Oil Drain backs

Is anybody, has anybody ran external drain back lines from cylinder heads to the pan on cast iron heads?

How did you go about it?

Best placement?

Size?

Any noticable advancements made? More relative to oil pressure.


My dilemma, running a stock block, bushed lifters .041 holes, .0035 clearance. Cam bearings are drilled .0625 and .0035 clearance on the rod and main bearings. Running a 1.7 SCP external oil pump and a vac pump producing 8-12".

During a run (approximately 30 seconds) The oil pressure will ramp up to 85ish and per my recorder about 10 seconds into the run pressure will drop to 60 psi will in the 7500-8500 rpm range with some dips down into the 50's and even 40's for split seconds. We have quite a few passes on this issue and have the engine torn down for winter maintenance and found no evidence of issues related to lack of oil, though we have found that oil drain back could stand improvement between the Jesel belt drive and the front of the block, potentially impeding oil pickup at that sump.


Thoughts? Ideas? Criticisms?

Thank you

Check the alignment of the drain backs holes in the heads and block plus the head gasket itself.

Doug Rahn wrote:Check the alignment of the drain backs holes in the heads and block plus the head gasket itself.

We did check that upon disassembly, I would give it a 7 of 10 on the alignment scale. Not bad, but could use some improvment.

So if I'm understanding you correctly that's about 30% blocked? The oil running into that flat surface could slow it down significantly. Adding the 2 drain holes in the block front is a plus, and a really cheap upgrade. I forgot to add you might want to lower the the inches of vacuum a little, at least below 10".

Doug Rahn wrote:So if I'm understanding you correctly that's about 30% blocked? The oil running into that flat surface could slow it down significantly. Adding the 2 drain holes in the block front is a plus, and a really cheap upgrade.

I would guesstimate a 30% blockage yes.

With the Jesel drive it will be difficult to regain the full potential of the front drain holes as that cover only gives .080" of drain back area. This is why I inquire about external drain backs

I should also add that I have seen a correlation between vacuum and oil pressure on my 598. I have a Peterson Wet/Vac pump and on my data logger when the vacuum would reach 12", I could see the oil pressure fluctuating. So I keep mine at 8/9", no issues.

Doug Rahn wrote:I should also add that I have seen a correlation between vacuum and oil pressure on my 598. I have a Peterson Wet/Vac pump and on my data logger when the vacuum would reach 12", I could see the oil pressure fluctuating. So I keep mine at 8/9", no issues.

I will agree with that. We have noticed the same

I try to keep the vac high though as it makes a significant increase in average and peak Dyno numbers

Accu sump system could help too.

Anything in your rules not allowing you to run a drysump system?

dfree383 wrote:Accu sump system could help too.

Anything in your rules not allowing you to run a drysump system?

Dry sump is legal, just not presently in the cards monetarily.

I have wondered about the Accu Sump systems but of coarse have seen somewhat mixed reviews on operation. My own worry about that system in my application is what the windage would be like once the sump has expelled with as long as my runs are. I suppose there would have to be a happy medium between lowest oil pressure during the run with the precharge of the accumulator?

Could do a smaller pump, reduce pressure or drive ratio.

You really don't need 80 psi

60 is more than enough

That would reduce the volumn used too

dfree383 wrote:Could do a smaller pump, reduce pressure or drive ratio.

You really don't need 80 psi

60 is more than enough

That would reduce the volumn used too

Very interesting thought! We may just have to try that once back together.

What percent of crankshaft speed are you turning the oil pump?

.

Lem Evans wrote:What percent of crankshaft speed are you turning the oil pump?

20 tooth drive
32 tooth driven

-12 suction
-12 to filter
-12 to block
-6 Lem inspired pressure line from front to rear of block

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EverySparePenny wrote:20 tooth drive
32 tooth driven

-12 suction
-12 to filter
-12 to block
-6 Lem inspired pressure line from front to rear of block

62.5% is faster than the pump needs to turn & the 1.700" gear is wider than it needs to be .

The engine is pumping more oil than it needs to. Reducing the pump speed to around 53% is the quickest and cheapest move.

Lem Evans wrote:

EverySparePenny wrote:20 tooth drive
32 tooth driven

-12 suction
-12 to filter
-12 to block
-6 Lem inspired pressure line from front to rear of block

62.5% is faster than the pump needs to turn & the 1.700" gear is wider than it needs to be .

The engine is pumping more oil than it needs to. Reducing the pump speed to around 53% is the quickest and cheapest move.

I believe we went as low as 57% preseason. I will see if we can get down to 53% once the engine is back together thank you

EverySparePenny wrote:

Lem Evans wrote:

EverySparePenny wrote:20 tooth drive
32 tooth driven

-12 suction
-12 to filter
-12 to block
-6 Lem inspired pressure line from front to rear of block

62.5% is faster than the pump needs to turn & the 1.700" gear is wider than it needs to be .

The engine is pumping more oil than it needs to. Reducing the pump speed to around 53% is the quickest and cheapest move.

I believe we went as low as 57% preseason. I will see if we can get down to 53% once the engine is back together thank you

How much oil is in the system.....filter included?

Lem Evans wrote:

EverySparePenny wrote:

Lem Evans wrote:

EverySparePenny wrote:20 tooth drive
32 tooth driven

-12 suction
-12 to filter
-12 to block
-6 Lem inspired pressure line from front to rear of block

62.5% is faster than the pump needs to turn & the 1.700" gear is wider than it needs to be .

The engine is pumping more oil than it needs to. Reducing the pump speed to around 53% is the quickest and cheapest move.

I believe we went as low as 57% preseason. I will see if we can get down to 53% once the engine is back together thank you

How much oil is in the system.....filter included?

As much as 13 and as little as 9 with much the same result

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EverySparePenny wrote:Is anybody, has anybody ran external drain back lines from cylinder heads to the pan on cast iron heads?

How did you go about it?

Best placement?

Size?

Any noticable advancements made? More relative to oil pressure.


My dilemma, running a stock block, bushed lifters .041 holes, .0035 clearance. Cam bearings are drilled .0625 and .0035 clearance on the rod and main bearings. Running a 1.7 SCP external oil pump and a vac pump producing 8-12".

During a run (approximately 30 seconds) The oil pressure will ramp up to 85ish and per my recorder about 10 seconds into the run pressure will drop to 60 psi will in the 7500-8500 rpm range with some dips down into the 50's and even 40's for split seconds.  We have quite a few passes on this issue and have the engine torn down for winter maintenance and found no evidence of issues related to lack of oil, though we have found that oil drain back could stand improvement between the Jesel belt drive and the front of the block, potentially impeding oil pickup at that sump.


Thoughts? Ideas? Criticisms?

Thank you

I would say you also probably have some kind of windage or aeration issue within the crankcase and oil pan.

To me, you probably have about a thou to much clearance on the rod bearings and with a 1.7" pump pressure section, somewhere around 45% drive ratio should be about right.

rmcomprandy wrote:

EverySparePenny wrote:Is anybody, has anybody ran external drain back lines from cylinder heads to the pan on cast iron heads?

How did you go about it?

Best placement?

Size?

Any noticable advancements made? More relative to oil pressure.


My dilemma, running a stock block, bushed lifters .041 holes, .0035 clearance. Cam bearings are drilled .0625 and .0035 clearance on the rod and main bearings. Running a 1.7 SCP external oil pump and a vac pump producing 8-12".

During a run (approximately 30 seconds) The oil pressure will ramp up to 85ish and per my recorder about 10 seconds into the run pressure will drop to 60 psi will in the 7500-8500 rpm range with some dips down into the 50's and even 40's for split seconds.  We have quite a few passes on this issue and have the engine torn down for winter maintenance and found no evidence of issues related to lack of oil, though we have found that oil drain back could stand improvement between the Jesel belt drive and the front of the block, potentially impeding oil pickup at that sump.


Thoughts? Ideas? Criticisms?

Thank you

I would say you also probably have some kind of windage or aeration issue within the crankcase and oil pan.

I was kinda trying to eliminate that possibility with the different amounts of oil, but it very well could be.

With the pan on the bench raked to the degree of installed in vehicle, 10qts is still a 1/4" under the windage tray

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But, is the oil getting past the running crankshaft assembly and back under the windage tray...?

rmcomprandy wrote:But, is the oil getting past the running crankshaft assembly and back under the windage tray...?

Very good question. I could not tell you for sure

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Id say the prob is not the right size ristrictors in the oiling system, pumping too much oil up top

Doug Rahn wrote:I should also add that I have seen a correlation between vacuum and oil pressure on my 598. I have a Peterson Wet/Vac pump and on my data logger when the vacuum would reach 12", I could see the oil pressure fluctuating. So I keep mine at 8/9", no issues.

I also have the Peterson WetVac v2 on my 598. I have Star Machine adjustable vacuum break on the VC set to 12". I don't see the flutter issue you report. What size feedline to the pump section do you use? I have a 1" (-16) per Peterson's advice)

CDMBill wrote:

Doug Rahn wrote:I should also add that I have seen a correlation between vacuum and oil pressure on my 598. I have a Peterson Wet/Vac pump and on my data logger when the vacuum would reach 12", I could see the oil pressure fluctuating. So I keep mine at 8/9", no issues.

I also have the Peterson WetVac v2 on my 598. I have Star Machine adjustable vacuum break on the VC set to 12". I don't see the flutter issue you report. What size feedline to the pump section do you use? I have a 1" (-16) per Peterson's advice)

Mine is -12 from pan to block, per SCP minimum recommendation.

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