I've tried to search .. .just couldnt find anything besides people talking about their turbos surging...

so my questions..

What extactly is going on when you have a turbo that surges?

What neg effects does it have?

 

anyone?

 

i didn't know so i searched teh interweb. here's what i came up with.

http://www.turbobygarrett.com/turbob...r/faqs.html#t9

 

Good question..

 

It's when you build boost, then let off the throttle, which closes the throtte plate, thus sending the boost pressure back down line towards the turbo. If the BOV doesn't release this pressure, then it reaches turbo and spins it backwards. This causes the car to buck, which is known as compressor surge. This can happen with a very stiff BOV, or when in higher gear, building low boost with part-throttle, then letting off slowly.

 

how do you know if it happens? ... do you get a funny sound.. or is just one of those things where if you have it.. you'll know

 

btw thanks warrtalon... you seem to be helping me with all my questions recently thanks

 

You might feel a little kick or just a sudden loss of power.. but it's BAD for the turbo. BOV's aren't just for the sound, they prolong the life of your turbo!

 

I was under the impression that the Turbo never accually spins backwards but just stops.

 

I wasn't saying it actuall spins backwards, but that the pressure pushes the blades against the grain, which causes the surging/bucking.

BowlOfRice, if you have an intake, you will hear this phenomenon as a fluttering noise coming out of you bov.

 

LOL!! thanks for your help....

soo surging would be a problem if you got an aftermarket blowoff without properly setting it?

 

The HKS valve on my 2g does this (i have it recirc'd)....I typically experience surge in high rpm (say 3rd @ 5k) and she will buck like crazy if you are on and off the throttle slightly. If you step in it then get off, she won't buck because the valve will blow most of the air out, where the slight boosting doesn't seem to open the valve as much (fluttering you hear with the HKS). It really depends on the BOV how much she opens and closes, but the pressure that isn't relieved by the BOV has to go somewhere and it then feeds back which attempts to slow down the intake turbine, however the exhaust is still spinning the exhaust turbine wheel. So this now puts undo stress on the bearings and turbine shaft causing surge.

I've thought about adjusting the valve (haven't touched the adjustment screw from the factory-older versions have this) but have been real cautious as to what it may do to idle and/or the psi it opens at.

*SOAP BOX ON*Of course this doesn't mention that with the HKS valve when you are at a stop and have to gun it in first, then push the clutch back in (to make a turn or whatever), the car will die because the valve stays open too long letting all the air out to recirc and starving the car of air allowing now too much fuel for the amount of air left to keep the car running, car has to die. I don't care much for HKS anymore, too many bad experiences (exhausts, BOV, talking to their customer service). I mean who the hell sells a BOV over $200 that has problems and instead of fixing the valve they come out with a unit that splices into the ECU to help control the idle problem, however costing you almost another $200. WTF over? Just fix the problems with your vavle.*SOAP BOX OFF*

Sorry 'bout the rant, but hope this also helps in explaining surge.

 

My surging issues have all but vanished since upgrading to the Forge RS BOV. I've tried to reproduce it in 3rd, even 5th gears as I was experiencing it very frequently. Nothing so far.

 

flutter, bov causes, turbo to stop as stated above..

 

Turbo surge isn't the flutter that happens when you let off the throttle on a car with an improperly adjusted BOV or no BOV.

Turbo surge is what happens when the turbo is delivering more air than the engine can accept. This typically happens at lower engine speeds, if the turbo spools faster than the engine can use the air. If you look at a compressor map, the left line that's almost vertical and runs on the left edge of the efficiency zone is called the 'surge line'. If the operating characteristics of your engine fall anywhere to the left of that line, you WILL experience surge.

If you experience surge, you'd typically do something to delay the spool of the turbo just enough to avoid surging.