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Posted by: gnomefabtech Mar 25 2024, 11:02 AM

Hello!

So I'm running a dry-sump system on my 'teen and it's all great except if the car sits for a few days the oil in the tank slowly fills the motor. This wouldn't be a big deal except it floods the turbo and then there's smoke. So much smoke.

Does anyone have experience using a low cracking pressure check valve to hold the oil in the tank until the car is running? I see a selection of these on McMaster but I'm understandably nervous about restricting the flow into the engine from the tank. It's a -12 an line coming out of the tank. What did Porsche do about this on their dry-sump systems?

I'm running a Hayabusa engine (build thread to follow) so it's a pretty unconventional build but the oiling thing is common to all dry-sumps.

Thanks for answering these questions.

Posted by: GregAmy Mar 25 2024, 11:18 AM

Edit: /4 or /6? Never mind

I have dry sump in my /4 race car. I put a manual valve in the tank line, that I turn off after each session and clip my master switch key to it as a reminder.

There are drainback valves for the 911s; Rothsport and Willhoit come to mind.

Posted by: gnomefabtech Mar 25 2024, 09:42 PM

Thanks for the suggestion. $300 is pretty steep for one of those valves. I'll see if I can find a more thrifty option first.

Posted by: fixer34 Mar 25 2024, 09:54 PM

Rothsport. Is your engine worth more than $300?? Mine is on a factory -6, there are 911 versions also. This is NOT your run of the mill 'check valve'. Too little sealing pressure and you might as well not bother; too much and you get oil starvation on startup followed shortly by spun bearings.
Some things in life you can go cheap on; this isn't one of them.

Posted by: mepstein Mar 26 2024, 04:59 AM

You might be able to find a used one on pelican. Not everyone is a fan.

Posted by: mlindner Mar 26 2024, 05:24 AM

Rothsport is the way to go. A lot of 911 use them. my 914-6 GT Tribute would empty the tank in a week. Perfect.

Posted by: gnomefabtech Mar 26 2024, 07:02 PM

Thanks for the replies. My oil line is a -12 AN so I have to also adapt to use the Rothsport unit. DOes anyone know the diameter of the stock Porsche "S" hose the valve clamps into?

Posted by: sixnotfour Mar 26 2024, 07:21 PM

I have a rear mounted oil tank and going install a 1/4 turn manual valve.. and I have a pressure gauge ...soo....
Thanks @http://www.914world.com/bbs2/index.php?showuser=27063

Posted by: gnomefabtech Mar 26 2024, 07:54 PM

SIXNOTFOUR- I like your resourcefulness there but I think that valve might not be rated for the heat of the oil. Also, an Amazon "no Q.C." part might be a bit of a risk in a critical place like the oiling system.

THere are some low cracking pressure check valves that might work. I'll order one and report back.

One like this:

https://www.mcmaster.com/1874N19/

Posted by: yeahmag Mar 27 2024, 10:11 AM

I use a quarter turn valve at the tank as well.

Posted by: stownsen914 Mar 27 2024, 10:44 AM

Depending on where the tank is mounted and how the car is used, there is another option. If the tank is front mounted, you can store the car jacked in the rear (or rear tires rolled onto a couple boards to elevate). This puts the engine higher than the tank, and keeps more of the oil in the tank. For frequent use it might be inconvenient, but I've done the above for 911 and 914 racecars and it works like a charm.

I'm not keen on putting something in the oil feed line to my motor. Too easy to forget, or have it fail, and trash the motor almost instantly.

Posted by: ClayPerrine Mar 27 2024, 03:14 PM

I actually tried a Rothsport check valve on my 4.0L motor. It would not allow oil to pass through it. ZERO oil pressure. The guys at Rothsport worked with me and they could not figure out why it didn't work. So I gutted it, and eventually put in a new line without the check valve.

Not trashing Rothsport. They supported it and I will never asked for a refund. But it just didn't work for me, and I can't risk my expensive motor for it.

Posted by: arbitrary Mar 27 2024, 03:40 PM

What pressure pump is the Hayabusa engine using? Is it worn to the point where oil is getting past the gears into the “sump”

Posted by: gnomefabtech Mar 27 2024, 06:32 PM

The dry-sump system I am using is a hybrid that uses the stock high pressure pump and adds a two stage scavenge to empty the sump. Since the 'Busa oil pump was never designed to stop flow when stopped it doesn't.

This wouldn't be a problem except that my turbo is mounted a bit low so it gets flooded with oil when there's a lot of drainback.

Here's a pic of the engine before it went in. I'll start another thread with more details. There are a LOT of details.

Posted by: r_towle Mar 27 2024, 08:04 PM

Stock 84 3.2 911 here.
Why does mine work?

Mine is all stock.

Posted by: arbitrary Mar 28 2024, 07:46 AM

I have a Hayabusa engine in a Caterham; it uses a dry sump system from SBD Motorsports. https://sbdmotorsport.co.uk/ They recommend that the bottom of the dry sump tank is at the same height as the bottom of the sump.

I used to have a 993tt - they would often have oil back flow issues. The solution had multiple facets:

- the correct Porsche oil filter that had a non-return valve built in
- a pressure valve at the oil feed line going into the turbo (pretty sure it was a 996tt part) that would only open under a slight pressure (greater than the head provided by the dry sump tank)
- the highest viscosity oil allowed
- scavenge lines (developed by Ruf?) that had a raised section acting as an anti-siphon

But not sure any of those will help your situation…

I’m guessing your turbo is a gravity drain back to the engine sump? Can you connect it via a T fitting to the scavenge side of the pump instead with a raised section like Ruf did?

Please do keep posting - I like Hayabusa engines and I like 914s.

Posted by: gnomefabtech Mar 28 2024, 10:03 AM

I think it has to do with how good your valve seals are and how old your oil pump is.

Posted by: technicalninja Mar 28 2024, 01:28 PM

I want to hear that run!


Scratch pics and add audio soundtrack!

Posted by: gnomefabtech Mar 28 2024, 09:21 PM

https://youtu.be/ZMesefymiTc

It's still a work in progress but it does run.

Posted by: gnomefabtech Apr 5 2024, 12:07 PM

I solved it. I am using this valve here:

https://www.mcmaster.com/1874N19/

I added a couple -12AN fittings (you could use barbed if you want that) and plumbed it in between the tank and the engine. Does a good job of preventing the oil from draining down and I see no change in the operating oil pressure. The only down side is that valve is kind of bulky. Not really a problem though.

Total cost of $130 shipped.