K&N Top Hat filters on 911 - breather options?

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Gary71
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K&N Top Hat filters on 911 - breather options?

Post by Gary71 »

I’ve got a set of K&N top hat filters I’d like to fit at some point but they don’t have any connection for the oil tank breather.

Any thoughts and suggestions on connection points/plumbing?

I’m running the original Zenith carbs and need to make new base plates anyway.

Thanks!
Lightweight_911
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Re: K&N Top Hat filters on 911 - breather options?

Post by Lightweight_911 »

.

If it was me I'd fit a separate (unobtrusive) oil catch tank in the right rear - similar position to that used in the Factory competition cars.

.
Andy

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- subtracting weight makes you faster everywhere”
neilbardsley
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Re: K&N Top Hat filters on 911 - breather options?

Post by neilbardsley »

I have an oil breather catch tank in my 914. Much better than pumping it into the carb. IMHO

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Gary71
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K&N Top Hat filters on 911 - breather options?

Post by Gary71 »

Lightweight_911 wrote:.

If it was me I'd fit a separate (unobtrusive) oil catch tank in the right rear - similar position to that used in the Factory competition cars.

.
Due to the wonders of Instagram (occasionally wonderful!) I’ve got these pictures and diagram of the 911R installation from Ernie. Tank vents down to the road.

Image


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Image

Image
Lightweight_911
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Re: K&N Top Hat filters on 911 - breather options?

Post by Lightweight_911 »

.

There's some info & pictures here:

http://www.ddk-online.com/phpBB2/viewto ... nk#p311856

Unfortunately the prices asked for the earlier swb washer reservoirs as used in the 911R, etc are (IMO) ridiculous - & even the '68-on washer bottles (as used for oil catch tanks on later Factory competition cars) have become expensive so I'd be inclined to find a 'generic' (ie cheaper) solution (but I'm a cheapskate :wink: ) ...

.
Andy

“Adding power makes you faster on the straights;
- subtracting weight makes you faster everywhere”
Gary71
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Re: K&N Top Hat filters on 911 - breather options?

Post by Gary71 »

Absolutely. I’ve got an old Castrol tin can that will be repurposed!

Originality or period correct is for other people :)
911hillclimber
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Re: K&N Top Hat filters on 911 - breather options?

Post by 911hillclimber »

Just my 2 pence
I have a Lotus Elise 'clear' catch / breather tank on my Lola's engine.
The feed to it is from the top of the dry sump tank into the catch tank.

If the catch tank is not 'clear' then it is easy not to see if it is filling up, though a good engine won't be discharging heavy oiled air into it.

The clear catch tank is simply vented to atmosphere.

The old Castrol can will look a million times better!

The top hats again on the Lola have a 20mm hole cut into the top pressing along the side. They are K&N supply for Webers/PMO's.
I think the idea is the breather hose is simply connected to this and the breather air simply blows onto the external surface of the air filter itself locally, the engine ingesting some level of oiled air for combustion.
Crude and messy if the engine has heavy oil in the breather fumes.
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
Gary71
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Re: K&N Top Hat filters on 911 - breather options?

Post by Gary71 »

The standard 911 air cleaner has a little strainer on the breather return that drains to under the car if I remember correctly.

The inside of my air box is pretty clean so I’m not worrying too much about heavy breathing.

Once I’ve got it all set up I’ll monitor how much ends up in there over a few hard drives and make a call.

I need to make up bases and stuff for them first so plenty to be done first :)
911hillclimber
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Re: K&N Top Hat filters on 911 - breather options?

Post by 911hillclimber »

Yes, a gauze type filter on my 2.4 when I had one.
In all my thrashing years with the Lola, never had anything in the catch 'can'.
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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