rotrex chargers
Turbo Mini Forums

I wonder how many people slagging a centri blower, have actually used one ??


Ive used turbos, and Ive used a centri ( not on a Mini of course ), but I reckon a centri would be an excellent choice for a Mini.

List all the downsides of a turbo.

Lag, heat, big torque when it does come on = no traction, no clutch, broken gearbox.

A centri will take some power to drive, and perhaps lack slightly down low. But they will produce the goods up top, and n/a cam profiles will all work very well. No lag, and instant throttle response, with very good throttle control.
That apparent lack of grunt low down, will be a savior for your box, and clutch, and hey, it might even help with traction.

What does this leave you ? A car that can make a lot of power, with great linear, controllable power delivery.

Lets see a similar powered turbo car match it for traction.

Or do all the high powered turbo cars here get good traction in every gear ?

Edited by stevieturbo on 25th Apr, 2008.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I've got a big centrifugal charger to put on my XE at some point, dunno what spec it is or owt, bought it off ebay, gonna chuck it in and see what happens.

When i say in...I mean on...it doesn't quite fit in the engine bay....LOL

I like the rotrex but only for its packaging advantages really, they're stupid expensive new and still not cheap second hand.

Here for the craic..

Supercharged Arden powered

stevieturbo: the fact people can not manage the high power the turbo provide does not mean turbos should not be used. Just install a smaller turbo :)

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

thanks all for your comments/opinions. i think its still a bit of an unknown area rotrex on a-series. im going to continue digging for info, if i find anything useful i'll post it up.

akirch - excellent, thanks a ton for the pics :)

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Has there been any further advances with rotrex, they seem like a nice Idea has anyone bar the dood with the red mini had a go with one I seem to remember someone putting pic of one up some months ago but cant find it with the search.

I'm thinking, very boradly, about the next engine to go in my cluman.

I want to go blow though supercharger and the rotrex charger has been suggested to me.

Has anybody else tried one/found one?

Neil_g - did your research go any further?

G13B has one but it's not an A series.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=255599

Oh yeah... I was drunk when I read/posted on that...

Stevie, you clearly are a man of super engineering ability and practice and I bow to that.

My point is that you either have flatter power/torque curves with a blower or a (getting better) spikey one with a turbo. Since you can make a blower behave like a turbo with cam selection and make a turbo behave like a blower with magic modern technology, it seems that a rotrex with a drive belt achieves something in the same continuum albeit with both power to drive it (probably up to about 25hp on an A series) and an exponential pressure response to rpm.

It isn't as good as a blower at being a blower and it falls short of being a turbo. It is however lighter than a blower AND turbo, but as we know these are largely irrelevant now that turbos are getting so good.

Bini blowers are cheap. If I had a lot of money, I wouldn't get a lysholm blower, I would eat my words and get a good turbo.

For the sort of revs/power response, I'd rather get more out of a turbo for less money.

I love blowers, but in theory which is so blatant you don't need to practise, the rotrex falls down.

I expect a rotrex is a more efficient compressor than a rootes at high rpm, but that's where you would fit a turbo anyway. If you want a spike response, you could always go old skool and fit an M45 with a 649 cam, it would be similar to a proper turbo or a rotrex.

A quick thought experiment.....

You have a hp/revs graph. With close gears and a spikey curve, you can optimise the best bits of the power curve to give you maximum welly at the wheels in a more limited wheel speed range, or you can go for more of a flatter curve, bigger gaps between changes and something which is better all over.

With the spikey curve, I most certainly wouldn't want a big fat drivebelt, oiled bearings and gears dragging Hp away from the engine.

Horses for courses. I would turn one down on the theory, but I can appreciate that some people make amazing fun cars using them.

That's my POV no matter how wrong it is.

Edited by Hedgemonkey on 23rd May, 2009.

Bugger off, I'm getting there.

You fail to grasp what these centrifugal blowers offer. For a low power build....I'd almost say they are pointless too.

But say you want to achieve a high output from your engine.

Rootes...

Crap. They might work at low rpm's and offer good torque, but then will fall flat on their face.
So good for a mild increase for a daily driver, even more so on small engines

Turbo.
Make good power, and that power comes in with a wallop unless boost is mapped with throttle or rpm, which many never seem to do.
Downsides. Lag, and that wallop of torque can break components and traction, as well as slower throttle response.
But we all know and love what a good turbocharged car feels like. It is very addictive ( says me having owned and driven turbo'd cars since I was 18...my mini being my first !!! )

Centri ( incl Rotrex )
They can make good power, and produce a very linear, very usable and instant power increase as you put your foot down. Until you have experienced it, and how good this feels...you'll be surprised.
So while the lack of torque whilst it might seem bad, it will be nicer to clutches, gears, and of course traction.
All of which can result in a more reliable, and easier to use power delivery. Which often makes it faster in the real world.


Same idea with my car. My car is more drivable now, and usable than it was with the old Rover V8 twin turbo. And it might make about twice the power it did with the RV8.

Downsides with any blower ?
Perhaps more expensive, and unless the belt drive is well engineered, can cause grief.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

you running a centrifugal blower? i was always unde rthe impression you had an ls* twin turbo setup :S

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.