Catch Can install

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Optimistic
480 Newbie
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Joined: Thu Dec 30, 2021 2:01 pm

Catch Can install

Post by Optimistic » Mon Apr 18, 2022 2:46 pm

Hello,

Now that I have the engine out of the car, I have thought of installing a catch instead of the pcv oil breather system. I haven't seen any posts about it. Does anyone have experience with doing that, or could advise on whether to do it or not. Thanks.

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jamescarruthers
480 Is my middle name
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Re: Catch Can install

Post by jamescarruthers » Mon Apr 18, 2022 3:17 pm

Isn’t that an MOT fail at this age of car? You can safely get rid of the EGR if you have it though.
1987 Volvo 480 ES, 507274, 217 - Red (Ness)
2006 Citroen C6 Exclusive 3.0 petrol/LPG
2008 Mini Cooper convertible (Mau)

Previous 480's:
J123 CFU -- ES
J449 MNL -- ES auto
D864 CPV -- ES
L691 JFC -- Turbo
F70 MNR -- ES
H858 FGV -- Turbo auto
E981 KHM -- ES (509849)

Alan 480
480 Is my middle name
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Location: Aberdeen

Re: Catch Can install

Post by Alan 480 » Mon Apr 18, 2022 4:59 pm

Optimistic wrote:
Mon Apr 18, 2022 2:46 pm
Hello,

Now that I have the engine out of the car, I have thought of installing a catch instead of the pcv oil breather system. I haven't seen any posts about it. Does anyone have experience with doing that, or could advise on whether to do it or not. Thanks.
Cranna did (does) have one on the modified 480 he has, and it's been MoTd a few times. .. . . :wink:
Alan

480 ES 2litre x 2 (1 x Normal, 1 x 'Celebration' ? ), C30 1.8ES, SS1

Optimistic
480 Newbie
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Re: Catch Can install

Post by Optimistic » Mon Apr 18, 2022 5:05 pm

Are there any guides on how to do that or anything? Or should I contact cranna

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Jay-Kay-Em
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Re: Catch Can install

Post by Jay-Kay-Em » Mon Apr 18, 2022 6:19 pm

Not all catch cans are born the same!

When I was 17, I tore off my "pancake" air filter from the top of my Pierburg carb, and fitted a Pipercross. I was the king of the college car park. Problem was, I now had a stray PCV hose. I stuck this in an empty can of Stella. That, ladies and gents, is your most basic form of catch can and nothing bad will happen. I did many many miles, and apart from an oily mess in a can that you have to empty now and again, no discernible difference.

Nothing to stop you doing the same. Plug up your inlet manifold + inlet ducts of all the PCV connections, throw all the PCV stuff in the bin and vent to atmosphere. Easy and cheap.

Also, as an added bonus, crankcase emissions are not part of the MoT.

For a more boring answer, read on... :bored:

Our internal combustion engines are designed to have a slight negative crankcase pressure (aka vacuum). This has the following benefits :

a) the oil seals work better, seal better and make it that bit harder for oil to escape. This is especially true of O-seals like crank and cam.
b) the pistons have less resistance on the down stroke and stop acting like a massive air pump. Marginal I know, but engines are proven to be more efficient with negative crankcase pressure as there is less crankcase air to push about. Air has a surprising mass - just stick your hand out of a moving car window to imagine what a downward piston has to act against at 5500rpm.

PCV venting to atmosphere will have a slight positive crankcase pressure due to piston blow-by, as the trapped air struggles to find its route to freedom - all with the pistons thrashing away.

Because of which, the downsides of venting to atmosphere is a very very very small loss of power and an increase in MPG. You'd never in a million years notice, I know, but it's there.

All engines have their own "catch can" really, called the oil separator. This will be full of baffles and coarse wire catching the oil particles and letting it drain back down into the sump. The benefit of a vacuum fed remote catch can is that all this caught oil (full of contaminants, acids, fuel vapour and condensate) is caught remotely meaning better quality oil in the sump as it doesn't drain back. It also makes for a cleaner inlet manifold too. Factory oil separators on the engine tend to be very compact - whereas a remote catch can is able to be much larger and more efficient.

This is all fine when you have vacuum. Cranna has a naturally aspirated F7R(?). I don't know if his system is vent to atmosphere or still vacuum fed.

If you want to maintain a vacuum fed crankcase, then turbocharging gets more complicated. This is because your inlet manifold is rarely in vacuum apart from over run. I think you are a turbo Optimistic?

The B18FT PCV system is much maligned but it does three really clever things :

1) It can regulate a maximum vacuum value (not allowing too much vacuum, via a controlled orifice).
2) it has a one way valve function for when the inlet manifold changes from vacuum to boost.
3) its multiple path - so when the inlet manifold is in a boost condition, it changes the PCV route to ahead of the Turbo.

You can do the above three things all with commercially available Audi parts for the BAM engine. One day I will do a "how-to" but I feel slightly guilty giving advice when I haven't done a single road mile with it all!

Venting to atmosphere is fine, but it's just not cricket :lol:

cranna21
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Re: Catch Can install

Post by cranna21 » Wed Apr 20, 2022 7:36 am

I feel like some form of mystical catch can deity :rofl:

SO:

Previously when my car was more standard, i did as Jay-Kay-Em hints at, on my original 1.7, i removed the pipe that comes from the oil breather/separator on the front right hand side of the block i don't have a picture to hand but someone might be able to help, its cylindrical and positioned kinda under cylinder 4 spark plug, has a single hose coming out the top of it, the hose and separator usually have some form of foam around them. So i removed that hose and its connection back up into the rubber boot that runs from air filter box to throttle body and at first bunged the hole left in the afore mentioned rubber boot and then ran a silicone hose from the afore mentioned now open oil seperator to a small air filter and vented to atmosphere, this made a hellova mess of oil residue in the bay so i cleaned it up and bought a chinesium ebay catch can, plumbed it into there mounted it somewhere on the passenger strut tower from memory and stood back to admire my work and it was like that for years! the only modification it received after that was that i swapped the 1.7's rubber air filter box - throttle body boot for a 2.0's one, as it has one hole less due to the oil seperator/PCV set up on it being a little different and that saved the need for a dodgy bung in a pipe.

moving on to these days i have a 16v F7R fitted as mentioned and these have a different set up entirely, but you'll see below hopefully what i have set up now, i think back in the day i had the old catch can mounted very similarly:

Image

hopefully this helps!
'91 480 ES 2.0l 16v 'Williams' Conversion - 208bhp/230nm
'90 940 GL 2.0l Estate
'09 S40 D5 Manual R-Design

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