Oil pressure drops on race track in S corners

[nissanfanatic]

Originally Posted by Ansix Auto

Good question.. I'm not sure if I have a good answer. A DIY kit is a bit of a half measure, you might as well just fully DIY then?

I'd def be willing to pay for the convenience of all the parts sourced and ordered from one location, and clear instructions for assembly. Though, I am but one rando on the internet. XD

[makinen]

Originally Posted by zeroomega

I would hope some company can build a similar product with reasonable price. The market for this might not very big or profitable though.

At least you can build a CAN bus interface with an Arduino by one prebuilt PCB like http://docs.longan-labs.cc/1030008/ .
Only need to connect a power, an oil pressure sender and CAN bus lines of the option connector behind the audio.

[zeroomega]

Originally Posted by makinen

At least you can build a CAN bus interface with an Arduino by one prebuilt PCB like http://docs.longan-labs.cc/1030008/ .
Only need to connect a power, an oil pressure sender and CAN bus lines of the option connector behind the audio.

That is an interesting option. I didn't know that. If I don't have knowledge to build a PCB I probably would use that. My customized board is much better though. The Atmega32U4 only has 10bit ADC while the ESP32C3 has 12bit. The oil pressure sensor is output 0.5v to 4.5v analog data so a more accurate ADC, the better. I also uses 2 CAN transceiver instead of one, the car's CAN bus data are copied to another isolated CAN bus, which is read by the data logger. The oil pressure data is sent to the isolated CAN to avoid causing CAN ID collision with car's CAN bus, which may trigger an CEL (very unlikely but possible).

[Blighty]

Originally Posted by KillerBMotorsport

Again, the pressure drop off or light throttle is not the concern here. Pressure drop at WOT is very much the concern, and easy to duplicate on the dyno.

The accumulator would be drained to whatever its minimum would be and recharged under load. I would do it at 1,000 RPM increments to start with. On the dyno you can prolong the pull, shorten it, or hold it at a certain RPM and just hold full load continually. So, you can set up some pretty severe conditions while very closely monitoring oil pressure, temperature and flow.

I didn't know it was easy - how exactly do you simulate low oil pressure?

[jes]

Originally Posted by makinen

At least you can build a CAN bus interface with an Arduino by one prebuilt PCB like http://docs.longan-labs.cc/1030008/ .
Only need to connect a power, an oil pressure sender and CAN bus lines of the option connector behind the audio.

Hey, great link

[KillerBMotorsport]

Originally Posted by Blighty

I didn't know it was easy - how exactly do you simulate low oil pressure?

Recharge the accumulator.

You're not simulating oil pressure loss under no/low load; you're simulating the effects of what happens when you recharge and lose oil pressure under load.

[Blighty]

Originally Posted by KillerBMotorsport

Recharge the accumulator.

You're not simulating oil pressure loss under no/low load; you're simulating the effects of what happens when you recharge and lose oil pressure under load.

Ahh, I see now. Sorry, pretty slow to catch on.

So its more about just how much the load of filling the accumulators is what you want to test, not so much recreating the tracks low pressure environment events and how if the accumulator stops dips past a certain level.

More concerning to you is whether the pressure required to refill the accumulator makes a worse situation in high RPM, and that is what you can test on a dyno (albeit probably in a full pressure environment, not just a 'above 25psi' environment).

[KillerBMotorsport]

Originally Posted by Blighty

So its more about just how much the load of filling the accumulators is what you want to test, not so much recreating the tracks low pressure environment events and how if the accumulator stops dips past a certain level.

Correct. Engines don't pop under no/low load with a partial oil pressure loss like what is being observed in the corners.

Originally Posted by Blighty

More concerning to you is whether the pressure required to refill the accumulator makes a worse situation in high RPM, and that is what you can test on a dyno (albeit probably in a full pressure environment, not just a 'above 25psi' environment).

Correct. When the accumulator recharges, there will absolutely be an oil pressure loss to the engine, and under full load. The worst time to have ANY oil pressure drop. Is this a 5psi drop or a 25psi drop? No one knows, but physics doesn't lie. Anytime you create a hole in a pressurized system, there WILL be a pressure drop.

[gnarjunkie]

Originally Posted by KillerBMotorsport

Correct. Engines don't pop under no/low load with a partial oil pressure loss like what is being observed in the corners.

There's a lot of corners out there that aren't at low/no load though. Half of our local tracks out here in CO have high-G, high speed corners where you are flat or nearly so through the apex.

[KillerBMotorsport]

Originally Posted by gnarjunkie

There's a lot of corners out there that aren't at low/no load though. Half of our local tracks out here in CO have high-G, high speed corners where you are flat or nearly so through the apex.

If you have logs showing heavy load right-hand turn starvation, please share them.

So far I've only seen data that supports starvation initiated at braking/lift/rise going into and continuing through a right-hand turn.

[gnarjunkie]

I have no data. Just pointing out that higher-g corners could still be a high load situation.

If it is only being observed in lower load corners though then that's great. My impression was this was being seen on higher-g right hand corners, especially if there's also elevation gain happening.

[blsfrs]

Another part of what the accumulator may do is, at low rpm/oil pressure, it discharges some oil to create an overfull condition. This would mitigate the problem of oil moving away from the pick-up in a high G turn. There is still the issue of recharge under load but the higher the oil pressure, more pressure exists in the accumulator restricting how fast it will recharge. So, hypothetically not taking too much needed pressure from the engine internals. More testing is definitely needed.

[nissanfanatic]

Originally Posted by gnarjunkie

I have no data. Just pointing out that higher-g corners could still be a high load situation.

If it is only being observed in lower load corners though then that's great. My impression was this was being seen on higher-g right hand corners, especially if there's also elevation gain happening.

Yea my thought on the elevation gain is that causes less accel/some decel. I kind of think a right hander plus decel causes oil to slosh forward and to the left,which is the least desirable for the pickup location.

It would be nice to test this on a skidpad or something where you can load the car laterally and then mess with accel/decel to try and reproduce the pressure drop.

[gnarjunkie]

Originally Posted by nissanfanatic

Yea my thought on the elevation gain is that causes less accel/some decel. I kind of think a right hander plus decel causes oil to slosh forward and to the left,which is the least desirable for the pickup location.

It would be nice to test this on a skidpad or something where you can load the car laterally and then mess with accel/decel to try and reproduce the pressure drop.

That would make sense.

There's a couple corners on local tracks that have a short braking zone followed by a big sweeping uphill right hand corner that's pretty close to or at full throttle depending on the car. I haven't gotten to track my 86 yet (bought it during winter), but in my STi I was pretty much flat through the curve and over the rise.