ZT-R Posted April 28, 2011 Share Posted April 28, 2011 Hey guys, RB26 with a intake manifold. i have a 6an line tapped. can i run that stright to my booster with the oem 240z check valve? or do i need to build a vacuum canister? i have disk brakes in the rear and will be running azc 12.2 front kit at some point with the 81 280zx 15/16th master. (btw isnt this the same as the 280z master, my 280z says 15/16 on it...) Quote Link to comment Share on other sites More sharing options...
djz Posted April 28, 2011 Share Posted April 28, 2011 I'm not quite following? You have an RB26 with an intake manifold? Are you using the factory plenum and throttle bodies or an aftermarket manifold and single throttle body? If you are using the factory plenum and have tapped that it's not going to work. Quote Link to comment Share on other sites More sharing options...
ZT-R Posted April 28, 2011 Author Share Posted April 28, 2011 oh yea sorry, i have a single throttle body. i was thinking about putting the check valve as close to the intake manifold as i can so it would store some in the hose too. i dunno if that matters or not though. guess i need to wikipedia brake boosters Quote Link to comment Share on other sites More sharing options...
gmac708 Posted April 28, 2011 Share Posted April 28, 2011 I agree with dgz. Stock RB has vacuum boost coming off back side of airchamber which is connected to balance tube. Anything upstream of TB/ITB has boost/ambient. Downstream of TB or ITB has vacuum when throttle lifted or "on speed". WOT would of course be boosted as well, but then WTF would you need brakes for at WOT. I see from your build (awesome by the way) You have single TB and you should be able to hook up check valve to your intake. Quote Link to comment Share on other sites More sharing options...
ZT-R Posted April 28, 2011 Author Share Posted April 28, 2011 wouldnt the check valve negate any boost? Quote Link to comment Share on other sites More sharing options...
synthtk Posted April 29, 2011 Share Posted April 29, 2011 You should be fine with just a check valve, I ended up using one off of a LS1 and it pops right into the brake booster. Quote Link to comment Share on other sites More sharing options...
gmac708 Posted April 29, 2011 Share Posted April 29, 2011 Sure. That's what it is designed to do. The vacuum assists your foot by pulling the piston in master cylinder. The check valve prevents boost from coming inside chamber and acting against your foot pressure. There should only be vacuum going to brake master. Boost=bad, Vacuum=good. Even the power brakes work without the vacuum, a little scary at first when you discover the loss, but they do work. or you could... Get regular or non-"power brake" master cylinders. Quote Link to comment Share on other sites More sharing options...
ZT-R Posted April 29, 2011 Author Share Posted April 29, 2011 yea its like turning your car off and hitting the brakes... oooooh **** shop baby Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted April 29, 2011 Share Posted April 29, 2011 I had mine with out a vacuum canister at first, like you said, with the stock one way, but never was happy with the brakes until I added a canister with a check valve from Jegg's. Quote Link to comment Share on other sites More sharing options...
ZT-R Posted April 29, 2011 Author Share Posted April 29, 2011 (edited) assuming the check valve is before the canister? and synthtk clean out your pm's i have been trying to pm you for a few years i was thinking about using some 2.5" pipe about 8" long do you think that would be enough? Edited April 29, 2011 by ZT-R Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted May 2, 2011 Share Posted May 2, 2011 Maybe Im not reading any of this right and it was already properly answered but, You need a plenum port. I do not know how the RB26 was setup from the factory with their different manifold, but Im sure it was simply plugged into one of the rear runners behind the TB(engine side of TB). I have a brake booster from a GTR with the check valve installed still. So with your current setup you would do the same thing. Get 'manifold' vacuum from the plenum behind the TB. Run a check valve between the booster and the vacuum source. Almost any Nissan check valve will do. Id dare say even the stock 240Z valve will work as I have ran them with L28et's and my RB25det. Just verify it only goes one way(flow towards manifold) and you will only get vacuum to the booster and not boost. As for a vacuum canister Id say you dont need it. Ive never used a 240Z booster with one of these engines, but the stock 260Z and 280Z boosters will hold enough vacuum in them for your braking. The only way your going to run into a vacuum issue is if your double footin it and hard. Where you would want to install a vacuum reservoir is in an application which doesnt produce enough vacuum in the first place. Engines that have radical cams(or no throttle body), or something that needs a constant source of vacuum like HVAC systems in which most cases get a dedicated vacuum motor. You can if you like, but seems like extra weight to me from what youve stated. Quote Link to comment Share on other sites More sharing options...
ZT-R Posted May 2, 2011 Author Share Posted May 2, 2011 yea i have a 1/4 npt (biggest on the manifold) that i am gonna use for the booster. i have a 280z booster in there now with the 15/16 master cylinder. Quote Link to comment Share on other sites More sharing options...
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