s14 vacuum questions (bov, wastegate, boost gauge) where to put?

[zrs6v4]

Ok so I have been reading and reading online but I cant seem to find a simple or sufficient answer. I have an s14 sr20 engine swap on my 95 240sx. The swap was done without modifications therefore a stock sidemount was used. With that said the stock bov vacuum was in the stock location, the wastegate vacuum was in the stock location (connected to stock IC piping), and obviously no boost gauge stock.

I am putting a front mount intercooler (ISIS) on the car this week and I already have the battery relocated to the trunk but need to have the vacuums figured out so when it arrives I can get it done and ready to drive.

Here is a picture of the s14 SR20 throttle body with 4 usable vacuums I have to choose from to put my bov, wastegate, and boost gauge vacuums:
here is where all the hoses go stock.



1- to the stock bov
2-goes to the charcoal canister
3-stays blocked off stock
4- goes to charcoal canister
5-coolant to the TB for cold-idle adjustment (ignore)
6-goes to the idle-air control valve and should be put between the TB and the I/C (ignore)

With all that said I plan on putting my aftermarket bov (HKS) vacuum on the stock bov location which is #1 above in picture.

Wastegate: I have read this needs a boost source before the throttle plate so when the plate closes there will be no vacuum on the wastegate to cause it to not work properly. As I said above the stock source was in the stock sidemount piping but my new piping will not have a nipple in it for the wastegate. Many writeups say to simply have a nipple welded on the intercooler piping hotside. I really dont have the time to take this and have it done unless it is my only option. I do have 3 possible locations for the wastegate seen in the pic above (numbers 2-4, I used #1 for BOV).

Boost/Vacuum gauge: This, unlike the wastegate, does require a boost and vacuum source which will be one that is after the throttle plate so when it closes it will read vacuum.

My ultimate question is which of the 4 stock vacuum (again, see pic above for numbered 1-4) locations are the proper places to connect my bov, wastegate, and boost/vacuum gauge?

[jr_ss]

3 and 4 are not vacuum sources... They are located directly at the throttle plate. Anything after the throttle plate is a vacuum source, such as 1, 2, and 6... There is also another vacuum source that the FPR solely uses on the side of the intake manifold. That leaves you with 1, 2, and the FPR sources. How you run them is up to you. I would not use the FPR source for a boost controller/BOV option. Put your gauge on there if you have to put it anywhere.

[zrs6v4]

Originally Posted by jr_ss

3 and 4 are not vacuum sources... They are located directly at the throttle plate. Anything after the throttle plate is a vacuum source, such as 1, 2, and 6... There is also another vacuum source that the FPR solely uses on the side of the intake manifold. That leaves you with 1, 2, and the FPR sources. How you run them is up to you. I would not use the FPR source for a boost controller/BOV option. Put your gauge on there if you have to put it anywhere.

Thanks, im gonna do 1 and 2 for bov and boost gauge and 3 or 4 for wastegate. I wont touch the fpr, ive hear much neg feedback on T-ing the fpr so im not touching that.

Any other critiques or suggestion?

[shinobis13hb]

I had to T off my hks to the biggest(2)? Line for it to work. If I connected it to the (1) it would not work.

[zrs6v4]

Originally Posted by shinobis13hb

I had to T off my hks to the biggest(2)? Line for it to work. If I connected it to the (1) it would not work.

So what would you do run the boost gauge on #2 then T off the Hks bov from it? #2, #3, and #4 on mine are capped off and usable from the swap.

[jr_ss]

You'll be fine off of 1 or 2 for the HKS... It's where I had mine and it worked flawlessly. Typically you don't want to T off the FPR line, but using it for a gauge isn't a big deal as long as the line isn't too long. I have all electronic gauges in my car, so the boost/vac line stays relatively short.

[zrs6v4]

So will 3 and 4 be good options for the wastegate?

[zrs6v4]

Wow, ok so I got my ISIS intercooler piping in and installed today. They told me there was not a nipple for the wastegate but actually there was. I had them weld on an hks flange on the hotside, and the cold side of the piping has 3 nipples. One for the wastegate, one for the iacv vacuum, and a huge one for the stock recirculation valve.

My new challege is finding a way to plug the stock bov nipple thats like 1.25" inner diameter. No auto stores had vacuum plugs near that size so any advice on that?

[jr_ss]

Take it to a fabricator and ask them to weld it up. Best way would be to cap it and weld it, however you could cut it off and then weld it, strictly up to you...

[h23]

Okay, I have a few questions as well. I don't want to make another thread, but if this gets no responses I will have to.

1. In your photo below, does hose #5 need to be hooked up? If so, where does it get hooked up to. I have heard on the throttle body, if so is it the BLUE circled nipple in the photo below? If so, where does the GREEN circled hose that's currently hooked up to it go? If not, where?





2. Where does the hose below go? It is to the left of where the injector harness clips into on the lower intake manifold.

[Breakbeat93]

Originally Posted by zrs6v4

My new challege is finding a way to plug the stock bov nipple thats like 1.25" inner diameter. No auto stores had vacuum plugs near that size so any advice on that?

I did mine up ultra ghetto style, mobil 1 oil cap fit snugly, put some rtv on there. Holds 14lbs no prob....haven't gotten around to getting it welded yet. I'm sure I'll get flamed for saying this but whatever function>form.

[jr_ss]

H23- those are your coolant lines to the throttle body. Hose 5 gets hooked up next to that red temp sensor, there should be a nipple there for it. The green hose is on the opposite side of the throttle body and gets hooked up to one of the coolant lines that runs under the intake manifold.

[h23]

Originally Posted by jr_ss

H23- those are your coolant lines to the throttle body. Hose 5 gets hooked up next to that red temp sensor, there should be a nipple there for it. The green hose is on the opposite side of the throttle body and gets hooked up to one of the coolant lines that runs under the intake manifold.

So JR I just want to make sure I'm understanding this right.

-The green hose is currently hooked up correctly on the blue circled nipple on the TB?

-And Hose #5 int he first picture is the same as the hose I'm holding in the third picture that is to the left of the red connector?

Thanks!

[jr_ss]

Hose #5 is what you have in your hand. The hose that exits on the passenger side of the TB goes under the intake manifold to the coolant pipe cluster. So in essence, yes you are understanding what I said.

Those two nipples in your green/blue picture are your fuel lines incase you didn't know.

[h23]

Perfect. And yeah I know they're fuel lines haha. There just isn't much out there on vacuum lines and coolant lines for the s14 sr.

[zrs6v4]

Originally Posted by jr_ss

Take it to a fabricator and ask them to weld it up. Best way would be to cap it and weld it, however you could cut it off and then weld it, strictly up to you...

Thanks, I think I will eventually. I would like to get that thing cut off and welded up.

Originally Posted by Breakbeat93

I did mine up ultra ghetto style, mobil 1 oil cap fit snugly, put some rtv on there. Holds 14lbs no prob....haven't gotten around to getting it welded yet. I'm sure I'll get flamed for saying this but whatever function>form.

I actually stumbled across a rubber trailer hitch cover. I plan on using a thick plastic cap, then covering it with the rubber cover, then hose clamping it just to drive it tomorrow. As said above, eventually, Ill have it welded up.

[zrs6v4]

More problems with isis s14 ic piping. There are three nipples on the cold pipe. 1 small for wasgate, 1 large for stock bov (cap off), and a medium sized one for the iacv vacuum. Well, the first issue is that you have to remove stock radiater fan houseing to fit the ic pipe in bc the stock bov nipple will smash it. I could deal with that but as i was finishing the install i went to hook up the iacv vacuum only to discover that the nipple is 1/2" from the stock clutch fan making it impossible to incorporAte any 5/8" hose without it interferring with the fan blades. My options are electric fans or bend the nipple so that the hose will angle away from the fan.

[jr_ss]

Pictures fool... I'd bend the nipple before I removed the fan shroud.

[zrs6v4]

Working all night

Both the iacv and stock bov nipples are problematic.

Im gonna have the stock bov nipple cut off and welded.

Im either gonna have the iacv nipple moved or bend it.

[zrs6v4]

I was going to get some pics up for anyone needing the info but it was pouring outside today.

I took the cold pipe and had the stock bov tube deleted and welded up. I also had them delete the iacv vacuum nipple and move it to the other side of the pipe. With that said all is done. Oh wait i forgot to mention the boost gauge i have is broken. When its off it reads 5psi go figure.

[zrs6v4]

By the way, if anyone decides to order ISIS ic piping its a good deal. For $240 i got mine with rubber connectors, hi pressure clamps, new wastegate vacuum line, and an hks flange welded on. Just make sure you have them fix their welding errors before shipping (which they will).

[jubee]

two words to make your life easier for vac source.

vacuum manifold

end

[2plus4plus0eq6]

Would you be able to post that initial pic again? I'm in the same spot but can't relate anything without the pic.

Thanks!

[AllAboutAuto]

Hey I know this is an old thread but Im having some issues deciding where to run my lines as well. I have a 95 240 with a Notchtop that is stock. The pic isnt available that has the nipples numbered. Is there a way to repost it. Or could somebody/anybody please post a pic of the different nipples and where they are supposed to lead to. I have a CXRacing FMIC that has the BOV welded onto the hotpipe and I believe 3 totally different nipples on the cold side. I can post pics if i need to. Thank you very much

[LoSt180]

Originally Posted by AllAboutAuto

Hey I know this is an old thread but Im having some issues deciding where to run my lines as well. I have a 95 240 with a Notchtop that is stock. The pic isnt available that has the nipples numbered. Is there a way to repost it. Or could somebody/anybody please post a pic of the different nipples and where they are supposed to lead to. I have a CXRacing FMIC that has the BOV welded onto the hotpipe and I believe 3 totally different nipples on the cold side. I can post pics if i need to. Thank you very much

I'm sorry this isn't the best picture, but should help you out. It's from when I was test fitting a P11 throttle body, but has a clear view of the vacuum lines. On the S14 SR, there are two small lines on the bottom of the throttle body, but one is capped from the factory, so for now just pretend there's only one small line.

In reality, there's only 3 vacuum lines to deal with. The small line off the TB and 2 larger lines that come out of the manifold. (There's a 4th that has a short line for the fuel pressure regulator, leave that in place, don't T off it either.)

The small line (approx 1/8") on the throttle body goes over to the charcoal canister.

Directly under that are 2 larger vacuum lines (approx 1/4"). One goes to the stock BOV and has a T connector for the stock boost sensor/gauge. The other one goes over to the charcoal canister.

With the stock intercooler, the wastegate gets signal from a nipple on the intercooler piping, cold side. My Greddy FMIC instructions actually have you T into the smaller charcoal canister line for the wastegate.

So to recap, if using a FMIC and no charcoal canister: Feed the wastegate with the small line, feed BOV and boost gauge from one large line, cap the other large line.

If you start tuning/cranking up the boost, install a nipple in the IC piping closer to the wastegate. But for stock turbo boost levels, the longer line will be fine.




Stock vacuum diagram for reference:


Greddy FMIC instructions:
Shows the T for the wastegate coming from the canister vacuum line (smaller one).
Also shows the T for the BOV and stock boost gauge sensor.