Help with turbo flutter.

[bb730]

Every forum I've been to has a hundred different explanations of what causes the turkey sound. I need some solid information on what it is. The only modification I've made is a corksport CAI so far. I have a small leak in my stock smic inlet hose leading to the stock bpv.

For clarification, this only happens when I let off the gas.
When the throttle plate closes in the throttle body, the trapped air SHOULD be release back into the intake system through the bypass valve right? But the fluttering is caused by air not being able to be released as fast as the engine needs it to.

The best reason ive found is that its caused by a weak bypass valve and air cant be released fast enough. but people with a new bpv still hear it. whyyyy

So I need some help. I know that when a turbo goes for 80k+ rpms and hits the breaks due to the fluttering air slapping back at it is NOT good for the fins and bearings in the end. What can be done to stop this?

 

[Spiced MSP]

dual bov/bpv setup or a bpv with a bigger inlet/outlet. the recirc tube on the intake needs to be the same size as well

 

[bb730]

youve done this?

So the bpv stays in the same location? Where is the bov located? also, does the bov need to be atmospheric or can it recirculate?(so i dont have to relocate the maf)

Lots of Qs I know.

 

[Spiced MSP]

if you have hardpipes, yeah the bpv can stay in the stay location and you will just have to put a bov on the cold pipe. most people with the dual setup usually vent the bov. If you are going to recirculate the bov, just get rid of the stock bpv and recirc the bov making sure that where ever you recirculate on your intake is the same size as the recirc fitting on the bov

 

[Tzar177]

You also want to go with 1" I.D. or larger recirc fittings and hoses

 

[jeffmsp]

http://www.youtube.com/watch?v=QfUBrQdztXU

So I need some help. I know that when a turbo goes for 80k+ rpms and hits the breaks due to the fluttering air slapping back at it is NOT good for the fins and bearings in the end. What can be done to stop this?

you have absolutely nothing to worry about.

the turbo can handle the flutter fine.

non ball bearing turbos cannot. yours is ball bearing.

ball bearing turbochargers can survive 50x the loading of non ball bearing turbos.

but it you find some proof of one actually failing from this let us know. last I checked there are plenty of MSPs that hit over 250,000KMs without issue. Took mine off at 7 years 217,000KM and sold to another member who is still boosting it fine today.

The only real reason to upgrade the valve is if its broken or if you cant stand the sound.

 

[bwalt]

Here's my setup: Stock bpv on the hotside, stock dsm bpv on the coldside. NO TURKEY, NO SURGE.

One thing I haven't really seen mentioned is having THE RIGHT BOV/BPV. Most of the aftermarket 'upgrades' are designed for higher boost than what we run in our msp's so they require more pressure from the turbo to vent properly. Since most don't run much higher than 10 psi, these valves still cause the surge and flutter. Take a look at the turbosmart bpv in the second picture, it has 38mm (1.4") fittings. Running that valve along with the stock bpv reduced (didn't eliminate) the surge to a loud 'chirp' and still surged/fluttered while driving around at lighter loads. It didn't matter where the adjustment was on the TS valve either, it still produced the same result.

If your trying to kill your turkey because it's driving you nuts and people are looking at you funny, do what has been said a million times. Add an extra 1" minimum fitting for a second bpv and make sure your vacuum sources are dedicated. Then find THE RIGHT VALVE, ie one that doesn't have an overly tight spring. Get it working and enjoy the surge-less driving. I'm sure there are more technical things like bpv/bov placement, ic piping, turbo configuration, or even the engine that would affect how efficient the pressure relief system is venting charge air so it doesn't back-feed through the compressor outlet of the turbo.

 

[bb730]

So it makes sense that a bigger inlet outlet for bpv would work bc of more air being able to be released. And even though the ball bearing turbo doesn't get damaged as fast, wouldn't it slow the initial turbo spool you would normally get after changing gears? So in other words, boost comes much later?

I'll need to brush up on my mig welding to pull this off. But it seems as though as if it can wait...I trust you guys.

 

[jeffmsp]

slow the initial turbo spool you would normally get after changing gears? So in other words, boost comes much later?

you would think so but I took the time to graph my boost using a blitz sbc ID electronic boost controller and found quite the opposite comparing the stock valve to a forge BOV. regardless of the spring setting in the BOV.

 

[jdwk]

That makes sense. The inadequate BPV and the fact that the turbo is still spinning keeps positive pressure against the throttle plate, so as soon as you crack it, you have boost, and the exhaust will take care of any slowing of the compressor caused by the charged intake. I believe a bigger BPV would just allow more air to get pushed out to the intake side of the compressor where it is essentially open to the atmosphere. You would lose that pressure and have to wait for the turbo to build it back up again.

I have all the parts to my hot side WGA boost source experiment ready, but realized watching a boost gauge really isn't going to tell me what I want to know. I need something that can datalog my MAP and I unfortunately sold my AEM a couple months ago. So I think I've decided to build a MS. Kind of a big leap for such a little experiment, but I'll chalk it up to a learning experience.

 

[jeffmsp]

ms is so great. im addicted to datalogging with mine. the blitz ebc is cool because you can datalog and graph boost/vac and any aux inputs if you get the add ons, but nothing compared to a ms datalog which records everything.