Catch tank.

[clivegto]

Looking for pictures and advice on catch tank from Turbo then to mechanical scavang pump. Any tips do's and don'ts. 

[wombat258]

Large enough to de-aerate the oil, scavenge line low and small diameter (AN6 OK), breather line high. My tank is 2"x 3"x 6", bolted direct to the turbo body, and has an internal baffle. I have an intentional dip in the scavenge hose to keep oil near the pump so it primes readily. Scavenges well. Never smokes on start.

[clivegto]

So the tank needs a breather as well as in and out pipes @wombat258

[MeanBean49]

49 minutes ago, clivegto said:

Looking for pictures and advice on catch tank from Turbo then to mechanical scavang pump. Any tips do's and don'ts. 

Why do you need a catch tank? If your scavenge pump is ckearing as much oil at flows through the turbo (or technicalky more) there is no need for one. Waste of time and money

[clivegto]

18 minutes ago, MeanBean49 said:

Why do you need a catch tank? If your scavenge pump is ckearing as much oil at flows through the turbo (or technicalky more) there is no need for one. Waste of time and money

This is what I need to know. Seems like lots of people have them, why ? 

[MeanBean49]

1 hour ago, clivegto said:

This is what I need to know. Seems like lots of people have them, why ? 

I can only imagine they either dont have oil pumps that move enough oil and are masking it with a catch tank, or they are just goimg on what they have been told by someone else.

Oil pump should shift whatever is put to it, whether its hot, cold, airated etc.

[Gixer1460]

As being mechanical and driven by the engine, they cannot drain the oil in the turbo or delivery pipework after shutoff. This can be sufficient to back up from drain to turbo bearings and leak through into both turbine & compressor housings giving the smokey start-up syndrome. Obvs electrical pumps can run on after shut-down so minimise the effects.

[clivegto]

After a bit of external OSS research these work well. As Gixer1460 says the oil needs to drain after engine shut dowto stop smokey startups. 

[MeanBean49]

1 hour ago, clivegto said:

After a bit of external OSS research these work well. As Gixer1460 says the oil needs to drain after engine shut dowto stop smokey startups. 

Id rather know the turbo has oil at the bearings and see a puff of smoke on startup than drain it all away and potentially have a dry spell.

Personally I dont understand why anyone would use a pump whos volume changes with Rpm to scavenge an oil supply/drain that runs at an pretty much constant volume. Just doesnt make any logical sense

[clivegto]

@MeanBean49before I start my turbo bike I start the electric scavang pump to clear the oil from the turbo. Looks to me like the little oil catch tank does the same job for the mechanical scavang pump. At least that's how I see it. 

[Gixer1460]

A turbo plumbed the 'usual' way will get oil pressure at the bearings at pretty much the same time as the camshaft, if not sooner. And unlike the cams, at start-up, the turbo bearings are unloaded and are at minimal rpm!

[wombat258]

11 hours ago, clivegto said:

So the tank needs a breather as well as in and out pipes @wombat258

Breather so you are not pulling a vacuum on the bearings and not influencing oil flow. Turbos are designed to have a free flow from the drain. In cases were that is not possible (turbo below sump), the sump allows for free drain, and the scavenge/breather setup removes the oil at atmospheric pressure. The added bonus is that on shutdown the surplus oil sits in the sump and cannot drain back into the turbo. I made mine from aluminium RHS with end caps, and crush spacers for the bolts to the turbo.

[wombat258]

4 hours ago, MeanBean49 said:

Id rather know the turbo has oil at the bearings and see a puff of smoke on startup than drain it all away and potentially have a dry spell.

Personally I dont understand why anyone would use a pump whos volume changes with Rpm to scavenge an oil supply/drain that runs at an pretty much constant volume. Just doesnt make any logical sense

Electric pumps are simple, heavy, unreliable (not designed for high oil temperatures), and draw a lot of current on a small charging system, especially if you go EFI. Mechanical is light, reliable if designed correctly,  draws no current, and has little parasitic drain on HP. Either way works in scavenging oil from the turbo, but have their own merits and limitations.

[no class]

I prefer to design and fabricate the header so the turbo sits as high as possible and the drain remains above the sump level ..... never had any smoke issues .

[no class]

[MeanBean49]

8 hours ago, wombat258 said:

Electric pumps are simple, heavy, unreliable (not designed for high oil temperatures), and draw a lot of current on a small charging system, especially if you go EFI. Mechanical is light, reliable if designed correctly,  draws no current, and has little parasitic drain on HP. Either way works in scavenging oil from the turbo, but have their own merits and limitations.

I found the opposite to most of that, facet pumps weighs no more than a mech scavenge pump (less than the one i looked at), seem more reliable due to less working parts and doesnt draw much current at all as well as working at a constant speed. Mines still going strong after 8 years.

Can see how it would help on an EFI bike where current draw is bit more important.

For me its extra expense and hassle, and most of the time people are asking about oil drain, catch tanks and smoky turbos, the people asking all seem to have mech pumps. Or that is ny observation.

Guess its a personal preference thing. I consider them the same way I do Cam Feed kits

[clivegto]

The 2 electronic facet pumps I used have been 100% reliable. Mechanical one is something new to me that's why I have been asking questions. 

[Spazpecker]

Where is the oil return piped into? Sump or side casings? 

[Gixer1460]

7 minutes ago, Spazpecker said:

Where is the oil return piped into? Sump or side casings? 

Better above static oil level as scavenaged oil will be aerated - not good mixing that into sump oil even if it does degas relatively quickly!

[Spazpecker]

Agreed, I built a remote oil tank for my ktm 990 which has a dry sump arrangement and twin pumps. 

So once the engine stops the oil will only have the head pressure of feed pipe. Electric scavenge pump to clear the oil in the pipe from the turbo to the higher engine inlet. Can't see the point of a tank tbh. 

Edited April 12, 2021 by Spazpecker

[Reinhoud]

On 4/11/2021 at 7:36 PM, clivegto said:

So the tank needs a breather as well as in and out pipes @wombat258

No!

I was told this and I tried this, no breather works much better..

[clivegto]

10 minutes ago, Reinhoud said:

No!

I was told this and I tried this, no breather works much better..

For a mechanical scavenge pump. I have done this, big pipe into little pipe. 

[Reinhoud]

I had to make my tank larger, when the bike was standing for a week it started to leak from the turbo, after that it takes 3 weeks before it starts to leak from the turbo