28 replies to this topic

[Goosenka]

Should mask any super charger whine

http://www.youtube.com/watch?v=dmJH84FnQa8

Caution: may destroy your ears

Sweet love of god...and i thought my car was noisy.
Bless my dog has just bolted.....

[techieboy]

I guess for trackdays - it would suit. But I love the noise! I wouldn't want to completely eradicate it on day to day driving.

I love the noise too but I'd love a free choice of trackday venues and days more. Maybe I can stick a remotely controlled flap in the airbox to give additional noise when needed and not at other times.

[Mangham54]

I guess for trackdays - it would suit. But I love the noise! I wouldn't want to completely eradicate it on day to day driving.

I love the noise too but I'd love a free choice of trackday venues and days more. Maybe I can stick a remotely controlled flap in the airbox to give additional noise when needed and not at other times.

Can't imagine that would be too difficult to do with less than £50s worth of remote control toy parts

[Exmantaa]

But as Exmantaa found, with a modified OEM airbox fitted, all of the whine goes. So I don't think it's purely mechanical noise from the charger itself.

I can't imagine he managed to completely exterminate it altogether though? The reason you can hear it is because evidently sound permeates air a lot better than metal, so the sound does escape through the intake, but I'm not sure exactly how much remains coming through the charger itself.

With my modded NA airbox, I have a very very faint whine on the background when full on. And that is with VXT backbox noise...
Still got 249.8HP on the rollers with a base mapping and OEM paper filter fitted.

Some people are just putt off by the loud SC whine, but when they drive my car they really like it. It just goes...

[maybach]

just checked my db level with a mates reliable meter was 91db at 4500. happy with that and one reason of the many i fitted the s/c was to hear the whine. which to be fair only comes apparent when giving it some and the novelty has'nt worn off yet.

[techieboy]

just checked my db level with a mates reliable meter was 91db at 4500.

Static though?

It's the drive-by's when the engine is properly under load that are the real unquantifiable's. I went through half a dozen different Piper systems until we finally got one that seemed reasonably quiet. Booked in for a sound check at Bedford. Breezed the static test. Head instructor then took the car out for a drive-by test and passed that with ease. So booked a day at Bedford for the following week and did three laps before being called in as I was registering .1db under the limit on three of the four meters and spent the rest of the day short shifting past them.

[Seb.F]

I might try and look into this then when I have some time...

[Bargi]

just checked my db level with a mates reliable meter was 91db at 4500.

Static though?

It's the drive-by's when the engine is properly under load that are the real unquantifiable's. I went through half a dozen different Piper systems until we finally got one that seemed reasonably quiet. Booked in for a sound check at Bedford. Breezed the static test. Head instructor then took the car out for a drive-by test and passed that with ease. So booked a day at Bedford for the following week and did three laps before being called in as I was registering .1db under the limit on three of the four meters and spent the rest of the day short shifting past them.

I'd imagine they all run A weighted for the readings, google away and you'll see it's the default for sound checks but not entirely accurate for loud sound levels.
A weighting trys to match how the ear perceives sounds. Our ears are tuned to be most sensitive around 1 Kilohertz which is about average for human voice.
At low and high frequencies out ears become inefficient, which is why amps and head units have a "loud" button which helps at low volumes and basically boosts bass and treble.
Any head unit worth it's salt will cut the "loud" effect when the volume gets up high.

So low frequency and high frequency sounds don't rate as highly to a SPL meter.
I haven't measured SC whine but I reckon it is in the "zone", lucky it only really kicks in under load or I reckon there would no chance of passing most statics otherwise.

But for a dive by throw in different frequencies are affected differently over the same distance reflecting off different materials and you end up like me at Coombe and getting told I'm borderline with a Milltek because they measure with a shed right behind them

Or worse, buy a 911 with the engine hanging out the back and you go over on the static because of the mechanical noise from the engine more than the exhaust.
Silly cars really, even the new ones still sound like an old beetle

Edited by Bargi, 03 June 2011 - 12:38 AM.

[FLD]

Random idea... The scorpio cosworth has a 'resonance chamber' (a box in the inlet post filter) to stop induction noise. Any thoughts on if something like this could work for us?