hey all, i'm about to buy a twin turbo soarer and looking at the engine mod upgrade i want to do to it

1st is the intercooler but that's under control my questions are


A ) will an external wastegate make the spooling up sound louder

B ) is it the waste gate making that air "fluttering" sound with a gear change or is the air being forced against the
fan blades that makes the sound when the wastegate shuts?

C ) how the hell is it some cars sound so loud with the waste gate flutter and others don't? (i think the sound is almost sexual and the louder the better...BOV's just don't sound as good)

call me a ricer if you must but i'm just not sure how the wastegate would make that sound. my understanding is it's only there to stop the boot from going to high by cracking open to alow the back pressue out hence making the louder spooling up sound when it's external not going into the exhaust

any feed back would be awesome (just very excited about my first forced induct car )

The wastegate doesnt 'make that sound', and that flutter sound you describe can and does damage the turbo.
The sound is created by a rush of air going back into the turbo and hitting the impeller blades, its bad for it. The reason why blow off valves are in use is to stop this.

The flutter also decreases performance, as when you back off the throttle it creates 'pressure stall' and the turbo spools down.


The wastegate simply controls the boost, its not a volume control.
You can get a 'screamer pipe' made, thats piping right off the waste gate and not into the exhaust. Keep in mind this is illegal. It also has nothing to do with the 'flutter' or any form of induction noise. It will make the exhaust side of the turbo louder.

If you want a loud spool up, run a pod filter and nothing else (read: no air box) but prepair for the computer to retard the ignition timing because of the increased induction temp.


Once you start playing with extra boost on the factory turbos, expect one day to have small peices of turbo in your exhaust system as the ceramic blades are known to delaminate.

If you just want that fluttering sound, remove the stock plastic Bosch BOV and get the hole welded and run no BOV at all. You'll have constant throttle flutter when you back off .. and plenty of blow turbos.

The flutter sound u hear, the chuf chuf chuf chuf.. hahha sounds a bit like ,that is just usually a stock car with an PODairfilter.
When the throttle closes this happens, why?
The air which goes through the airfilter is suddenly stopped by the throttle so the only way to go is.... back where it came from, hitting the turbo fins, chopping the air up, and u get chuf chuf chuf chuf... flutter. [not good for turbo, but can sound really loud]

Also if you are running a BOV, u can also have this flutter. Supposedly you just tighten the BOV so it shuts quicker and therefore the air wil be trapped and hit back into the turbo fins.

If u want sound from Wastegates u use a screamer pipe. This is illegal, and is very very very loud.
This modification, is not worth it unless it is a track car only. Becuase if you get caught its not worth it.
The screamer pipe is just like a car with no exhuast, it doesn't go through the exhaust past the cat convertor therefore its illegal, cause of emissions.

philz

Anyways apart from the explainations:
Good choice on car, 1jzgte is a very good engine, practically the same as a 2jz but without those extra CC.

What i would do is change those turbos to a big single. For street use i say about GT40 would be good or just go all out on power T78 hehehe.

The 1jzgte is easy to extract power from, just intercooler, extra boost, exhuast. It should be enough fr 200kw atw.

thanks guys!


i had a feeling this would be the case i basicly wanted to know if buying a new wastegate would
be any use since there is no performace boost from using an external one...just thought it might have sounded purdy hehehe

i think i'll just buy a better BOV/intercooler and be done with it (and single turbo conversion down the track )

the reason why some cars sound very loud and others don't pends primarily on intake setup. as mentioned, don't run a boxed air filter, this will be MUCH louder.

different types of turbo's make different amounts of noise, i know people swear that they love the sound of their ball bearing turbos spooling away, but i haven't heard anything like my old roller bearing T25

if you want basic performance mods, ask the 1jz / 2jz boys on supra forums etc. they will know what improves the most hp for least amount of money

What a coincidence! Im a complete Supra nut and now Im nearly getting my car back on the road after a two year engine conversion job Im starting to read up on my audio stuff. Thanks for the kind words, we are always looking for new members. (Even if they are evil Soarer scum )

1JZ is an EXCELLENT engine! Many people are getting well over 220rwkw from simply a new exhaust, intercooler and a slight boost increase. A full exhaust on a 1JZ should include the famous 'Y' pipe that replaces the stock dump pipe as this factory part is a major restriction. I have seen over 600hp from an internally stock 1JZ (possibly had different cams).

The general performance upgrade route on a JZ would be:
Exhaust
FMIC (front mount intercooler)
Boost controller
FCD (fuel cut defender to stop fuel cut on higher than factory boost)
AFC (fuel controlling computer such as an Apexi S-AFC or perferably an aftermarket ECU)

Then onto bigger and better things like a big single turbo conversion.

The flutter noise is known as compressor flutter (not to be confused with compressor surge). Is can cause damage over time but is not as severe as many people make out. Any stock turbo engine will make this noise but you cant normally hear it unless you remove the air box. These turbo last well over 100,000km so I can assure you this slight noise is not a major problem. Running no BOV at all will increase the sound and increase the rate of turbo damage so I wouldnt recommend it at all. You dont really need an aftermarket BOV but if youve got money to burn do what you like with it.

If you want it louder get a large pod filter and induction pipe but be aware it is illegal to have an unhoused filter in australia. Get someone to make you up a nice box around the filter and you have a slightly louder noise, with a nice feature to your engine bay....plus keep the cops happy.

A wastegate doesnt really make a sound. A screamer pipe is an incredibly stupid idea on a street ar and tests have been done that prove there is no performance gain to be had by such a thing anyway (over a proper job with the external gate piped back into the exhaust.)

GT40 is basically the same as a T78, and both would give awesome power but may be a little laggy for a street 1JZ. Id go for something more like a GT35.

The computer will NOT retard the timing due to increased air temp if you have an un-housed pod filter but you will loose power by feeding the engine overly warm air. Cold air will always give better power.

Good luck!

flutter is the turbine stalling. or blow off valve opening an closeing if the spring is too tight.

Isn't it only illegal to have an oiled pod filter without a box eg a dry pod filter is perfectly legal without a box

Sounds like you want a "dose pipe"
Fit the air flow meter in the intake piping AFTER the cooler and before the throttle body.
Then run no air filter off the turbo, just a short length of pipe. Maybe a bit of mesh to stop the crap getting in there.
Doesn't do performance any good (since you are sucking in hot air from pretty much 150mm in front of the turbo, but you will get that crazy sound all the muzzas love. Heard on VL turbo's a lot.
I'd rather hear that than a Pshhh any day.

The other thing you could do is instead of dumping the exhaust from the waste gate back into the exhaust, you have a separate pipe coming off it. They call it a screamer pipe. Highly illegal, but will definitely get attention!

good work jono, nice mining.....

beat me to it

whoops i think i arranged the posts acending instead of decending or somthing. i realized after. PWNT = oneoneoneone

Is this Fact in NSW aswell?
If so, them apexi pod filters are legal because there not oiled. On the other hand K&N pods are illegal, though does a cover on the pod, like them heat shield ones, count has been in a box lol.

Cheers,
Matt

That's still compressor reversion. It does it when the spring is too tight on the BOV because the air can't get through the BOV (rendering it useless) and making it's way back out through the compressor wheel anyway.

there is a video on youtube of a VL turbo cruise.. MUCH MUCH doseing on there.. i will find it.. sound f***ing wicked.

hehe, this one's pretty funny: http://www.youtube.com/watch?v=u4BNtM-EDZQ

Haha, f***en muzzas.

Is "dosing" essentially flutter?
And why is it soo common on VL's rofl.

Yeah dosing is the muzza term for flutter.

As for why is it so common on VL's? I dunno, must be a muzza thing. Although a mate of mine recently done it on his R32.

I myself will admit, it's a crazy sound. I am very anti BOV but love a good dose! Maybe its because I dream my car will be a turbo one day lol.

just about every statment in this thread is wrong.

A wastegate and a blow off valve are two totally diffirent things. With a forced induction setup the turbo/supercharger force pressurised air up to the throttle body. When you accellerate the throttle body opens and allows a certain amount of air in, this means that there is still pressurised air in between the turbo and the throttlebody which has to go somewhere. This is where a blow off valve comes in to the story, when you take your foot off the accelerator the throttle body closes which then opens up the blow off valve which vents all the excess pressurised air into the atmosphere. A wastegate on the other hand does prettymuch the same thing but instead of venting when the throttle body closes it will vent when the pressurised air gets to a certain psi. The ch ch ch ch ch ch ch sound that he is refering to is the wastegate, this is not in any way, shape of form bad for the car, it is not the air being forced back into the turbo propellors either. A wastegate vents in a way that it preportions the pressurised air therefore making the ch ch ch ch ch ch noise. Without wastegates or blow off valves things will just break so easy.

im confused.

the first idea sounded good. as in the turbo fins chop up the air being furced back, making the flutter noise. but then the waste gate thing sounds ver y informed :s

im still new to F/I but how does a wastegate work? and how is external and internal gates diffenrent?

ok ell i did a little bit of research, and found this on a wesite... seems easy t understand..



goes one further to explain inernal/external gates etc.

SOURCE:
http://www.streetracersonline.com/articles...o/wastegate.php

maybe that will help a bit

The dose you hear on VL's etc is not the wastegate making the noise. If that was the case, relocating the airflow meter to the piping in between the cooler and the throttle body, and then playing with the pipe size coming from the front of the turbo would have nothing to do with it.
Different pipes off the intake of the turbo have an effect on the pitch of the sound, whilst running an air filter severely muffles the sound.

well from what i learnt fom my own research last night, wastegates allow only a certain amount of exhaust gas to the turbine, which is set to a certain PSI.

IE: if your turbo is set to say 8psi (actuator pressure on a TD04L turbo) then the wastegate will allow enuff gas to hte turbine, to produce 8psi, then once it starts pushing more gas in, the wastegate redirects that excess gas, AROUND the turbine, plumbing it back into the exhaust, AFTER the turbo. or in some (illegal) cases, just out to atmosphere (ie, it leads out to free air)

where as a BOV, when the throttle body closes, the pressurised air being forced in by the trbo, has no where to go, except backwards, towards the turbo fins again. so you plumb a BOV into it, which open when a certain vaccum pressure is made, opening the BOV, alowing that air that has nowhere to go, OUT. either plumbed back into the zorst, AFTER the turbo, or out to atmoshere again.

is this correct?

dose or flutter, is caused by that air that SHOULD be vented via a BOV, being forced back towards the turbo fins, getting chopped up, and creating that flutter sound we love so much

a 'dose pipe' just replaces a filter on the intake side of the turbo. differnt lentghs etc. can change the sound of this flutter/dose, but it is still the same thing.

a pod filter off the turbo, muffles that sound greatly.

am i correct so far?

so in my mind, i cant see how a wastegate, be it external OR internal, can make a noise like a fluter?? if it is just venting some excess air around the turbo, basically a D tour for the gas that is not needed, then how can it make a flutter sound?
if anything, shouldnt it be a sound similar to an exhaust??

External and internal blow off valves differ in that external bov's vent externaly and internal bov's vent internally.

Just say you have a supercharger, the bov will be inbetween the charger and the throttle body. with an external bov it vents straight back into the atmosphere but with an internal bov it vents back to the piping inbetween the airflow metre and the supercharger.

With a bov or a wastegate the air shouldn't go back into the turbo unless theres a problem with the installation of the setup.

the fluttery noise is a wastegate, a wastegate vents when a certain psi of boost goes through it. So if its set at 10psi then your car boosts up to 12psi then the extra 2 psi are just vented out so that a maximum of 10psi can go up to the throttle body. Wastegates vent out pressurised air in incriments, therefore creating the ch ch ch ch ch ch ch noise.

-Daniel

but a wastegate works when you are accelerating, thats when there will be more/excess air being flowed into the turbo. so if what your sayign about the flutter being the wastegate is true.. should a car flutter whilst on boost, and accelerating, rather than when it comes off boost, and the throttle is closed?

i have never heard about internal/external BOV's. only wastegates.

isnt a BOV escetially a vaccum operated valve, plumbed between the turbo and throttle? whether it be before or after the cooler?

ie: 1) turbo ----> BOV ----> cooler ----> throttle
or
2) turbo ---> cooler ---> BOV ---> throttle

internal wategates and external wastegates aree differnet in the way that an internal one, uses a actuatr inside the turbo. which is opened/closed when a certain PSI is reached, 'activating' the internal wasegate, flowing excess gas around the turbo.
whereas and external one is activated via a boost controler, be it mechanical or electrical.

if this is the case, i cant see how a wastegate can make a flutter sound.

dont they make a roar typr noise. like when you start a car with no exhaust on it.



that is why you only get flutter on turbo cars with no BOV is it not? as rather then being vented back out, it hits the turbo fins, creating flutter?

i dont see how a wastegate can stop flutter.

wastegate stops toomuch gas flowing on acceleratoin, whereas BOV stops excess air flowing BACKWARDS when the throttle closes

Ok, air comes in through the filter, then through the AFM (which measures the amount of air coming in so the ECU can calculate the amount of fuel required).
The air is then sucked into the turbo, where the compressor wheel increases its pressure and sends it to the engine. On the way there's an intercooler to lower the air temp, because a by product of the turbo is quite a lot of heat.
Before the air gets into the engine it passes through the throttle body, which is what your accelerator pedal is connected to.
The throttle valve restricts airflow into the engine so that you can vary the power it makes.
When it's open the engine tries to produce maximum power, and when it's closed (almost closed) the engine will be at idle.

So the path of air is: filter -> AFM -> compresor (turbo) -> intercooler -> throttle -> engine.

The exhaust gas flow from the engine is roughly proportional to the amount of power it's making, and that flow is what spins the turbo's turbine, which in turn drives the compressor.
So, the more air going in, the more power, and hence more exhaust coming out, which means more boost, which means more air, hence even more power. It's a feedback loop which is kept under control by the throttle input from the driver.

To keep the maximum boost at a safe level there's the wastegate, which is just a valve allowing exhaust to bypass the turbo, and therefore not spin the turbine any faster, or create more boost.
It works in a very simple way. The valve is held closed (all gas goes through the turbine) by a spring, until it is forced open by a diaphragm driven by boost pressure.
When the appropriate boost is reached the wastegate starts to open, and the turbo will stay at the set boost level while the exhaust flow can still increase as the engine revs rise.

All of this works quite simply under constant acceleration:
Air comes in, is compressed to the set boost level, intercooled, used by the engine, and the exhaust keeps the turbo spinning.

It becomes more complex when you start changing throttle settings.
If the throttle is wide open, and you're at full boost accelerating, then close the throttle (for a gear change, or back off) suddenly the turbo is pushing against a closed throttle, and at the same time the engine has stopped producing exhaust gas, so the turbo starts to slow down.

Now that there's a whole intake system full of compressed air with nowhere to go, and the compressor is not being driven by the turbine - so it can't hold the same air pressure that it did while spinning flat out. The air will start to flow the other way, which means going backwards through the still spinning compressor.
This is where compressor surge comes into play. The compressor is still trying to pump air, but at the speed it's going it can't provide as much pressure as there already is in the pipe.

This causes the compressor to "stall". Stall is a misleading turn used here, because it doesn't mean stall as in to stop spinning. It's the aerodynamic stall, like a plane that's tried to climb too steeply, or has slowed down too much to maintain lift.

The smooth air flow through the compressor blades is broken up, and some of the air will flow back out through the compressor, making a hissing noise.
Centrifugal compressors work on a "squared" relationship for speed vs flow / pressure, so if the turbo slows down to half speed it will only be able to hold a quarter of the boost pressure.

The "chopping" or "fluttering" sound is caused by the accoustic effects in the intake system, determined by the size and length of the piping / cooler.
Rather than air constantly flowing back out of the turbo it tends to come out in bursts, triggered by pressure waves in the piping hitting the compressor.

Generally though the flutter is the sound of the pressure wave cause by the throttle closing bouncing back and forth between the turbo and the throttle plate (the longer the pipes the slower the flutter).
Every time the wave hits the turbo it causes the compressor to cavitate, which makes the noise.

It's not the blades chopping the air making the flutter. Since the blades are spinning at 80000+rpm you wouldn't be able to hear the individual "chops"

If you listen closely you'll actually hear a more constant hiss sound at higher boost levels and rpm when backing off. (ie, a "whooosh" rather than a "chop chop chop")

The loudest flutter tends to occur at lower rpm and boost levels of only slightly above atmospheric pressure (0psi). This is partly because the sound is "chopped" up more noticeably, and partly because the rest of the car is making less noise at lower speeds. This is also where it's least damaging.

Car manufacturers don't like weird noises from the intake system, so they use restrictive airboxes designed to muffle the sound, and more recently (SR20 onwards) used a Blow Off Valve.
The blow off valve provides a new path for air to get out past the compressor. Instead of forcing its way back through the spinning blades it is piped out of the intercooler piping and back into the intake piping before the turbo.

Obviously it could be vented straight out to the atmosphere, but the AFM has already measured that air coming in, and if it doesn't reach the engine the ECU will be injecting too much fuel in its absence.
(Also, venting to atmosphere makes a bit much noise for conservative owners and manufacturers)

The BOV works a bit like the wastegate, in that it's held closed by a spring, and controlled by a pressure operated diaphragm.
This time though the boost pressure helps keep it shut rather than open it.
The control air pressure for the BOV comes from the plenum, which is the chamber between the throttle and the engine.
When the throttle closes the engine creates a vacuum (negative pressure) in the manifold / plenum as it tries to suck air past the closed throttle.
The vacuum is used to "pull" open the BOV, to vent the excess air in the intake system, preventing "flutter" and other noises.

A BOV is a compromise device because, to eliminate all fluttering it will have to open at very low boost levels, and very quickly - which means that it must have a very weak spring. This can cause some leaking of boost due to the valve not staying sealed properly, and also means that every time you back off the throttle, all the pressure in the intake system is vented. When you open the throttle again the turbo will have to build up all that pressure again, whereas if there was no BOV there'd be more pressure remaining as it's a lot harder to get out through the compressor.

Most aftermarket BOVs won't open until you reach 6psi or so of boost (because with an atmo venting BOV if it leaks boost you'll have major problems - whereas a slightly leaking plumb back type won't cause bad running, just a very slight loss of power)

When you start running well over stock boost, and have larger intercoolers / intake piping obviously there's a lot more air in the intake system, and it will be at higher pressure - so when you back off the throttle there's a lot of air trying to escape through the compressor. This means it will be slowed down quite quickly and violently, which puts large loads on the turbo bearings, wheels, and shaft. Repeated hammering by high boost backoffs can harm the turbo, and the amount of slowing each time causes a lag when the turbo spools back up after each backoff / gearchange.

The best compromise setup is to have a BOV which will open when you back off at over say 6 psi, and vent back into the intake to prevent the rich running problems of atmo BOVs. If it's too loose you'll lose boost response due to too much presure being lost on gearchanges, and if it's too tight you'll lose response due to the turbo being slowed down too much - and potentially damaged by the rapid deceleration.

Nice read. Cant comment on anything you wrote coz i know next to nothin about forced induction but i hope i've learned something useful.

good researching Nathan.

Liberate, im sorry, but everything you have said is incorrect. unless you are 100% sure you know what you are talking about, then dont, because it is misleading, and confuses people.

now, to go further, in regards to dosing. as you can tell from nathans description, normaly the AFM is placed before the turbo. what these muzza's do, is place the AFM between the 'cooler and TB

so instead of going:

FILTER----->AFM----->TURBO----->COOLER------>TB

it goes

TURBO0------>COOLER------->AFM-------TB

and thus when the air comes back towards the turbo and gets chopped up by the blades, it vents directly to the atmosphere, rather than going thru the AFM and air filter. changing the length/diameter of the pipe coming from the intake changes the loudness, and pitch of the flutter, much like tuning a ported sub box

a wastegate will NOT MAKE chuffing sound, maybe a slight pssssss noise as the turbo reahces maximum boost.

if the wastegate is not plumbed back into the exhaust, and just vented to the atmosphere, it will be insanely loud when the turbo reaches full boost, as the exhaust is not being "muffled" by anything, and thus called a screamer pipe.

haha.... pretty smart for a 16 year old huh hahahaha

Flutter is caused by backpressure hitting the compressor when the throttle closes.. think about it, it's been compressed and hits the closed throttle, causes back pressure, what happens then ? The air escapes out the easiest exit, namely back out the compressor.

So, you fit a pressure release valve.. obviously the shock the throttle and compressor get from the back pressure isnt good for them.. in big boost applications it can bend the throttle plate ! We call them BOV's..

The factory handles them by putting in a vacuum actuated valve that opens when the vacuum shifts from positive (boost) to negative (closed trottle).. the excess air between the compressor and throttle then takes the path of least resistance, which is now this wide open valve in the inlet pipe, and the air is then ducted into the factory air box. This makes it QUIET and EPA legal.

But you and I want everyone to know we have a turbo car, and they better be careful picking a racing with us 'cos we've got the big boost.. and ditch that pipe to plumb back into the airbox. Which we werent using anyway 'cos we fitted this nice K&N pod filter anyway ! So, our BOV is the same as the factory one, but spits out the compressed air thru tuned sized vents into the atmosphere.. why tuned ? To make it sound cool ! HKS SSV do the same job as a $70 home turned job, but cost more 'cos they sound better.

Anyways.. I know this 'cos I've got a phat 3" dump pipe, big intercooler, 12PSI boost and a Type 1 Turbosmart. If its boosting less than 5PSI, I'll only get flutter back out the compressor... the BOV's set very tightly to keep it on-boost longer. At 6ish PSI, I'll get an initial flutter, then PISHT. Anything over 7 and its all about the BOV baby.

OMFG I found a sik dosepipe video over on YouTube:
http://www.youtube.com/watch?v=L5V01zH3KEg...ated&search

That is the gayest sounding thing EVER !

Oh yes, and theres also this guy selling dosepipes on eBay:
http://cgi.ebay.com.au/VL-TURBO-CUSTOM-DOS...1QQcmdZViewItem

It's a Mexican Muzza thing. You will learn one day

I'll learn ? They'll learn when they sit there going choochoochoo and I'm screaming past them