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Joemart
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crankcase breather pipe - thoughts?

Post by Joemart »

Hi All

I have a question re the crankcase breather pipe - Originally, it ran into the air intake, which ran back into the plenum,...(i would have thought that this would then mean "contaminated" air back into the motor??), but I have since, in the last month or so, removed it from the intake, and am running it into an overflow bottle ...

Now the question - would this have an effect on power - maybe due to reduced crank presssure?? - I have noticed that the power has gone DOWN since then and am wondering if this could have an effect??

Help welcome

Joe
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Re: crankcase breather pipe - thoughts?

Post by Duk »

In standard form, the crank case gasses are drawn out of the engine by 2 means.
Firstly, there will be some vacuum between the airflow meter and the throttle body.
Secondly, the fitting that crank case breather attaches to, protrudes into the air stream. As air flow past the fitting, a lower pressure area is created which also helps to draw crank case gasses out of the engine.

By having the gasses venting to atmosphere, the gasses now vent to higher pressure than standard. So it's more likely there are more crank case gasses inside the engine causing drag.
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Re: crankcase breather pipe - thoughts?

Post by Mats »

Also, the amout of measured air is wrong since you vent to atmo instead of back into the intake.
Does it have a check-valve? Surely it must have..?
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GTV27
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Re: crankcase breather pipe - thoughts?

Post by GTV27 »

Unless your rings are stuffed and it is breathing very heavily, it will not impact on power. If your rings are stuffed, then your engine will be compromised on power anyway, so not much point. Also, the hydrocarbons that come out that hose are not good for you, so are much better put into the combustion chamber than your lungs.

Also, I think Mats is on the money re EFI impact - IIRC, even pulling the dipstick can cause the jetronic to skip a beat (or is that an urban legend?...can't check this on mine as it is sans AFM and is running on a MAP sensor).
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Duk
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Re: crankcase breather pipe - thoughts?

Post by Duk »

GTV27 wrote:
Also, I think Mats is on the money re EFI impact - IIRC, even pulling the dipstick can cause the jetronic to skip a beat (or is that an urban legend?...can't check this on mine as it is sans AFM and is running on a MAP sensor).
I'd say there would be a fare degree of truth in that 1.
Because the airflow meter is a flow restriction that the air has to push out of the way to make its way into the engine, even at low loads. By taking the dip stick out, air can go into the crank case via the dipstick hole, out the breather tube and end up in the inlet air plumbing behind the airflow meter. The crankshaft even turns the right way to encourage that :P
Because the engine can now get its (small amount of) air supply without deflecting the AFM, the computer won't know how much air is going into the engine and won't inject enough fuel.
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Re: crankcase breather pipe - thoughts?

Post by kterkkila »

There's not much flow coming from the engine and that's mostly exhaust and lubricant anyway. I would look reason for power loss from some other reasons.
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Re: crankcase breather pipe - thoughts?

Post by Joemart »

Hi All

Thanks for responses - I have now drilled a hole in the Air-intake and am running a pipe through to it...

no longer in the bottle... difference - Cant feel any :?
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