Dry sump catch cans

[Boston]

The rules seem pretty clear on this, but id just like to be sure. Is it true that if a car has a dry sump, only one catch can is required for the dry sump resevior and the engine, or would the car require a catch can for the dry sump resevior and the engine?

[Boston]

The rules seem pretty clear on this, but id just like to be sure. Is it true that if a car has a dry sump, only one catch can is required for the dry sump resevior and the engine, or would the car require a catch can for the dry sump resevior and the engine?

[Maverik]

We've wondered the legality of using one catch cans a few times since we run a dry sump. We always run one for cooling, one for oil in addition to the dry sump resevoir. A little more insurance for the hectic endurance if you ask me.

[Marshall Grice]

I think the question was in refrence to needing 1 or 2 catch cans for the oiling system in addition to the one for cooling. The answer is you only need 1 catch can for the oiling system. that's not to say that you couldn't have 2 hoses going to 1 can but there really aren't any vents on the engine that you want going to a catch can after you install a dry sump.

[VFR750R]

My recommendation would be a seperate catch can for the dry sump tank, regardless of legality.
The tank will have to be vented to work properly, and inevitably some oil will come out when you don't want it to.

[Akos]

If you run your crankase under vacuum, plumb up the engine breather from the engine with a check valve to the dry sump tank. From there you will need only one catch tank.

If the case is vented, I would plumb up the vent from the dry sump tank to the block. The oil fill plug is a pretty convient spot to connect to. The catch tank than goes to the engine breather.

Either way make sure that nothing can every become pressurized, and any blow-by goes into your catch can.

Cheers,

Akos

[BryanH]

Why have 2 catch cans on any car? I don't see a problem with venting the Rad and the engine into 1 recepticle if it is the correct volume.

[Maverik]

Because your radiator "catchcan" should be a properly thought about overflow bottle... ie so that the water can be pulled back in. The only reason I can see why you would run one catch can is if you don't care about the possibility of losing water permanently until you refill it... Also a good breather for the dry sumps should be able to drain excess oil back down into the tank,so I wouldn't want water in there either.

[VFR750R]

Akos I'm slightly confused about the need for double hooking the drysump tank to the case with checkvalves and such.

The simple case is there is crankcase vacuum, so you seal the crankcase up. Vent the drysump tank to a catch can.

I don't see a senario where you would want to vent the crankcase seperatley unless you didn't have enough pump to overcome blowby. Does anyone have this problem?

[Akos]

The reason you add in the check valve (could be a standard PCV valve) and plumb to the tank, is that in case of engine failure you don't pressurize your crankcase and blow out your rocker cover gasket. Not mandatory, but won't hurt.

[tamir5005]

Hey all,

I have a question about the proper routing of the catchcans - The one for the cooling system must have a venting hole that is vented to the lower part of the frame, and the one for the oil must be vented upstream of the restrictor. Are there any limitations about the location of these venting holes?

We are a new team, so anyone with a good competition experience about this subject would be helpful - things to avoid or what to do\not to do.

Thanks in advance,

Tamir

[Wesley]

I would recommend against running a PCV system in a wet-sump engine. You have to pull that air through the restrictor, which reduces the amount of usable oxygen you get by a factor much larger than the power you save by aiding ring seal (which is minimal in most OE engines.) Since you change the oil regularly and warm the engine up before driving hard in a race engine anyways, you don't have to worry about sludging or condensation buildup.

In a dry sump, the pumps are already pulling a vacuum on the crankcase so you don't need to worry about venting the engine more than the stock setup.

[tamir5005]

Wesley,

As you must have noticed, this topic is from 2007, and now as I understand the rules, connecting crankcase breathers to the exhaust is illegal, but if you can reffer to what I wrote I will be grateful.

Thanks!

Tamir

[Wesley]

My bad. I don't expect people to resurrect 4 year old threads.

[Rex Chan]

Re:tamir5005 - the rules in 2010 don't mandate venting your oil system into the intake, and I haven't seen many/any teams doing this. Most just run oil vents into a catchcan. This will make life much simpler than finding a place before the throttle to vent oil into.

About oil system catchcans for wet-sump & dry-sump. I've only dealt with dry sumps, where the scavenge pump is pulling air/oil out of the crank, and there is a cam cover breather for blowby (on the stock wet sump). If your scavenge pump pulls more air than blowby at all RPM, then you may seal up all vents, and have a single breather/overflow hose going to a single catchcan.

I measured blowby on the dyno, running a wet sump; and compared to scavenge pump airflow on the car. On car data was measured using a cheap $50 hall effect impeller style meter, so not very accurate. Dyno blowby was measured using an old-school vertical Fischer&Porter mechanical ball in tube style flowmeter, so again not the best. Based on these two measurements, I was not confident that there would always be negative pressure/vacuum in the engine, so we ran hoses from both vents to separate cans (the reason for 2 cans was to keep any ethnaol vapours away from each other, and out of the oil system).

In the end, we had 3 cans: coolant, cam cover, and dry sump oil tank overflow. Seems excessive, but alum drink bottles are light. The biggest problem was finding space to put them, routing hoses, and emptying the overflow (if it already hadn't tried to empty itself...)

[Jan_Dressler]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rex Chan:
Based on these two measurements, I was not confident that there would always be negative pressure/vacuum in the engine, so we ran hoses from both vents to separate cans </div></BLOCKQUOTE>
Try to measure it the other way round... Install the dry sump on your dyno, seal the crankcase breather, install a pressure sensor and just have a look - That's the way we did it, and voilà: Found out we always have negative pressure (a bit more without load, a bit less under load), so we only have 2 catch cans.
(By the way, that sensor is a cool "fatal engine damage just happening"-measuring device http://fsae.com/groupee_common/emoticons/icon_biggrin.gif )