83turbo280zx Posted November 22, 2009 Share Posted November 22, 2009 hey i posted this on zcar.com haven't gotten any replies yet, so im wondering what you guys think I've been searching around on here but haven't found much. Im getting ready to run intercooler piping on my 83 tubo and the new piping doesnt have a bung for me to use the big hose that supplys vacuum to the AAR, AAC, and VCV. I have read a few posts about people deleting their vacuum control modules and giving the AAC a constant vacuum source without having any problems. I went a did a test run with the AAC hooked up to constant vacuum and the car still idled fine. I was wondering can i run this hose to the AFM boot behind the afm so that i still have an air source that is already metered air, that way i wont have to have a bung welded to my IC piping. I've suggested in the past just cutting the J-pipe before the bung and use that to mate up to my IC piping, but my piping is going to be welded and the few connections that i dont have welded will be joined with silicone couplers, t-bolt clamps, and bead rolled ends, so im trying to stray away from that idea of cutting my J-pipe. Any input? Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 23, 2009 Share Posted November 23, 2009 It doesn't supply vacuum, it supplies fresh filtered and metered air and acts as a bypass around the throttle body for idle speed control. Put a bung in your piping coming back from the intercooler, and you will have the same thing you got now for functionality. The constant source for Manifold Vacuum to the AAC will work fine, if you have a later model AAC, with the little setscrew in it, you can just screw that screw in till the bypass allows the idle speed you want, and you don't even need to connect vacuum to it at all, it will act as a fixed idle bypass just like on EuroTurbo cars. Realiztically, all you need for idle is a 1/4 line, that is more than enough. I took a hose barb from one of the turbo scroll connections for the wastegate (my wastegate is hooked up to the plenum...) and ran 1/4" hose from there to a modified N/A idle air bypass screw thingamajig, and then plumbed it with a 1/4" hose to the manifold as a premanent bypass (like the Eurospec Turbo cars had...no AAC for them!) It will suppy enough air for anywhere from 300 to 2200 rpms. With a 1/4" barb hooked up like that, none of your pipes will need to have anything put into it. But it needs to have that boost reference, because if you hook it to the boot between the AFM and the turbo inlet....when you go on boost, it will leak through whatever metering device you are using (AAC, fixed idle bypass thingamajig) and blow boost into that same area. This is why it's on the J-Pipe to begin with. Hope that makes sense. I have photos of some of it on the 260ZT page at cardomain of sharkie73z... Quote Link to comment Share on other sites More sharing options...
83turbo280zx Posted November 25, 2009 Author Share Posted November 25, 2009 ahh ok i gotcha, well what about running a hose from the manifold to the "fresh air" inlet to the AAC, AAR, etc. I was thinking about threading a hollowed out PCV valve into one of the allen head bolts in the bottom of the intake manifold and running a hose from that to the actual fresh air inlet. This way im still getting metered air, and i will also have positive pressure going through it under boost to keep the AAC from opening under boost. Im trying to keep away from having a bung welded to my IC pipe since im already on a tight budget, so if i can get away with using a hollowed out PCV valve in one of the holes in the manifold, then i will try that. What do you think Tony? Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 25, 2009 Share Posted November 25, 2009 ahh ok i gotcha, well what about running a hose from the manifold to the "fresh air" inlet to the AAC, AAR, etc. I was thinking about threading a hollowed out PCV valve into one of the allen head bolts in the bottom of the intake manifold and running a hose from that to the actual fresh air inlet. This way im still getting metered air, and i will also have positive pressure going through it under boost to keep the AAC from opening under boost. Im trying to keep away from having a bung welded to my IC pipe since im already on a tight budget, so if i can get away with using a hollowed out PCV valve in one of the holes in the manifold, then i will try that. What do you think Tony? NONE of the lines are 'fresh air' they are ALL under pressure. The distinction is before throttle plate or on the engine side of the throttle plate. All what you are referring to as 'fresh air' are before throttle plate (after turbo). That is the source of the AAC and AAR's supply. IT can not be taken AFTER the throttle plate. There will be no 'bypass' for the valves to function! The only place for the source is the J-Pipe or off the scroll of the turbo on that small fitting. That is where the air bypass has to come from to work properly under boost without a leak to atmosphere. Quote Link to comment Share on other sites More sharing options...
83turbo280zx Posted November 26, 2009 Author Share Posted November 26, 2009 ok i gotcha, well i mocked up my piping today and i wont have to have too much welding done, maybe i'll be able to afford having a nipple added to my intercooler pipe, if not i will try one of the fittings coming off the scroll on the turbo. thanks for all the help and info sir!! Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 26, 2009 Share Posted November 26, 2009 You don't have to get a nipple welded to your pipe! Have the guy take a piece of 1/8 thick sheet or a block of 1/4" aluminum and simply weld it 'all round' to the underside of the IC return pipe (this way you get cool air). When it comes time to plumb it in, you simply drill and tap a hole. The 1/4" thick aluminum is more than thick enough for threads, and you can use any standard threaded barb to install whatever size bypass like you like! On steel J-Pipes I have successfully welded to them a piece of 1/8 X 1/2" strap steel and threaded it. Though a 1/4X 1/2" strap chunk 3" long ended up supplanting it once I found out how easy it was to tap into and take pressure off for this and that (like for pressure probes to check pressure at turbo outlet, I/C outlet and inlet, just before the TB, and to run RTD's in the same places as well. it's an easy way to make a penetration to the piping without putting a permanent nipple in there, just a piece of flat stock. If you have steel piping, then all you need for materials is at home depot or lowes! Strap steel rack, here you come! You can simply plug any hole you don't need, put a piece on there 3 or 4" long, and you got plenty of area for several hoses to come off. Slightly wider and you can use the same technique to mount additional injectors, but we don't need to go there, do we? Muahahahaha! Quote Link to comment Share on other sites More sharing options...
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