Install R33 Bov On S13 - Considerations?

[No Crust Racing]

Hey guys, I've picked up a factory plumb back R33 BOV to put on my S13 (CA so no BOV factory) and I'm in the process of working out where best to put it.

I can't easily find an R33 engine bay pic that shows me where the air rejoins the system after flowing through the BOV on an R33 but here's what I'm thinking.

From what I understand the ideal location for the BOV itself is as close to the throttle body as possible but this won't be possible on my car without a lengthy return pipe crossing the engine bay (CAs have a forward facing plenum and I have a front mount).

So the BOV itself would go on the hot pipe then merge it back in before the front mount, as there is a bung/hose on the cooler pipe already. This would leave a pipe run of maybe 60-70cms and would be neater. I could also mount the bov on the piping on the cold side of the cooler then run it back under the cooler to the other outlet, from the engine bay all you'd see would be the feed from the intake going to the top of the BOV.

Does the length of the return pipe matter? Will it affect how useful it is mounting it so far away from the throttle body if I go the hot pipe route?

In my head the shorter the return pipe the better as there's less additional volume added to the intake that requires pressurising. On the other hand, if the return is too small there may be be enough volume for the vented air to escape into when the valve opens - but this seems moot as that side would technically already be pressurised?

Some clarification would be great. My 33 GTS-T and GT-R both had factory BOVs in place and remained that way so this is a bit new to me.

Cheers

[R31Nismoid]

You think about stuff far too much Dan

A GTR BOV setup is behind the driver side headlight area, so it too goes cross-bay, back to the turbo side.

There is no issue with a long return pipe. Plumb it in between turbo inlet and AFM.

Ideally you want it as close to the T/B as possible, but it's not a show stopper. I've run BOVs pre-cooler without issue.

[No Crust Racing]

Well I like to make sure I have a grasp on something before I go cutting holes in things

"Plumb it in between turbo inlet and AFM"

Soon as I read that I face palmed because it seems so obvious now.

Will be interesting to see how I go about that as my intake between the turbo and afm is still the factory plastic one. Will have to see what my options are.

[R31Nismoid]

Just make a metal one.

The AFM has already measured that air, so it expects it and you cant do it again.

Hence why a lot of cars stall when people put ATMO BOVs on - car expects the measured air to be in the system and then suddenly it's being starved.

[No Crust Racing]

One does not simply make a metal intake pipe... but I do have a mate who works at an Engineering place who should be able to dodge me up something.

See how we go.

[Beer Baron]

yeah the bov outlet must be feeding back in before the turbo but after the AFM. no good doing it post turbo.

as far as where to mount the bov? anywhere on the cooler piping is fine really. mounting it post intercooler is a good idea though. so somewhere between cooler outlet and the throttle body.

[No Crust Racing]

Cheers Rich

I should have it under control now, though I think I might end up mounting it pre cooler simply as there is already a spot for and it will keep my plumbing tidy.

[SargeRX8]

Also when plumbing it back in, try to point it towards the turbo inlet rather than straight down or towards the AFM. If the air hits the AFM, it will run like arse.

I had a metal intake that would stall every single time air flowed through the BOV. The way the pipe was designed could result in air hitting the afm and the engine filling up some fuel for the air causing the engine to stall because the throttle is closed.

[No Crust Racing]

Yeah had already considered that I'd want the air to merge as seamlessly as possible, but cheers for the tip anyway