turbo/intake whine..?

[F430TECH]

Well I run the blue spring with both shims in the Forge BPV which seems to be the consensus of what most people on the boards run.

Maybe I will try taking both the shims out, at least until I get the Intake installed.

 

[spdjnke]

Well I run the blue spring with both shims in the Forge BPV which seems to be the consensus of what most people on the boards run.

Maybe I will try taking both the shims out, at least until I get the Intake installed.

I ran my Forge with the Blue Spring also and believe it or not the car felt slower and didn't pull as hard as when I reinstalled the Yellow spring it really came back to life and then some. It's strange but less tension is better in my opinion and all the manufactures that I've spoken with.

 

[PCspeed3]

Did you hot rod it when the engine was cold? That may have cracked somthing.....

 

[F430TECH]

Nah...I always warm em up nice and easy...

Interesting point about the yellow spring...does anybody have the ratings for what psi and such? Did you use both shims with the yellow spring? I suppose it stays open longer and allows MORE air back in...

Thanks...

 

[spdjnke]

I only used the Yellow spring, no need for shims, its rated up to 17psi

 

[F430TECH]

Yellow spring it is then...should have time to try it tonight..

 

[F430TECH]

http://www.forgemotorsport.com/content.asp?inc=product&cat=0007&product=FMDVTUN

Apparently the Yellow Spring is good for 17-23 psi

 

[08_MS3_GT]

i too will try the yellow spring as an update. the blue valve with two shims may indeed be too much tension - i was actually a bit concerned that its sound when actuating did not indicate a COMPLETE open and close. i'll leave the shims but install the yellow spring and see what happens.

F430TECH, i'll defer to you on the unbalancing shaft concern - i'm a chemE, so, while i understand the basic function of a turbine, i am not an expert on the mechanical nuances.

the DV spring concerns do not necessarily apply to my initial problem, however. i have listened again and continue to suspect that the HKS intake may be making noise given higher airflow.

could the whine be related to opening of the wastegate? i believe i can hear when the wastegate opens, which could be related to the airflow through the system. i'm not necessarily saying the wastegate is failing. but, if it is my intake, then the sudden change from the wastegate airflow could coincide with a sudden change in intake sound.

does anyone with this issue have a stock airbox?

 

[spdjnke]

Believe it or not the LESS tension the better and Faster the turbo will Spool, you'll see and feel it for youself, and it holds just as much boost as it set in blue, but it releases when it's suppose to instead of not letting it air out when it's suppose to, the car will run smoother and less HOT, this is all monitored by my Dash Hawk so I do have facts to back it. just incase anyone has questions.

 

[F430TECH]

UPDATE:

So I changed out the blue spring and dropped the yellow in last night but left both shims. Initial impressions are that is doesnt pull as hard. For me anyway. Went for a nice long drive down to a sushi place and got her nice and warmed up as its cold here now. Then got on her on the way home. Theres less surge and stuttering thats for sure, the valve opens sooner and is a little bit louder, but so far as pulling harder or spooling faster...I can't tell a difference butt dyno wise, and mines pretty sensitive, I can tell the difference between jets on my shifter kart which is 1/2-3/4 of a horsepower...

I don't see how less tension lets the turbo spool faster unless its opening slightly and allowing boost to slip past therefore letting the turbo not have to push as hard, and the air in general will just flow faster because of this.

On a side note after the sushi place while I was "testing" I ran into what looked to be an old eagle talon/mitsubishi eclipse/chrysler lazer GS-X, and figured I had better do some "testing" against him.

DAMN did he launch hard...I am thinking I need another project car now, while the Kart is in STASIS (engines out for rebuild soon). He was faster than me about 3 car lengths to a ton.

He was bored out to 2.3 and had a bigger turbo (we chatted a bit at the light) and the whole car was stripped and as I said he launched hard!!! I don't really launch my car so just waited till we got on the feeder and he was pulling on me slowly, funny thing was it looked like a total junker from the outside...I love sleepers....

Oh and the noise was still there, but quieter...

 

[08_MS3_GT]

This is almost approaching the point where the noise would need to be recorded.. you reckon it's possible we're hearing the same thing?

I'll try the yellow spring and see if I experience the same result - I am guessing I will. I haven't had any surging or stuttering, though, so I don't expect to see changes related to those. Opening sooner, as long as not too soon, should be better for the turbo and associated hardware. Would you say you experienced a legitimate power loss?

Those old DSM's are a force to be reckoned with. I almost bought one several years ago. The first-gen looks like crap but works the sleeper angle, the second-gen looks much better IMO but gets more attention. I've been wanting a 'toy' to play with - was considering a 1.8T VW/Audi although DSM's are cheaper and faster near as I can tell. Only problem is the notorious crankwalk on the AWD models. Given enough money, I'd go with a B5 S4... six cylinders and two turbos sounds soooo good.

F430TECH - can you describe the noise you experience? Be specific. Also, I'll be in the Milwaukee and/or Chicago area over Christmas, so possibly if you are passing through we could do some troubleshooting.

 

[F430TECH]

I will be in Northwest Wisconsin over Christmas for like 8 days. A little place called Lake Nebagamon, close to Duluth. I am flying in so only transport would be my moms car.

The noise...well its just not clean, like when I hear a turbo spool I expect it to be a clean whistle if that makes sense?

This sounds more like a strained whistle or moan...I honestly think its one side of the turbo working harder than the other. I need an intake, but still humming and ha-ing over which one to get.

The COBB's are out again, but I am kind of disappointed in how long it took them, but you know it will be compatible with their Accessport for later tuning AND you can get the for 150 shipped on Ebay right now. The Corksport seems to be a nice piece AND it comes with the inlet pipe, its a great deal with great gains, but not sure about the whole no air straightener no check engine light that they claim...The NANO is nice and has air straighteners, but again drawn to the Corksport as its got higher dyno ratings...

Need to make a decision...soon...

 

[Rotus8]

A note about springs: There are two parameters, spring rate and preload. The spring - yellow, blue, whatever determines the spring rate. The shims adjust the preload. The preload determines when the valve starts to open. The spring rate determines how fast it opens after it starts to open.

I think the ideal BPV would have a mechanism to have essentially zero spring rate. At the desired pressure, the thing would open full, then when the turbo spools down, or you put your foot back into it, it would go to full closed. I wonder why it isn't an ECU controlled solenoid so it could have this ideal behaviour.

I think the best setting for the forge is with the light spring (yellow) and enough shims to set the opening just beyond your maximum boost.

Remember, the valve is measuring the difference between the intake manifold vacuum (after the throttle plate) and the boost. The idea is when you close the throttle, the BPV opens due to increased vacuum, to dump the boost.

 

[08_MS3_GT]

i certainly understand the spring concepts, which would indicate that the yellow spring can work just fine. the dv opens when the pressure differential between the inlet air and pressurized air. in the proper situation, the max boost doesn't cause it to open unless the intake air decreases to vacuum pressures.

is it safe to assume that both blue and yellow have similar spring rates while their preloads differ? that would explain why adjusting for a preload just above max boost is the thing to shoot for. also, forge does not specify what a shim adds for preload, at least from what i've read.

F430TECH - i think that most any intake, given the appropriate criteria such as air straighteners, will work. i use the HKS unit. regarding your noise, i might actually say the culprit is not so much one side being strained as it might be a specific part being strained - bad tubing, a small boost leak, etc.

 

[Rotus8]

A few comments here:

i certainly understand the spring concepts, which would indicate that the yellow spring can work just fine. the dv opens when the pressure differential between the inlet air and pressurized air. in the proper situation, the max boost doesn't cause it to open unless the intake air decreases to vacuum pressures.

The valve opens when the pressure differential between the intake manifold and pressurized air is large enough to overcome the preload - I think this is what you meant to say. With this change I agree with you.

is it safe to assume that both blue and yellow have similar spring rates while their preloads differ? that would explain why adjusting for a preload just above max boost is the thing to shoot for. also, forge does not specify what a shim adds for preload, at least from what i've read.

No, the blue has a greater spring rate than the yellow. The amount the shim adds to the preload is the thickness of the shim times the spring rate. For a given compression amount, the blue will yield a higher pressure setting than the yellow.

The correct way to adjust this is to have a boost gauge between the intercooler and throttle plate. When you back off the gas, you should see the pressure spike up somewhat past max boost, but not much. If it doesn't spike at all, you need more preload. If it spikes up a lot, you need less. If the car won't reach max boost, you need a lot more.

 

[F430TECH]

Alright so I drove all weekend with the Yellow spring with two shims and once the ECU learned the car definitel drives better. No more surge and getting off the throttle produces less movement of the engine, it doesnt feel as strained. The turbo does seem to spool quicker also. Now this I dont understand because essentially the BPV should have TWO modes, open or closed. It should stay closed until the pressure differential+vacuum overcomes the spring. I guess maybe the only explanation I can think of is the yellow spring allows it to open further for longer allowing more air through which means more air back into the intake tract which means less time for the air to reach the throttle body, power is made quicker hence boost is made quicker...

The noise is still there but definitely not as loud, so now I am thinking of removing both of the shims and see if it helps even more. My car only has 6000 miles so if it has leaks already I would be pretty disappointed.

Will keep updated on the removal of both shims.

 

[08_MS3_GT]

i switched to the yellow spring and have not driven with it extensively, BUT my first impressions are that it functions more effectively than with the blue spring. i can hear more actuation (full Mario 'CHING!' or swords clashing) at lower boost levels, indicating that the yellow spring is operating not only at high boost but at low boost as well. the blue spring didn't seem to do a full open+close at lower boost.

i've also noticed better response upon getting off the throttle and an associated quicker spool. overall, i wouldn't say the car is faster, but it seems as though the yellow spring allows the valve to operate more smoothly.

 

[DaleNixon]

I hate to jack the thread, but I'm running the blue spring due to comments I've read on this board about the yellow being designed for 2.0 VW engines.

Would you guys recommend the yellow spring instead? Would I lose performance with it? Would it be safer for my stock turbo?

 

[Rotus8]

I hate to jack the thread, but I'm running the blue spring due to comments I've read on this board about the yellow being designed for 2.0 VW engines.

Would you guys recommend the yellow spring instead? Would I lose performance with it? Would it be safer for my stock turbo?

As I said in a previous post, the lighter spring should perform better, if the preload can be adjusted so it doesn't open at full boost. To adjust the preload, you put shims in. However, you can't put in more than two shims because the spring will pack up and limit the opening.

The stock valve, according to the service manual, starts to open at about 7 psi. Remember, this is the difference between the pressure at the BPV and inside the intake manifold after the throttle butterfly. If the throttle is full open, the BPV won't open because both pressures should be almost the same. It will only open when the throttle is part closed allowing vacuum to build in the manifold.

I think the way to determine the correct preload is to have the BPV on the bench and use a Mity-Vac with a gauge to determine the vacuum required to start opening the valve, then adjust with shims to about 7 psi.

I haven't done this yet - has to wait for the weekend.

 

[DaleNixon]

Interesting! Please let us know if/when you do this. I want to have my Forge as close to the stock BPV as possible.