Possible oil pickup tube solution

[GTTuner]

You are definitely stronger than me if you can pick up a longblock bare-handed!

 

But you are right, beefy it is. Bolt it down, and you could easily stand on it.

 

:lol: I can pick up a short block bare handed!

[MasAyinde]

I doubt it.

 

Had a feeling it was snake oil

[MasAyinde]

Haha well overall consensus is that it is a silly idea and that I am a silly man for thinking that it would work. I think I'll mock one up anyway for shits and giggles to see how it looks.

[ClimberDHexMods]

What you need is a pickup tube milled from a single block of titanium. No welds. And it needs to be billet, or all the ricers won't be your BFFs.

 

But in all seriousness, you could just make your own pickup tube from scratch, and it would probably be a fun experience to do so, if for no other reason than to enjoy making something.

[PhilT]

Make it out of a hydraulic hose, then it will absorb the vibrations and never crack

[mwiener2]

yeah. we're all looking at it all wrong. we should make it flexible. It's like UpPipes, at first we all wanted solid ones because we thought the flex ones sucked. But then all our solid pipes began to crack so now flexible is awesome.

[BAC5.2]

The pickup is solid for a reason.

[RabidWombat]

If you make it stiff enough it might help, or it might fail even faster. The trick is that the OE pickup will fail due to vibration. If you can stiffen the pick-up enough that its resonant frequencies are above the normal vibrations of the car (~20-200 Hz) it will make a significant improvement. If you accidentally line up the resonant frequencies with car vibrations it'll fail much quicker.

 

I agree that starting with an all new solution such as KB is probably better.

[boosten-n-bluntin]

You will just move the problem down the sleeve.

 

Welding will in addition to that add a material change that makes it more sensitive to cracking

 

^+1...

welding will weakin the pipe

[mwiener2]

The pickup is solid for a reason.

 

what reason is that?

[ehsnils]

All parts - even the oil pickup tube is a compromise between functionality and cost for the manufacturer.

 

So blame any problems on the bean counters.

[PhilT]

what reason is that?

 

It's cheaper.

[BAC5.2]

It's not so much a matter of cost, but a matter of function.

 

Solid tubes have very consistent and well defined flow properties, and one of the concepts of that involves a decreased headloss over a similar, but flexible, design. When it comes to flow of higher viscosity fluids, this kind of thing matters. And since gear pumps (like our oil pumps) are much better at pushing than pulling, you need to decrease headloss as much as possible.

 

A rubber line's flexible nature has a pretty drastic effect in it's ability to flow. Things like temperature, elastic properties of the material itself, surface roughness, pipe diameter at bends, things like that all play a role. It's easier, cheaper, and better practice to use a solidly affixed tube. It's probably not a massively higher head loss, but why just give efficiency away? There isn't a problem with using a solid tube. In the case of failed Subaru pickups, it's the result of a compilation of problems. I think GTTuner is right, that you could make the pickup much more resiliant if only you shimmed the support arm.

 

The comment about natural frequency above is kind of valid. Stiffness isnt the only player in the natural frequency, though. Mass plays a significant roll. In fact, stiffness over mass is the defining feature of natural frequency. Simply making the pickup lighter would increase it's natural frequency. This is the fundamental reason why MEMS devices are typically vibration proof.

 

IMO, the oil pickup should be replaced when you rebuild a motor. A new OEM one is only ~$20, and I believe the part number is 15049AA110.

[OBieXT]

So I've posed the question before in similar threads, but does anyone know what type of steel is used in these pickups? I've read that brazing Cr-Moly steel can actually cause it to crack. What about other types? Most of the pix I've seen of broken pickups seem to have cracks right at the edge of the braze line.

[outahere]

So this pickup tube issue has been on my mind lately. I know that the Killer B tube is a solution, but at $200+, I figured there had to be a less expensive way to solve it. I have a bunch of STI pickup tubes laying around and was thinking about doing this to them. Here is a crude drawing of what I have in mind. The black represents the stock pickup tube, the red is a short but robust metal sleeve to go over the tube, and the green is where the sleeve would get welded on. This would just involve cutting the tube at the flange, sliding the sleeve on, and welding..............

 

That sounds like the 1st generation KillerB tube, IIRC. See post #181 in this thread:

http://forums.nasioc.com/forums/showthread.php?t=1141982&page=8

[PhilT]

It's not so much a matter of cost, but a matter of function.

 

Solid tubes have very consistent and well defined flow properties, and one of the concepts of that involves a decreased headloss over a similar, but flexible, design. When it comes to flow of higher viscosity fluids, this kind of thing matters. And since gear pumps (like our oil pumps) are much better at pushing than pulling, you need to decrease headloss as much as possible.

 

A rubber line's flexible nature has a pretty drastic effect in it's ability to flow. Things like temperature, elastic properties of the material itself, surface roughness, pipe diameter at bends, things like that all play a role. It's easier, cheaper, and better practice to use a solidly affixed tube. It's probably not a massively higher head loss, but why just give efficiency away? There isn't a problem with using a solid tube. In the case of failed Subaru pickups, it's the result of a compilation of problems. I think GTTuner is right, that you could make the pickup much more resiliant if only you shimmed the support arm.

 

The comment about natural frequency above is kind of valid. Stiffness isnt the only player in the natural frequency, though. Mass plays a significant roll. In fact, stiffness over mass is the defining feature of natural frequency. Simply making the pickup lighter would increase it's natural frequency. This is the fundamental reason why MEMS devices are typically vibration proof.

 

IMO, the oil pickup should be replaced when you rebuild a motor. A new OEM one is only ~$20, and I believe the part number is 15049AA110.

 

You are giving Subaru way to much credit; the engine needs an oil pump, Subaru put one there and put a pipe down into the bottom of the sump to suck up oil. I am pretty sure they didn't calculate the flow properties of anything

[rao]

I bet they did on the Sti and the Spec B

[MasAyinde]

That sounds like the 1st generation KillerB tube, IIRC. See post #181 in this thread:

http://forums.nasioc.com/forums/showthread.php?t=1141982&page=8

 

That looks a lot like what I had in mind, except mine wouldn't have gone as far up.

[BAC5.2]

You are giving Subaru way to much credit; the engine needs an oil pump, Subaru put one there and put a pipe down into the bottom of the sump to suck up oil. I am pretty sure they didn't calculate the flow properties of anything

 

I absolutely assure you that this was an engineered decision, and this kind of thing is important.

[mwiener2]

I absolutely assure you that a flexible tube could be used in it's place with no loss in performance.

 

 

After reading this thread, I ordered the Cosworth Dry Sump kit

 

 

 

Wait a tic edit: If Subaru spent $$$ to have these guys study the suck on these tubes and how squishy rubber hoses are, why didn't they study how to have it not snap off?

[ehsnils]

I absolutely assure you that a flexible tube could be used in it's place with no loss in performance.

 

 

After reading this thread, I ordered the Cosworth Dry Sump kit

 

 

 

Wait a tic edit: If Subaru spent $$$ to have these guys study the suck on these tubes and how squishy rubber hoses are, why didn't they study how to have it not snap off?

 

Time for you to sit down in a vehicle design project and you will figure out that a lot of stuff in the cars are made by desk jockeys that doesn't have a clue about what an oil pickup tube is good for. (I'm in such a project right now... )

[BAC5.2]

I absolutely assure you that a flexible tube could be used in it's place with no loss in performance.

 

 

After reading this thread, I ordered the Cosworth Dry Sump kit

 

 

 

Wait a tic edit: If Subaru spent $$$ to have these guys study the suck on these tubes and how squishy rubber hoses are, why didn't they study how to have it not snap off?

 

There would be a loss in performance. Whether or not it would be a problem for the car is different than it not being as efficient. Gear pumps aren't good for suction, so it's good practice to reduce flow obstructions as much as possible. If you think it's no big deal, then cut the pickup, replace it with a piece of rubber line, and see how it works. It's not the best solution to the problem.

 

I just checked out the Cosworth dry sump kit. Holy smokes, that thing is friggin expensive.

 

I believe the problem with the pickup is at a manufacturing level. If you look through Subaru history, you can almost pinpoint a rise in failures, right around 2005. It's likely they switched vendors, and their new vendor had slightly lower QC standards. If they had improperly brazed the tube, then that could result in a more brittle tube right at the area of peak stress.

 

What I think happens is as the head of the pickup moves around, the area right at the bend is constantly being work hardened. It becomes brittle, and snaps off. All of the failures I've seen look like brittle failures more than anything. I think the solution to the problem is an extra support leg and a spacer below the foot like GTTuner used. I bet that would drop the chance of failure to nearly zero. Alternately, you could get an aftermarket reinforced pickup. I chose the latter for no other reason than I got a smoking deal. Otherwise, I would have just left it stock and not worried about it.

[rao]

You can't put a price on piece of mind. Anyone who DOESN'T install the Cosworth Dry Sump kit doesn't care about their car.

 

/thread

[PhilT]

There would be a loss in performance. Whether or not it would be a problem for the car is different than it not being as efficient. Gear pumps aren't good for suction, so it's good practice to reduce flow obstructions as much as possible. If you think it's no big deal, then cut the pickup, replace it with a piece of rubber line, and see how it works. It's not the best solution to the problem.

 

I just checked out the Cosworth dry sump kit. Holy smokes, that thing is friggin expensive.

 

I believe the problem with the pickup is at a manufacturing level. If you look through Subaru history, you can almost pinpoint a rise in failures, right around 2005. It's likely they switched vendors, and their new vendor had slightly lower QC standards. If they had improperly brazed the tube, then that could result in a more brittle tube right at the area of peak stress.

 

What I think happens is as the head of the pickup moves around, the area right at the bend is constantly being work hardened. It becomes brittle, and snaps off. All of the failures I've seen look like brittle failures more than anything. I think the solution to the problem is an extra support leg and a spacer below the foot like GTTuner used. I bet that would drop the chance of failure to nearly zero. Alternately, you could get an aftermarket reinforced pickup. I chose the latter for no other reason than I got a smoking deal. Otherwise, I would have just left it stock and not worried about it.

 

I appreciate your input, but you are wrong.

 

I just had a flexible section manufactured for an MAN 9L58/64 as the rigid pipe kept cracking; no loss of oil pressure or flow. I appreciate that auto engines are a little bit smaller than the ones I am used to working on, but the principals remain the same

 

[ame=http://www.youtube.com/watch?v=LkErYlhA_88]YouTube - MAN Diesel Typ 9L 58/64 II * 17100 hp *[/ame]

[mwiener2]

I know for a fact, that a flexible tube could be made that would have no loss in performance compared to the oem rigid tube. I don't know what it would be made of or what it would look like, but ti could be done.