Have I got this right...Listening to this vid. I can hear a chuffing noise as the turbo is spooling.
Is that Surge or just a bad recording.
Is that Surge or just a bad recording.
-
Volcano ABY coupe
Ant -
It does sound a bit like surging, but is it imagination when trying to listen for it, dunno.All quattro products have been dermatologically tested, and are safe for daily use.
-
that last vid was what i had always understood to be surge. I.e. Broke TBV or too small.
Think that is stall instead...but u hear it on alot of performance cars and i cant see any benefit to stalling ur charger? Neva quite understood that one. Surely you're lengthening the spool time?
Anyone to confirm?
Volcano ABY coupe
AntComment
-
Broke TBV or too small.?
Not sure what TBV is.....
And yes, spool time is to long.Comment
-
I bet that car has no TBV (throttle bypass valve) or DV (dump/diverter valve) if you prefer that term. LOTS of turbo stall alright...
I thought I heard some surge once or twice... I did find a couple of vids on youtube in the past with great clips demonstrating surge - I'll see if I can find them.Paul Nugent
Webmaster http://S2central.net
Administrator http://S2forum.com
1994 S2 Coupe ABY - aka Project Lazarus
2001 A6 allroad 2.5TDi - family tank
2003 S4 Avant 4.2 V8 - daily burble
Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)
There are only 10 kinds of people that understand binary - those that do, and those that don't
Comment
-
I have a TBV installed.......Comment
-
Its a very fluttery noise on load - NOT when you lift off with that distinctive 'chatter' noise of turbo stall -
Paul Nugent
Webmaster http://S2central.net
Administrator http://S2forum.com
1994 S2 Coupe ABY - aka Project Lazarus
2001 A6 allroad 2.5TDi - family tank
2003 S4 Avant 4.2 V8 - daily burble
Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)
There are only 10 kinds of people that understand binary - those that do, and those that don'tComment
-
Paul Nugent
Webmaster http://S2central.net
Administrator http://S2forum.com
1994 S2 Coupe ABY - aka Project Lazarus
2001 A6 allroad 2.5TDi - family tank
2003 S4 Avant 4.2 V8 - daily burble
Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)
There are only 10 kinds of people that understand binary - those that do, and those that don'tComment
-
Be careful when browsing youtube for vids of surge clips - seems like 9/10 'experts' cannot distinguish stall and surge - and they post all sorts of drivel in comments to many vids.
Quick / rough explanation in plain language from me -
SURGE is when you get an instable flow through the compressor when too much boost is is trying to be applied for the amount of air flowing. When you look at compressor maps, you see the hard curve on the left of the graph - this is the surge line... A boost profile that steers the turbo too far to the left of that line will cause surging... It sounds like a fluttery unstable noise when you are loading up with heavy throttle.
STALL is completely different... This is what happens when you go from high boost to vacuum (lifting off for a gear change typically) - the throttle plate closes and the momentum of the spinning turbo wants to keep compressing air - if it is not dumped or diverted in sufficient amounts, then the air backs up in the compressor and you get that strange 'chika-chika-choo' noise of the compressor stalling. This noise is often called 'wastegate chatter' which is a bit of nonsense really. All the UR rally cars made this noise as the ran without diverter valves... If you want to make this noise on your S2 - disconnect the vacuum pipe (and block it) to your TBV - it reduces life of turbos, but does make you sound like UR-Stig coming down the street - but you'll be faster thru the gears with a healthy TBV fitted.Paul Nugent
Webmaster http://S2central.net
Administrator http://S2forum.com
1994 S2 Coupe ABY - aka Project Lazarus
2001 A6 allroad 2.5TDi - family tank
2003 S4 Avant 4.2 V8 - daily burble
Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)
There are only 10 kinds of people that understand binary - those that do, and those that don'tComment
-
My video has surge as it comes on boost - but the video and sound are out of sync - you can see the filter pulsing when it has surge.
I popped a diverter at some point on that dyno/that night - it runs 2 710Ns - it does not surge with a popped diverter!S2,RS2,S4 WB,RS4,S4 B8,RS6 C5,RS6 C6,R8Comment
-
If by popping You mean taking off, and plugging the connection, it does not cure the surge.
If by popping You mean taking off the vacume hose from a 710N, yes, I believe it might cure the surge, in that case boost pressure opens the Dv and the compressor leaps a lot to the right on the map.Everything less than 2 bar is considered to be naturally aspiratedComment
-
I meant popping as in split the diaphragm - so one DV was leaking so that was enough of a leak to not get surge.S2,RS2,S4 WB,RS4,S4 B8,RS6 C5,RS6 C6,R8Comment
-
I remember Tom used to sometimes run without a DV, around the time when that first video was shot.
You can hear what Paul describes as stall on lift off.
I guess stall is still surge. Throttle is shut, so the turbo is flowing too much air.
It doesn't sound good when on boost, that's for sure.SSComment
Comment