superchargers

[strat6v]

Is anybody thinking of fitting a supercharger to their alfa v6?.
I've seen various units for sale on ebay (usa), one fits to a ford focus with a seperate driven shaft which has the blower sat over and in front of the gearbox. By the look of things this would be a similar method that would suit the alfa. Anybody got any other ideas?

[Martin K]

Sizing of superchargers is critical - just a sizing turbo chargers is. A unit matched to a 2 litre engine will more than likely have poor efficiency on a 3 litre, because it will have to flow more air to give the same boost level. This normally means it will have to be geared to run faster. Then you may run into the problem that they all have a maximum operating speed as this may mean that at maximum rpm that you use for your engine the supercharge is running overs it's maximum design speed.

The probability is that the efficiency of the unit will have deteriorated due to the mis-match, putting more heat into the incoming air. With the low boost levels NORMALLY associated with superchargers you can generally get away without any charge cooling, but if the supercharger is running at low efficiency you may have to use charge cooling to keep inlet temperatures sensible.

Nice idea though!

If you really want one, take a look at this as it may well be 'big' enough!

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=72205&item=7965088031&rd=1

[strat6v]

It was the drive mechanism that caught my eye. 'IF' i could stretch to a blower then it would probably be a centrifugal type, ie: vortech or rotrex or something similar but correctly sized. What are the pro's and con's with the centrifugal and rootes type blowers?

[Martin K]

Screw compressors are the most efficient, but go here to check:

http://www.sprintex.com.au/BlowerCalculator/Blower_Calculator.xls

Play around and find out what your choice of supercharger should be.

To me, it looks like you need an Eaton M090 giving 1.1 bar of boost at 7000 rpm and 436 bhp.

Or a Sprintex S3-335 giving 1 bar of boost at 7000 rpm and 415 bhp.

Else, why bother with all the expense?

[strat6v]

The chap with the other blower you saw has an eaton 'm90' on ebay also. Only problem i can see is fitting it. Is it supposed to sit on top of the engine on a dedicated manifold like a dragster motor or could it be put where the aircon pump is and plumbed through to the plenum?

[Martin K]

The chap with the other blower you saw has an eaton 'm90' on ebay also. Only problem i can see is fitting it. Is it supposed to sit on top of the engine on a dedicated manifold like a dragster motor or could it be put where the aircon pump is and plumbed through to the plenum?

You can mount it anywhere you can get a drive belt to. Mounted in the 'V' without intercooling you can only extract a few psi. Mount it on the side, somehow, and you can put a charge cooler between it and the throttle body - then you can run some proper boost! It is an engineering project on it's own, so don't ask me for details as to how to do it - but on the side of the engine where the air-con pump should be sounds fair enough. You need to plan to include a tensioner wheel, to keep the belt adjustment right, and you need to wrap the drive belt round more that 180 degrees of both pulleys to be on the safe side, so the belt should run in a 'kidney' shape, the inner bend of the kidney provided by the tensioner wheel.