Bypass Valve on Stock Oil Filter Console, Looking for relief pressure of bypass valve to help with design of remote oil filter and cooler Options

[GregAmy]

I don’t want to answer for OP but my understanding is he is worried about bypassing his external oil cooler and overheating.

I suggest it's a non-issue. But if you're that worried about it then stop using those cheesy cheap-ass sandwich adapters and use one of Chris' good bespoke ones:

https://tangerineracing.com/shop/ols/produc...-oil-cooler-kit

[Superhawk996]

I suggest it's a non-issue. But if you're that worried about it then stop using those cheesy cheap-ass sandwich adapters and use one of Chris' good bespoke ones:

(IMG:style_emoticons/default/pray.gif) (IMG:style_emoticons/default/aktion035.gif)

And now we’re back to the post #8 in the thread (IMG:style_emoticons/default/av-943.gif)

[Mr Beckstar]

The spring will dictate the [force], the [area] is calculated as mentioned anbove, and that allows calculation of relief [pressure]. I know there are other factors when the valve opens eg pressure drop on opposite sides of the ball when oil flows through the valve, but I don’t think that sort of accuracy is needed here. I’m more concerned about opening pressure.

If you are going to ignore the annular sealing area effects completely, then why not measure the check valve spring force directly and get the answer you originally were seeking?

That’s an option. My first preference was to ask whether someone knows the spec. I can only do this work in my driveway and we’ve had 40 deg C days, thunderstorms etc. plus I’m leaving on a 1,200 km trip in the morning so I need it together and running now. I’m going to the Bathurst 12 hour this weekend. Disassembling and measuring needs to wait a few weeks.

[Mr Beckstar]

Can I insert just a couple basic questions here?

- If you're removing the oil filter and replacing it with a sandwich plate...why would oil go through the bypass, given same psi on both sides of the ball with, as noted, a larger surface area on its back side; and

Because it’s not the same PSI on both sides. That’s the issue here. The pressure difference between the upstream side of the valve and downstream side increases because of all the backpressure in the hoses, remote filter mount, cooler and fittings that are now positioned between the upstream and downstream sides of the valve.

- Even if it does go through the bypass, whether fully or even slightly, why do you care? You could remove the checkball and spring entirely and the oil is still flowing from the inlet to the outlet.

Because bypassing the valve bypasses the remote filter and the oil cooler. I don’t want it doing that when cooling is needed. I installed a remote cooler so it would cool the oil, not bypass.

And...discuss.

EDIT: Here's where you shold be focusing your energies:

http://www.914world.com/bbs2/index.php?showtopic=236133
https://tangerineracing.com/shop/ols/produc...re-relief-valve

Haven’t looked at these yet.

[Mr Beckstar]

I looked at those two links and they’re not relevant. They’re considering the engine pressure relief valve, not the oil filter bypass valve.

[Mr Beckstar]

I don’t want to answer for OP but my understanding is he is worried about bypassing his external oil cooler and overheating.

I suggest it's a non-issue. But if you're that worried about it then stop using those cheesy cheap-ass sandwich adapters and use one of Chris' good bespoke ones:

https://tangerineracing.com/shop/ols/produc...-oil-cooler-kit

Because I’ve never seen this option! I’ll check it out.

[Mr Beckstar]

The oil filter bypass valve piqued my interest so I bought a second hand filter console and just did a quick test on the bypass pressure using compressed air. It started bypassing at about 12 PSI and peaked at about 16 PSI with a lot of air flow going through. (Refer next post before using these values!)

Conclusion: if the remote oil filter and/or remote oil cooler circuit has more than 12 PSI pressure drop at highway cruising rpm or hill climbing rpm, then the remote circuit will start bypassing and the performance of those remote components will start to diminish. And, if the pressure drop is upwards of 14 PSI, then the remote circuit will probably not be effective during those cruising/hill climbing rpm just when it’s needed. Of course that assumes the oil is up to full operating temperature.

My guess is that the pressure drop won’t go near 12 PSI if the remote circuit hoses and fittings are generously sized and oil is warmed up. The next stop for me is to measure the pressure differential in the remote circuit at high rpm with oil temp over 190 deg F. If that’s e.g. only 5PSI, then it proves theres absolutely nothing to worry about.

[Mr Beckstar]

The above pressure readings were measured using the bottom 1/3 of a leak down tester pressure gauge so accuracy is a question mark on this method. So I thought I’d verify using a different method.

I just used electronic kitchen scales to measure the force required to crack open the valve (0.45 kg) and to fully open the valve (0.85 kg). I then used vernier calipers to measure the valve seat inner diameter (11.1 mm). If you do the calculations you get 6.6 PSI to crack open the valve and 12.5 PSI to fully open the valve. Quite a lot different to the air pressure readings.

I’ll have to do the actual pressure test on the valve again with improved accuracy as the two methods should somewhat verify each other.

[Superhawk996]

Interesting data points.

Food for thought on the differences between measurement methods.

Air is a compressible fluid and will behave somewhat differently than oil which is incompressible.

Likewise measuring the spring force was done using a solid incompressible probe of some sort and will be different than what compressible air does.

Very cool that you’re getting some data points. (IMG:style_emoticons/default/smilie_pokal.gif)

[Mr Beckstar]

Okay, I just used a brand new gauge with 0-15 PSI scale to measure bypass pressure with air using a leak down tester.

Bypass starts to open: 6 PSI but flow is just seeping through
Bypass fully open: 10 PSI with significant flow

These values are very similar to the values I calculated using kitchen scales so I have a high confidence that the values are ballpark within say plus or minus 1 PSI.

[Mr Beckstar]

Next step is to fit the two pressure tappings into the oil cooler lines and measure the differential pressure. Hopefully it’s less than 6 PSI at peak engine rpm.

[Mr Beckstar]

…I view this discussion as largely theoretical. Unless the external oil cooler and plumbing is stupid restrictive the bypass in the oil filter console is a non issue….

Referring back to the above comment, I’m interested to know whether you have a feel for whether the external oil filter/cooler circuit is likely to represent more than 6 PSI pressure drop at redline. It’s a genuine question because I don’t have a feel for the quantum of pressure drop at all. I spent 20 years in the water industry doing a lot of pressure drop calculations on large pump systems (e.g up to 5,000 gallons per second) but that’s on cold water, not on hot viscous liquid through tiny hoses and fittings!

Comments have been made in this thread that there shouldn’t be more than a couple of PSI drop over the filter, so that leaves say 4 PSI for the remainder of the circuit. That’s not much, but maybe the flow velocities are very low??

[Superhawk996]

You’re in uncharted territory as far as I know.

I certainly have not done the data collection and in general I’m not a fan of external coolers and trying to keep oil at 180F so I have that built in bias.

Here is a Samba thread on flow volumes for a T1 engine with a 26mm pump has oil flow volumes in the 6-7 GPM range that seem plausible to what I have previously seen published for Small Block Chevy circle track engines that want filters rated for 10 GPM.

Samba
https://www.thesamba.com/vw/forum/viewtopic.php?t=166608

Chevy
https://www.chevrolet.com/content/dam/chevr...NAL-2-13-23.pdf

I know this doesn’t answer your question about pressure drop across the external cooler and plumbing but may help with the magnitude of flow rate.

Interesting side note: at 100C oil can be lower viscosity than water. Might be interesting to use your pressure drop calculations and see what your prediction is vs what you measure.

[Mr Beckstar]

You’re in uncharted territory as far as I know.

I certainly have not done the data collection and in general I’m not a fan of external coolers and trying to keep oil at 180F so I have that built in bias.

Here is a Samba thread on flow volumes for a T1 engine with a 26mm pump has oil flow volumes in the 6-7 GPM range that seem plausible to what I have previously seen published for Small Block Chevy circle track engines that want filters rated for 10 GPM.

Samba
https://www.thesamba.com/vw/forum/viewtopic.php?t=166608

Chevy
https://www.chevrolet.com/content/dam/chevr...NAL-2-13-23.pdf

I know this doesn’t answer your question about pressure drop across the external cooler and plumbing but may help with the magnitude of flow rate.

Interesting side note: at 100C oil can be lower viscosity than water. Might be interesting to use your pressure drop calculations and see what your prediction is vs what you measure.

Yes it’s helpful thanks Superhawk.

I did some calcs and it tells me I should expect about 7 PSI pressure drop at 5,000 rpm considering only the hoses.
I haven’t calculated the pressure drop through the filter, the fittings, the oil cooler.
I’d say it backs up the thinking that there’s cause for concern and that oil pressure drop measurements would be a good idea.

[Superhawk996]

Food for thought

If you look at histograms of average vehicle speed, engine speed, and vehicle acceleration you will find that the amount of time an engine spends at 5000 rpm is trivial. It is out beyond 3 standard deviations.

Full on racing is different. Occasional autocross and track events would only skew that distribution minimally. The reality is engines don’t operate at 5000 rpm much at all despite what we think as enthusiasts.

Likewise at 5000 rpm the engine fan is providing the bulk of cooling. Not the oil cooler.

The worst case for cooling is when engine speed (ie fan speed) is low and load is high. This is usually in town at idle or when repeatedly accelerating away from traffic lights. On the highway, where aerodynamic loading becomes significant, you’ll find that your engine speeds are more like 3000-3500 rpm.

So ask yourself why would you be concerned if the external oil cooler had some minor bypass at 5000 rpm?

[Mr Beckstar]

Food for thought

If you look at histograms of average vehicle speed, engine speed, and vehicle acceleration you will find that the amount of time an engine spends at 5000 rpm is trivial. It is out beyond 3 standard deviations.

Full on racing is different. Occasional autocross and track events would only skew that distribution minimally. The reality is engines don’t operate at 5000 rpm much at all despite what we think as enthusiasts.

Likewise at 5000 rpm the engine fan is providing the bulk of cooling. Not the oil cooler.

The worst case for cooling is when engine speed (ie fan speed) is low and load is high. This is usually in town at idle or when repeatedly accelerating away from traffic lights. On the highway, where aerodynamic loading becomes significant, you’ll find that your engine speeds are more like 3000-3500 rpm.

So ask yourself why would you be concerned if the external oil cooler had some minor bypass at 5000 rpm?

Yes all very pertinent considerations.

However, for my rig the oil temp gets hottest when cruising on the highway and I’m not changing the fan so that pretty much leaves an oil cooler as the alternative.

At 68 MPH, the engine’s doing 4,200 rpm. Being an auto, it drops into second gear on significant inclines and then it’s up to the driver whether to sit on e.g. about 5000 rpm at 55 MPH or something less. There are plenty of long hills like that over here and whilst I agree it’s going to represent a small percentage of driving time, it’s in my opinion the most important time for the cooler to be doing its job at best possible efficiency. The last thing I want at that time is for the cooler to be bypassed. And yes, I probably wouldn’t be too concerned about the bypass slightly cracking at 6 PSI at 5,000 rpm (I rarely push it that hard), but if it’s 8 PSI at 4,000 or 9 PSI AT 4,500 then that is something I’d like to fix! The calculation said I’ve already got 7 PSI without considering fittings so I think it’s heading that way.

[Superhawk996]

At 68 MPH, the engine’s doing 4,200 rpm. Being an auto, it drops into second gear on significant inclines and then it’s up to the driver whether to sit on e.g. about 5000 rpm at 55 MPH or something less.

Wow! There’s so much going on in that one statement.

The only thing I can do is cheer you on with the data acquisition and testing! (IMG:style_emoticons/default/cheer.gif)

I’m truly impressed at what you’ve measured thus far. Will be curious to see what you come up with measuring the pressure drop across the operating system.