BOV issue/question - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 02-03-2010, 01:48 AM   #1
Junior Member
Thread Starter
 
Join Date: Jun 2007
Location: Lenexa, KS
Posts: 129
Total Cats: 0
Default BOV issue/question

Not really sure if it's the BOV specifically, its from an FM kit. Anyway just wanted to get a few opinions on this.

Cruising at low rpms in 4th or 5th gear if I go to WOT it will build to about 5-7psi and the BOV starts to flutter. Mid to high rpms no issues whatsoever builds to 15psi with no problems.

Also notice while cruising on the highway in 5th just the slightest pedal fluctuation at or around 0psi it will start to flutter and if I hold the pedal still (like if I'm cruising up a hill) sometimes if will just keep fluttering.

It doesn't so much concern me just something that bugs me a little cause I'm like "what the hell". Any and all opinions are greatly appreciated thanks!

Andy
crnrhrd is offline   Reply With Quote
Old 02-03-2010, 03:40 AM   #2
Newb
 
Join Date: Oct 2009
Posts: 32
Total Cats: 0
Default

compressor surge?
silvertn350 is offline   Reply With Quote
Old 02-03-2010, 04:00 AM   #3
Senior Member
iTrader: (7)
 
nicacus's Avatar
 
Join Date: Jul 2006
Location: SLC UT
Posts: 1,133
Total Cats: 0
Default

^ if that's the case try adjusting the spring to a softer setting.

Is it a go fast bits blow off valve??
nicacus is offline   Reply With Quote
Old 02-03-2010, 09:31 AM   #4
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

Quote:
Cruising at low rpms in 4th or 5th gear if I go to WOT it will build to about 5-7psi and the BOV starts to flutter. Mid to high rpms no issues whatsoever builds to 15psi with no problems.
I hope it' fluttering when you lift right? Fluttering typically means the valve is too tight. The boost is pushing against the spring and it's rapidly opening and closing. Are you confusing flutter with surge in this instance. are you for certain it's comming from the BOV and not the turbo? At idle, hold your hand over the bov outlet and rev the motor up, since the boost cannot purge out the valve, you should be able to clearly hear the surge at the turbo. I know I can on my setup when I do this.

Quote:
Also notice while cruising on the highway in 5th just the slightest pedal fluctuation at or around 0psi it will start to flutter and if I hold the pedal still (like if I'm cruising up a hill) sometimes if will just keep fluttering.
I'm going to have to think your valve is hooked up wrong or the diaphragm is bad.

With any sort of throttle opened, the spring pressure on the diaphragm coupled with the vacuum pull on the intake should keep the valve sealed.
In boost, the boost pressure pushing down on the valve coupled with the spring will keep it sealed due to the pressure differentials.
When you lift, the vacuum pull on the diaphragm coupled with the boost pushing back against the spring allows the the boost to purge through the valve.

Please show us how you have you valve plumbed. Pictures beat words.
Braineack is offline   Reply With Quote
Old 02-03-2010, 11:56 AM   #5
Junior Member
Thread Starter
 
Join Date: Jun 2007
Location: Lenexa, KS
Posts: 129
Total Cats: 0
Default

Quote:
Originally Posted by Braineack View Post
I hope it' fluttering when you lift right?
Please show us how you have you valve plumbed. Pictures beat words.
The fluttering is occurring when the pedal is still pressed to the floor in 4th or 5th. Was toying with the BOV spring last night and tightening or loosening the crap out of it didn't seem to change a thing. You can't see it in the picture but the vac line on the end of the BOV is running to the intake manifold. Revving up and letting off I can feel the BOV purging plenty of air out of it.



crnrhrd is offline   Reply With Quote
Old 02-03-2010, 12:03 PM   #6
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

check the vacuum line for holes/splits/leaks, otherwise I think the valve is dead. The fluttering you are hearing in this case is the boost pressure forcing the diaphragm open...does you boost levels ever fluctuate or your turbo performance seems lacking/slow?
Braineack is offline   Reply With Quote
Old 02-03-2010, 12:07 PM   #7
Junior Member
Thread Starter
 
Join Date: Jun 2007
Location: Lenexa, KS
Posts: 129
Total Cats: 0
Default

Quote:
Originally Posted by Braineack View Post
check the vacuum line for holes/splits/leaks, otherwise I think the valve is dead. The fluttering you are hearing in this case is the boost pressure forcing the diaphragm open...does you boost levels ever fluctuate or your turbo performance seems lacking/slow?
Yeah I was looking at it yesterday the line is in real good shape, any recommendations on a decent bov without spending an arm and a leg? I really liked this flyin miata one, but don't want to spend $200 for the new one they carry now.

Boost levels are solid, except for low rpm 4th and 5th.
crnrhrd is offline   Reply With Quote
Old 02-03-2010, 12:20 PM   #8
Elite Member
iTrader: (10)
 
Join Date: Oct 2008
Location: Seattle, Wa
Posts: 1,780
Total Cats: 30
Default

Quote:
Originally Posted by crnrhrd View Post
Yeah I was looking at it yesterday the line is in real good shape, any recommendations on a decent bov without spending an arm and a leg? I really liked this flyin miata one, but don't want to spend $200 for the new one they carry now.

Boost levels are solid, except for low rpm 4th and 5th.
Hop over to siliconeintakes or ebay and look for one. If you want something PNP, they have forge knockoffs at siliconeintakes that would just slide right in there.
Jeff_Ciesielski is offline   Reply With Quote
Old 02-03-2010, 02:48 PM   #9
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

Flyin' Miata : Turbodog's deal of the day!


click to zoom
New FM BOV!
We've got a whole pile of these. They were once used in the FM turbo kits, but alas, were replaced by the lighter and better sealing GFB valves. The footprint is 1 3/8" from the 2G DSM turbo cars.
Part 05-90105.
Fits 1990-2005
Price: $50
Braineack is offline   Reply With Quote
Old 02-03-2010, 03:11 PM   #10
Elite Member
iTrader: (15)
 
Join Date: Dec 2007
Location: San Antonio, Texas
Posts: 4,889
Total Cats: 28
Default

Quote:
Originally Posted by Jeff_Ciesielski View Post
Hop over to siliconeintakes or ebay and look for one. If you want something PNP, they have forge knockoffs at siliconeintakes that would just slide right in there.
+1. I had an ebay Forge clone that worked fine. Like this one
SS Style BOV Flange

That or snag that FM turbodog deal.

Only reason I do not have the forge knockoff anymore is I felt compelled to buy a Tial-Q which is awesome, but also awesomely expensive compared to the knockoffs.
ZX-Tex is offline   Reply With Quote
Old 02-03-2010, 05:14 PM   #11
Junior Member
Thread Starter
 
Join Date: Jun 2007
Location: Lenexa, KS
Posts: 129
Total Cats: 0
Default

Quote:
Originally Posted by Braineack View Post
Flyin' Miata : Turbodog's deal of the day!


click to zoom
New FM BOV!
We've got a whole pile of these. They were once used in the FM turbo kits, but alas, were replaced by the lighter and better sealing GFB valves. The footprint is 1 3/8" from the 2G DSM turbo cars.
Part 05-90105.
Fits 1990-2005
Price: $50
Nice find thanks man!
crnrhrd is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Fab9Tuning's NC MX-5 Turbo Kit Discussion- EFR/Garrett V-Band FAB Prefabbed Turbo Kits 216 03-22-2017 05:00 PM
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 10:39 AM
why is my car running like pewp? (tune/datalog) itsMikey MSPNP 3 09-28-2015 07:40 AM
E-Manage Base Maps faviles5566 ECUs and Tuning 0 09-04-2015 12:50 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 11:51 AM.