastic bits of kit, but a little pricey.

SP30-94 on a well specced 325 motor would be awesome though


As above, they tend to make more boost at high RPM, which IMHO is perfect, because it means you can keep the CR high and dont end up with loads of midrange torque, its a much more traction friendly way to make power.


SP30-84 would be the one to go for if you are only after very moderate gains, but TBH i cant see the point in the expense involved unless you are going for 300bhp+

[will325is]

How much are they, Dont superchargers normaly have some kinda of clutch on to stop boost at low rpm

[jmc330i]

There was a lot of stuff on the US forums last year about people being ripped off by lowen design and them not answering Emails, phone calls etc.

[benjy]

just do a google search on "supercharger". Theres more than enuff info to keep you goin for days! at the moment i seem to be favourin a "lysholm" type, similar to the Eaton type but with modern modifications, merc have done a lot of research an development on this type and currently use them in their "kompressor" cars. hope this helps

[bottlecapE30]

i wouldn't want to deal with the manifold mods on a roots type thats why i'm looking at the rotrex. thanks for the heads up on lowendesigns, i will say away. This sould help alot

[lentec]

i wouldn't want to deal with the manifold mods on a roots type thats why i'm looking at the rotrex.

You dont need any manifold mods to fit a roots style charger
http://lentec-e30.tripod.com/
Is still a lot of work tho!

[bottlecapE30]

doesn't it have to fit after the throttle body not before. from what i have read this shouldn't work

[lentec]

Belive me mate it works

Look at http://www.jagweb.com/aj6eng/supercharging_article.html
near the bottom of the page are two pics showing throttle body position and bypass valve details ect

HTH