Very difficult to explain but when I accelerate I get a deep howling noise. throttle related, and also load, if I were to accelerate downhill it would be quiet, uphill it would be "normal" engine noise, but typically this happens on the flat, so probably 30% throttle.

If I push the throttle further then the noise changes to just engine noise, if I back off the noise goes instantly. In neutral, whatever the revs - the engine sounds as it should.

My gut is telling me its Intake related, I've changed the air filter and examined for anything out of place but all looks OK. I guess it could be exhaust - maybe a CAT breaking down and doing odd things?

I tried t get a recording of it to no avail - but will try again.

Any thoughts? 

Might be worth monitoring battery and alternator voltage if you can. I had what can best be described as a howling noise and that was the alternator packing up.

Engine speed related obviously. Bit tricky to tie down to load etc because the RR does some intelligent control on the alternator in order to make the vehicle more fuel efficient. Ed

Thanks - but it's too loud really to be Alt related. 

Hi there dan_uk_1984

Did you ever get to the bottom of the noise?

The exhaust system is being replaced tomorrow. Not inc the cats initially, will report back tomorrow evening.

Dan 

Replaced the exhaust - no change  

Sorry to hear Dan

mine is similar. Also do not believe it to be alternator related.

Sounds like driving an ISUZU 260 D/C from the days:( gone by.

Tried recording the noise but you cant really discern anything.

Going to buy some remote microphones to attach them around the car.

https://drive.google.com/folderview?id=0Bw...sp=sharing 

Next time it's making the noise, try turning the air con off, my SC made a noise on partial throttle and when switching the air con off it stopped. I've got a new compressor here I just haven't got around to fitting it yet.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Thanks David - Double checked that on the way home, still the same though.

I'm concerned it may be the SC - but considering it is only at 1700-2000RPM is that possible?

What makes noises at a particular RPM that can't be picked up by a microphone? 

I spoke to Powerhouse about changing the pulley on my SC, they did mention that the bearings in the SC can occasionally give problems at around 100k. Apparently it's not that common though.

They did tell me that they have taken the belts off the SC before and then taken the car for a drive to see if that's cured the noise. They said that the air going through the inlet will turn the charger enough to let the engine run as if it were normally aspirated.

Apparently that's the easiest way of ruling out the SC as being the cause of a problem.

If I remember rightly, for around £600 I think he said, they will rebuild the SC with new bearings and stick a 10% pulley on it whilst they've got it.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Thanks for that info David, I didn't appreciate that the charger would still turn...

I wonder though... if it is still turning, I assume it will still give the noise (if it is indeed the cause of my issues) 

I'd imagine it'll be turning a hell of a lot slower with just air turning it compared to what it would with the belt though.

I'd be surprised if it was your bearings as you'd expect them to get noisier the faster it went. Might be wrong though.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

This is doing my head in, the garages round here (Bude, Cornwall) are so utterly inept!

Sorry, needed to vent.

I need to come up with a list of things to go through. To reiterate:

It is relative to Engine RPM only, not vehicle speed. This rules out tyres, wind noise and final drive (diffs, axles, CV's etc)
It is only noticeable at part throttle - 25-50%
RPM Range 1800-2200
It is very much a noise rather than vibration as it cant be felt through the car.
It is a resonance, from something spinning, almost makes your ears want to pop sort of sound.

The heatshields have been checked (not sure how thoroughly) the exhaust (cats back) has been replaced.

I'm leaning towards gearbox (but no vibration?) or air intake system - Supercharger fked? But would the noise go away etc?

Thoughts?  

Could it be a brittle belt howling/slipping on a pulley? There are quite a few in there. Present* 2006 Santorini SC Vogue SE.
Gone* 2006 4.4 AJV8 Zermatt Vogue.
Gone* 2004 TD6 Bonatti Vogue.