GaryM
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| posted on 2/6/08 at 06:26 PM |
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Xflow crankcase breather venting
As one of my winter upgrades, i've replaced my xflow's original PCV arrangement (recriculated into inlet manifold) with a breather and
catch tank.
It works OK but I was quite surpised how much the engine 'breathes' through the crankcase vent.
At present I have the crankcase vent plumbed into one end of my rocker cover and the (vented) catch tank plumbed into the other (well a vented oil
filler cap actually). The theory behind this (I read) was to allow any droplets of oil that make it out of the crankcase to recirculate back to the
sump through the top of the engine.
Should I be concerned that the hot crankcase gases (mostly exhaust blowing by the rings i guess) is passing through my rocker cover before being
vented to atmos?
Cheers
Gary
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AndyGT
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| posted on 2/6/08 at 07:38 PM |
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no need to worry. The only thing is you might smell some of the fumes when the car is running, stationary and hot.
Its better for the engine as now it can take in just air and fuel and not a mix with crankcase. You may even notice a slight increase in mpg figures.
Unfortunately some of the nasties will be released into the atmosphere!
In my escort, I ran the access fumes through the chassis leg. Needless to say that the chassis legs have zero rot in them.
nothing is impossible
everything is possible
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andylancaster3000
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| posted on 2/6/08 at 07:53 PM |
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Not a x-flow but theory is the same. We had the same issue with a CVH. In a previous in'car'nation the engine was dry sumped. In this form
the breather from the crankcase and head both went to the catch tank. There never was any problem with it breathing heavily and blowing oil out.
However, as it is dry-sumped you have a wacking great skavenge pump sucking out the contents of the sump and crackcase which is where the contents
would tend to go.
Since the engine has been in the seven it has been reverted to wet-sump for class regs. Didn't give a significant amount of thought to breather
plumbing and plumbed it in the same way. For the first couple of runs it was blowing A LOT of oil out. We found this suprising as the
bores/pistons/rings were known to be in good condition and there is trap in the CVH crankcase breather to help prevent this from crank windage etc.
Reverted to they method you mention above (and since found out that is how it is in the car as standard) and the problem disappeared. So IMO it should
be ok. There really shouldn't be that much blowing by the rings unless of course it is rather tired, even on a x-flow! 
[Edited on 2/6/08 by andylancaster3000]
[Edited on 2/6/08 by andylancaster3000]
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