Strange Charger sound?

[supercharged spaniel]

Sometimes if I drive my car and turn it off and start it back up a few mins later...say ten mins?  The charger sound is different?  Its like a fluttering sound?  If i rev the car it goes away?  The other day the car was idling and it started doing it? then it disappeared?  It doesnt effect the cars driving at all its just strange that's all.  Anyone else had this problem or have any ideas whats going on?  It doesnt sound at all mechanical or rattling its more like the air flow is different or something?

[PeteG40]

my full blend does that on hot days! more of a woowowowowoowoww

[supercharged spaniel]

yeah totally that!  its always when the cars hot...

[supercharged spaniel]

Ive often wondered that the cutting away of material for porting etc will subsequantly change the tone of the charger as a result of the air moving differently through the chamber.  Obviously warm air will respond differently won't it.  Does it go away when you rev the car a bit?

[PeteG40]

its at different revs to be honest, mostly at idle...


different chargers have different notes, and different porting gives different notes.

They all tend to be louder/more vibration at different rpm too, which also alters with porting and pulleys.

[supercharged spaniel]

Well mine only does it at idle and goes away pretty much straight away with a bit touch on the throttle...  never particularly worried me to be honest just wondered if anyone else had experienced it.  Defo does it when hot though so it must be the warm air that effects it...

[Puncharado]

Nice description Pete ha ha! But I know exactly what you mean, my R1 made that noise too. My mate knew if I'd passed his house from inside!

I can't comment on the noise being different on start up though Dan, it's been a long time since I've heard mine.

I don't think warm air would make a difference, the ambient temp isn't likely to change much in 10 mins or so. And a few degrees difference going in won't matter, it's going to be 100°C or so out the charger if you're on full chat. I do remember measuring ambient, compressor out, and inlet temps when I had the R1 run in. For about 20°C ambient, the inlet was always hovering around 30°C, even when nailing it. Which shows how efficient the standard intercooler is, and is why I didn't bother changing it.

[supercharged spaniel]

well temperature or whatever  something makes the charger change its note after being turned off and back on within a reasonably short period of time.  I bet a few people have noticed this before though....

[Puncharado]

I am guessing mind, but perhaps the temperature of the actual charger, or the bearings. Even if it isn't being worked hard, it's all going to stay warm due to friction and the air compression. Do you notice it changing as the car warms up? I'm thinking there'll be a gradual change in the sound as it warms up, perhaps gradual enough for you not to notice any change in sound. Then, once the car's been left standing the charger will cool down and the sound at start up will then be noticably different. Having said that, I wouldn't have thought it's going to warm up very much with just a blip of the throttle.

[grayg40]

mine does the same noise as pete discribed when sitting about at a constant speed.

[cheddarcheese]

mine does the same noise as pete discribed when sitting about at a constant speed.

Thank fuck i am not the only one who has this noise i get it when sitting at a constant speed too or at idle!

[hardchargin40]

Lol, I used to get that on my old ones when sitting at 4000rpm, but they were both DIY ported chargers.
 WHOMWHOMWHMOWHOMWHOMWHOMWHOMWHOMWHOMWHOMWHOMWHOMWHOM

Stopped me doing 90mph everywhere though as soon got irritating   But you can get some funny looks if your side by side on the motorway with another car.

Try 2 G40's side by side doing it, sounds cool!   Me and RichieK used to piss around doing it for a laugh.

[supercharged spaniel]

ha ha interesting to see other people have the smae thing.  I've only ever noticed it on mine on idle though not when I'm traveling along.

[cheddarcheese]

My G is fully stripped out no sound deadening so i notice the sounds more i guess!

[tdh-syorks]

i just picked up on this thread, mines started doing it since i put it back on the road last week, it sounds more deeper tone and as tho theres some vibration. it wasn't doing it in the summer.