Stopping the madness

[steelman]

Greetings all

I am doing a 2.3l turbo swap, the donor is a Turbo coupe, and I've been reading this forum for a while now. My question regards power brakes. I notice in photos that are posted here that most of the trucks are running brake boosters, if the manifolds are under boost pressure how do the boosters work?, what am I missing?

 

[shadetree]

You only have boost pressure when the engine is under load and the throttle plates are open. When you close the plates and reduce the engne load, no more boost, and the manifold returns to vacuum.shady

 

[steelman]

Shady
Thanks, I had thought that was the case but did not know if there would be a "lag" (sorry) time between boost and vacuum.
Wayne

 

[Bill G]

There are a few guys who add a vacuum reservoir. I'm not sure one would be needed.

 

[Davis]

nah, don't worry about it. there is a check valve and you dont brake under boost anyway. (well, most people dont)

 

[Sevensecondsuv]

^^^^ What he said. All the ford brake booster vaccuum lines I've seen have check valves in them (meaning the engine can only "suck" on the booster, not "pressurize" it). I didn't touch mine when I did the swap and my brakes work exactly the same as they did before the swap.

 

[Wicked_Sludge]

There are a few guys who add a vacuum reservoir. I'm not sure one would be needed.

isnt the brake booster itself a pretty large reservoir already?

 

[Bill G]

isnt the brake booster itself a pretty large reservoir already?

Yes it is, but it just for the brake system.
I know george added one for his EGR system. I have read a few threads of people adding one to their trucks.

 

[shadetree]

Shady
Thanks, I had thought that was the case but did not know if there would be a "lag" (sorry) time between boost and vacuum.
Wayne

There can be some lag. You can use a "blow off valve" and feed the pressure back into the turbo intake. This will aid in reducing lag, and take stress off the impeller blades when letting off the accelerator at high engine speeds.

When you are in high boost with high rpm then suddenly close the throttle plates, you have a very high pressure spike at the intake, blower side. This high pressure can sometimes bend impeller blades.

You can vent this pressure to the atmosphere, or feed it back into the turbo. Some like hearing the "whoosh" the valve makes when venting to the atmosphere. I like feeding it back to the turbo to increase efficiency.shady

 

[turbo cat]

all the brake boosters ive seen already have a check valves inside. its the round piece on the brake booster thats the vaccum line is connected too. Once the throttle shuts you will have instant vacuum to work your brakes wether you have a bov or not

 

[shadetree]

all the brake boosters ive seen already have a check valves inside. its the round piece on the brake booster thats the vaccum line is connected too. Once the throttle shuts you will have instant vacuum to work your brakes wether you have a bov or not

BOV has nothing to do with brake booster. We were talking about lag from closed throttle to open throttle. There is no BOV on the engine side of the intake.shady

 

[scotts90ranger]

yep, that's what I did, used the leftover fuel hose from running new lines to my filter (had just enough) and ran from the intake bung to the booster with the stock check valve, for some reason my brake pedal is softer than it was before... I don't know...