Surge on Stage 1 K04 - Cured

[S3 Nattie]

I see what you mean. Not sure why its doing that but sounds like you could be experiencing compressor surge under WOT, dont really know but sure Bill will know once you can get some data up maybe. Never heard/experienced compressor surge for myself but just going from videos on youtube sounds like what your saying. Hopefully its just a leak or loose jubilee clip.

Any chance you can get a video or get a link from youtube. Thats why I think a boost gauge a is a minimum on turbocharged engines, help show what your turbo is doing.

Does it sound like this video.

http://www.youtube.com/watch?v=nCj6Spwl1CU&feature=related

 

[JamJay]

Yes, that's the noise that I have. In that video when they show the turbo and it has that fluttering sound under boost, that's what I have. Not all the time, only when I'm full throttle from low revs, if I stick my foot down gradually throughout the revs or hard from higher revs then I don't get it. Why am I getting this and what should I do? I'm really worried now . What should I check?

 

[rsmith]

Here is an example of surge on a LCR(mine), does it sound the same, looking at your logs of G/S it would also suggest this as the G/S reading is up and down at low RPM, (close to the turbo surge line)

http://www.youtube.com/watch?v=WBRWTWqGohc
http://www.youtube.com/watch?v=PdVlOl0W7ZA



P.S Sam your logs show this also!

 

[JamJay]

That's it Robbie , what does this mean?

 

[rsmith]

It means with the installation of the new TIP, the surge line of compressor has been moved to the left, so you are pushing in more air than the engine can consume, this hopefully can be mapped out but is very interesting as i have only ever seem this on a hybrid with the B5 Tip.

What FMIC are your running?

 

[sambryant]

Thanks robbie, but they are old logs. My turbo was spiking 2bar at just over 3k rpm. I now have the mbc fitted and things look much better, also i made better gs. Jamjay you might want to looking into fitting a mbc, my boost is clipped to 1.4bar now.

 

[S3 Nattie]

If you was getting the noise when the throttle was closed (WOT then completely off the throttle) I would have said your DV could be dead or the vac line wasnt connected/split as you get flutter when that happens. But on WOT im unsure what to look at.

The only thing I can think of is that the compressor is not able to flow and maintain the amount of flow that can be drawn through the 3" tip at high full throttle. My knowledge on this is limited though. Just stay off boost for now though, maybe hard seeing as you just fitted your exhaust system too lol.

 

[JamJay]

It means with the installation of the new TIP, the surge line of compressor has been moved to the left, so you are pushing in more all than the engine can consume, this hopefully can be mapped out but is very interesting as i have only ever seem this on a hybrid with the B5 Tip.

What FMIC are your running?

Ok I think I understand, so basically my k04 is sucking in so much that the TC cannot deal with it all? This sounds odd as I though more air = better and this 3" TIP was the revolution? How will this be mapped out? Do you think That I am getting this because I am running Stage 2 mods on Stage 1 code? No FMIC as yet but everything else fitted ready for Stage 2, would a FMIC cure this?

Found this on Garrett's website:

What is compressor surge?
The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side.
Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself.
Common conditions that result in compressor surge on turbocharger gasoline engines are:

◦A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body
◦The outlet plumbing for the bypass valve is too small or restrictive
◦The turbo is too big for the application

 

[rsmith]

Scroll down to surge.
http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html

Sam yes you can drop the boost down early so you are not pushing so much air and keep to the right of the surge line. But 1.4bar?!

 

[sambryant]

Haha i know 1.4 seems low but bill spent ages trying to get the best out the car. 280bhp at 1.4 bar on bills dyno is a great result. Rob if im honest it feels the fastest its been and i love it, temps are down and car is very consistant. Also with the added bonus of more gs

 

[rsmith]

Ok I think I understand, so basically my k04 is sucking in so much that the TC cannot deal with it all? This sounds odd as I though more air = better and this 3" TIP was the revolution? How will this be mapped out? Do you think That I am getting this because I am running Stage 2 mods on Stage 1 code? No FMIC as yet but everything else fitted ready for Stage 2, would a FMIC cure this?

Found this on Garrett's website:

All Turbo's have a surge line, its a very fine line and you can make any turbo surge.
Air flow is the key but all engines have a volumetric efficiency, if you go over this the engine just cannot cosume the air, the VE will change over the RPM range so further up the RPM you can cosume more air.

We had a very lengtly discussion about this here, i posted up maps of the 2280 and 2283 compressor maps as expamles and i also worked out to my best guess'timate the VE of our engines and what they can comsume and when.

Grab a beer and have a read: if anything you will learn a good bit about turbo's
http://www.seatcupra.net/forums/showthread.php?t=298188

Haha i know 1.4 seems low but bill spent ages trying to get the best out the car. 280bhp at 1.4 bar on bills dyno is a great result. Rob if im honest it feels the fastest its been and i love it, temps are down and car is very consistant. Also with the added bonus of more gs

280bhp is a very good/honest result IMO,

 

[JamJay]

That link makes sense but it refers to DV's. It suggests that a BOV will aid the surge issue by venting the excess pressure away from the system where as a recirc valve just dumps it right back. Could my issue be DV related?

I will have a read of your link, more knowledge would be good but I need to know how to fix this as it seems pretty major, is this a job for Bill? Luckily I don't drive the car so much but I don;t want to damage the turbo.

 

[RS6]

can you record yours jamjay be interesting to hear it?

 

[rsmith]

That link makes sense but it refers to DV's. It suggests that a BOV will aid the surge issue by venting the excess pressure away from the system where as a recirc valve just dumps it right back. Could my issue be DV related?

I will have a read of your link, more knowledge would be good but I need to know how to fix this as it seems pretty major, is this a job for Bill? Luckily I don't drive the car so much but I don;t want to damage the turbo.

If the flutter is on WOT its not the DV, also our Me7.5 ECU don't like BOV's as its a recirculating system, i have heard of guys using leaky DV's to get around this but its a dirty fix.

Talk to Bill he can help you.

 

[sambryant]

Yeah i think so to. Got the extra bhp if i want it but with the risk of my rods seeing daylight jamjay i think mbc is the way to go

 

[JamJay]

can you record yours jamjay be interesting to hear it?

Sounds exactly like Robbie's video, no different at all .

If the flutter is on WOT its not the DV, also our Me7.5 ECU don't like BOV's as its a recirculating system, i have heard of guys using leaky DV's to get around this but its a dirty fix.

Talk to Bill he can help you.

How about a 50/50? However I though the 007 was perfect for this engine. I will await Bill's response.

Yeah i think so to. Got the extra bhp if i want it but with the risk of my rods seeing daylight jamjay i think mbc is the way to go

MBC might be the answer but I don't get why I am seeing these issues at just Stage 1, fisrt ever documented case? I do honestly wonder if it's the fact that my mods are too great for the ECU code now and I need to go to Stage 2 code?

 

[rsmith]

Your map may only need to be tweaked.DV 007 is perfect for us, how do you mean 50/50, part throttle? I will look over your logs VS the compressor map.

 

[JamJay]

Your map may only need to be tweaked.DV 007 is perfect for us, how do you mean 50/50, part throttle? I will look over your logs VS the compressor map.

Perhaps it does, in which case I will get this sorted or just Stage 2 it taking inot account all mods inc 3" TIP.

Sorry I meant 50/50 BOV...Split-R, TS Kompact Dual Port, GFB 50/50.

 

[rsmith]

Perhaps it does, in which case I will get this sorted or just Stage 2 it taking inot account all mods inc 3" TIP.

Sorry I meant 50/50 BOV...Split-R, TS Kompact Dual Port, GFB 50/50.

I can't comment on the BOV, i am not a fan.Also It might just mean you need to tone down the intial boost spike, let more exhaust gases bypass the turbine in effect slowing done the compressor wheel from flowing so much.

I think this will be the fix for you. What are you boosting now, Initial spike that is?

 

[S3 Nattie]

Robbie, out of interest what max VE and cfm did you estimate for our engines