With regards to the lines from the plenum to recirc valves, is there any reason why I cant bring a single hose down and 'T' it to operate both recircs? I can't understand why there's two? I'm referring to the yellow and red lines on this diagram.
You can do that, although the hardware from the oem setup will still be there. Perhaps not as efficient as stock as each valve sees pressure from a different bank.
Cheers Rob. All the old gubbins was binned long ago and was previously running with no dump/recircs so I've refitted recircs. I did consider the efficiency but due to there being a balance bar I didn't think it would matter? Do you think it would be better to run the two lines?
I don't think it will make a measurable difference. Actually oem system the drivers side is off the balance tube anyway so just T off that one
Dave from UAS was pretty firm in his assertion that they should have their own individual in split lines. Apart from that I wouldn't hesitate in agreeing with you.
Only thing I would be worried about is those lines have to do work, your little 6mm vac line has to let enough air through to move a 60sqmm, or whatever it is, diapgragm pretty quickly, tee-ing the line doubles the amount you have to get through one. There are probably standard values out there so you could calculate how big/how many lines you need or you could just test it and see. Or play it safe and leave it with two.
What do you mean; no air is "let through"? They are just a pressure reference, and Im guessing Teeing off the line could influence response times. Or am I misunderstanding you? I'm planning to just chuck one line in with a T and change it only if I have issues.
For the diaphragm to move you've got to pull air out, when everything is the same size its not an issue but the volume of the BOV is larger than the cross sectional volume of the signal line so the air has to move quicker through the line. If you ran a capillary line used for mechanical gauges to the BOVs you would definitely have a problem with slow response and increased surge, I have no idea what the ballpark flow rate is for 6mm hose or what the volume change in the bov signal chamber is but I might check before ditching one of the lines.
Cheers for the input guys. Due to my plenum being modded it's lost the two feeds on the right of the actual plenum so here's what I'm planning, let me know what you think... I blanked the AIV ports on the underside of the plenum with 3mm aluminium plate. I propose to drill and tap a M5 thread in the centre to house one of these each side. These will go down to operate the recircs. http://www.ebay.co.uk/itm/10-Pcs-6m...rb-Fittings-/121689404917?hash=item1c5540f5f5 Q. Will 3mm ali be thick enough for tapping a thread or shall I make them again out of a thicker sheet? If so, how thick? The 6mm barb on the right of the balance bar will be the reference for the Greddy Profec B solenoid which is sitting right next to the battery. Nice and short. One of the 4mm barbs from the balance bar for the FPR. The other 4mm barb will go into the cabin for the Profec B controller. The route will be from the balance bar down through the rubber of the drivers 'A' beam that the engine bay loom comes through - above the peddles to the centre console. Q. Short enough route to be accurate? The final 6mm barb on the left of the balance bar will go into a receiver with three 4mm outlets that will feed the two aftermarket boost gauges in the cabin and the stock boost gauge sender. Will they be accurate setup like that?
3mm sounds a bit thin to get a secure fitting, there are probably standards out there somewhere so maybe an engineer will chime in on a suitable thickness. Also note that o-ring fittings require a machined boss to fit into to get a proper seal so that will take some more material out of the threaded area, you can get fittings which have a retaining ring for an o-ring so that you don't have to machine one into the face. Welding a nut onto the back is probably a simple solution for getting enough thread. If you're doing a bunch of modifications and would like to have one less hose in the engine bay then stepping the vac line up to 8-10mm would give a good amount of headroom over 6mm then you can use a tee down to whatever size you BOV ports are. The rest sounds fine, gauges might be a little laggy but shouldn't effect accuracy significantly.
Just use a nutsert in the 3mm ally to make a longer tap available. Then wind in a male/male m5 to 6mm barb fit to ng on each one. At my old shop we used a 3 meter long vac line hooked to the PC for boost reference. No issues. But I'm sure people will chime in saying otherwise...
A wellnut (basically a polymer nutsert) would be a good choice as they're designed to seal, would need to seal the fitting with pipe sealant or tape but should work fine, not like you're going to get a big vacuum leak through the threads but might as well reduce it as much as possible. The length of the line isn't an issue so long as it's large enough for the diaphragms it's trying to move, just teeing off a small line for lots of different components can give you lazy response. Boost gauges aren't super important anyway so long as the controller and wastegate have suitable sources.
so have we come to a conclusion about seperate feed or not ? i only put one feed and t it up but i havnt finished car yet so havnt used the setup... if we must put seperate feeds someone confirm so i can run another line
Don't think a rivet but is going to seal, or a metric thread... All the other air fittings are pipe thread.
There are Z's with single BOV's out there that state they have no problems (that they know of ) Flow and resistance alone dictate there is a some difference (even if negligible) therefore it is wiser to feed both recirculation banks regardless unless you have test data results for both with a defined difference that you can accept. I figure Nissan engineers put two of them there for a reason based on testing as above (it has two banks remember) - don't invent the wheel again in the shape of a square when its all ready round. JC :zlove:
If you're worried about a single line not moving enough air... A single 6mm line has a cross section of 9pi mm2. A single 3/8" line has a cross section of 22pi mm2. I'm sure you can find a 1/4" x 1/4" x 3/8" T piece somewhere
Thanks for all the responses and advice guys, much appreciated. After much looking I can't find a metric barb with a long enough thread to go through the 3mm plate and into a riv-nut or well-nut without it being to wide to fit the hole in the plenum. They also don't seem to do riv-nuts or well-nuts in BSP thread. Seems my best option will be to use thicker plate, buy a 1/8 BSP tap and go that route. I have some 5mm ali kicking about, do you reckon that'll hold ok with some loctite to stop any thread seepage?
5mm will be ok but use a good sealant/locker. Loctite 577 is the best. Because you have minimum thread and it is in alli this will make sure it dose not come loose or leak. No you will not use silicon! A nutsert would not be a good idea as it may give you sealing issues and they can come loose over time.
