24 replies to this topic

[purple_fly06]

Sorry to hijack this thread, I've done a fair bit of reading on breather set up and have come to the conclusion that there are multiple ways to achieve it. 

 

I'm in the process of rebuilding my mini and I am using the SC EFI system. The issue I have is there is no where to run my breather hoses back to like I would've have had on my previous SU.

 

On my old carb I had a "pipe" coming from the inlet manifold (I believe this was for a servo?). I'm planning to run my breather hoses to an oil catch tank, then rather than vent to air I'll return to this "pipe" (in red). This means I am still using a closed system, venting the crankcase and preventing the majority of water vapour and oil residue from going back into the combustion cycle of the engine. I am not running a servo so this connection is currently un-used.

 

Would connecting to the "pipe" (in red) be a suitable alternative connection in the absence of having the SU type connection?

 

 

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Edited by purple_fly06, 17 May 2023 - 12:29 PM.

[nicklouse]

That would work. But any suitable hose plumbed in to the engine side of the throttle butterfly will be fine.

[purple_fly06]

That would work. But any suitable hose plumbed in to the engine side of the throttle butterfly will be fine.

 

That's great, thanks for confirming 

[DeadSquare]

Sorry to hijack this thread, I've done a fair bit of reading on breather set up and have come to the conclusion that there are multiple ways to achieve it. 

 

I'm in the process of rebuilding my mini and I am using the SC EFI system. The issue I have is there is no where to run my breather hoses back to like I would've have had on my previous SU.

 

On my old carb I had a "pipe" coming from the inlet manifold (I believe this was for a servo?). I'm planning to run my breather hoses to an oil catch tank, then rather than vent to air I'll return to this "pipe" (in red). This means I am still using a closed system, venting the crankcase and preventing the majority of water vapour and oil residue from going back into the combustion cycle of the engine. I am not running a servo so this connection is currently un-used.

 

Would connecting to the "pipe" (in red) be a suitable alternative connection in the absence of having the SU type connection?

 

 

It wouldn't be my choice way of doing it.

Every time your engine is over-running, there will be a high vacuum in your engine/gearbox, trying to suck crudd in past the diiff oil seals.

Edited by DeadSquare, 17 May 2023 - 01:43 PM.

[Lplus]

 

Sorry to hijack this thread, I've done a fair bit of reading on breather set up and have come to the conclusion that there are multiple ways to achieve it. 

 

I'm in the process of rebuilding my mini and I am using the SC EFI system. The issue I have is there is no where to run my breather hoses back to like I would've have had on my previous SU.

 

On my old carb I had a "pipe" coming from the inlet manifold (I believe this was for a servo?). I'm planning to run my breather hoses to an oil catch tank, then rather than vent to air I'll return to this "pipe" (in red). This means I am still using a closed system, venting the crankcase and preventing the majority of water vapour and oil residue from going back into the combustion cycle of the engine. I am not running a servo so this connection is currently un-used.

 

Would connecting to the "pipe" (in red) be a suitable alternative connection in the absence of having the SU type connection?

 

 

It wouldn't be my choice way of doing it.

Every time your engine is over-running, there will be a high vacuum in your engine/gearbox, trying to suck crudd in past the diiff oil seals.

 

Agreed, any breather plumbed in downstream of the throttle butterfly should have a pcv valve to restrict flow into the manifold.

[purple_fly06]

I was planning to put something like this in between the catch tank outlet and the inlet manifold:

 

https://www.carbuild...rn-valve-12mm-2

 

Wouldn't this rectify concerns you've both mentioned?

[DeadSquare]

I was planning to put something like this in between the catch tank outlet and the inlet manifold:

 

https://www.carbuild...rn-valve-12mm-2

 

Wouldn't this rectify concerns you've both mentioned?

 

 

Please forgive me if I am wrong, but I read the original post to mean that your proposed system is totally sealed from the engine vent to Inlet manifold, with no vent to air anywhere that might alter the equilibrium of the fuel air ratio.

 

If this is the case, adding a nonreturn valve will retain a partial vacuum in the engine/gearbox for longer than if the valve were not included.

[purple_fly06]

 

I was planning to put something like this in between the catch tank outlet and the inlet manifold:

 

https://www.carbuild...rn-valve-12mm-2

 

Wouldn't this rectify concerns you've both mentioned?

 

 

Please forgive me if I am wrong, but I read the original post to mean that your proposed system is totally sealed from the engine vent to Inlet manifold, with no vent to air anywhere that might alter the equilibrium of the fuel air ratio.

 

If this is the case, adding a nonreturn valve will retain a partial vacuum in the engine/gearbox for longer than if the valve were not included.

 

 

I may also be wrong, so the intention currently is to:

 

1. Run the 2x Engine breathers to oil catch tank (in side)

2. Oil catch tank (out side) to inline PCV

3. Inline PCV to inlet manifold

 

Unlike the previous standard setup I had which just piped back to the carb with no catch or PCV, I think this setup would screen off the majority of oil/water vapour whilst allowing the crankcase pressure to remain lower and have a minimal effect on combustion (although on a road car I'm not too concerned about this).

 

I'm hoping that this would be a suitable solution without having to rely on a race style "vent to atmosphere" oil catch tank.

[Lplus]

I was planning to put something like this in between the catch tank outlet and the inlet manifold:

 

https://www.carbuild...rn-valve-12mm-2

 

Wouldn't this rectify concerns you've both mentioned?

No, that isn't what I called a PCV valve (possibly incorrectly).  The valve I'm talking about is item 1 on http://minispares.co...ts.aspx?1~2~27  which minispares calls an emissions control valve.  The idea is to prevent the vacuum in the crankcase getting too high.  A simple non return vavle won't do that.  Any breather system which doesn't have one of those vacuum restrictor valves must be placed upstream of the butterfly/slide or whatever SC use to restrict air flow.

Edited by Lplus, 17 May 2023 - 03:22 PM.

[Spider]

Sorry to hijack this thread, I've done a fair bit of reading on breather set up and have come to the conclusion that there are multiple ways to achieve it. 

 

I'm in the process of rebuilding my mini and I am using the SC EFI system. The issue I have is there is no where to run my breather hoses back to like I would've have had on my previous SU.

 

On my old carb I had a "pipe" coming from the inlet manifold (I believe this was for a servo?). I'm planning to run my breather hoses to an oil catch tank, then rather than vent to air I'll return to this "pipe" (in red). This means I am still using a closed system, venting the crankcase and preventing the majority of water vapour and oil residue from going back into the combustion cycle of the engine. I am not running a servo so this connection is currently un-used.

 

Would connecting to the "pipe" (in red) be a suitable alternative connection in the absence of having the SU type connection?

 

I wouldn't be connecting full manifold vacuum to the crankcase !  It will suck a lot of oil out in very short time.

 

If it were me, I'd run a PCV System. Pop in to your local Auto Parts store and they'll likely have a rack of PCV Valves there. There's several In-line types as used on some of the smaller Japanese cars, that has 12 or 13 mm fittings, fit one of the between the Crankcase Oil Separators and the Port in the Manifold. Note that they do need to be fitted the right way around, they have in them a non-return valve.