Car Forums  

Go Back   Car Forums > General Discussions > General Chat
FAQ Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-09-2006, 06:32 AM   #1
ehhh
CF Newbie
 
Join Date: Nov 2005
Posts: 32
a simple question i can't find or two

what exactly does a B.O.V. do with the turbo just curious i couldn't find it but i'm just guessin it releases the hot exahust air not to overload the turbine i guess
ehhh is offline   Reply With Quote
Old 02-09-2006, 06:38 AM   #2
chris_knows
๑۩۞
 
chris_knows's Avatar
 
Join Date: Apr 2005
Location: Ontario, Canada Status:Trying to find my ish
Posts: 7,630
http://en.wikipedia.org/wiki/Blow-off_valve

Its use is to vent extra pressure being developed by the turbocharger when the throttle is closed, such as during a shift. During a shift in a car with a manual transmission, the throttle plate is closed. The pressure produced by the turbocharger has nowhere to escape to. This excess pressure could potentially cause damage to the turbocharger's impeller and may also slow or even stop it, thus causing turbo lag when the throttle is pressed again.

A blowoff valve is connected by a vacuum hose to the intake manifold after the throttle plate. When the throttle is closed, a strong vacuum develops in the intake manifold after the throttle plate and "sucks" the blowoff valve open. The excess pressure from the turbocharger is vented into the atmosphere or recirculated into the intake upstream of the compressor inlet; when vented into the atmosphere this can cause erratic engine behavior on motors that use an air flow meter for the electronic fuel injection. Engines using a MAP (manifold absolute pressure) are not affected. Externally-vented blowoff valves have a very distinguished "psshh" sound that is desired by many who own turbocharged sports cars. Some blowoff valves are marketed with trumpet shaped exits that amplify the "psshh" sound.

Blowoff valves are generally not required on automatic transmission vehicles. Automatic transmission vehicles shift without closing the throttle, but are still fitted with blow off valves by many manufacturers so the turbo is able to provide boost sooner if the throttle is only released for a short amount of time.

I think that pretty much covers it...
__________________
chris_knows is offline   Reply With Quote
Old 02-09-2006, 06:47 AM   #3
ehhh
CF Newbie
 
Join Date: Nov 2005
Posts: 32
sweet that pretty does much cover it. ok two more questions one its about exotics, i saw this vid right and well while dude man was driven on his cluster a green symbol popped up lookin like a spolier and i was wonderin what it was i got four diff answers 1) its the spolier it deploys itself at a certain speed 2) it not a spolier its the wings on the side of his gallardo that vent the car or something or other because the car's curves and design give it the ability of not needin a spolier 3) its neither its sayin his spolier is stuck up
ehhh is offline   Reply With Quote
Old 02-09-2006, 07:02 AM   #4
chris_knows
๑۩۞
 
chris_knows's Avatar
 
Join Date: Apr 2005
Location: Ontario, Canada Status:Trying to find my ish
Posts: 7,630
Did it look like this?:



If so, then my best guess would be that the spoiler was coming out...do you have the vidoe so we can see it?...And if it was something jamming, I doubt it would be green...
__________________
chris_knows is offline   Reply With Quote
Old 02-09-2006, 07:04 AM   #5
ehhh
CF Newbie
 
Join Date: Nov 2005
Posts: 32
http://videos.streetfire.net/categor...988C976662.htm thats the site
ehhh is offline   Reply With Quote
Old 02-09-2006, 07:18 AM   #6
chris_knows
๑۩۞
 
chris_knows's Avatar
 
Join Date: Apr 2005
Location: Ontario, Canada Status:Trying to find my ish
Posts: 7,630
Well the spoiler on the Gallardo does activate at a certain speed, so it would make sense...
__________________
chris_knows is offline   Reply With Quote
Old 02-09-2006, 07:22 AM   #7
ehhh
CF Newbie
 
Join Date: Nov 2005
Posts: 32
hmm works for me just didn't know which one to actually believe ok one more question than i got none left ok my car right is auto right and well like yeah it shifts it self and everything right of course but you know right when you decide to mash on the gas it will switch to where it would be best like 1st is 0-40 2nd is 40-70 and 3rd is like 70 to i believe 100 what i'm curious is when i mash the gas and i'm at like 50mph why does it like stay in 3rd or even go in 4th and try to pull from that instead of droppin to 2nd
ehhh is offline   Reply With Quote
Old 02-09-2006, 07:38 AM   #8
chris_knows
๑۩۞
 
chris_knows's Avatar
 
Join Date: Apr 2005
Location: Ontario, Canada Status:Trying to find my ish
Posts: 7,630
Quote:
Originally Posted by ehhh
hmm works for me just didn't know which one to actually believe ok one more question than i got none left ok my car right is auto right and well like yeah it shifts it self and everything right of course but you know right when you decide to mash on the gas it will switch to where it would be best like 1st is 0-40 2nd is 40-70 and 3rd is like 70 to i believe 100 what i'm curious is when i mash the gas and i'm at like 50mph why does it like stay in 3rd or even go in 4th and try to pull from that instead of droppin to 2nd
...Now after removing the likes and rights, and stuff...
Quote:
Originally Posted by ehhh
Hmm, works for me. I just didn't know which one to actually believe. Okay, one more question and then I'm done. My car right is auto, and it shifts itself and everything. But you know when you decide to mash on the gas it will switch to where it would be best like 1st is 0-40, 2nd is 40-70, and 3rd is like 70 to I believe 100 what I'm curious is when I mash the gas and I'm at 50mph why does it stay in 3rd or even go in 4th and try to pull from that instead of dropping to 2nd
First of all...what car, and second, are you talking km/h or miles?...Because that's a bit too high for miles/h....
__________________
chris_knows is offline   Reply With Quote
Old 02-09-2006, 07:42 AM   #9
ehhh
CF Newbie
 
Join Date: Nov 2005
Posts: 32
one a car not even worth mention its a nissan sentra
ehhh is offline   Reply With Quote
Old 02-09-2006, 08:18 AM   #10
GreekWarrior
CF Extraordinaire
 
GreekWarrior's Avatar
 
Join Date: Jul 2004
Location: "Down-under"
Posts: 2,369
Quote:
Originally Posted by ehhh
what exactly does a B.O.V. do with the turbo

It makes it go PSSSSHHHHHH!!!!!!
__________________

GreekWarrior is offline   Reply With Quote
Old 02-10-2006, 03:50 AM   #11
Mathew
-BMW 3rd Year Apprentice-
 
Mathew's Avatar
 
Join Date: Aug 2004
Location: Vancouver, BC
Posts: 2,053
Quote:
Originally Posted by ehhh
hmm works for me just didn't know which one to actually believe ok one more question than i got none left ok my car right is auto right and well like yeah it shifts it self and everything right of course but you know right when you decide to mash on the gas it will switch to where it would be best like 1st is 0-40 2nd is 40-70 and 3rd is like 70 to i believe 100 what i'm curious is when i mash the gas and i'm at like 50mph why does it like stay in 3rd or even go in 4th and try to pull from that instead of droppin to 2nd

Automatics are generally designed to give the best fuel economy, so they always try to keep the rpm as low as possible. But for performance you wan't high rpms. Say you're going 50 mph in 4th gear in your auto. If you mash the accelerator to the floor, it should drop down to third gear, thereby causing the revs to go way up and getting more torque. Same with if you are accelerating hard, it will stay in the same gear close to the redline before shifting, to get as much torque out of the engine as possible.
__________________
Mathew is offline   Reply With Quote
Old 02-10-2006, 05:27 AM   #12
ehhh
CF Newbie
 
Join Date: Nov 2005
Posts: 32
Quote:
Originally Posted by Mathew
Automatics are generally designed to give the best fuel economy, so they always try to keep the rpm as low as possible. But for performance you wan't high rpms. Say you're going 50 mph in 4th gear in your auto. If you mash the accelerator to the floor, it should drop down to third gear, thereby causing the revs to go way up and getting more torque. Same with if you are accelerating hard, it will stay in the same gear close to the redline before shifting, to get as much torque out of the engine as possible.

i know that but that the thing it sin't doppin down it stays in the same gear and tries pullin from that like say i'm driven normal and the car goes into third at like say 40 or 45 right or lower what ever if i accelerate all the way it should drop to second but it doesn't it stays in third
ehhh is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Forum Jump



All times are GMT +1. The time now is 05:58 PM.

Powered by vBulletin Version 3.5.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright 2002 - 2011 Car Forums. All rights reserved.