Dump Valve

[mini-dazza]

Not had much experience of Supercharged engines, but can you fit a dump valve to them? I love the noise they make on turbo engines, and was curious if I'll be able to get one......

Cheers

Dazza

[smiffy]

Dump valves are only available for Turbo engines as far as Im aware

[Racer]

Dump valves are used to begate the negative pressure you can get in the turbo on decelareation / gear change due to the lack of exhaust gas pressure - Since the supercharger is driven from engine itself and not exhuast gases you shouldn't need one -

If it's just the noise you're after why not record it and play it on your ICE as you drive along!

[noahe]

Is what you call a "Dump Valve" also referred to as a "Waste Gate" on a Turbo?

The Eaton Twisted Vane Roots-Style Supercharger does not have a traditional waste gate. On a turbo, the turbo still generates boost off of momentum. A supercharger is geared to the engine, and it's revs remain in sync with the engine at all times, unless the belt slips. So, most of the time, it does not generate excessive boost.

When downshifting and heavily engine braking, the supercharger will deliver more air than the engine needs, and to this effect, the Eaton supercharger opens a little flap and feeds the boosted airpressure back into the intake of the blower. That way you're not compressing extra air, just to waste it. By feeding excess air into the blower, your only penalty is driveline resistance, and not actually the air pump resistance - or at least not much. Pretty cool really, but probably does not make the cool sound you like.

The Eaton website has details. Sorry, don't remember the URL.

[ADO15]

Wastegate is located on the turbo itself [exhaust "side"] - while the "Dump-valve" is usually located between the turbo and the plenium-chamber (air-intake) or on the plnium chamber itself. The main objective for this valve is to prevent excessive pressure build-up in the plenium-chamber - which can actually burst if the pressure is high enough... (talking racecar engines here)

[karmuze]

Blow-Off-Valve sound bite from a Sooby WRX with a Forge Valve.

http://www.stratmosphere.com/wrxatmosmall.wav
_________________________________________________

Karmine------apologies to the MOODY BLUES
I took a ride in a Cooper S
I took a road I've never been
Drivin' in a slide zone
I could be motorin' thru a time zone

[noahe]

I guess I'm going to demonstrate my lack of familiarity with turbo's here, but that is an alarming sound!

Maybe it grows on you, but I don't really like it. It sounds like the guy has blown his engine right before every shift.

[Steve 555]

Alarming sound arn't they. But they do keep that turbo spinning and as such reduces lag. If you want a quiter and more efficient option the recirculating dump valves are for you. You have the performance without the whoooosh

[Andrewfuzzy]

Just to add my 2 cents not all dump valves are that LOUD!!!!!!

Most are ust a small whoosh but thatis a little over the top......personally il take the whine from my supercharger when i dump the clutch on the S

[Victor Vance]

Greetings I found this site via Google while searching for blow off valves and if you want the sound, there's a thing called the Sunami, here's a link: http://www.superdiscountstores.com/S...6126037-1.html

Its just the sound though, is activated by either drops in engine vacuum pressure or a remote button. Also, they suck IMO, but if you really want the sound go for it.

BTW that subie sucks my favorite BOV is the HKS SSQV

http://www.935motorsports.com/media/HKSwhistle.wav

BTW nice site, I have a taste for Minis (small and light - a winning combination)

[uae mini]

there is another post about this in this forum...
another repeated topic.. unless you prove wrong

[MrMini748]

Dump valves aren't always neccessary on a turbo'd engine anyway. Depends on the power, performance, back pressure etc.

I must admit I love the noise they make - its a bit like Marmite - you love it or hate it Love to hear it coming out of a MINI for a change rather than a RS Turbo

Pat

[miniplayer]

Although the dump valve is not available for supercharged cars, there is any other valave called by-pass valave acting at the same way for them.

http://www.superchargersonline.com/content.asp?ID=14

Due to what they say in the web site, we all need a by-pass valave to protect our engines. Does anyone know if the cooper s comes with a by-pass valve? And could the by-pass valave give out the similar sound that a dump valve gives out?

[noahe]

That is bizarre. If you follow the links, there is a .wav sound that the electronic simulated dump valve makes.

I'm really surprised there is a market for this kind of thing. I guess that just proves I'm not the intended market (read: getting old).

On a semi-related note, there was a product I stumbled across several years ago, that was at least as useless, but may have had a broader appeal. It was a fanciful product, not a serious one...

It consisted of an electronic box, bigger than that, a large and powerful weather-proof speaker, and a lead that clipped to one of your spark plug wires. Another wire lead to a control box inside the cabin of the car.

After installation, you'd select how many cylinders your car had, 4, 6, or 8. (5-Cyl need no apply), and the ridiculous box would play a loud overlay sound, that appeared to alter the sound of your vehicle. The best applications were cars with quiet engines, and quiet factory exhausts.

Then from inside, you could change the sound of your car's powerplant to a big-block V8, a jet turbine (think Knight Rider), steam locomotive, or space propulsion (think Jetsons). In all there were quite a few programs to choose from, but that's all I remember right now.

I don't really know how good it was, as I only saw a brief clip, probably on TV some time ago. I think it was on one of those Beyond 2000 knock-off shows.

Anyway, it was pretty funny. If someone's in the market for a fake electronic blow-off sound, why not try find something like this, and get a bunch of other sounds too! Much more fun.

[noahe]

Quote: Originally Posted by miniplayer

Does anyone know if the cooper s comes with a by-pass valve? And could the by-pass valave give out the similar sound that a dump valve gives out?

The MINI's Eaton Roots type supercharger incorporates a recirculating bypass. The attached diagram is a typical application of a roots-type supercharger.

The recirculating bypass runs the pressurized air back through the supercharger inlet, reducing the parasitic drag on the engine, at whatever RPM & engine condition is producing more inlet pressure than the engine can handle.

It the air were vented to the atmosphere, there would be more drag on the engine, caused by the supercharger. Even still, the relatively low RPM positive displacement air pump that a supercharger is, probably wound not make the same sound that a wild RPM turbo makes.

I'm just guessing now, but if you were to incorporate a blow-off type by-pass valve on our tiny superchargers, I would expect there would be a brief slightly louder whine, and no whoosh audible over the engine.

I'm convinced that the recirculating by-pass on our cars is better for our applications, than a blow-off type by-pass. These aren't usually used until you're talking about huge displacement superchargers, and incredible boost applications. Think of the "Mad Max" blower, on his big-block V8.