Any experience in main cap dividers to oil pan?

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Any experience in main cap dividers to oil pan?

Post by Jeff Lee » Sat May 12, 2018 2:51 am

Building big bathtub under the engine. I know a guy that built a S/G BBM pan and claimed putting dividers under each main cap was good for 1.5 MPH.
I’m sure there will be doubters but has anybody experimented with this and what were your results? Can it hurt? I understand a window is needed in each bulk head which allows piston windage to escape.
Wet sump with external oil line application.
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Re: Any experience in main cap dividers to oil pan?

Post by mag2555 » Sat May 12, 2018 6:33 am

I don't know about that 1.5 mph gain , as in 3000 lb car that calls for a 10.5 hp gain!
I have seen more of a hp gain in motors above 6K rpm with a scraper, but I don't think what your taking about will do it!
Heck. A light tail wind during a pass at the track will make for a change mph like that!

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Re: Any experience in main cap dividers to oil pan?

Post by B Original » Sat May 12, 2018 9:04 am

Although are the horsepower numbers may be debatable I can definitely see an advantage. I go as far as what I would loosely term porting the bottom of the block. Contouring the sharp edges the machine surfaces between the pan Rail and the bottom of the cylinders the main bosses at the bottom of the cylinder such and so on. You want to create smooth radius areas for the oil to stick to and drain back into the pan so you don't have areas of oil puddling for the windage to pick up increasing the viscosity of the air the crankshaft is rotating through. I never did a side-by-side comparison of this part of the modification the block to tell you how much horsepower is gained there. As far as the main cap dividers in the pan for the windage to pick up increasing the viscosity of the air the crankshaft is rotating through I never did a side-by-side comparison of this part of the modification don't have the numbers to back it up but I have seen small Gaines on the dyno from different style oil pans on a 500 foot pounds 6800 RPM engine we gained just under 5 horsepower with an open bathtub oil pan with no main cap dividers and slightly less with dividers

I will care to speculate differential platforms are going to have different air flow characteristics in the bottom end. Scrapers may have their benefits but they can also keep you from taking advantage of maximizing the use of your airflow directing efforts

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Re: Any experience in main cap dividers to oil pan?

Post by ptuomov » Sat May 12, 2018 6:03 pm

I’m slow. Which direction and what kinds of dividers?
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Re: Any experience in main cap dividers to oil pan?

Post by Jeff Lee » Sat May 12, 2018 7:19 pm

Bulkheads that are trimmed to fit the main caps and go the bottom of the pan; with allowance for oil flow at the bottom of the pan of course. Basically, one pair of rods is contained within bulkheads. There is windage as the pistons go up and down so there is a window of some sort at the middle (?) of each bulkhead to push / pull the windage.
I know this is done and I will be doing this on my new ProPan unless I hear strong recommendations against this by experienced users. I do find that many, and those you would suspect would think better, have the belief that large, bathtub style, kickoff oil pans are a waste of money. Based on dyno numbers and ET/MPH improvements I have witnessed, I completely disagree. I would consider this bulkhead idea as a further improvement. Unless I hear otherwise...
Thanks.
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Re: Any experience in main cap dividers to oil pan?

Post by nhrastocker » Sat May 12, 2018 9:51 pm

Jeff,
What you are referring is to a segmented oil pan.
It seals the oil between each cap.
It requires a dry sump style oil pump to pull the oil and vacuum from each segment to feed the engine.

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Re: Any experience in main cap dividers to oil pan?

Post by vortecpro » Sat May 12, 2018 10:34 pm

505 pan.jpg
My pan is wet sump and is segmented.
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Re: Any experience in main cap dividers to oil pan?

Post by Jeff Lee » Sun May 13, 2018 1:39 am

Ahhhh...segmented. Thank you. NHRAStocker. The BBM pan I saw was a wet sump and segmented.

Vortecpro....have you ever added segments and determined there is a real benefit? Any oil problems or issues?

Thanks!
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Re: Any experience in main cap dividers to oil pan?

Post by B Original » Sun May 13, 2018 8:57 am

Referring to LS GM engines I'm not sure if it was General Motors or someone in the aftermarket drilled holes in the main cap bosses own their dry-sump engines to equalize the pressure between the banks because a windage issues do you two isolated Banks

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Re: Any experience in main cap dividers to oil pan?

Post by ptuomov » Sun May 13, 2018 9:10 am

Are these segment barriers intended to manage air flow or oil flow?

In terms of air flow, in a four cylinder engine, one wants to either seal the bays completely or make them completely open. Small breathing holes are worst, because they neither allow the air to work as air spring nor allow for relatively constant pressure in the bay.

For a cross-plane V8 engine, managing the air flow is harder because per cylinder displacement is usually even larger and because there is no way to seal off the pistons on the same crank pin. Because of this, theory says that pulling a vacuum in the crankcase is especially beneficial in a big V8.

So what’s the theory why one would want to hose bay to bay dividers in a big wet-sump V8 without crankcase vacuum?
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Re: Any experience in main cap dividers to oil pan?

Post by nhrastocker » Sun May 13, 2018 11:57 am

vortecpro wrote:
Sat May 12, 2018 10:34 pm
505 pan.jpgMy pan is wet sump and is segmented.
A segmented pan seals and compartmentalizes between each main cap; it does not have openings allowing oil to flow between the main caps.

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Re: Any experience in main cap dividers to oil pan?

Post by peejay » Sun May 13, 2018 12:19 pm

B Original wrote:
Sun May 13, 2018 8:57 am
Referring to LS GM engines I'm not sure if it was General Motors or someone in the aftermarket drilled holes in the main cap bosses own their dry-sump engines to equalize the pressure between the banks because a windage issues do you two isolated Banks
GM ran into that problem with LS1 development, which is why they windowed the mains.

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Re: Any experience in main cap dividers to oil pan?

Post by Kevin Johnson » Tue May 15, 2018 1:56 pm

Radius the ends of the caps. I believe you are running 4-bolt mains -- if they are not radiused already then you should do this. It is not an accident that OEM caps are often radiused. Numerous examples. It allows better bay to bay breathing -- lower pumping losses. Just don't extend your dividers past the top bolt pad (center two main bolts of four).

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Re: Any experience in main cap dividers to oil pan?

Post by Jeff Lee » Wed May 16, 2018 12:21 am

nhrastocker wrote:
Sun May 13, 2018 11:57 am
vortecpro wrote:
Sat May 12, 2018 10:34 pm
505 pan.jpgMy pan is wet sump and is segmented.
A segmented pan seals and compartmentalizes between each main cap; it does not have openings allowing oil to flow between the main caps.
Sorry...slow response...Mothers Day weekend activities and work....

I guess I’m considering a hybrid of sorts. I realize a wet sump can not be completely compartmentalized as oil needs to find it’s way back to the pickup. Even in my Stock Eliminator oil pan, there was scrapers that fed oil to a trough which led to the rear sump. Did it work? Hard to say without a spintron I guess. My initial thoughts were basically extending a wall from the main caps to (maybe) 1” from the bottom of the pan in order to cut down on the roping of oil that occurs. This may see upwards of 8,000 RPM. The first time I saw a x-ray drawing of the then new LS1, I immediately noticed the window between the upper main saddle and the cam tunnel. My understanding was that allowed not for fluid movement, but air movement. I am aware of others that have emulated this window in the same area but as the AMC has an oil feed that runs diagonal in that area, I am not brave enough to take on that challenge.
I guess my big question is; if engineered, is there a detriment? If there is no improvement in performance but no detriment to engine longevity, it wouldn’t be the first time for me!
I have sent the outside requirements to the oil pan guy (Doug Lee at Pro Pan) and it will be 8.25” deep at full length with a 2” kick-out. He said he built a couple segmented wet sump drag pans, but never received feedback. Somebody mentioned that as this is an external oil pump with external suction line, the pan would be similar to a SS/Modified which run external (although belt driven) oil pump. My pump is driven by the camshaft gear as per OEM and mandated. This pan will replace a rear sump 1.5” kick-out pan I acquired. It’s a good pan, I just think a full length sump is a better idea. This will require modification to my chassis but that’s ok.
Thanks for the comments. This is an area I have very little understanding.
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Re: Any experience in main cap dividers to oil pan?

Post by Jeff Lee » Wed May 16, 2018 12:24 am

Kevin Johnson wrote:
Tue May 15, 2018 1:56 pm
Radius the ends of the caps. I believe you are running 4-bolt mains -- if they are not radiused already then you should do this. It is not an accident that OEM caps are often radiused. Numerous examples. It allows better bay to bay breathing -- lower pumping losses. Just don't extend your dividers past the top bolt pad (center two main bolts of four).
Yes, I have Pro-Gram Engineering 4-bolt caps on the center and their 2-bot caps front and rear. I am not aware of rounded main caps. Interesting idea and I’ll definitely look at that this weekend and consider incorporating that idea. Thank you.
What OEM has this feature?
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