Car in bits again...
AO Silver Member
Join Date: Feb 2007
Location: Hampshire, UK
Switched to K&Ns, what about the crankcase breather?
Hi guys - I've been running a pair of K&Ns for the last year or so, and they are great, but I am concerned about the crankcase breathing on my 1.5 Ti twin-carb.
I have retained the breather hose from the oil filler tube to the little plastic condenser/oil separator, and the 4 smallbore hoses that go to each inlet manifold. But the vacuum generated by these hoses is very small (probably so as not to upset the mixture below the carbs), so most of the scavenging must be done by the larger (~10mm ID) hoses that connect to the cast alloy "elbows" normally fitted to the top of the carbs - am I right?
Trouble is, these pipes have nowhere to go on the K&N setup - the hoses essentially vent to air. I know you can get a little adapter plate that allows you to connect the hose to the filter itself, but as its getting its air from all around, there will be very little vacuum generated in the hoses to scavange the oil vapour from the crankcase.
My engine seems to get very oily in use, and I would like to sort out a more effective scavanging system to see if that might help. Failure of this feature on my Barracuda caused oil to blow out of the dipstick etc. which is why I am thinking along these lines.
I don't use the vacuum servo connection at the base of the offside carb inlet manifold. This is ~10mm OD, same as the breather pipes.
Would I be able to hook one breather pipe to this inlet and then plug the other side so as not to create a mixture imbalance? Or would this burn too much oil on one bank of cylinders?
Would my best bet be to fabricate some airboxes for the K&Ns so that I can control the partial pressure and improve the scavanging?
I've got spare ~10mm OD take off ports, and the inlet manifolds have blanking plugs on the unused ports. Could I put a take off on each cylinder bank to equalise the scavanging effect?
Sorry if this seems trivial, but there is just soooo much oil around the engine. I suppose the easiest test would be to put it back on the road with the original Alfa air cleaner, but I just love my K&Ns too much!
Alfanauts are GO!!!