Wastegate Flutter.

[TT350]

Hi.

 

You may have seen YouTube vids of Supras with a lovely sounding wastegate flutter or Audi S1 rally quattros with the same thing.

 

Why do some turbo cars have it and some don't.

 

Most importantly, how do I get it?!

 

Thanks.

[Jay Kay]

Block off the waste gate (dump valve, BOV or whatever else you want to call it) and you'll get flutter. It's basically boost washing back into the turbo and the blades chopping it up and stalling.can sound good but long term will cause damage - don't believe anyone who tells you it won't.

[Ekona]

Only with ceramic turbine blades. Metal blades running sensible amounts of boost will be fine.

 

I didn't run a BOV on the MR2 (by Toyota's own design) and it ran so much better than on my older car where I had one. Different noise on lift off, more like a demented squirrel than the usual noise, but still cool. No harm in removing your BOV and trying it, you may see throttle response differences though: Could be better or worse, in theory it should be worse but I've driven cars that were improved by removing the dump valve.

[Richf]

Wastegate and dump valve are two totally different things

[Hell presidente]

Wastegates don't make noise. Ever.

[ilogikal1]

Wastegates don't make noise. Ever.

 

They do when they hit the wall you've just thrown them at. [/VOE]

[andybp]

Wastegates don't make noise. Ever.

I beg to differ have you never heard a rear mount turbo

check this link out

 

Edited April 19, 2016 by andybp

[Husky]

Block off the waste gate (dump valve, BOV or whatever else you want to call it) and you'll get flutter. It's basically boost washing back into the turbo and the blades chopping it up and stalling.can sound good but long term will cause damage - don't believe anyone who tells you it won't.

 

Yeah, please don't do this, it won't end well for your turbo.

[Tricky-Ricky]

LOL! yes no waste gate and your replacing your motor, on the other hand not running a dump valve wont cause any problems, other than perhaps an a minimal slowness in re spool if you have a big turbo, if you want flutter and are running a dump valve just adjust it so it doesn't dump to easily, that way you can have the best of both a nice tish, and flutter.

[TT350]

Wastegates don't make noise. Ever.

I beg to differ have you never heard a rear mount turbo

check this link out

 

 

Can really hear the wastegate there. I think mostly because it's mounted at the back.

[Husky]

LOL! yes no waste gate and your replacing your motor, on the other hand not running a dump valve wont cause any problems, other than perhaps an a minimal slowness in re spool if you have a big turbo, if you want flutter and are running a dump valve just adjust it so it doesn't dump to easily, that way you can have the best of both a nice tish, and flutter.

 

 

So all that pressurised air then has to flow back through the turbo... Wait, I've been inspired to research...

 

Ok, here you go. I'm off to the celica to take off my BoV that drops pressure too early. http://www.autospeed...gestions&A=1457

 

But then... the overfuelling it's going to do because of the double metered air... More research required.

 

And then surely it builds up a large pressure differential either side of the throttle body...

 

I have no idea any more. sorry celica, you shall continue to dump too early until I buy a new BoV

Edited April 20, 2016 by Husky

[Richf]

I killed my afm when my dump valve started to play up on my Skyline, removing them can also make the car stall every time you come to a stop, that gets old fast , a blow off valve serves a useful job

 

Also my wastegate on my Evo used to make a hell of a noise they are known for it

 

[-G-]

Hi.

 

You may have seen YouTube vids of Supras with a lovely sounding wastegate flutter or Audi S1 rally quattros with the same thing.

 

Why do some turbo cars have it and some don't.

 

Most importantly, how do I get it?!

 

Thanks.

 

You mean the "angry pigeons" sound?

 

[Husky]

I killed my afm when my dump valve started to play up on my Skyline, removing them can also make the car stall every time you come to a stop, that gets old fast , a blow off valve serves a useful job

 

Also my wastegate on my Evo used to make a hell of a noise they are known for it

 

 

Yeah, I can't see it doing the AFM any favors kicking air back at it from engine side, considering my oil kicking about in the intake at the moment, I think it's a short route to a dead AFM. Ahh well, I need to count my pennies for a new BoV still, the blitz one blows way too early and there's no way to adjust it

[Ekona]

I killed my afm when my dump valve started to play up on my Skyline, removing them can also make the car stall every time you come to a stop

How so? Not doubting you at all, genuinely curious as I've never encountered that

[Husky]

I killed my afm when my dump valve started to play up on my Skyline, removing them can also make the car stall every time you come to a stop

How so? Not doubting you at all, genuinely curious as I've never encountered that

 

Any oil in the intake pipe would be pushed back into the AFM?

[Ekona]

Sorry, I was referring to the stalling.

[Rock_Steady]

i had this on previous cars and was told that not running a dump valve leaves the pressure no where to go so, it will go back out where in came from i.e. the inlet and the flutter is the sound of it escaping back out that said part. Apparently it can cause impeller stall which isn't good but i think some people are being a bit of an old lady about it.

[Ekona]

The fluttering sound you hear is the impeller stalling. Back in the old days of ceramic blades it did used to be a huge issue, but with metal ones I personally don't see it being a problem at all, I agree.

[Husky]

The fluttering sound you hear is the impeller stalling. Back in the old days of ceramic blades it did used to be a huge issue, but with metal ones I personally don't see it being a problem at all, I agree.

 

Hmm from what I've read it's not actually that.

 

all you're hearing is cavitation. What happens is, you've shut the throttle, the turbocharger is doing 100,000 rpm and now has a boost spike of 50 psi. Because it's working in a higher region than what it's designed for, it slips; it basically does a skid like a car tyre does when you dump the clutch. That's the noise you hear - the whoof-whoof-whoof is the air doing a skid."

Put in rather simple terms there but it does make sense.

 

i had this on previous cars and was told that not running a dump valve leaves the pressure no where to go so, it will go back out where in came from i.e. the inlet and the flutter is the sound of it escaping back out that said part. Apparently it can cause impeller stall which isn't good but i think some people are being a bit of an old lady about it.

 

From all the interwebs reading I've done so far it looks like, unless you are running massive boost, the turbo will be fine. The issues seem to be: Metering the air a second time as it goes back past the MAF on the way out which causes overfuelling, thus backfire and dead cats. Personally I think it'll put unwanted strain on your throttle body, but I've seen zero people saying it's an issue so far. Also if you have any oil in your intake pipes, that's going to be spat back into the MAF which can't end too well for it, I guess the air filter too.

[Richf]

Sorry, I was referring to the stalling.

 

You are blowing metered air out of the system , the engine goes rich and stutters , its very common and happens with vent to air dump valves as well

[Ekona]

Would that not depend on where the MAF is located? I.e. pre or post turbo?

[Richf]

Would that not depend on where the MAF is located? I.e. pre or post turbo?

 

I've never had a blow through one so wouldnt know

[Tricky-Ricky]

I thought this would inspire a lot of debate, anyway if a turbo motor has a MAF/AFM and is fitted with a dump valve, because the air has already been metered and the dump valve lets off the metered/pressurized air, the resulting fuel air mixture will be momentarily over rich, which in some circumstances can result in partial stall, but normally it will just cause the unburnt mixture to ignite in the exhaust, (if hot enough) giving the characteristic pop/bang.

 

Unlike turbo engines that are fitted with a MAP sensor (mass air pressure) which are usually fitted to the plenum and so only measure the volume of air that already past the dump valve, so the mixture remains stable, these are much better suited to a turbocharged engine.

 

Now I have never heard of a non dump valve system killing a AFM because of the throttle being closed, the airflow would need to not only flow back at enough pressure and turbulence, which is Highly unlikely due to the volume in the system, IE pipework and intercooler, it would also have to get through the still sinning compressor turbine, and still retain enough force to do damage... I don't think so.

 

There have been many debates regarding whether fitting or not fitting a dump valve is better for the turbo or not, and as far as I know the jury is still out, its all opinions and conjecture,, I personally have run with and without, and neither method has been any longer lasting than the other, and re spool has also been negligible even on a big turbo, I like the flutter sound better than a dump myself.

 

I also hope that the confusion between a dump valve and a waste gate has been put to bed.

 

 

Edit, also just noticed that someone had the thought to mention using a blow through system, which I forgot about, which is another reason I seriously doubt pressure/airflow would kill an AFM.

Edited April 20, 2016 by Tricky-Ricky

[Ekona]

So are we saying this happens? On a pre-turbo (or draw through) system:

 

1. On full boost at WOT, MAF reads X amount of air. Engine adds X amount of fuel.

2. You come off the gas completely. TB shuts closed.

3. Compressed air has nowhere to go, so pushes back into the turbo.

4. Air goes through the turbo back past the MAF into atmos pressure, causing the MAF to read air again.

5. As the MAF is reading air movement, the engine adds X amount of fuel despite no extra air going past the TB.

 

That's the only way I can see a non-BOV system adding fuel after you close the TB. On a system with a VTA BOV that sits after the MAF, then yes that would cause the engine to run rich as you've dumped metered air (as has already been said).