what does vented bov to atmosphere mean? - Miata Turbo Forum -Boost cars, acquire cats.

Welcome to Miataturbo.net   Members

DIY Turbo Discussion greddy on a 1.8? homebrew kit?

LinkBack Thread Tools
Old 07-18-2006, 10:00 AM   #1
Junior Member
Thread Starter
Join Date: Jun 2006
Posts: 70
Total Cats: 0
Default what does vented bov to atmosphere mean?

haha. ok so I am not a noob or anything, just never heard this. so I guess I have missed out about what it means. Can someone please explain, as I am about to install a turbo kit.
thatguy is offline   Reply With Quote
Old 07-18-2006, 10:24 AM   #2
Senior Member
LOLA - 92's Avatar
Join Date: Oct 2004
Posts: 1,161
Total Cats: 0

VTA - Just means that it Vents to atmosphere (excess pressure from the Turbo) - The VTA's do not recirculate back into your intake.
LOLA - 92 is offline   Reply With Quote
Old 07-18-2006, 11:31 AM   #3
Boost Pope
iTrader: (8)
Joe Perez's Avatar
Join Date: Sep 2005
Location: Chicago
Posts: 24,434
Total Cats: 1,528

A VTA valve discharges air from the intake piping (pre-throttle) directly out into the atmosphere. A recirculating valve discharges it's air back into the intake system, between the air flow meter and the turbo compressor inlet.

The difference has primarily to do with what type of engine management is being used. A system which uses only a MAP sensor is fine with VTA valves. The idea being that since the ECU is measuring the pressure inside the intake manifold (post-throttle) it doesn't really know or care how much air is being dumped overboard before it gets to the throttle plate. You could remove the whole intake system up to the throttle plate and it would run just fine.

Systems such as ours which use airflow meters (be they flapper or hotwire) can have issues with VTA valves. The problem is that, during a vent condition, all the air that's being exhausted out the valve has already passed through the metering system, and the ECU assumes that it's going into the engine. The ECU adds what it believes is an appropriate amount of fuel, but since the air is in fact being wasted the result is that the engine runs rich during this period.

Recirculating valves solve this problem by keeping the system closed and reintroducing the air back into the turbo after the metering device. This way, the air gets measured once, and as it loops through the system it does not get measured again. So the airflow meter sees only the equivalent amount of air that's actually being ingested into the engine, and the fuel mixture is correct.
Joe Perez is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 11:04 AM
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 09:39 AM
why is my car running like pewp? (tune/datalog) itsMikey MSPNP 3 09-28-2015 06:40 AM
E-Manage Base Maps faviles5566 ECUs and Tuning 0 09-04-2015 11:50 AM

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 On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 04:31 AM.