SR20DET Compressor Surge

Compressor surge is a phenomenon experienced when boost pressure inside the intake tract builds up and has no convenient relief method. This is usually caused from the throttle plate closing quickly. Changing load conditions (off throttle) resulting in varying amounts of exhaust gas can also simulate such conditions.

In such a case, the pressure takes the only way out through the turbocharger compressor housing. The unique sound is caused by the pressure charge encountering the spinning compressor wheel on its escape from the engine.

Compressor surge goes by many other names such as compressor stall, turbo dose or dosing, pigeon, turbo flutter/chatter and sometimes mistakenly wastegate chatter.

The car was thoroughly warmed up before filming. The boost controller has been disabled allowing the car to run directly off wastegate pressure. The body panels have been removed due to a slowly progressing facelift. For more info on my car:

www.fizzerkart.com/s14.html

Props to Salman, my cousin, for introducing me firsthand to this wonderful, ridiculous phenomenon and also to Quail from sxoc for doing this s**t ages before I did. ;-D

Category:

Autos & Vehicles

Tags:

• compressor
• surge
• turbo
• dose
• flutter
• dosing
• chatter
• stall
• 240sx
• 180sx
• 200sx
• s12
• s14
• s13
• silvia
• sr20
• sr20det
• bov
• t25
• t25g

[ej20daZe]

Finally, Yes a prolonged surge can wear more soon our housings or blades in any type of turbocharger or pump_ I got bored_ Cheers mate!

[dadoVRC]

Surge happens during the acceleration, not during the decelerations...this sound is the return of compressed air coming from the pipe when you close the accelerator.

Put on it a good flux bypass or pop-off valve and you just forget this return sound...

[JCaSs1001]

that vid sure does show REAL surge damages engines... doesn't take long at any power to blow apart an engine when u hit the surge limit.

i also have trouble believing that once a throttle is closed and no exhaust pushing the turbo there is enough force acting on the turbo to do damage. also dont forget the sound isnt caused by the air going into the turbo, it is the pulse of the throttle closing reverberating through the cooler and piping.

[golferchin76]

@JCaSs1001

lastly, see this vid 'SMKNUP SR20 throwing a rod on the dyno at AUTOSALON Final Battle 2007'

there's that fluttering sound before the whole thing when "BANG"

[golferchin76]

@JCaSs1001  Let's presume this set-up in the vid does not have a bov to vent the pressurized air (it sounds like none), so when he lift the throttle the butterfly closes and all that pressurized air has no where to go but back to the compressor through the 100,000 rpm compressor, brutally stopping the spinning blades, even can make it spin backward, in the process produce that fluttering sound. Sure this is not compressor surge, I call it cowboy engineering time bomb stupid :-)

[golferchin76]

@JCaSs1001

running 500 hp without problem for three years does not mean the next time you boost up or let go of gas the compressor blades won't break into pieces. The only way to prolong the life of your compressor is to have a proper bov set up for your application. The higher the boost you are running the more efficient bov you need. You really don't want to have a 30psi air bombarding your compressor blades. some think the fluttering sound maybe cool, then come the bills.

[golferchin76]

@JCaSs1001

I've seen enough people running high boost, 30 psi+ for example with BOV not operating properly. Then break their compressors blades. And engines destroyed in the process because some tiny shrapnels somehow gets through the intercooler and enter the engine. When they open up the engine you can see tiny hit marks, and trace back to the source of problem you see chipped off compressor blades.

[golferchin76]

@toyotasuprabov I don't know if this engine has a BOV or not. But the fluttering swoosh sound is the result of pressurized air got nowhere to go because the throttle body is closed, so it went all the way back to the compressor housing through the blades venting back into the intake tube while dramatically reduce the speed of the compressor while it was still spinning at god who knows how many tens of thousands of rpm. This is not a proper way to turbocharge an engine.

[golferchin76]

@MrSlowSkyline not to offend you but where did you learn that off throttle back pressure doesn't hurt compressor? it is to my knowledge that all manufacturer designed turbocharged engines are equipped with dump valves which vent pressurized air back into the intake tube.

[golferchin76]

surge and stall happens during "acceleration" when boost builds up to your target PSI you hear the fluttering sound like 'sh.....sh....sh...sh..sh.sh' from slow succession and continue to very rapid succession. This means your turbo is not design to produce the target boost. It can break your compressor blade and worst case senario shrapnels get into your engine and end up expensive engine rebuild. You really should have a BOV to vent the pressurized air when the throttle body closes.

[MrSlowSkyline]

Off throttle surge doesn't hurt turbos. END OF STORY. You 12 year old boys who keep saying it does need to fuck off and go to school.

[coltenW1]

first off tighten up that engine... 2nd you do know to much compressor surge isnt good right?