Richard_M Posted November 7, 2010 Share Posted November 7, 2010 Had the race car out for a first post-rebuild test this week, 18 months into the project. It's a 1296 Spit based engine with the usual race upgrades. The crucial difference over standard for this thread being that it revs to 8500 and beyond.Pretty much all went well - great power, blinding handling and good brakes.One big issue did emerge - the engine was pushing oil out of the dipstick hole. It did this with the dipstick in, and with a pipe attached routed to the top of the head, so I figure the unscheduled oil exit is due to presssurisation of the crankcase at high revs.So, what to do? Gotta do something with the oil, or I'm going to get black-flagged every time out ;)I'm thinking I need a crankcase breather. Maybe from the unused petrol pump orifice. This would give the oil somewhere to go and avoid the high crankcase pressures, but wouldn't it just be an efficicent way of losing my nice Motul oil? How do I do this in such a way as to minimise oil loss?High revving wisdom sought please....ThanksRichard Link to comment Share on other sites More sharing options...
Clive Posted November 7, 2010 Share Posted November 7, 2010 If you want a breather, the petrol pump orifice will probably be the best bet. I would fit a plate with a 90degree bend going vertical, as large a bore as possible (maybe 15mm copper pipe, 22 may even work?) and then take that up to a catch tank. Any oil thrown out should drip back down? may be worth sticking a small baffle too, to go inside the orifice (great word that ;D) Link to comment Share on other sites More sharing options...
Richard_M Posted November 7, 2010 Author Share Posted November 7, 2010 Thanks Clive.I guess a vertical copper pipe that tapers as it goes up would be best to induce oil condensation (working on whisky distilling theory ;) ).By 'small baffle' do you mean a gauze/filter type thing?R Link to comment Share on other sites More sharing options...
Clive Posted November 7, 2010 Share Posted November 7, 2010 I would have thought a flat plate, to stop most of the oil splash.I don't think oil condesation will be the issue, just stopping the liquid should do the trick! But yes, I like coper as fittings are easy to find and work. Plus it can be soldered to steel easily enough. On the point of baffles, the pipe could enter the block, and have a tab bent over at the end, sort of thing? plus thinking about it, the pipe may well nit want to be at right angles when entereing the block, but angled up to help the oil drain back. Maybe a 45degree or something? Link to comment Share on other sites More sharing options...
Richard_M Posted November 7, 2010 Author Share Posted November 7, 2010 Mmm - I see - thanks again.Sounds like a bit of braize/solder fabrication. I'll tie in the rocker breather to the same circuit, and maybe put the catch tank inboard where the welded shut battery area is.Ta muchlyRichard Link to comment Share on other sites More sharing options...
cammmy Posted November 7, 2010 Share Posted November 7, 2010 I would definitely have a windage tray made. I put one on my pug (which only goes to 7,400) and the difference was huge! At 8,500rpm it would be noticably more free revving.Also, depending on legality. Pipe connecting to crankcase that bends upward, then route it down and blend into the exhaust at a very shallow angle, so it goes with the flow . The exhaust going past will create a vacuum which draws out the vapour from within the crankcase. This should also free up power as your motor won't be spending energy trying to pressurise the crankcase. Will also help keep your rings seated.If you cannot do that, enquire about whether you can if you put a catch can with gauze filter between the crankcase and exhaust.Check out the 4 stroke performance tuning guide for a better explanation of the above. Link to comment Share on other sites More sharing options...
Nick Jones Posted November 7, 2010 Share Posted November 7, 2010 Not sure about connecting breather to exhaust.......?!This is interesting though:http://www.teglerizer.com/triumphstuff/emissions/index.htmNick Link to comment Share on other sites More sharing options...
cammmy Posted November 7, 2010 Share Posted November 7, 2010 It ALL comes down to the angle of the join.There's more detail in this book:TBH. If you are building a race engine, you should probably own this anyway. Link to comment Share on other sites More sharing options...
JohnD Posted November 8, 2010 Share Posted November 8, 2010 I've used the fuel pump orifice for a crankcase vent for many years, and had no probs, but that's on a six cylinder.Another approch is to design a system that vents the crankcase from the rocker cover to a catchtank, and drains the catchtank back into the crankcase via that opening. Several TR racers do this. Of course, you return water as well, but if you're a racer, then you'll change the oil frequently.JOhn Link to comment Share on other sites More sharing options...
Richard_M Posted November 8, 2010 Author Share Posted November 8, 2010 Thanks for the input all!John - like the pic - Silverback, I get it ;)Windage : My sump is baffled, with a tray near the top over the majority of the oil - so maybe that will prevent some of the potential crank/oil vortex. A proper windage device may be a good idea, but its something for the future for me.Exhaust assist : Sounds interesting, and ensures a persistent neg pressure in the crankcase. Worth looking into over the winter ready for 2011.Catchtank : Seems the most viable short term. Probably a combo of Clive and JohnDs ideas. Richard Link to comment Share on other sites More sharing options...
cammmy Posted November 8, 2010 Share Posted November 8, 2010 If you already have a windage tray type device and are looking at having something else made. Check out a windage tray/crank scraper.This is what I have on the pugThe raised lip is very close to the crank. This effectively scrapes the oil off without quite touching it. Again, reducing drag on the crank and I believe it also helps cooling by scraping hot oil off and allowing cooler oil on in cycles (not sure how big an effect that has though)You can have custom bits made from teflon that fit the profile of the crank near perfectly, these can actually touch it for a better scraping effect, without damaging anything.Worth researching as at the RPM's you are running, reducing windage make a big difference. Link to comment Share on other sites More sharing options...
Roger Keys Posted November 8, 2010 Share Posted November 8, 2010 A windage tray wuld be good, but if you are fitting a breather you need some of that crushed slivers of metal or a plastic equivalent in there. This will take the oil out of suspension, allowing the air up and the oil down. Link to comment Share on other sites More sharing options...
spunkymonkey Posted November 8, 2010 Share Posted November 8, 2010 Not Triumph related but the little Daf 2 cyls suffer from pretty severe crankcase compression (something to do with two opposing cylinders shooting towards the crank case at the same time apparently :P ) To cope with it they have a breather from the crank case to the air filter housing with a "Carter" valve - a rubber tube (about 5/8" diameter) tapered on two sides to form a slit valve. As the valve pulses with the airflow, any oil mist in it condenses out and drops straight back into the sump. May be possible to do something similar from the fuel pump hole? Link to comment Share on other sites More sharing options...
cammmy Posted November 8, 2010 Share Posted November 8, 2010 roger_keys wrote:A windage tray wuld be good, but if you are fitting a breather you need some of that crushed slivers of metal or a plastic equivalent in there. This will take the oil out of suspension, allowing the air up and the oil down.Do you mean some gauze/steel wool type material? Link to comment Share on other sites More sharing options...
JohnD Posted November 9, 2010 Share Posted November 9, 2010 Triumph used to do that (Steel wool in the vent).Many late Six rocker covers have a metal box, spot welded inside the cover, over the exit hole.The box had steel wool inside.In my experience of worn-out, neglected engines for rebuild, the wool is so full of condensed crap that the vent is blocked!So if you go that way, make sure the wool is easy to get at and change it frequently.John Link to comment Share on other sites More sharing options...
AndyV Posted November 12, 2010 Share Posted November 12, 2010 In a race car the simplest solution is the best, so a breather from the fuel pump hole fits the bill, T into your rocker breather and lead to a 2litre catch tank. Inboard where your battery was works well but be prepared to defend its location to scrutineers (as I have sucessfully done many times, don't forget you'll need to drain it too)The less hose/fittings you use the less weight you add.Windage trays are good but lets get you out on track first (when you make one, do one for me too)pics of my breather attached:CheersAndy Link to comment Share on other sites More sharing options...
Richard_M Posted November 13, 2010 Author Share Posted November 13, 2010 Thanks Andy - nice of you to share hard won race info in pictorial form.The breather is taking shape, I'll post pics soon!R Link to comment Share on other sites More sharing options...
Roger Keys Posted November 14, 2010 Share Posted November 14, 2010 880 wrote:Do you mean some gauze/steel wool type material?Yes indeed! Link to comment Share on other sites More sharing options...
Richard_M Posted November 17, 2010 Author Share Posted November 17, 2010 Finished the breather today - thanks for all your input guys.I've gone for a pragmatic, achievable first solution and will test it thoroughly at a track day on 3rd December.Here's a couple of pics - it's similar to the idea that Andy posted, but the tube is baffled and enters the crankcase by about 40mm. Much use has been made of copper plumbing bits!Here's the raw item, showing baffle (22mm end cap) and steel blanking plate (twice, and I can't work out how to delete a pic!!): Link to comment Share on other sites More sharing options...
Richard_M Posted November 17, 2010 Author Share Posted November 17, 2010 And here it is on the engine: Link to comment Share on other sites More sharing options...
Richard_M Posted November 17, 2010 Author Share Posted November 17, 2010 The T piece at the top receives from the rocker breather and takes the combines oily haze through the bulkhead to a catch tank in the passenger footwell.I now have to devise a way of venting the catch tank!R Link to comment Share on other sites More sharing options...
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