# Brake booster hose ID or OD..?



## warranty225cpe (Dec 3, 2008)

Anyone know what size hose fits the brake booster port on the manifold? Trying to figure out what size hose is needed. 

Also, how many check valves do we need in the line? 1..2..? One at the booster, and 1 in the line right?


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## deepblueT (Jan 26, 2008)

not sure the actual size...its a larger one tho, thats a big port that comes off the end, i have seen people pull that out and tap threads in to the manifold itself to get a smaller hose on there...not sure the size matters. as for check valves, i have one right at the exit of the manifold (it helps me make the 180* turn back up to the firewall) then i have one at the throttle body, i assume its the same system. you just have to make sure they close under pressure and open at idle.


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## warranty225cpe (Dec 3, 2008)

Yeah me 2. My set up is about the same. Are you using silicone for your overflow tank?


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## deepblueT (Jan 26, 2008)

yeah, but only that top hose, which i assumed only saw coolant in an overflow situation...am i wrong? no leaks or splits that i know of, i'll have to check it out when i get the car back....


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## warranty225cpe (Dec 3, 2008)

deepblueT said:


> yeah, but only that top hose, which i assumed only saw coolant in an overflow situation...am i wrong? no leaks or splits that i know of, i'll have to check it out when i get the car back....


Your probably right. Just asked because it seemed out of place.


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## lite1979 (Sep 9, 2005)

Generally, the top hose will pour in coolant at higher rpms.


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## warranty225cpe (Dec 3, 2008)

I still need hose dimensions if anyone can help.


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## 20v master (May 7, 2009)

lite1979 said:


> Generally, the top hose will pour in coolant at higher rpms.


It'll return coolant all the time in that hose while the engine is running, not just at high rpms or an overflow condition. Noobs.  I'm no help on the brake booster hose. I hate that OEM plastic they use and the step rubber piece near the manifold (on passenger/right side throttle setups).


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## warranty225cpe (Dec 3, 2008)

20v master said:


> It'll return coolant all the time in that hose while the engine is running, not just at high rpms or an overflow condition. Noobs.  I'm no help on the brake booster hose. I hate that OEM plastic they use and the step rubber piece near the manifold (on passenger/right side throttle setups).


If we can get measurements, I can get us a bad ass booster hose made. I also need to know how many check valves need to be in the line.


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## 20v master (May 7, 2009)

warranty225cpe said:


> If we can get measurements, I can get us a bad ass booster hose made. I also need to know how many check valves need to be in the line.


I can measure this weekend if you don't have it by then. You only "need" one check valve, to prevent boost from going into the master cylinder. Two is just redundant.


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## warranty225cpe (Dec 3, 2008)

20v master said:


> I can measure this weekend if you don't have it by then. You only "need" one check valve, to prevent boost from going into the master cylinder. Two is just redundant.


Yes please! I really only need to know the hose size to fit the big port underneath the mani. But I guarantee that the end result will be the nicest option we've ever seen, for the 1.8t. Once I get mine worked out, I'll see if we can get a group buy going.


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## Marcus_Aurelius (Mar 1, 2012)

20v master said:


> I can measure this weekend if you don't have it by then. You only "need" one check valve, to prevent boost from going into the master cylinder. Two is just redundant.


No need to measure anything Adam because I just did. It's 0.5 OD on the nipple, so you need a 1/2" or so ID hose for that line. I also agree that two check valves isn't needed (providing that you use a metal valve that won't crap out like OEM ones).

What I don't get, beside the cosmetics appeal, is the need for anything better than common silicone hose. This thing will not see pressure/vacuum and heat above what is in the manifold... if it needed to be rated higher, any vacuum hose would also need that as well.

Eric, in terms of improving booster vacuum assit, what you can do is what I did. I added a "T" in the booster line and ran it into the TIP (the closer it is to the compressor inlet, the better... but any unused port would do). The TIP is constantly under vacuum and provides an auxiliary source of vacuum to assit the braking process. This is great because it backs the manifold sourced vacuum and provide extra vacuum that is stronger than what the engine can produce alone. (Doing this mod would require a second check valve in the added line)

Situations where this will help tremendously is:

1) on-boost when the manifold is seeing positive pressure and can't vacuum assit. This is a requirement for left-foot-braking while keeping the turbo spooled (if you were to try modulating the brakes while keeping the turbo spooled, you'll realize that you have no assist and the infamous wooden pedal)

2) Vacuum leaks. As you know more than anyone on this board, this complicated vacuum system in our cars often have leaks. When that happens, you loose efficiency. However, when you have the permanent auxiliary vacuum source from the TIP, leaks are not an issue to your brake assist.

3) Upgraded cams. They shift the powerband and reduce the amount of vacuum generated in the process. Adding the TIP vacuum source ensures that you retain efficiency in your brake assist.


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## warranty225cpe (Dec 3, 2008)

Good **** M. Way to come through and class up the thread. Always good info. Thanks. 
I'm doing this for a few reasons. 

1.) My Booster hose has (I think), 8 worm clamps on it! That's embarrassing! Between the reduction in hose size, the need to add a valve, and the overall length, there are lots of areas that could have a potential leak. 

2.) What I want would be a little more user friendly. Especially when it comes to holding a curve/shape, and NO WORM CLAMPS

3.) I want something that looks good and will hold up to the elements.

I realize I could just run a silicone line. But I don't think just silicone is the best possible answer. I do like the idea of Tee ing off back to the turbo inlet though. Great idea:beer:


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## Jpulll (Mar 16, 2015)

Marcus_Aurelius said:


> I added a "T" in the booster line and ran it into the TIP (the closer it is to the compressor inlet, the better... but any unused port would do). The TIP is constantly under vacuum and provides an auxiliary source of vacuum to assit the braking process. This is great because it backs the manifold sourced vacuum and provide extra vacuum that is stronger than what the engine can produce alone. (Doing this mod would require a second check valve in the added line)


I just sent you a PM but whatever you respond to first works...
So it seems you want it to go manifold>check valve>T connection> Brake boost
(extra line has check valve with flow pointed towards TIP)
Is this correct?


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## Marcus_Aurelius (Mar 1, 2012)

Jpulll said:


> I just sent you a PM but whatever you respond to first works...
> So it seems you want it to go manifold>check valve>T connection> Brake boost
> (extra line has check valve with flow pointed towards TIP)
> Is this correct?


Oh sorry, the PM box often gets neglected (the limited forum time I have is better spent reading/posting in the open forums than my busy PM box. It's one or the other).

On the component placement. Line coming from the TIP> check valve > T connection to main booster line.

Check valves in the brake assist system serves one purpose, they are there to prevent positive pressure from the manifold to reach the booster (which uses negative pressure/vacuum to operate). Therefore any check valves in this system will have the flow going towards the manifold, and block airflow coming from the manifold. 

PS: make sure the main booster line retains it's own check valves, this will add redundancy (if placeed downstream of the T connection) and act as a failsafe if one check valve had a failure.


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