ko4 wastegate chatter...

[Shy19s]

Is this possible to do on the k04s? if you take the dump valve off and let the turbo spin back on itself to make that beautiful sound... are the turbo's strong enough.. even though not recommended anyone done this?

 

[Ess_Three]

Taking the DV off will potentially stall the compressor - which isn't good for throttle response, but unlikely to be fatal to the turbo unit.

Making the compressor 'spin back on itself' is compressor surge and will limit the life of your turbo to minutes. Very much NOT recommended.

Wastegate chatter is something completely different again...and safe for the turbo.
Stalling is not good.
Surging is bad.
Wastegate chatter may sound good to you...

Surging sounds like the devil himself has indigestion, closely followed by the sound of your engine ingesting your turbo internals, closely followed by a loss of power and all the red lights on your dash coming on, followed by your car stopping and the driver feeling sick as a pig.
Best avoided, in my book.

 

[HTC]

It is possible, just put a very tough spring in the DV, but it sounds like a strangled pigeon.

God knows how long the turbo would cope with air running the wrong way through it. Buy two K04s just in case.

BTW, I don't know why it's called wastegate chatter. Has nothing to do with the wastegate.

Your choice.

 

[Ess_Three]

God knows how long the turbo would cope with air running the wrong way through it. Buy two K04s just in case.

Well, if 30" inlet industrial gas compressors can destroy themselves in seconds whilst shaking structural steelwork to pieces when surging, and have very complex anti-surge control systems to prevent it...I can't see the fine tolerances and bearings of a K03/4 holding up any longer.

Seconds I'd say...once it's surging.

 

[Shy19s]

lol you guys are hilarious... i love the way you worded your response glen.. thanks for the replies... and im glad i didnt try it!

my friend just did the same on his evo 6, hes got a turbo from a 9 and apparently that can handle it.. sounds better than a coke can opening.. whats the best way to get the flutter, chatter, whatever you want to call it with the ko4 turbo in your opinions?

isnt that how all the cossies get the dolphin screech after they let off the throttle? caping the DV?

 

[HTC]

I know a guy with a ford and it flutters, whizzes, whoops and farts all day long. There are enough vids on you tube too. If you like the noise then you like the noise..............but you gotta know the consequenses buy blocking the DV.

I'm all for having a laugh.........like I say it's up to you.

But it just can't be doing the turbo any good at all. Roller bearing CHRA might be stronger on a garrett over KKK thrust bearing like on the K04.

What the hell............I can't believe I'm even contemplating the pros and cons. I go now

 

[Shy19s]

lol lol.. kev i think you should be called the guru...

i dont really want to be sending air down the wrong way on the turbo, but id prefere this noise.. is there any other way of doing it then on the BAM engine?

 

[HTC]

It is what it is. The sound comes from the chopping of waste air.

Safe ways of weird and wonderful noises are produced by vacuum operated open exhaust flaps and/or a screamer pipe off an external wastegate. The latter isn't possible with a K04 and both are illegal over here.

 

[Shy19s]

emissions right? :S

thanks tho..

 

[HTC]

........and permitted noise Db levels.

 

[Ess_Three]

i dont really want to be sending air down the wrong way on the turbo, but id prefere this noise.. is there any other way of doing it then on the BAM engine?

No, you don't prefer the noise of sending air the wrong way down the turbo.
Honestly, that's not the noise you want.

The sound of a compressor surging is heard once...just before the engine ingests the compressors internals. That doesn't make a whooshing/twittering/fluttering/whizzing/whooping or farting noise.
It makes a horrible groaning noise not unlike hot metal on metal scraping and shattering...because that's ecactly what it is!

You DO NOT want that...

The trouble with the 1.8T is that it's a very complex engine with many safeguarding features to keep it from lunching itself. Trying to make one do something it doesn't want too and shouldn't do is foolish.

Best you fit a Renault 5 turbo lump if you want to make it do daft things...the BAM/AMK type 1.8Ts are set up to be efficient and long lasting...not to whoosh/twitter/flutter/whizz/whoop and farting for a few seconds before lunching themselves and leaving a pool of oil on the road.
Honestly...it's not a good/cool look.

 

[Mr.G]

Can i just say.....

I love the noise personally. What i do think though is that Ess is mistaking it for something else!

Wastegate chatter happens on my car although very quiet i can hear it occassionally while lifting off boost. Maybe my diverter valve is a little perforated or has a worn spring.

http://uk.youtube.com/watch?v=Th5uDe5fmGQ

Cosworths do it and some are louder than others, it depends on the amount of boost the turbo is producing. I'm no expert and don't pretend to be but understand how a turbo works, i mean it's not exactly rocket science.

It must be possible to safely make our cars do this to a louder degree. i wonder if re-mapped S3's would have more chance?

G

 

[Mr.G]

However....if the video is anything to go buy it is a little chav.

Highly tuned rally cars especially the UR Quattro Rallye car. Must be something to do with the amount of boost.

 

[HODD]

I have a neuspeed induction kit and since it was fitted i get a bit of chatter between gear changes.

 

[Prawn]

Jesus guys, read the ******* thread.

the noise you hear is NOT chatter, be it of the wastegate or anything else.

it's compressor stall.

Mr. G, your DV is ******. change it. the reason for the noise is the diaphram is split, so the vacuum line on top isn't able to open the DV fully/at all. the result is air isn't being vented back into the TIP, it's comming back through the compressor stalling it. THAT is the noise you can hear.

ANY chatter on a 20vt engine that's still running a recirc valve with the standard MAF based ECU, is bad. unless some **** has put a stupidly strong spring in the DV.

End of. it's a bad noise, no matter how much you like it.

Have you seen the size of the cossie turbo? running low boost on such a big turbo isn't going to do it any harm, but take a look at the soze of a ko4 core assembly, it's pathetic. The loading increase on the thrust bearings during compressor stall mean it can never last long.....

 

[Mr.G]

Would this make a difference to performance if my DV is messed!?

 

[Shy19s]

Now it makes sense.. thanks prawn.. lol glen i think you made your point on the first post.. thats why i checked with you guys first to see if its possible but i didnt get the BAM engine just for that noise.. i just thought it would be a little different! lol

Thanks for all the input guys!

 

[Prawn]

Would this make a difference to performance if my DV is messed!?

I found when my original one went, I got way worse mpg (probably 3-4mpg reduced) and noticably less throttle response, and the turbo was much more laggy after gear changes, as it was stalled totally and had to respool completely.

generally, the car was flatter and not as smooth to drive

 

[Mr.G]

Does anyone have a standard recirc for sale?

 

[Prawn]

they're only about £23 from the dealers mate, may as well buy a new one! people are never going to sell standard ones, as they're always broken!

 

[yellowgti]

i have a standard cheapo round air filter (k&n style) on and it chatters lovely and pretty damn loud!

 

[Prawn]

AAAAAAAAARRRRRRRRRGGGGGGGGGGGHHHHHHHH!!!!!!!!!!!!!!

Man, please, for the love of the children....

.... READ THE THREAD!!!

it IS NOT chatter, it's compressor stall. it's NOT GOOD, the noise is NOT GOOD

Your recirc valve is ******. change it.

 

[Ess_Three]

Can i just say.....

I love the noise personally. What i do think though is that Ess is mistaking it for something else!

I can assure you I am not mistaking things.

The whooshing type noises some want can be made is several ways...safely, if not always in the best interest of performance.

Compressor stall is something else...and not ideal.
Compressor surge is very bad and kills compressors stone dead, catastrophically, in seconds.

I know what compressor surge is...I make my living calibrating and operating anti-surge systems on gas compressors.

There seems to be some confusion around what makes that lovely GroupB type noise...but one thing's for sure...it's not produced by sending air the wrong way down the turbo - as suggested in an earlier post!
Causing the flow to reverse through a compressor is surge. And that is very very bad.

 

[Ess_Three]

Now it makes sense.. thanks prawn.. lol glen i think you made your point on the first post.. thats why i checked with you guys first to see if its possible but i didnt get the BAM engine just for that noise.. i just thought it would be a little different! lol

Thanks for all the input guys!

Just remember Shy...the 1.8T is a very modern advanced engine, designed to be efficient.
It uses a closed inlet system with measured amounts of air, to keep lag to a minimum...anything you do to the DV that involves dumping air external to the engines measured inlet air will have a bad effect on performance.

You fit a dump valve and you get worse throttle response, more lag and therefore less performance.

This isn't an opinion...this is FACT.

Keep the DV, keep the throttle response, keep the ECU happy and keep the performance.
Fit a Dump Valve, screamer pipe, or anything else that messes with the ECUs control of the boost circuits, and you increase the throttle response time, add lag and loose performance when on-off the throttle.

The K04 is just too small to need anything other than a closed loop DV system.

 

[yellowgti]

AAAAAAAAARRRRRRRRRGGGGGGGGGGGHHHHHHHH!!!!!!!!!!!!!!

Man, please, for the love of the children....

.... READ THE THREAD!!!

it IS NOT chatter, it's compressor stall. it's NOT GOOD, the noise is NOT GOOD

Your recirc valve is ******. change it.

that meant for me? il get one at the end of the month if it was.... cheers

 

[Prawn]

sorry if I came across a little rude, but people keep saying it's wastegate chatter, when it's not, it's compressor stall.

Glen, do the anti surge housings you see with extra holes around the compressor wheel actually work? if so, how do they work?

 

[Prawn]

also, SO many people don't seem to realise that when a 20vt starts making that noise, it's because the standard DV is broken, and it's making their car slower and less economical!

 

[Ess_Three]

Glen, do the anti surge housings you see with extra holes around the compressor wheel actually work? if so, how do they work?

I have no idea.
Seems a bit pointless to have a bleed back for compressed charge when it's not required...but I've never heard about them so can't comment.

The normal way (industrial machines) is to have a fast acting recycle valve to vent the pressurised gas back to the inlet, therefore removing the discharge pressure and providing additional volume of gas back to the starved suction.

 

[HTC]

Garrett anti surge housings allow you to get away with running small a/r turbines with very large flow compressors at the expense of a lower compressor effeciency.

Comparing compressor maps for the same turbo with and without the anti surge inlet gives a surge line that moves to the left. Less likelyhood of surge at high boost. You'll probably lose a little low end torque, but the gains far outweigh the loses.

 

[Ess_Three]

Am I the only one that gets excited about reading surge graphs for compressors?
Or hearing the phrase "gives a surge line that moves to the left"?

Left, is good... :thumbsup:

Good info there...cheers for posting!

 

[HTC]

You are not alone!

 

[Mr.G]

Ok lads...

Thanks for the informative and very interesting posts.

So...

My DV is definately broken? Its only minutely audible. I have to listen out for it. It sometimes happens when i'm driving my car out of the garage and up the driveway in the morning, lifting off boost you could say.

It's not loud and i can not compare it with the earlier video's of the cosworth as it sounds nothing like that. Just a little chirp noise if you get what i mean.

From what you are all saying on here the K04 turbo is a bad setup? Small and therefore not that good for power? How does a hybrid compare? If i was to whack a hybrid on and re-map would i get the magic 300Hp?

Would that make much of a difference to MPG's? I know the obvious answer is if i'm using lots of boost yes. While normal driving would it be more economical?

I'm toying with the idea of tuning the S3 a little. I don't want a Big turbo conversion as i cant justify the cost. There are other things i like to spend money on. But £1500 doesn't seem to bad for a turbo and re-map.

Any advice welcomed and very much appreciated!

G

 

[HTC]

The k04 is not a bad turbo at all. It's a tough little mofo. You can get alot out of them and for a road car they are really quick spoolers so great for the traffic light grand prix. They do run out of puff a little at higher revs tho.

A hybrid will get you 300bhp with great spool.........but you will get used to it, just one of those things.

MPG should not change or be better when driving off boost. Toe it, and of course you'll use more fuel.

 

[Ess_Three]

From what you are all saying on here the K04 turbo is a bad setup? Small and therefore not that good for power?

K04 is just fine for a lardy S3 that has lots of traction available.
It's just people are pre-occupied with chasing big numbers...and the K04 doesn't 'do' big numbers.

Over 265 BHP it's turned into a heat pump, so you really need massive increases in intercooling to use it beyond that...you can get 280 geniune BHP from one...which combined with 320+ lb-ft is enough to make the S3 interesting.
Also, it spools up very fast...so you can make the power delivery 'interesting' by having it go from around 100 lb-ft to over 300 lb-ft in a few hundred RPM!

Once people change their driving style to short shifting and using the torque, the K04 makes for a rapid car.

Just don't go expecting more revs to equal more power as in a Japanese turbo'd car.

How does a hybrid compare? If i was to whack a hybrid on and re-map would i get the magic 300Hp?

A pretty good compromise from my experiences...
you loose some of the low down torque usually associated with the vanilla K04, but get more up top, and over a longer RPM band.

I'm toying with the idea of tuning the S3 a little. I don't want a Big turbo conversion as i cant justify the cost. There are other things i like to spend money on. But £1500 doesn't seem to bad for a turbo and re-map.

I think people should drive proper BT S3s before committing...
Sure, 330-350 BHP seems a lot...but the torque is normally a lot lower than a hightly strung K04, at around 270-280 lb-ft.

In average driving, and on proper backroads, the much higher torque, much lower down the revs actually makes the K04 S3 a quicker car...

For flat out stuff, top speed and drag racing the BT car is obviously going to be faster...but for fun, and back roads...I was never convinced.

It's not as much fun anyway...
A K04 S3 making 275+ BHP and 330+ lb-ft is a wild thing...that's for sure!

I have driven a few BT S3s and they've all felt much more 'ordinary' than my highly strung K04 S3...maybe it's all down to whether you want fun and involvement or big numbers on paper.

 

[TurboDave]

There are some people which argue that a blocked BOV to enduce compressor stall does in fact increase throttle response especially between changes because all of the air compressed by the turbo is not vented through the bov so when the turbo begins spooling again after gear change the intercooler/pipes will still be somewhat pressurised.

When the BOV is blocked and the charge has nowhere else to go apart from back through the compressor wheel and back through the induction piping the compressor wheel never slows down enough to spin the other way and doesnt stop it simply gets slowed slightly by the charge which is chopped up by the comp wheels inducer and exducer to produce the flutter noise.

My previous car had a tiny turbo in comparrison to the KO4 a Toyota CT9 hybrid turbo and that was running 1.5 bar for over a year with serious amounts of flutter.

Surge is totally different to the flutter noise we are talking about and it is normally caused by poorly matched comp housings and wheels specs etc.

 

[Shy19s]

This has become a very interesting thread.. Glen/kev, whats the most boost you can run on a standard BAM ko4 set up.. remapped set up and BT set up?

I would love over 300 lbs of torque! Glen so from the sounds of it, you prefer the ko4 remapped.. is this running the turbo on its limits, or can i get over 300lbs on a remapped BAM ko4 quite comfortably?

 

[Ess_Three]

There are some people which argue that a blocked BOV to enduce compressor stall does in fact increase throttle response especially between changes because all of the air compressed by the turbo is not vented through the bov so when the turbo begins spooling again after gear change the intercooler/pipes will still be somewhat pressurised.

I don't buy that though...

If you look at the time it takes the exhaust gas to get the compressor wheel up to it's operating speed and produce the desired boost (the lag) then you add a factor of that every time you change gear if you don't vent via a DV or Dump Valve.

OK...the pressurised air dissipates quickly once you open the throttle...but then you have to spool up the compressor from a position of stalled.

With a DV or Dump Valve the compressor remains spinning, so the lag is less.

 

[Ess_Three]

This has become a very interesting thread.. Glen/kev, whats the most boost you can run on a standard BAM ko4 set up.. remapped set up and BT set up?

I was running 1.85-1.89 bar peak boost on a K04 for years...and as far as I know, the S3 still is, 3 owners later. (although it's probably back on a standard N75 so nearer 1.7 bar now)
Mine was an AMK by the way.

Holding 1.3 bar to the fuel cut.

BTs will produce the same levels of torque, but the delivery is always less aggressive and it's further up the revs.

I would love over 300 lbs of torque!

Not on a FWD car, you wouldn't...

Glen so from the sounds of it, you prefer the ko4 remapped..

I liked my S3 with a flat-out K04 as it suited the car, the car's purpose and my driving style.
I was running around 320 lb-ft everyday and with a very well set up S3 on completely different suspension components and settings to be able to use it.

I had it set up with lots of grip, so you could open the throttle, hit boost mid corner, grab a half turn of opposite lock as the Haldex dumped the torque rearwards and power-slide through the bend with no understeer.
The key here is getting the front end sorted to grip properly...if you haven't got the grip, that doesn't work and you power understeer into the hedge.

I did try running the car at 332 lb-ft, and in winter when the air was cold and the roads greasy it was too much...the car would spin all 4 wheels and became unpredictable and verging on undrivable.
You spent as much time fighting the car as driving it quick...so in winter, 320ish lb-ft was best...in summer 332 lb-ft was fine.

The power and torque delivery was only any good as long as you short shifted though (almost like driving a diesel) and had the chassis set up to actually use the torque.

For FWD, a BT will be easier to drive.

is this running the turbo on its limits, or can i get over 300lbs on a remapped BAM ko4 quite comfortably?

The key to running big boost on a K04 is intercooling.
Above 260 BHP/270 lb-ft you start to heatsoak the ICs...by the time you are up to 300 lb-ft the turbo is a heat pump and the timing is being hacked back to protect the engine - loosing power.

So, sort the intercooling. I had a bespoke, deep, alloy, modified Golf 4 Forge SMIC and a bespoke Star Performance designed, Forge built FMIC in series to get the inlet temps down to levels where I could run 1.85 bar+ and 1.3 bar sustained all day, everyday.

Without it...there would have been problems.

I believe a simple re-map can be made to give 300 lb-ft on standard ICs...but personally, I'd not risk it.
Each to their own though...

 

[Ess_Three]

Something to consider:

It's not just the pressure you need to consider, it's the volumetric flow of the turbo.

The k04 will fill the cylinders fully at peak torque and let you run 1.85 bar + with no problems...but as the revs rise, the K04 is just too small to move enough air to keep the engine fed.

A k04 running 1.3bar is likely to make far less power at the top end than a BT running 1.0 bar (turbo trim dependant of course).

The other point is, the bigger the turbo, the less heat is transferred into the inlet charge.
But more spool up time.

The smaller the turbo, the more heat is transferred into the inlet charge.
But faster spool up time.

You don't need better ICs with a BT.
They don't usually produce enough heat to demand better ICs.

There are pros and cons for each.

 

[Shy19s]

very interesting read.. im currently working on suspension components, ive done shocks n springs (KW) im impressed with it so far, strutbrace bolted through the turrets.. just need to get the ARBs done as in finding the new limits, it does understeer, so once that is sorted i can think about power, but its all very useful for future reference.

thanks again.