13 replies to this topic

[Steve.i.am]

Just curious about this... From footage I've seen, it seems the supercharger whine noise seems to vary in loudness with throttle opening / engine load rather than just simply with revs. Just wondered why this is, as I had assumed that since the charger is driven directly from engine crank it'd be doing the same thing at, say 4k rpm small throttle opening and 4k rpm wide open throttle? (ie producing same boost). I'm missing something and curious to know the answer. Cheers.

[CocoPops]

This is correct. If you drive at half throttle or at cruise you would never know. I think it's down to airflow, ie in your example the rotors spin the same at 4k but on full throttle they will grab max air as throttle butterfly will be fully open.

[Bargi]

It's the load on the engine, more load more noise . if you sit there and review it in neutral you get very little whine.

[slindborg]

Load = torque demand. = air flow = noise if you have an intake setup for that.

[OneYet]

If I would use my original airbox. Would the noise/whine levels go down?

[Mike (Cliffie)]

If I would use my original airbox. Would the noise/whine levels go down?

Yes, considerably

[Steve.i.am]

Ah. So hadn't realised the throttle butterfly is upstream of the compressor. If so I can see that at small throttle opening there is less air pressure feeding the compressor so it's doing less work. At open throttle its got full atmospheric pressure feeding it so is blowing more air, under more load and so making more noise. A bit like covering the air intake of a hair dryer (bear with me). If you do its revs increase indicating reduced load on the fan. Is that right?

[slindborg]

Other way round.

[OneYet]

If I would use my original airbox. Would the noise/whine levels go down?

Yes, considerably

A project for the winter then.

[Steve.i.am]

Other way round.

Yes I see. Cheers.

[Rosssco]

The SC uses a bypass valve that directs air through a bypass channel at idle and low throttle demand, which effectively allows the rotors to 'free wheel'. This reduces SC load on the engine when not required / increases efficiency. The SC doesn't create any whine when operating in this way. Theres an animation on YouTube showing this..

[haggi961]

Another reason why some are louder then others is because some supercharged vxs are stage 3 and others are stage 2. With stage 3 you have to fit a smaller pulley which is alot louder then what a stage 2 pulley is.

[davemate]

You are also watching a video on YouTube no doubt, from experience the whine is absolutely nowhere near as annoying as on the videos, from the one I saw on YouTube I would have never gone for the conversion. Go out in one they don't sound bad. Out of interest, is stage 3 possible with a standard airbox, or would this cause a big air restriction?

[Anarchy]

I was quite surprised how noisy it was with a standard airbox but with the bottom cut off. Now I am used to it a bit more noise would be acceptable.