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Oil pressure dropping to critical levels under hard braking (Headscratcher)

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steveespo

Lord knows I'm a Voodoo Child
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Cookeville TN
I'd expect that if the check valve was both working and installed backwards, he'd have lots of oil pressure at the sensor which is upstream of the valve and none in the engine which is downstream. As you say, though, if the pan has enough oil, he shouldn't need the Accusump. Maybe a test drive with it switched off is in order - a lap or two working up the speed and g's to see how the pressure goes.
 

steveespo

Lord knows I'm a Voodoo Child
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4,116
2,257
Exp. Type
W2W Racing
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10-20 Years
Cookeville TN
I'd expect that if the check valve was both working and installed backwards, he'd have lots of oil pressure at the sensor which is upstream of the valve and none in the engine which is downstream. As you say, though, if the pan has enough oil, he shouldn't need the Accusump. Maybe a test drive with it switched off is in order - a lap or two working up the speed and g's to see how the pressure goes.
No I don't think so, if backwards his engine would see zero oil pressure and other bad things would happen.accusump_article8.jpg
 
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In the V6L
No I don't think so, if backwards his engine would see zero oil pressure and other bad things would happen.View attachment 95986
Exactly. We agree.

What I was talking about with pressure at the gauge and at the engine is that while the layout drawing in Post 12 shows the sender on the engine, in Post 18 the OP says "My oil pressure sender is located in the small port of the M-6881-M50A Ford Racing Remote Oil Filter adapter" which would position the sender at the filter which is in-line before the check valve. If the check valve was a) working and b) backwards, the way the sender is located could create a horrible situation - you start the engine, see the pressure on the readout is high and relax while the engine runs with no oil at all. That's not what's happening here, thank goodness.
 
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Sil Spg MD
Check valve was definitely installed correctly (direction-wise)...it just wasn't working. Got a junkyard motor (complete head to toe) put in the racecar now. Due to time constraints, I am not installing the GT500 pan, pump, valve covers , I just moved over the cooler, lines (without check valve or tee fitting) and remote filter. Going to shift at 6000rpm and see if I can get some good data. Going to make sure oil level is just below the top dot. Not having the baffled pan I don't want to run hard.....plus I need to get some points on the board :D
 
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Sil Spg MD
Looking better....stock oil pump, pan, pickup tube, but still w/remote oil filter and -12 lines, and big oil cooler. Oil pressure only dipped down to idle pressures under braking into T1 but the recovery was instantaneous!
Screenshot 2024-06-11 013418.png
 

steveespo

Lord knows I'm a Voodoo Child
Moderator
4,116
2,257
Exp. Type
W2W Racing
Exp. Level
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Cookeville TN
Looking better....stock oil pump, pan, pickup tube, but still w/remote oil filter and -12 lines, and big oil cooler. Oil pressure only dipped down to idle pressures under braking into T1 but the recovery was instantaneous!
View attachment 96112
You definitely need a pan that keeps the oil pickup covered. I don't like the oil pressure down at 32 at 3825 rpm under only a -1g brake peak. We see -1.5g and lateral g sums of 2.0 sometimes and don't have any pressure drop with either the GT500 or FPRP steel road race pans. Your G Sum at this point is 1.7 which is pretty high. Did you check clearance of the pickup to bottom of pan? Looking for 1/4"-5/16". 3/8" is the absolute outside limit.
 
34
20
Exp. Type
W2W Racing
Exp. Level
5-10 Years
Sil Spg MD
You definitely need a pan that keeps the oil pickup covered. I don't like the oil pressure down at 32 at 3825 rpm under only a -1g brake peak. We see -1.5g and lateral g sums of 2.0 sometimes and don't have any pressure drop with either the GT500 or FPRP steel road race pans. Your G Sum at this point is 1.7 which is pretty high. Did you check clearance of the pickup to bottom of pan? Looking for 1/4"-5/16". 3/8" is the absolute outside limit.
Definitely want to keep the pickup covered. Will be putting the GT500 pan (and pump) sooner rather than later. The pickup clearance of the engine that's in the car was not checked (stock unopened OEM engine). Thank you for the clearance limits, we will make sure we're within that range.
Question: can you run the GT500 pan w/the stock 5.0L pickup tube?
 

steveespo

Lord knows I'm a Voodoo Child
Moderator
4,116
2,257
Exp. Type
W2W Racing
Exp. Level
10-20 Years
Cookeville TN
Definitely want to keep the pickup covered. Will be putting the GT500 pan (and pump) sooner rather than later. The pickup clearance of the engine that's in the car was not checked (stock unopened OEM engine). Thank you for the clearance limits, we will make sure we're within that range.
Question: can you run the GT500 pan w/the stock 5.0L pickup tube?
No and you wouldn't want to. The whole GT500 pump and pickup is substantially larger than the stock steel or plastic pan setup. Gears are thicker and stronger. I see 115 psi warm at 2800+ RPM, full hot never drops below 88, that's why I'm concerned with that much drop on your car.
 
34
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Exp. Type
W2W Racing
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Sil Spg MD
Pulled back up motor out and have installed the GT500 pump, pickup, and pan. Threw on an ATI dampener and GT500 valve covers (from the blow'd up motor) while we were in there. Dropping the engine back in tomorrow...Looking to see how the oil pressure acts now. Will be going to Watkins Glen on the 29th-30th (for the 1st time), so between not being familiar with the track and tip toeing around, not sure how good the data will be.....
 

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