Brake Boost under FI?
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Joined: Aug 2011
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From: Myrtle Beach
You are going down the road at full boost and you suddendly have to brake hard. You take your foot of the gas and immediately apply to the brake, .5 seconds. There is no way 10, 15, whatever pounds of boost has gone off your system via the BOV. So yes I would say you are braking with a positive pressure so there is no vacuum to run the brake booster. Somebody slap somebody.
Joined: May 2012
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From: SOMD
You are going down the road at full boost and you suddendly have to brake hard. You take your foot of the gas and immediately apply to the brake, .5 seconds. There is no way 10, 15, whatever pounds of boost has gone off your system via the BOV. So yes I would say you are braking with a positive pressure so there is no vacuum to run the brake booster. Somebody slap somebody.
Joined: Apr 2010
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From: Roc
Fellas, the booster stores vacuum...
Start the car, shut it off, you will still have a press or 2 of vacuum assist on the pedal.
That's the whole point of the check valve being there, the booster IS a vacuum reservoir.
Unless you plan on being in boost and pumping your brakes repeatedly, you'll be fine.
Start the car, shut it off, you will still have a press or 2 of vacuum assist on the pedal.
That's the whole point of the check valve being there, the booster IS a vacuum reservoir.
Unless you plan on being in boost and pumping your brakes repeatedly, you'll be fine.
Joined: Apr 2008
Posts: 669
Likes: 16
From: Burbs of Philly, PA
Fellas, the booster stores vacuum...
Start the car, shut it off, you will still have a press or 2 of vacuum assist on the pedal.
That's the whole point of the check valve being there, the booster IS a vacuum reservoir.
Unless you plan on being in boost and pumping your brakes repeatedly, you'll be fine.
Start the car, shut it off, you will still have a press or 2 of vacuum assist on the pedal.
That's the whole point of the check valve being there, the booster IS a vacuum reservoir.
Unless you plan on being in boost and pumping your brakes repeatedly, you'll be fine.
I never knew that......Awesome info. Now it makes sense why when I want to move my car in neutral (moving down a slopped driveway) with the engine off, the brakes work normally for a couple of pumps and then if I need to use it again on the 3rd pump I really need to muscle the pedal to get it to stop.
Joined: Apr 2010
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From: Roc
Originally Posted by illestrolla' timestamp='1381959521' post='22831148
Fellas, the booster stores vacuum...
Start the car, shut it off, you will still have a press or 2 of vacuum assist on the pedal.
That's the whole point of the check valve being there, the booster IS a vacuum reservoir.
Unless you plan on being in boost and pumping your brakes repeatedly, you'll be fine.
Start the car, shut it off, you will still have a press or 2 of vacuum assist on the pedal.
That's the whole point of the check valve being there, the booster IS a vacuum reservoir.
Unless you plan on being in boost and pumping your brakes repeatedly, you'll be fine.
I never knew that......Awesome info. Now it makes sense why when I want to move my car in neutral (moving down a slopped driveway) with the engine off, the brakes work normally for a couple of pumps and then if I need to use it again on the 3rd pump I really need to muscle the pedal to get it to stop.
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Joined: Jul 2013
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From: Cape Town
Guys you are overlooking one massive point here..... The blow off valve itself is actuated by intake manifold vacuum, it wouldn't open unless it saw vacuum therefore the brake booster should have no problem.
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Joined: Aug 2011
Posts: 1,935
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From: Myrtle Beach
Throttle body snapping shut, BOV not opening until it sees vacuum, booster stores vacuum, all good logical stuff guys thanks. Now I can go back and talk some shit with my mechanic friend!!! What is worse I knew everything you all said, once you said it like Duh, of course the TB closes and as soon as you take your foot off the gas, when it does that engine is going to suck a good vac in milli seconds, and Duh again, of course the BOV acts on engine vac. Sometimes you can't see the forest for the trees.
and I have to Google roll racing
and I have to Google roll racing
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