compressor surge still

[BoostedAWD91]

I wanted to confirm this before i went ahead and replaced it. I am running a Tial BOV and when i am driving its fluttering like crazy underload like going up a hill before i hit and boost and if i push the throttle down to get into boost it will go up to like 5-8 psi and then flutter like crazy and wont let me boost any higher. Also at idle my BOV is 1/4 of the way open. Now that i am running a SMIM and have 22psi of vaccumm im thinking that the spring in the BOV isnt strong enough and that is causing all this. Can someone confirm this or have any other diagnosis?

 

[1941Galant]

Have you pulled the top of the BOV off yet to see what spring is in it?

 

[BoostedAWD91]

yea there is a white spring in there which is the 9psi spring for -14 to -17 in/hg
of vacuum and i am at 22 in/hg of so i need the 12 psi pink spring. this has to be
the problem. any conformation on this?

 

[Brianawd]

Check you line to the BOV. My friends started doing that and we found the line was leaking. Fixed the leak and the fluttering went away.

 

[slugsgomoo]

wow, that is high vacuum, are you running stock cams?

Certainly running the spring that matches the vacuum will help though.

 

[BoostedAWD91]

yeah im running stock cams. Im gonna order the correct spring and ill also check the vac line but im sure thats fine.

 

You guys, its called "Compressor Surge".

I understand that it makes a "Fluttering" sound, and that it sounds like its coming from the BOV, But its not.

Its the BOV's lack of response that causes the compressor of the turbo to Surge pressure back through the intake.

For the sake of searching I am adding this reply.

 

[prove_it]

sounds like the spring is too weak. Good thing your running speed density!

 

[mikus]

you have two contradictory symptoms?
- BOV opens early/leaks due to weak spring, and
- BOV doesn't open, or doesn't open enough

Def. get the new spring... but doesn't sound like it will solve your woes entirely.

Has this setup functioned correctly before?

 

[BoostedAWD91]

well i never had any problems with the tial bov on the old setup with a 16g and maft
. this setup is all new with t3/t04, jmf smim, tial 40mm so i cant say it worked fine before
cause its all new. what else should i look at if the stiffer spring thats the correct one
for the vaccum im running doesn't solve the problem.

 

[mikus]

Are these all correct?
- you're fluttering during acceleration regardless of how much positive PSI
- you can only get up to ±8PSI
- you're still maft right, not recirc (not huge but worth asking)


I truly cannot figure out my own BOV surge/flutter so am curious where this goes. My BOV opens, just not early enough, and I've tried everything short of new cams, new intake, the big stuff. You have more than just flutter going on though, I think.

 

[BoostedAWD91]

im running the vpc/gcc setup so i have a map sensor. it flutters different all the time, sometimes i can only get 5psi of boost and it wont let me go any higher and other times i can get to 10psi before it does it. at idle the bov is 1/4 of the way open. going up a steep hill is real rough, it flutters instantly going up a hill before i even hit and boost so i have to give it gas alittle and then let off and do that over and over again just so i can make it. other times just cruising along it flutters at like 15% throttle

 

T3/TO4

That's a huge compressor on a not so huge turbine housing, that might be part of your problem.

Whats the size of the turbine?

Have you verified the voltage coming out of the MAP?

Is it still good?

Flutter fluuuutter. I like fluttering butterflies with butter. Nutter budder fluttering flutter flies.

"Compressor Surge"

"Surge"

/ubbthreads/images/graemlins/wink.gif

 

[BoostedAWD91]

its a t3/to4b h-3 v trim from bullseye power which i purchased like 3 years ago and never used it yet so i dont remember what the specs on it are anymore and they dont sell it anymore

 

[mikus]

I must caveat that I'm a hack at more advanced turbo applications, this is all from reading up on this specific topic.

at 5-8psi boost I don't understand why it would surge much as long as vacuum gets to the BOV - not enough air moving at this point that it shouldn't be able to deal with it. It says to me something's amiss with the vacuum line, BOV or recirc path that's compromising recirculation.

- vacuum line to BOV issue should be clear on a boost leak test
- a short run of blow off to atmosphere could eliminate the recirc path as a restriction issue
- not sure best way to test a somwhat functional BOV for full functionality other than a swap...

I had a theory that the larger air capacity of teh SMIM could cause a delay in acheiving sufficient vacuum (I have a big ' mailbox' style VENOM intake) and that delay could cause momentary flutter before enough vacuum is available to open the BOV. Aftermarket cams have also been suggested as possible cause. Would love to hear thoughts from people that know more.

 

[cOmpressor]

<-- stands corrected, didn't think you guys were talking about stall surge. Sell the turbo to some Honda guy and start over.

 

[Whistler]

Quote:
its a t3/to4b h-3 v trim from bullseye power


Another vote for compressor surge. I am fairly certain that particular combination is very prone to compressor surge. The BOV "flutter" is a symptom, not the cause.

 

[icurunnin]

I have run several hks ssq's with no compressor surge. its a dual piston for low boost and high boost which= no mother flutter

 

[BoostedAWD91]

Quoting Whistler:
Quote:
its a t3/to4b h-3 v trim from bullseye power


Another vote for compressor surge. I am fairly certain that particular combination is very prone to compressor surge. The BOV "flutter" is a symptom, not the cause.




why would that turbo be so prone to compressor surge?

 

[Whistler]

Quote:
why would that turbo be so prone to compressor surge?



Because Bullseye sells a bunch of cobbled together parts that don't always work well together in their intended applications. From the information given, it is hard to tell what kind of components are really on the turbo. Is it a to4b h-3 or a to4b V trim compressor? What exhaust wheel in what housing?
The turbo it is spooling up too quickly at low engine airflow and stalling.