Oil Pressure Question - location/values

[prandelia]

Does anyone else take oil pressure from the Oil cooler sandwhich plate? Does it read higher that at the oil galley port?

I've tried searching but with inconclusive results. I have an AIM MXM for data logging, and I use the port on my JR Oil cooler for my oil pressure. It's the most convenient, and I don't want to remove the factory warning location.

I won't be able to use the oil galley port location, as that's where my Accsump will be plumbed to, so no point in suggesting that. I've read that is the "most accurate" location at the mains/crank, and if so, I assume it would then potentially read lower than at the oil cooler. Why though, is still beyond me.....

I'm currently seeing a very solid 70-90psi through high RPM's on 5W40 at 195-220 temps, so pressures are good there. Just trying to confirm if those pressures are accurate, or if they are actually a bit lower at the mains. This will help me determine what pressure to activate my Accusump at, since I may activate it using my AIM, instead of the pressure reading on an EPC valve at the galley port. If there is a difference between the two locations, the that would affect what pressure I activate the Accusump.

[jcw99]

There's an old thread on this and I remember that the sandwich plate setup gives higher pressure at idle but am not sure about high rev psi. Another member will probably chime in and give you more help than I did.

[prandelia]

Well hell, might as well just turn this into a "how have you tried to address oil pressure for race cars" thread.....I'm using the OE/OBD sensor for oil temp., so I know that's fine, but I've attached an oil pressure trace from my local track. As you can see, they are rock solid when the car is pointed straight, but in heavy brake zones and high-load corners, you can see how big the oil pressure swings in this car. Looks like some amount of potential pump cavitation or starving going on, because it's not from oil temps, the temps are perfect. While the graph looks bad, the actual numbers aren't too bad. There are a few corners where I would def. like to see another 20psi for sure though. Hence, why I am trying to figure out how accurate these pressures are. Comparing them to what I've seen from others who use the galley port, and lower weight oil, mine seem inline, as I would naturally be higher due to the heavier oil weight.

My car already has the V2 Moroso baffle (which is actually a solid design and a lot like TMG's), 5W40 oil, Oil cooler.....but I think the big swings are being driven by a few things:

1. Given our pump is RPM dependent, naturally when you jump off the gas and on the brakes, the oil pressure readings will plummet.
2. Boxer motors inherently oil starve due to design on high g-loads as the heads don't allow for oil to drain back fast enough
3. High oil temps and too low of viscosity grade used (or more rare, too high viscosity).

I recently spoke to TMG Europe about their switch from 10W60 to 5W50, and they stated it was to help lower oil temps, and free up some HP via lighter oil viscosity. It seems they feel the sweet spot for pressure/temps/protection is using a XW50 oil. I actually plan on trying 10W50 to see how that affects pressures. Anybody else using a 50 oil?

[prandelia]

Here's a closer magnified look at a few corner sequences, where it's full throttle into a big brake zone, then tight 3rd corner gear, then slowly opening up onto a straight, then into a really fast sweeper followed by a huge brake zone into another tight, slow 3rd gear corner. Once under braking and/or the car loads up, you can see the first really low dip area, and that's where it seems oil is in the head's or sloshing in the pan and there is no pickup.

Again, it's not horrendous looking at this, as the revs are in the high 4K, and pressure is about low 40psi's, but would be nice to see another 10psi or so, to try and keep that magic 10psi/1000 RPM. The next big drop toward the right end of the graph starts with a 100mph+, long sweeper, so you can see how it slowly loads the head up with oil, and/or is seeing some starve in the pan. I dunno.

Then followed by the biggest brake zone on the track, again, pressures seem relatively in-line with RPM, but it's just the huge swings that are so alarming.

I guess I need to just chill out more, and understand part of this is the 2-stage oil pump, or should I be more alarmed. High of ~90psi, low ~35psi. I dunno? I need somebody more data-smart to interpret this better than I can. I just drive that car...lol.

[ls1ac]

You were first asking about the accuracy of the readings, right? Your charts show a normal increase with RPM. I am assuming that you are worried about tracking the car. The exact pressure is not important but rather if abnormal changes take place while driving. I think you maybe over thinking.
To push the way back machine Butten: we used to put tape on the glass to cover about one quarter of end of the needle on the oil pressure gauge in the range that was normal. The gauge was also turned so the normal reading was strait up.When the gauge got outside normal the full needle would be seen and the drivers attention would be drawn to the gauges. The gauges were mechanical with a P-tube so the needle moved a lot. (To day the gauges often have over/under warning lights that will often flicker at idle.)




Edit: In you last post you asked about the loss in a sweeper, check other posts about the many ways to combat that problem.

[CSG Mike]

This looks fairly typical; if you were actually starved, you wouldn't see a "low plateau" so to speak.

If you want to maintain that 10 psi/1k rpm, you want to set your accusump around 52-55 psi based on the data presented.

[prandelia]

Originally Posted by CSG Mike

This looks fairly typical; if you were actually starved, you wouldn't see a "low plateau" so to speak.

If you want to maintain that 10 psi/1k rpm, you want to set your accusump around 52-55 psi based on the data presented.

Thanks Mike, that makes sense. Yeah, we kinda decided on about 55psi (and above 4000 RPM) from the AIM, that way it only discharges when I'm at speed on track, and not cruising around or at idle, . This way you don't have to worry about forgetting to toggle switch "off" before even coming off track. We'll try this and see if it keeps the EPC valve happy, and if not, we can use the optional Canton pressure switch at 55/60psi.

I spoke with them about my plan, and they said it should be fine, even though the discharge/refill pressure is the same value (55psi), and there isn't a "dead" spot of 5psi in between like their switch.

I also plan to supplement hot summer ambient temps with a 10W50 motor oil weight.....for me the Accusump is less about pressure and more about maintaining oil flow to the mains. Numerically speaking I guess my pressures look good, but who know exactly what is going on at the mains in those situations. The extra oil can't hurt, and I run the Crawford AOS that recirculates captured oil, so no worries about catch-can overfilling. My guess is the amount of oil discharged by the accusump won't be a whole lot anyway.

[CSG Mike]

Originally Posted by prandelia

Thanks Mike, that makes sense. Yeah, we kinda decided on about 55psi (and above 4000 RPM) from the AIM, that way it only discharges when I'm at speed on track, and not cruising around or at idle, . This way you don't have to worry about forgetting to toggle switch "off" before even coming off track. We'll try this and see if it keeps the EPC valve happy, and if not, we can use the optional Canton pressure switch at 55/60psi.

I spoke with them about my plan, and they said it should be fine, even though the discharge/refill pressure is the same value (55psi), and there isn't a "dead" spot of 5psi in between like their switch.

I also plan to supplement hot summer ambient temps with a 10W50 motor oil weight.....for me the Accusump is less about pressure and more about maintaining oil flow to the mains. Numerically speaking I guess my pressures look good, but who know exactly what is going on at the mains in those situations. The extra oil can't hurt, and I run the Crawford AOS that recirculates captured oil, so no worries about catch-can overfilling. My guess is the amount of oil discharged by the accusump won't be a whole lot anyway.

I've used 5W30 with a turbo, without issue, for years.

Anecdotal, but just saying. My temps are typically slightly higher than yours, but never over 225F. The turbo is oil cooled.

I've run grip levels up to takeoff hoosier, but haven't played with any pirellis or michelins.

[prandelia]

Originally Posted by CSG Mike

I've used 5W30 with a turbo, without issue, for years.

Anecdotal, but just saying. My temps are typically slightly higher than yours, but never over 225F. The turbo is oil cooled.

I've run grip levels up to takeoff hoosier, but haven't played with any pirellis or michelins.

More data points the better. That makes me feel better. All my data is from 225 Hoosier grip, either in practice, or actual GLTC races, so this is what the engine/oiling sees at it's highest stress levels.

Just for reference, here is a huge zoomed in section of a corner from another track (Gingerman), which has a lot of switchback corners and sweepers so it really tests your oil pressure. Here, I am the end of a decal (braking phase) and you can see where I turn-in and then RPM's increase from about 5500-7600 as I accelerate through the turn. See how the oil pressures "hunts" up and down? 75psi then 2/10th of a second later, it's 35psi lower.....is that pump cavitation or oil starve? I mean the good news is that the overall pressure (and low points) rises with RPM, so that seems to indicate things are working as they should, but there are definitely lots of places where the oil pressure is below where it should be using the magical 10psi/1000RPM guidelines.

I wonder if that is simply the pump picking up any oil that it can from the sump, then as it depletes it, pressure drops and the cycle continues until the car straightens up and enough oil drops back from the head.

When you zoom in, you can see that some of the drops aren't as bad as from totally zoomed out, but then you can also see more of this oscillation in oil pressure during cornering exit phases....

Sorry for the nerdy technical crap, but like I have anything better to do right now...LOL.

[CSG Mike]

Originally Posted by prandelia

More data points the better. That makes me feel better. All my data is from 225 Hoosier grip, either in practice, or actual GLTC races, so this is what the engine/oiling sees at it's highest stress levels.

Just for reference, here is a huge zoomed in section of a corner from another track (Gingerman), which has a lot of switchback corners and sweepers so it really tests your oil pressure. Here, I am the end of a decal (braking phase) and you can see where I turn-in and then RPM's increase from about 5500-7600 as I accelerate through the turn. See how the oil pressures "hunts" up and down? 75psi then 2/10th of a second later, it's 35psi lower.....is that pump cavitation or oil starve? I mean the good news is that the overall pressure (and low points) rises with RPM, so that seems to indicate things are working as they should, but there are definitely lots of places where the oil pressure is below where it should be using the magical 10psi/1000RPM guidelines.

I wonder if that is simply the pump picking up any oil that it can from the sump, then as it depletes it, pressure drops and the cycle continues until the car straightens up and enough oil drops back from the head.

When you zoom in, you can see that some of the drops aren't as bad as from totally zoomed out, but then you can also see more of this oscillation in oil pressure during cornering exit phases....

Sorry for the nerdy technical crap, but like I have anything better to do right now...LOL.

Well, if those dips disappear with the accusump, we'll know!

The tiny sample of cars I have data from that log oil pressure just all accept it as "normal" at this time. There's not an overabundance of spun bearings, but I wouldn't call that conclusive either.

[racingfool]

Originally Posted by CSG Mike

There's not an overabundance of spun bearings.

Just reading that makes me cringe. You ever spun a rod bearing? Ever stick a piston? Yes and yes for me. =(

I just watched a show where they show how too much oil causes cavitation worse than with just a little less.

They say on some engines the recommended level is too high causing the crank to splash through the oil.
Causes drag and whips the oil into a foam.

With an engine on the dyno they took out a little oil at a time.
Each time oil pressure improved and hp went up.

The level they ended up at was well below what was recommended.

[redlined600]

Do you have data from Road America? While I don't/can't Log pressure with the SoloII I have noticed that my pressure gauge alarm flashes toward the middle end of the carousal(not exact, as I can only catch it out of the corner of my eye). IIRC that's about 20~30psi, with 5w30 oil, normal temps.

what I experience looks very similar to your first posted graph.

[CSG Mike]

Originally Posted by racingfool

Just reading that makes me cringe. You ever spun a rod bearing? Ever stick a piston? Yes and yes for me. =(

I just watched a show where they show how too much oil causes cavitation worse than with just a little less.

They say on some engines the recommended level is too high causing the crank to splash through the oil.
Causes drag and whips the oil into a foam.

With an engine on the dyno they took out a little oil at a time.
Each time oil pressure improved and hp went up.

The level they ended up at was well below what was recommended.

No, but I have data from multiple national championship winning cars that run slicks on banked ovals, that would otherwise have dead engines if the engine were starved of oil.