Oil Catch Can Splatter

[Graham Hutton]

I spoke with Tony (workshop manager) at Williams Automobiles today and he reckoned no need to vent it at all just stick a bung in the top or use something like that sexy Fiesta ST one. Interestingly he says that the duratecs tend to push much more oil into the catchcans than the Sigmas, presumably they have more crank windage or something. Apparently the sigma catch cans can sometimes be half full at service whereas, I have no more than a few ml in the bottom of mine.

I'd love to see your final install Beagler!

Cheers all

[aerobod - near CYYC]

With a dry sump Duratec and the oil at the right level in the tank (5mm below centre baffle when hot), I don't get more than a couple of millimetres in the catch tank after hard track use, even with slicks on and keeping it between 5,000 and 7,800 RPM all the time.

[ScottR400D]

#27 certainly the case for me too. In 7 years I've never had to really empty the catch bottle, though I have cleaned it of a trace of oil/condensation a couple of times. 
 

 

[7 wonders of the world]

Running the DS 'sealed' reduces the discharge too as the volume of air is significantly less.

[Beagler]

Graham,

New Catch Can should be here on the 17th will post pics subsequent.

Just thought wont be fitting it to front engine spare tapped holes due to vibration. Will attach to Chassis.

[Graham Hutton]

I've done a thing! I have fitted a breather to the top of the catch can instead of the overflow pipe as I need to get the car back on the road for the Taffia run this weekend. It was an easy mod using a spare rubber gater (from the ball joint on the end of the front ARB) and a cheap crankcase breather filter I picked up at Halfords for £6.99. Hopefully that'll sort it but I think I'll still upgrade to a proper Aluminium catch can once I've seen Beaglers pics! Thanks everyone.

[Beagler]

Ok Graham thats a plan. CC must have cut the elbow inlet/outlet holes in mine with knife and fork as there are gaps and not sealed. Another reason for changing mine.

[MattB]

The effort of a catch can that Caterham provided in my 420 is a shocking embarrassment for a car costing over £40k.

I've just fitted a somewhat better replacement from Amazon, which cost not much more than Caterham want for a replacement plastic washer fluid tank with holes badly drilled in it.

The vent line vents downwards into the propshaft tunnel, about halfway along the gearbox.  No more oil vapour smell when driving and no more oil/oil vapour over the engine bay ...

The only downside is the slightly smaller capacity, but it's easy enough to drain straight out of the bottom of the can.  I can go back to the original in a couple of minutes if necessary.

MattB

[Graham Hutton]

Thanks for the pics Matt, that is miles better than the plastic one and I'm definitely going to do the job properly before my next track day. How did you fix the backplate to the chassis. Was it just big P clips?

I found myself looking at the premier power website the other night and I notice that one of the first things they do on every upgrade is put an aluminium Mocal catch can. Their photos show it on the bulkhead which isn't possible when you have a heater and standard airbox. Anyone out there got any pictures of a Mocal style can installed at the front of the engine bay?

https://www.demon-tweeks.com/uk/mocal-alloy-oil-catch-tank-245403/

 

[SLR No.77]

I previously had a Mocal catch tank but due to the vented cap I swapped it for a sealed tank. As already stated, venting into the engine bay is fine for a race car but not a road car where you spend longer in the car and breathing in the fumes is not a great idea.

On a standard engine blow off gases are routed back into the intake plenum, you wouldn't vent them into the cabin area.

Stu.

[MattB]

#34 - Yes, the can is mounted to a 2mm aluminium plate which is then mounted to the forward chassis tube with two 22mm p-clips. An aluminium strap is rivetted to the top of the plate and fixed to the rearward chassis tube with another p-clip to prevent the can rotating around the forward chassis tube.

MattB

[Dan R]

Quick question regarding the catch cans .... I currently have a standard plastic one that the engine vents in to, bit no hose or vent out, apart from a perforated bung, so the engine bay gets coated in a thin film of vapour.   If an upgraded can is fitted, what is the purpose of the vented cap variety if you are going to use the 'outlet' hose from the can to vent under the car etc? 

[SLR No.77]

Re #37  If you vent under the car you don't need the vented cap, the two connectors enable two inlets to the tank. In the Caterham install you only need one inlet.

[Beagler]

For me the can should be sealed. I believe there should be no venting to atmosphere and the gases should go back into the inlet as part of emission control. I don't think any mass manufacturer vents emission gases to atmosphere to comply with regulations.

[MattB]

Venting emission gases directly to atmosphere - isn't that what the exhaust does?

MattB

[Beagler]

Hi matt yes but I think the idea is to reroute blow by back into the engine to increase burning efficiency particularly of unburnt gases and they go through the Catalyst. I think its what emission control seeks to achieve. Remember the old ford kent engines with the box on the side of the block and a pipe pointing to the ground chuffing away on a knackard engine and discharging to atmosphere. The emission control regs were designed to stop this.

[MattB]

Cynicism aside, it would be easy to plug the vent line into the inlet manifold which has a blanked off intake for just that purpose (at least that's what I think it's for).

MattB

[GulfSeven]

As I said previously, current cars have one hose from the crankcase to the can, and one hose from the can to the inlet manifold. They still have a vented cap though.

[7 wonders of the world]

If the catch tank is sealed it will blow a hose off, the gas being force in has to be able to escape, the tank is only their to catch oil.

If you have a high discharge you need to consider the DS install and look to seal system and reduce the amount of air the crank case induces, also consider the detrimental implication to combustion of simply routing hoses into the intake.

 

[Dan R]

On a related note, what hoses are people using for this, and can you post links to suitable items please ? 

[Beagler]

An extract.
The problem is all motors have some sort of blow by, where some of the combustion gases go past the rings. These gases are not removed as efficiently if you have a vented can vs. sealed, causing the oil break down and become "dirty" faster. So you must change the oil more often if you have a vented can. 

[SLR No.77]

I suspect that is an extract related to a system where the catch tank is then routed back into the intake, thereby sucking the gases out of the catch tank, effectively reduced if a vented cap is fitted?

[7 wonders of the world]

Not sure where that extract is from...??

Most of the replies on here regarding 'catch tanks' relate to Dry Sump (DS) set ups, where as your trying to add a 'filter' inline between the rocker cover and inlet manifold in a wet sump set up? - different application 

However you will still be introducing crankcase gas into the inlet manifold which will affect combustion, especially during spirited driving when windage increases.

[GulfSeven]

.

[Graham Hutton]

What a lively discussion. On reflection, I think it is better if the catch can is unvented and the pressure just goes back to the inlet manifold. The caterham chap told me to omit the over flow pipe and stick a bung in the top which is exactly what some of the factory built cars (including Tim's 310R) have. This seems to work fine without the catch can exploding! It seems not right to vent under the bonnet on a road car for two reasons. Firstly, the emissions and secondly because I don't want to have to clean oil mist off everything.

I guess Caterham fit a catch can because many of the engines are used for racing but the solution to the problem would seem to be for them to fit a decent unvented and baffled can rather that the 50p washer bottle system currently provided.