20 replies to this topic

[Mei]

Hi all,
i know that the Mini's breathing system hooked up to the Carb is a good system and there is no need to change it....however if i was to add more breathers and hook them up to the closed system going to the Carb, would this help a performance engine, and can i over breath the engine, so i could have 1 from the Rockers, 1 over the Transfer, 1 from the Dizzy hole, 1 from the Fuel, 1 from Tappet Chest and one from the timing chain..would this be completely useless or harmfull for performance...so what im asking in essence, is..
Can you OVER breath the Positive Crank case breathing system for the mini?

Mei

[liirge]

I would say all those Breathers are a little unnecessary, Breathing helps the engine alot, like on a 998 that only has one Breather, one of the best things to cure oil leaks and to help the engine is to add another breather, this is a necessity on a performance small bore to get the most out of it. i would say that 2 breathers are probably anough for any A-series, 3 at max

Edited by liirge, 01 June 2009 - 06:35 PM.

[Retro_10s]

It wouldn't do your mixture much good - the breather system running to the carb is already diluting your fuel mix with an oily mist and this would only increase by adding more breathers.

It's not completely useless - but probably more pointless than anything else.... If you want a breather system that really does do something positive for the engine try Googling the word 'EVACUSUMP' and i'll quote daid iazard for how good this system is for relieving crankcase pressure

The system is effective enough to turn a real smoker into a clean burner

Even worn oil control rings can prove capable of good oil control.

the system pretty much eradicates crankcase pressure by sucking it out....

[liirge]

Wow that evacu system looks pretty good, You know anyone that sells it in a Kit kind of form? Interesting to see different breathing systems, i think if explored properly there could be some gains from it.

[Retro_10s]

Yes i've been half tempted to run it myself for a while but it's probably something i'll look into once i have some spare time to mess with engines - only needs a few bits and bobs and can be plumbed in directly to the crankcase breather the mini already has...

takes a lot of pressure off seals - and of course - the benefits on the piston rings are immense.

i think if explored properly there could be some gains from it.

Vizard has explored/built and tested the system and is very positive about it! good enough for him is good enough for me

[liirge]

So the breather canisters already do the job of the Air to Fuel Seperator, and the one on the tappet chest is about the right height. If this is then plumbed into the exhaust after an LCB Y-piece or after the 3 - 1 of the Cooper freeflow. What would you use to plumb it into the exhaust that is both air tight and heat resistant?

[Retro_10s]

You could buy a metal valve and get it threaded to screw into the exhaust pipe - or weld it in.

[liirge]

hmm i think im really going to look at that as ive got one Mini that wants good breathing for performance, and ive got one Mini thats smoking like old boots, so if i can make a system to suit both problems that would be brilliant. Im thinking people like Car builder sollutions might be able to sort me out with some stuff.

[liirge]

Further Thoughts into this
Would the Following system work..

Questions about it:
1. Would i need to involve the Intake System, as surely the exhaust system always has a vacuum?
2. Would the Exhaust side need a PCV valve aswell as a 1 way valve?
3. Do i need an oil catch tank?
4. If i need a catch tank, where would the best place be to return the oil to the sump, if at all?

[Retro_10s]

from Vizards book- this is why the PCV is needed:

At idle - the vaccum in the intake manifold draws air out of the crankcase through a PC valve. When the engine is under load there is no vaccum in the intake manifold because the the butterflies will be wide open on the carb.

Under such conditions, the high speed passage of the exhaust in the collector part of the exhaust manifold will cause suction on the pipe connected to the anti backfire valve. This will draw air out of the sump.

The anti backfire valve also seals the system at idle so that the exhaust isn't drawn into the intake manifold via the crankcase and the PCV valve.

[liirge]

That's what i read, but i was wondering if we take the intake system out of the PCV completely...there is surely going to be enough vacuum from the exhaust, pretty much all the time even at idle, to use for the PCV system. so thats why a PCV valve isnt needed, The Anti backfire valve only activates if there is gas coming back up from the exhaust, not into the exhaust.
Have i missed something completely?

Edited by liirge, 01 June 2009 - 08:15 PM.

[Retro_10s]

i think there isn't enough at idle liirge.

I need to sit down and stare at the plan Vizard has made for a bit to understand it.

I know that Sproket knows of this mod too...

[liirge]

Hmm, maybe there isnt at idle then, there's a high Vacuum at the intake on idle, i know that, so it ,might be higher than the exhaust hense in vizards the oil mist goes there, but if intake is taken out of the equation completely i wonder if it would still just go through the exhaust...

[998dave]

Further Thoughts into this
Would the Following system work..

Questions about it:
1. Would i need to involve the Intake System, as surely the exhaust system always has a vacuum?
2. Would the Exhaust side need a PCV valve aswell as a 1 way valve?
3. Do i need an oil catch tank?
4. If i need a catch tank, where would the best place be to return the oil to the sump, if at all?

Not the best idea, would really mess up your emissions come MOT time, plus the exhaust really isn't a vacuum due to the silencer causing back pressure, it's just the exhaust is at lower pressure then inside the cylinders! Also how are you going to remove all oil mist without creating back pressure, (the one way valve will create back pressure too), and effectively pressurise your exhaust system, you'd be better to put it through a carbon canister and filter then straight to atmosphere.

Hmm, maybe there isnt at idle then, there's a high Vacuum at the intake on idle, i know that, so it ,might be higher than the exhaust hense in vizards the oil mist goes there, but if intake is taken out of the equation completely i wonder if it would still just go through the exhaust...

The intake is at lower pressure then the crank case, (itself pressurised by blow-by), so the air flows round, you could create some form of pumping system to evacuate this air, which I presume the Evacupump (sp.) system does.

I'll see if I can think of anything that may work and be quite simple.

[King_Rodney]

Just following the Vizard plans is the easiest option - it works.