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Oil Drainback/Windage Issues

General engine tech -- Drag Racing to Circle Track

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rustbucket79
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Re: Oil Drainback/Windage Issues

Post by rustbucket79 »

Kevin, when I used to travel, I had pad heaters on the oil pan, as well as the differential and transmission pan. These days, local track is pretty sparse in attendance so I give it a hard squirt up the return road and back and call it good. First and second qualifiers usually line up pretty close so the procedure works for me. Swapping to a roller cam many years back was the end of running tar for oil for me, but the first time you pour a bottle of 5W 20 you second guess yourself. : :o
matt69nova
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Re: Oil Drainback/Windage Issues

Post by matt69nova »

Quick testing update from this past weekend:

Run 1: Disconnected accumulator, drained 2 qts of oil for a total of 6qts. in engine. Oil pressure rose with RPM until the top of 2nd gear, where it fell back down to around 30psi for the remainder of the run, which is the same pressure it finished with with the accumulator hooked up

Run 2: Change to 10W40 oil, 6 qts. No change to pressure or curve.

Run 3: Drained 1 qt. of oil for 5 qts. total. The pressure graph shows the oil pressure still rising to the top of 2nd gear, and again falling off, but only back down to 40psi. Interestingly, in the last half second or so of the run, the pressure shoots back up to around 75psi (the bypass spring pressure) at the top of high gear.

I will post the graph when I have it available, but it seems to me there is a combination of windage and drainback issues going on. I wasn't comfortable going down to a 5W oil yet, but this winter it looks like I will add the crank scraper and possibly change oil pans to a Moroso 21015 pan, and add the oil preheater. I don't know that I'd feel great about dropping the oil level down to 4 qt. total.
smeg
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Re: Oil Drainback/Windage Issues

Post by smeg »

matt69nova wrote: Mon Sep 13, 2021 12:18 pm Quick testing update from this past weekend:

Run 1: Disconnected accumulator, drained 2 qts of oil for a total of 6qts. in engine. Oil pressure rose with RPM until the top of 2nd gear, where it fell back down to around 30psi for the remainder of the run, which is the same pressure it finished with with the accumulator hooked up

Run 2: Change to 10W40 oil, 6 qts. No change to pressure or curve.

Run 3: Drained 1 qt. of oil for 5 qts. total. The pressure graph shows the oil pressure still rising to the top of 2nd gear, and again falling off, but only back down to 40psi. Interestingly, in the last half second or so of the run, the pressure shoots back up to around 75psi (the bypass spring pressure) at the top of high gear.

I will post the graph when I have it available, but it seems to me there is a combination of windage and drainback issues going on. I wasn't comfortable going down to a 5W oil yet, but this winter it looks like I will add the crank scraper and possibly change oil pans to a Moroso 21015 pan, and add the oil preheater. I don't know that I'd feel great about dropping the oil level down to 4 qt. total.
Does the pressure go back up just after you get off the throttle and the revs drop?
matt69nova
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Re: Oil Drainback/Windage Issues

Post by matt69nova »

smeg wrote: Tue Sep 14, 2021 11:38 pm
matt69nova wrote: Mon Sep 13, 2021 12:18 pm Quick testing update from this past weekend:

Run 1: Disconnected accumulator, drained 2 qts of oil for a total of 6qts. in engine. Oil pressure rose with RPM until the top of 2nd gear, where it fell back down to around 30psi for the remainder of the run, which is the same pressure it finished with with the accumulator hooked up

Run 2: Change to 10W40 oil, 6 qts. No change to pressure or curve.

Run 3: Drained 1 qt. of oil for 5 qts. total. The pressure graph shows the oil pressure still rising to the top of 2nd gear, and again falling off, but only back down to 40psi. Interestingly, in the last half second or so of the run, the pressure shoots back up to around 75psi (the bypass spring pressure) at the top of high gear.

I will post the graph when I have it available, but it seems to me there is a combination of windage and drainback issues going on. I wasn't comfortable going down to a 5W oil yet, but this winter it looks like I will add the crank scraper and possibly change oil pans to a Moroso 21015 pan, and add the oil preheater. I don't know that I'd feel great about dropping the oil level down to 4 qt. total.
Does the pressure go back up just after you get off the throttle and the revs drop?
Yes, it has consistently gone back up (if the engine stays running) after crossing the finish line and letting off the gas. On the last run I made with 10W-40 oil and 5 qts of oil (instead of 6), the oil pressure shot from 40psi to 75psi in the last half second of the run when I was still under power.
smeg
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Re: Oil Drainback/Windage Issues

Post by smeg »

matt69nova wrote: Wed Sep 15, 2021 12:58 pm
smeg wrote: Tue Sep 14, 2021 11:38 pm
matt69nova wrote: Mon Sep 13, 2021 12:18 pm Quick testing update from this past weekend:

Run 1: Disconnected accumulator, drained 2 qts of oil for a total of 6qts. in engine. Oil pressure rose with RPM until the top of 2nd gear, where it fell back down to around 30psi for the remainder of the run, which is the same pressure it finished with with the accumulator hooked up

Run 2: Change to 10W40 oil, 6 qts. No change to pressure or curve.

Run 3: Drained 1 qt. of oil for 5 qts. total. The pressure graph shows the oil pressure still rising to the top of 2nd gear, and again falling off, but only back down to 40psi. Interestingly, in the last half second or so of the run, the pressure shoots back up to around 75psi (the bypass spring pressure) at the top of high gear.

I will post the graph when I have it available, but it seems to me there is a combination of windage and drainback issues going on. I wasn't comfortable going down to a 5W oil yet, but this winter it looks like I will add the crank scraper and possibly change oil pans to a Moroso 21015 pan, and add the oil preheater. I don't know that I'd feel great about dropping the oil level down to 4 qt. total.
Does the pressure go back up just after you get off the throttle and the revs drop?
Yes, it has consistently gone back up (if the engine stays running) after crossing the finish line and letting off the gas. On the last run I made with 10W-40 oil and 5 qts of oil (instead of 6), the oil pressure shot from 40psi to 75psi in the last half second of the run when I was still under power.
That is exactly what mine did when it was oil pump cavitation as my data logger was showing, I fixed it with different oil pump. It could also be your pick up too close to pan bottom. It is telling you that you have this problem when it dropped revs and the pressure went up. Just put a std volume pump on with the large pick up and try it.
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