Surge killing turbos
- Thread starter DCT_JAY
- Start date
pressure ratio / flow above surge line.
i.e. too much boost / too little flow.
This happens mostly with too much boost at low rpms or with a diverter/bov that doesn't open.
i.e. too much boost / too little flow.
This happens mostly with too much boost at low rpms or with a diverter/bov that doesn't open.
If it's only when you let off the gas, either your bov is sticking or your vac source is no good. The Tial 50s need the black spring on N54.
I have a really similar issue it sounds like. When im on mhd e30 blend is the worse. I have inlets and outlets on my car. From what i was told im over boosting and im getting throttle closure thus causing my compressor surge. Mhd doesn't account for inlet/outlets so im told the only way to alleviate it is to get a custom tune. Not sire if that helps you much. I get heavy throttle surge on power and when i left off it does the same 3 stage blow off as you say
Check your tune. Throttle closures in combination of too strong a spring or poorly setup BOV can cause this. N54's need the black spring for proper BOV action on a Tial, orange for Turbosmart. Run a dedicated line to your manifold, no "tees" or branches off. 1/4" line is recommended. If you do that, and still get surge, have a long talk with your tuner.
Don't use the 10 psi spring. Use the 8 or 6 psi spring. There have been many conversations about this but here is the short version:
Your intake manifold pressure fluctuates a lot, it isn't a binary on/off reading and combined with a fly by wire throttle blade that blips and acts on its own then sprinkle in people with insufficient vacuum tubing, vacuum leaks and part throttle scenarios you can imagine there are various opportunities to have less vacuum in your manifold than you need to pry open the 10 psi bov spring.
So you can either:
1) Be a lemming and run the stiff ass 10 psi spring in the name of keeping the bov closed at idle for no other reason besides OCD and as a consequence you increase your occurrence and likelihood of hitting the surge line
2) Run a soft spring so your BOV can pop open freely at the first sight of vacuum which reduces your likelihood of hitting the surge line. The downside is your bov may be open at idle. The good thing about that is you can add shims, problem solved.
For some awful reason, people continue to choose option 1 and they have these triple blow off sounds, choo choo'ing noises, sqeaking sounds and so on. Hello folks, the sound of air escaping is PSHHHHHHH.... Not choof choof choof... That is the sound of air being unable to escape in one solid purge because you have a spring that is too stiff for the parameters it is operating under.
There are many much worse forms of compressor surge which are caused by other things like wheel sizing but I'm addressing something more fundamental: Using the lightest spring possible, not the most restrictive spring. Why would anyone believe it makes sense to use a spring so strong the bov can barely operate? That is ludicrous.
Your intake manifold pressure fluctuates a lot, it isn't a binary on/off reading and combined with a fly by wire throttle blade that blips and acts on its own then sprinkle in people with insufficient vacuum tubing, vacuum leaks and part throttle scenarios you can imagine there are various opportunities to have less vacuum in your manifold than you need to pry open the 10 psi bov spring.
So you can either:
1) Be a lemming and run the stiff ass 10 psi spring in the name of keeping the bov closed at idle for no other reason besides OCD and as a consequence you increase your occurrence and likelihood of hitting the surge line
2) Run a soft spring so your BOV can pop open freely at the first sight of vacuum which reduces your likelihood of hitting the surge line. The downside is your bov may be open at idle. The good thing about that is you can add shims, problem solved.
For some awful reason, people continue to choose option 1 and they have these triple blow off sounds, choo choo'ing noises, sqeaking sounds and so on. Hello folks, the sound of air escaping is PSHHHHHHH.... Not choof choof choof... That is the sound of air being unable to escape in one solid purge because you have a spring that is too stiff for the parameters it is operating under.
There are many much worse forms of compressor surge which are caused by other things like wheel sizing but I'm addressing something more fundamental: Using the lightest spring possible, not the most restrictive spring. Why would anyone believe it makes sense to use a spring so strong the bov can barely operate? That is ludicrous.
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I will buy the 8 psi spring and will report back to everyone with my findings
i prob should put my mod list here
Car- 100k miles - Maintained at 3k liquimoly 5w-40 oil change intervals with Ceratec additive at every 5th oil change
VRSF- 3.5 inch street exhaust
VRSF- Catless downpipes
VRSF- Stock location Inlets&Outlets
VRSF- Intake
VRSF- Chargepipe with TiAL BOV w/ 10psi spring as advertised on the site
NGK 2 step colder spark plugs
New index 12 injectors
Stage 2 LPFP
E45 mix on custom tune
So on my car I get some compressor surge during medium / light throttle upshifts when i dont let off the throttle using the paddles on my 6AT n54 e92. Any type of typical boost situation the blow off valve will completely open with no surge when letting off throttle. I have a tial that has the 3/8 line tapped to the intake manifold etc..
That’s what I thought but isn’t that a gradual degrade ? Not all at once after a pull, as well as it sounds like it’s a moving part and not a rattle. I can rev it up and it gets louder and just sounds like to me that something spinning is barley hitting something. Idk at this point brother, but I agree at some points it sounds like wastegate rattle.
I did everything except have a black spring, I ordered it and will see what happens
