Unusually quiet turbo/bypass valve
01-17-2009, 12:05 PM
#16
Rennlist Member
what kind of recirc valve is it. Ive driven stock 951's that you could hear the recirc valve working w/ the stock valve- but sometimes even w/ the MAF its pretty quiet- depends on the valve.
01-17-2009, 12:10 PM
#17
Race Director
Thread Starter
Could also be the turbo you are using, if the wheels have been clipped it will make a much more pronounced spooling whine, my TT makes no whine at all, but my 951 has a pronounced spool up whine with the stock airbox installed due to the clipping of the wheels....
I have actually met several people complaining about the cost of replacing their K&N, not knowing they could clean the old one, one of the tools I work with actually threw out his K&N, replaced it with a stock filter, and then was asking why after replacing the dirty old K&N with a stock filter his car didn't run the same....my apologies for jumping to conclusions on that, but I have run into it more than a few times...
Do you get a spoolup whine with the cone filter removed all together? try it in the driveway and see, if you have no whine without the filter installed changing the filter isn't going to give any results...Different turbos make different noises based on their setup...
On another note, you are sitting at work on a Saturday.... Damn I am sorry... But at least you are working...
I have actually met several people complaining about the cost of replacing their K&N, not knowing they could clean the old one, one of the tools I work with actually threw out his K&N, replaced it with a stock filter, and then was asking why after replacing the dirty old K&N with a stock filter his car didn't run the same....my apologies for jumping to conclusions on that, but I have run into it more than a few times...
Do you get a spoolup whine with the cone filter removed all together? try it in the driveway and see, if you have no whine without the filter installed changing the filter isn't going to give any results...Different turbos make different noises based on their setup...
On another note, you are sitting at work on a Saturday.... Damn I am sorry... But at least you are working...
. I'll pop off the filter in the driveway and check it out.Dan - thanks for the info. I've actually never driven (or heard) another 951 in my life so I don't have anything to compare it to.
FWIW, this is my bypass valve :
http://www.lindseyracing.com/LR/Pors...-0609-100.html
01-17-2009, 12:12 PM
#18
Nordschleife Master
thanks that is the type of feedback I was hoping to hear. The work isn't bad today.... I'm on the home stretch of a 15hr shift . I'll pop off the filter in the driveway and check it out.
Dan - thanks for the info. I've actually never driven (or heard) another 951 in my life so I don't have anything to compare it to.
FWIW, this is my bypass valve :
http://www.lindseyracing.com/LR/Pors...-0609-100.html
. I'll pop off the filter in the driveway and check it out.Dan - thanks for the info. I've actually never driven (or heard) another 951 in my life so I don't have anything to compare it to.
FWIW, this is my bypass valve :
http://www.lindseyracing.com/LR/Pors...-0609-100.html
01-17-2009, 01:22 PM
#19
Addict
Rennlist Member
Rennlist Member
Are you sure your BOV is working? Or that it's connected correctly? I'm sure it is but since yours sounds different than most it's a valid question....
01-17-2009, 03:29 PM
#20
Race Director
Mike,
I think you need to strip down your car and send me all your mods. I can install here then report back to you this time next year.
I know it is a PITA, but this is the level of commitment that I have to help you solve your problem
*BTW...rear clears in 11 days, finally
I think you need to strip down your car and send me all your mods. I can install here then report back to you this time next year.
I know it is a PITA, but this is the level of commitment that I have to help you solve your problem
*BTW...rear clears in 11 days, finally
01-17-2009, 04:04 PM
#21
Drifting
Join Date: Oct 2003
Posts: 2,008
Likes: 0
Received 0 Likes
on
0 Posts
I'm not really concerned about this, just a bit curious. I was watching 951s on youtube and on every car with a MAF kit you can hear a distinct turbo spool/ bpv release. I have the typical MAF setup with a billet bypass valve and I can just barely hear the onset of boost.
Would a dirty K&N explain this? I haven't replaced the one that the car came with (and it is certainly well used) but have a new one on the way as I'm more worried that a dirty filter isn't doing its job or is an unnessecary restriction.
Would a dirty K&N explain this? I haven't replaced the one that the car came with (and it is certainly well used) but have a new one on the way as I'm more worried that a dirty filter isn't doing its job or is an unnessecary restriction.
01-17-2009, 04:38 PM
#22
Drifting
I Installed a vitesse Maf and K&N cone filter on my stock turbo '87, and it was a HUGE noise difference. I have a stock bypass valve and everything. Before the MAF, I had all stock intake, with a K&N drop in and modded airbox. I could hear turbo spool from 3-4k rpm, and if I let off abruptly, with my window down in 2nd gear at 3800rpm, I could hear the bypass valve work.
Now with the MAF, the turbo spool is very loud and the bypass is as well. The bypass makes a flutter sound, and I personally neither like it nor hate it.
It can all depend on the MAF setup, the condition of that turbo, the clearances between the vanes and the housing. More then likely, it is that filter though. Gotta think, you can bearly hear spool up on a stock intake car, and look at all the restrictions: snorkel, paper filter, AFM, then the J-Tube. A MAF is normally a K&N (very free flowing), and a metal pipe. No restrictions. But if the filter is dirty, there's a restriction.
Do you know what the inside diameter of your MAF piping is? That could play a part as well.
Now with the MAF, the turbo spool is very loud and the bypass is as well. The bypass makes a flutter sound, and I personally neither like it nor hate it.
It can all depend on the MAF setup, the condition of that turbo, the clearances between the vanes and the housing. More then likely, it is that filter though. Gotta think, you can bearly hear spool up on a stock intake car, and look at all the restrictions: snorkel, paper filter, AFM, then the J-Tube. A MAF is normally a K&N (very free flowing), and a metal pipe. No restrictions. But if the filter is dirty, there's a restriction.
Do you know what the inside diameter of your MAF piping is? That could play a part as well.
01-18-2009, 12:10 AM
#24
Rennlist Member
Mike, other than exhaust, I have a stock setup. I definitely hear the spool, but have never been aware of hearing the BOV.
Obviously, if the BOV is vented to the atmosphere, you should hear it... I'd guess that if it's vented to the intake, if it's closer to the air filter, you'll hear it more... if it's vented closer to the turbo, you'll hear it less. Some of those MAF kits look like the hard pipe piece could be installed either way (putting the BOV port closer or farther from the air cleaner).
01-18-2009, 12:48 AM
#25
Intermediate
Join Date: Jan 2009
Location: SOUTH FLORIDA
Posts: 36
Likes: 0
Received 0 Likes
on
0 Posts
me too!!
Hey there,
I just installed my APE MAF kit in my 86 951 and the spool noise and BOV are a million times louder than they were!! i've only got 3 inch cat back exhaust, stock turbo, shimmed wastegate, LBE and a boost guage, but man at 16 psi there is a LOT of noise going on!! i was just checking things out here, to see if anyone else had this issue, i'm glad it's not that abnormal, so it seems. car runs great and i'm glad that i'm not alone.
marco
I just installed my APE MAF kit in my 86 951 and the spool noise and BOV are a million times louder than they were!! i've only got 3 inch cat back exhaust, stock turbo, shimmed wastegate, LBE and a boost guage, but man at 16 psi there is a LOT of noise going on!! i was just checking things out here, to see if anyone else had this issue, i'm glad it's not that abnormal, so it seems. car runs great and i'm glad that i'm not alone.
marco
