Is it ok to make your turbo flutter like the supras?

[talontsiboy24]

I noticed i can make my turbo flutter if i pick up and let my foot a lil off the gas pedal but otherwise if i pick up and let my foot of completly from the pedal it will make a clean psshhh bov sound.

is it bad to make ## turbo flutter?

 

[jayman089]

Sounds like you are describing compressor surge, which is very bad. It's my understanding that compressor surge occurs when air is being forced back INTO the turbo instead of being released via the BOV.

If I'm misinformed, please anyone feel free to correct me.

 

[jayman089]

Got this from another thread, thanks to Boosted98GSX

http://www.dsmtuners.com/forums/turbo-system-tech/321087-compressor-surge.html

Comp surge is too much air out of your compressor for your engine to digest or your blow off valve to release. Basically, your turbo makes too much air, and so instead of exiting the system through the combustion chamber, it reverts through the compressor housing.

This is bad because it causes your compressor wheel to spin backwards, which spins your turbine backwards, and puts backpressure on your engine, normally in pulses, which can make your car jerk, and hurt your drivetrain.

Too much load per given rpm is the main cause. Examples, going up a hill in a RPM too low, having your A/C on in an RPM too low, a turbo that spools very easily under load (small turbine / housing).

Also, a blow off valve that doesn't release enough airflow can cause surge (or BOV "flutter").

It can be avoided by increasing your turbine size or turbine housing A/R ratio, getting a larger BOV, or a less efficient turbo

 

[JEFFREYCASTGSX]

Jayman089 is correct, the backpressure created from the throttle closing, immediately stops the flow and basically stops the turbo. Imagine what is happening to the seals/bearings when you do that.

 

[talontsiboy24]

Got this from another thread, thanks to Boosted98GSX

http://www.dsmtuners.com/forums/turbo-system-tech/321087-compressor-surge.html

no i dont have surge at all or flutter im just sayin i can make my turbo do that if i want to otherwise my bov is recirculated and sounds clean.

im just sayin is it ok to get into 3-4000 rpms and release your foot off the gas just a little so it makes that noise? otherwise when i fully release my foot i here my greddy type s go off real clean.

 

[viperlp01]

I know what you talking and i dont think it is that bad.. It slowly and lightly does it.. I have heard loud bad compressor surge and this is a different sound.. It is light.. It in theory is not good at all but i dont think it is going to ruin your turbo

 

[talontsiboy24]

I know what you talking and i dont think it is that bad.. It slowly and lightly does it.. I have heard loud bad compressor surge and this is a different sound.. It is light.. It in theory is not good at all but i dont think it is going to ruin your turbo

well i think my turbo is strong enough also i have the fp green but i will not be doin this anymore since its bad but it sounds awesome and im glad u know what i mean.

you guys should try what im sayin and tell me if that is bad or not like get into 3-4k rpms and let ## foot off a lil off the gas.

 

[AWD-TSI]

mine did that all the time under partial throttle. it sounds like the wastgate fluttering. so it partially opens and closes. My audi does the same thing. I didnt think it was comp surging. tons of people said its just wastegate flutter.

 

[Bluefire16]

First compressor surge happens when you are acclerating or on the gas. True Compressor Surge

^This is a video of what compressor surge is...

If its just fluttering thats considered "ok" as long as it happens when you are letting off light on the throttle, which you say you are. My car does the same thing...you should be fine.

 

[JusMX141]

Blow off valve flutter (what you're hearing on Supras) is still actually compressor surge. As the turbo spools down, it's still generating pressurized airflow while the throttle plate is 100% closed. This is airflow that normally escapes through the blow off valve (bypass valve) and is no longer heard from, but in the case of the Supra or some other high-boost cars you cannot have a valve that both releases quickly and fully at low boost and holds 30+psi.

What you're hearing will destroy a journal bearing turbo in a short time. The blow off valve isn't fully opening so the air has no place to go. The pressurized air in the piping is loading the turbine shaft, forcing the shaft to contact the journal bearings which are normally separated by a thin film of oil. In a ball bearing turbo application this really isn't an issue because the shaft is fully supported by the bearings at all times.

 

[JEFFREYCASTGSX]

FP green? Big compressors in little compressors covers just add to the surge.

 

[talontsiboy24]

FP green? Big compressors in little compressors covers just add to the surge.

yea i have a forced performance green turbo with external dump. like i said my bov is super clean and fine when i totally let my foot off the gas but im sayin i can make my turbo or bov flutter if i dont let my foot off all the way.

 

[Dsmj89]

funny you posted this as i started to do this a week ago. I have been playing with my bov in 4th gear at around 40mph and up and lightly release it and it sounds like a tial type of flutter just smoother and slower.

 

[talontsiboy24]

funny you posted this as i started to do this a week ago. I have been playing with my bov in 4th gear at around 40mph and up and lightly release it and it sounds like a tial type of flutter just smoother and slower.

well i have a tial wastegate and yea i mean lightly release it u can here a flutter now is that bad for your turbo i dont reall think so cause its ###### what all turbos can do.

 

[Dsmj89]

It's not bad at all. The bov is releasing the air that you are letting the motor see which is barely none when releasing the gas very slowly. so since not as much air is being pushed through the system (releasing gas slowly, less air pushed into motor), there is only so much air now needing to be released, therefore causing the flutter.
It's fine.

 

[JusMX141]

FP green? Big compressors in little compressors covers just add to the surge.

The cover on the FP Green is made for a 20G compressor, and a 50-trim compressor isn't THAT much bigger. Hell the same cover is used on the FP Red (60-1 compressor) with great success.

 

[JEFFREYCASTGSX]

The cover on the FP Green is made for a 20G compressor, and a 50-trim compressor isn't THAT much bigger. Hell the same cover is used on the FP Red (60-1 compressor) with great success.

True I guess.

 

[jjrock5]

I'd like to chime in and ask. I have the 1st gen HKS SSQV(with adjustment screw), under full boost I hear a SLIGHT flutter and under partial boost, I can hear it a bit more. I hear this is normal on these but is there anyway I can make sure this is NOT surge?

Here is a link to my setup.

http://www.dsmtuners.com/forums/hangout/345171-jjrock5-gsx-under-construction-5.html#post151969329

 

[polarmoment]

Got this from another thread, thanks to Boosted98GSX

http://www.dsmtuners.com/forums/turbo-system-tech/321087-compressor-surge.html
This is bad because it causes your compressor wheel to spin backwards, which spins your turbine backwards, and puts backpressure on your engine, normally in pulses, which can make your car jerk, and hurt your drivetrain.

This statement is 100% false. There is zero- and I mean zero possibility of an impeller that is spinning with the equivalent of the energy in your flywheel at redline being forced to spin backward because of a pressure spike.

There is just too much energy stored in a turbine spinning at 100,000+ rpm.

Acceleration surge loads the impellers a LOT more than lift off surge. The really damaging surge happens when you have full drive pressure across the turbine trying to spin it, and full backpressure in the charge pipes trying to stop it. That's where huge angular forces are generated.

There are plenty of cars that never came with a bypass valve from the factory that are out there, still chugging along on the OEM turbo. Turbo T-birds didn't have them, Celica All Tracs didn't have them, early saabs and Volvos, etc. At higher boost pressures they may or may not increase the longevity of the turbocharger. On OEM applications, their primary purpose is to reduce NVH (noise, vibration, harshness) to improve the overall "feel" of the vehicle. Customers don't want to hear CH CH CH CHCHCHCHCH whenever they lift off the gas.

As far as BOV's having a "performance benefit," consider that the Porsche 962 didn't use them, nor did any of their IMSA GTP competition (you can clearly hear surge as they come down to the corners). Turbo era F1 cars didn't use blowoff valves, and they ran boost pressures up to 75PSI. The BMW and Renault cars used pre-turbo throttles to allow the compressor to spin in vacuum during shifts, but none used blowoff valves. I wish I could find it again, but I once saw a datalog of a car on a track, with the BOV activated and deactivated, and with it DEactivated, the car was multiple seconds per lap faster.

All that said, I still haven't gotten rid of mine

 

[MrBoxx]

If memory serves, I answered this question via PM with the original poster on AIM.

FORCEDPERFGSX24 (10:38:49 PM): i noticed when i spool my turbo and let off the gas a lil it makes that noise like the supra like that tickling sound
MrBoxx001 (10:39:20 PM): the BOV sound?
FORCEDPERFGSX24 (10:39:28 PM): like a surge sound
FORCEDPERFGSX24 (10:39:38 PM): supras always make that noise
MrBoxx001 (10:39:58 PM): I guess i haven't been around that many supras lately
MrBoxx001 (10:40:12 PM): in any case, surge is bad
FORCEDPERFGSX24 (10:40:33 PM): i dont have surge but im sayin i can make the turbo do that noise its pretty kool
MrBoxx001 (10:41:08 PM): it might be surge, actually
MrBoxx001 (10:41:41 PM): you're closing the throttle plate, which is creating a pressure wave in front of it, but if you're not creating enough vacuum in the intake manifold to open the BOV completely, then you're surging.
MrBoxx001 (10:41:59 PM): and, as stated, that's bad.

FORCEDPERFGSX24 (11:25:17 PM): so no matter what type of turbo u have its not good?
MrBoxx001 (11:25:26 PM): yeah, pretty much
MrBoxx001 (11:25:46 PM): it puts a lot of stress on the bearings of the turbo

But I like Justin's explanation better.