Ok anyone want to discuss catch tank designs? I'm thinking of fabricating a new catch tank for my valver and am considering a few things. First of all the catch tank I run is just the standard screen wash bottle that has a breather pipe in from the 16v engine block, it then runs a line out, up to the back of the ITB filter plate, this is so that any fumes are recirculated and do not enter the cabin because the smell gets on my nerves. The problem with the catch tank is not what it is or it's construction, it is the fact that the oil vapour seems to pass straight through the catch tank and then hit the air filter and pool at the ITB trumpets! Not great, any of the generic catch tanks would do the same I guess at a guess. Im planning to therefore baffle the tank to make the vapour deposit into the tank and not the air filter. Thinking about materials that are light weight for this, stainless steel scouring pads or foam similar to the air filter (as this seems to work well at the filter end!). Any thoughts on the above? how would you build your ideal catch tank? Would you add anything else? Cheers Tom
the cup car we built ran was one of these http://www.demon-tweeks.co.uk/Produ... Catch Tanks&gclid=CObSrZ3NhLUCFW7HtAodemcAmA bolted to the inner wing, there is a wee clear tube that acts as a sight glass between the two tubes on the side. Which is handy to enable you to drain it before it gets too full. the suggestion of the scotch bright type stuff (or wire wool) would be a clever addition If you are trying to keep the oil vapor to a min then running quite a long pipe to the tank would let the vapor cool before it gets there.
Good topic Tom. Most decent tanks have baffles on the inlets so that the vapour catches on these and pools in the tank instead of staying vapour and being sucked out into the inlet/airfilter. I would imagine your tank has a bit of a vaccum caused by being plumbed straight back to the inlet which may not help? I assume the washer bottle is sealed apart from the inlet & outlet? I bought myself an OBP 1ltr baffled tank when they had a sale. Looks a really nice bit of kit ( haven't tried it yet, cars still not running ). It has two inlets which are baffled, and one outlet on the top which is separated from the rest of the tank by another baffle so in theory should stop oil from escaping. linky Cheers, Bruce.
What about a bigger return pipe to lower the presure to the tip thus leaving more oil molicule's behind?? I dont have a clue to be honest still sussing out how to plumb one to my engine.. lol but i'm liking the thinking of this
What i hate about the catch tanks available off the shelf is the diameter of the outlets. Im running a catch tank on my Mk2 1.8T, in place of the PCV system. The smallest hose i could use was 19mm, due to the size of the oil breather outlets, so i had to slightly modifiy my catch tank outlets to suit the piping!
Good points guys, I run lines close to the size of the OEM pipes and my washer bottle is sealed. I like the look ofhe tanks in the links and want to know what there baffles look like, very interested to see hoe they differe fron the cheap rubbish and feel the baffle is key. To keep an eye on the levels I will use clear pipe fixed with banjo connections.
Indeed the baffle is the key because some particles can travel back to the inlet. So you want a very good baffle design
Goods points cerips, I like the idea of the pipe internally, I was also thinking about a small cheap air filter, putting on on the end of the inlet pipe would force the vapour to pass through it and hopefully condense. I wander if the filter would last long in this situation, it would be covered in oil...
Think you'd be ok with an airfilter on the top as long as the outlet is baffled too. Will try take some pics of my setup later.
What about using something like a heater matrix, that should condense the vapour well and be cheap as chips to boot?
That would work but I don't want the fumes, that's why I want to recirculate them to the filter plate.
I have been thinking about the problem of the vapour some more. Ideally I would want to keep all the oil vapour in the engine and just vent any crankcase gas build up. Comparing the 8v to 16v engine, it seems the valver breaths 'heavier'. I cannot see that 8 more valves is the cause, it could be the higher revs? But I'm not convinced either. I think that it is more to do with the position of the breather system and their construction. The 8v breaths from the cam cover so vapour has more chance to deposit the oil, the 16v breather is positioned part way down the block. The 8v also has a mesh system in place to stop oil vapour leaving the engine, the valver does not seem to have anything like this in place, so the oil vapour is free to exit the engine. Prehaps I should be looking at improving the 16v block breather system and making the oil condense at the block like the 8v. Thoughts on this please? Would keeping the oil vapour in the engine be detrimental? Seems the 8v is not effected by it.
i have a swirl pot before my catch tank, so i just empty catch tank every so often, tends to keep things alot cleaner Also this way i have an outlet from tank which vents near the mid exhaust section, so no fumes in the car
I went outside and took off the 16v breather flange. I think a simple way to make the vapour stay in the engine and condense is to add a machined billet of Ali into the end of the flange, it has many small holes drilled into the end which pokes into a void, these small holes should help the vapour to condense keeping more oil in the engine and less in the catch tank. Just for Jon another quick sketch!
^^^^ I was about suggest, a tube or angled plate with 2-3mm holes is better as a coalescing medium than steel wool.
Nice engine bay, how does the swirl pot work, it looks like there are three connects pipes? Where do they lead to come from?
Why not graft a flying saucer type breather oil separator to the outlet from the block - such as found on the 8v rocker cover.
