Oil Pressure Loss in Braking

[ddd4114]

I just got the car back together, and I found that the wiring harness connector does not reach the level sensor in the Moroso oil pan. Did you guys have this problem too? Strangely, there was no dummy light for it when I went for a test drive.

 

[ArizonaGT]

I just got the car back together, and I found that the wiring harness connector does not reach the level sensor in the Moroso oil pan. Did you guys have this problem too? Strangely, there was no dummy light for it when I went for a test drive.

It BARELY reaches, if you do NOT use the factory wiring harness clips. Pretty ghetto but it will reach if you just let it dangle.

 

[ddd4114]

UPDATE

I just returned from another weekend at Mid-Ohio, and while the oil pressure was much more stable with the new oil pan, it still dipped down to ~30 psi in long braking zones. Without a filter change, I put 10 qt into the pan after installing it, and the level on the dipstick was WAY over max. Fortunately, it didn't seem to cause frothing at high engine speeds.

In the following graph, oil pressure is on the top, and longitudinal acceleration is on the bottom. Data from last time is black, and data from today is red:

I'm assuming that given the oil flow rate of the engine and the length of the braking zones, no amount of baffling and trap doors will prevent starvation because at some point, the volume in the sump will be depleted. I'd like to start running Hoosiers soon, so I'll see what happens with the added grip.

Also, I wasn't able to get the level sensor connector to stretch enough, so I extended the harness. It's kind of a pain to get a soldering iron and heat gun in the space next to the pan, but it worked. I did some research, and it seems that the sensor is only used in the oil life monitoring system, so actually, it wouldn't be such a big deal to leave unplugged.

 

[ArizonaGT]

Fill 12 quarts now and you will be fine. That is what I do but I have a 25-row air-oil cooler. No consumption issues and never below 70 psi anecdotally looking at AIM data.
Hot idle, no load, you may come down to 15-20psi but that is nothing to be alarmed about.

 

[ddd4114]

How high up on the dipstick does the oil get when you put in 12 qt? Mine was over by ~3/4".

 

[ddd4114]

I experimented a little with overfilling the Moroso oil pan at Gingerman Raceway this past weekend, so I thought I would resurrect this thread again to share my findings.

I had previously filled the pan to ~11 qt, and I added another 1/2 qt before starting the weekend. I'm not sure how much oil I've burned since originally filling the pan, but I doubt it's much.

Here is a comparison of oil pressure (in red) with vehicle speed (in black), lateral acceleration (in green), and longitudinal acceleration (in blue):

Just like at Mid-Ohio, the majority of the pressure loss occurred in longer braking zones. However, now I'm seeing a drop in the middle of a corner (turn 6). I don't quite understand why because there is no pressure loss in 7-8-9, and lateral acceleration is just at high there (both left and right). I don't know the specs of the oil pressure relief valve in the oil pump, but it's possible that the lower engine speed causes weird things to happen when the hot, aerated oil goes through the pump.

After sorting through data, it definitely looks like there is a correlation with oil temperature (on the top half of the following graph):

In general, oil pressure loss occurs in long braking zones regardless of oil temperature. However, the hotter the oil gets, the more pressure loss occurs in turn 6.

The next day, I put in another 1/2 quart to see what happens. Here is the result:

Overall, there was a large improvement in pressure except in the braking zones going into turn 10 (which is downhill) and into turn 12 (which is 400' long). There was no pressure loss in turn 6 until the oil temperature was ~280 degF. As ArizonaGT suggested, the system is very sensitive to oil volume, and despite the 10 quart capacity specified by Moroso, you have to overfill the pan.

Since I mostly just run time trial events, I don't really want to drop hundreds of dollars on an oil cooler when I only need to put down 1-2 laps per session. I'll continue to add oil in 1/2 quart increments to find a safe range that will reduce starvation but still not let the oil level get so high that it hits the crankshaft when it sloshes.

Something else I noticed at this event was that I had to drain my catch cans after every session. If I stayed out for the whole 15 minutes, I would drain close to 1 cup of oil out of both my breather and PCV catch cans, and previously it was only a few tablespoons. I don't know if this is caused by the higher oil level or from excessive blow-by. Hopefully I didn't break something...

 

[neema]

Don't know if I didn't catch it but are you still using 20w oil? If so, that might be your culprit. A 20w oil at 280° will probably be less viscous than water. Put something thicker in it, especially if you're not going to opt for an oil cooler (which I recommend--don't handicap yourself). I know Vorshlag used higher oil viscosity in their 11 GT, finally ending up with Mobil 1 15w-50

 

[ddd4114]

Good question. I'm using Mobil 1 0w40 right now. I'll probably try 15w50 next after seeing the relationship with temperature.

I'll probably get a real oil cooler eventually for the same reason. If the 15w50 oil completely fixes the problem, then I should be good. If not, then it might be an investment for next year.

 

[Sky Render]

I second the suggestion of thicker oil.

I might have missed it, and if so I apologize, but where are you measuring oil pressure from? Is it possible that the loss of oil pressure you're seeing is due to gee forces making the actual pressure sender move?

Sent from my Samsung Galaxy Note 4 using Tapatalk

 

[ddd4114]

Yeah, I should change the oil soon anyway, so I'll switch to 15w50 and see what happens at my next event.

I put a T fitting at the OEM pressure switch location to mount the transducer. Since the pressure loss doesn't occur "randomly", I think it's real. Everything is mounted pretty rigidly.

 

[ddd4114]

UPDATE: Mobil 1 15w50 does not solve the problem.

Speed is in black, oil pressure is in red, oil temperature is in pink, and longitudinal acceleration is in blue:

It looks like I'll have to break down and buy an oil cooler. I did an event at Road America this weekend, and after one hot lap, the oil temperature was saturated at ~290 degF. I'll try to put something together for my next event in the middle of September, but if I can't, I'll definitely make the investment for next year.

Also, I'm still draining about 1 cup of oil out of the catch can in my breather hose after every 15-minute session. I suppose that's a result of overfilling the oil pan? Just like last time, I ran ~12 qt in the 10-qt Moroso pan.

I'll post back again after trying a cooler. Hopefully that solves the problem...

 

[Vorshlag-Fair]

I'm assuming that given the oil flow rate of the engine and the length of the braking zones, no amount of baffling and trap doors will prevent starvation because at some point, the volume in the sump will be depleted. I'd like to start running Hoosiers soon, so I'll see what happens with the added grip.

I admire your testing and desire to get the oil pressure under control while braking. The data you have shared is pretty eye opening...

And while it may be anecdotal evidence, I don't think you need to worry this much - we never had oiling problems in our TT3 car. The oiling system on the 5.0L Coyote is far superior to many other modern V8s, and we had excellent results over 5 years of racing our 2011 GT, above. Stock oil pan, stock everything except headers and cold air (443 whp in its final 93 octane tune).

We used R-compounds (Kumho and Hoosier) race tires for 4 of those years, and data logging showed 1.5g braking under most circumstances. Lateral gs of 1.5 (low speed) and up to 2.0 gs (with aero) were also regularly measured. We logged over 20,000 miles of use, and all we did was change the oil regularly, plus we had two front O2 sensor replacements over that period. That's all the service work this engine required while racking up dozens of wins in NASA TT3.

The OEM clutch (see above) also looked perfect after 3rd gear was replaced under warranty. But we did go to great lengths to keep the revs low, with peak power at 6500 rpm (I shifted at a max rpm of 7000). The temptation to move away from the Coyote intake and go to the Boss302 is huge - it just looks so badass - but the loss of mid-range torque and shifting of peak power up +1000 rpms only complicates issues.

Dyno results from the same dyno with our car (Coyote) and a customers car (Boss302) with identical mods, as noted

Generally speaking, higher RPM use leads to accelerated engine wear, the common clutch failures, and long term oil pressure problems. So anyway, just keep that in mind. The oil pan mod seems to be a good one, but I don't know if its 100% necessary.

Just my two cents....

 

[Sky Render]

You need to get those oil temps under control before you roast your bearings.

 

[Vorshlag-Fair]

You need to get those oil temps under control before you roast your bearings.

Wow, Agreed... just saw that post. 290°F in one lap is sky high. What kind of car is this? I cannot seem to find a description in this thread.

Year, motor, mods...

This isn't supercharged, is it??? Blown 5.0s are a major chore to keep cool on track.

 

[SlowJim]

I believe his 11GT is mostly stock under the hood, as necessitated by running NASA TTB.

 

[Mark Aubele]

How are the oil temps so high so quickly?

 

[Sky Render]

Where is your oil temperature sender installed? Mine is currently installed in a "sandwich plate" adapter--near the header--so my oil temps read a bit higher than they actually are.

 

[ddd4114]

Thanks for the feedback.

The car is 2011 GT with basically a stock engine. I'm using 245mm Hoosier R7's to stay in TTB, so I'm only getting ~1.2g lateral acceleration and ~1.3g braking.

Getting to 290 degF in one lap was a bit atypical because Road America is a very fast, long course. Also, with my tire size and gearing, I'm riding the engine out to 7000 rpm at the end of the long straights (before turns 1, 5, and 12), so that will dump a lot of heat into the oil. On my other local tracks, it takes 4-5 hot laps before oil gets above 280 degF. Of course, that still isn't so great.

Before upgrading my oil pan, I put a thermistor in the drain plug to measure temperature, and before installing the Boss 302 oil heater/cooler, it got as high as 310 degF. The heater/cooler dropped the temperatures by ~20 degF. After upgrading the oil pan, I put a thermocouple in the side of the pan instead, and that's what's used in all of the graphs I've been sharing.

Honestly, the fact that the oil gets to 290 degF (and doesn't continue rising) isn't such a big deal and won't cause bearing failure by itself. Considering a variant of this engine is found in the F150, I'm sure that Ford has tested it to well over this temperature. You can see in my graphs that most of the time, oil pressure is > 60 psi, and that's not bad. The reason the higher temperature is a problem in my case is because the pickup is being exposed to air more easily when the oil is less viscous and sloshes more. You can see that happening in the graphs I shared in post #26.

 

[ddd4114]

UPDATE: I coughed up the money and installed a Mishimoto oil cooler.

I just ran an event at Autobahn, but unfortunately, it didn't go so well. After a couple laps in the warm-up session, 3rd gear broke. All of the other gears seem fine, but with very little warning, I converted my 6-speed MT82 into a 5-speed MT82. I still ran a few laps each day because I need the points for the regional championship, but I had to be in 4th and 5th gear the whole time.

Since I was already handicapped from the broken transmission, I didn't feel like pushing the car and breaking other things too. I just ran a few "participation laps". Given that limitation, I'm ambivalent about the oil cooler's performance. The oil temperature stabilized at ~260 degF, and I was really hoping for more than a 20-30 degF drop over the Boss 302 cooler. I'm pretty sure that if I pushed the car harder on a hotter day, I would have easily raised the oil temperature by 10+ degF. I'll probably contact Mishimoto and see what their expectations are for this application.

Once the oil temperature was stabilized, there was still some oil pressure loss under braking, but it wasn't that concerning. The lowest it got was 51 psi, and that should be sufficient for the engine (in small doses).

Here is a graph of my fastest lap (in which the engine would be working hardest). Speed is in black, oil pressure is in red, oil temperature is in pink, and longitudinal acceleration is in blue:

I'll be limping the car through the final event of the year, and hopefully I get a new transmission for the spring. It's possible that I have the oil pressure under now, but I won't know for sure until I can push the car as hard again.

 

[2008 V6]

Adding multiple quarts of extra oil to the sump is questionable (My opinion). The easiest Band-Aid is an Accusump. I have used several and they work to keep steady oil pressure. Pre-start engine lubrication is a great added bonus.

Boss 302 Radiator is a joke - The only advantage is pre-oil heating for street cars on first start up in cooler weather. My opinion also.
A properly ducted oil cooler and slow opening remote mounted thermostat located away from exhaust heat is your best solution to controlling oil temps and street driving.
Please - Don't mount the oil cooler so it is on top of the radiator unless your radiator is massive - separate ducted cold air source is optimal so maximum radiator air exposure is possible.
Properly duct the radiator for best results. The stock configuration is not efficient
Fee advise is worth what you pay for it.