Dry sump oil pump increasing Horsepower and the reason

[PandaBear]

So I have looked at how it works typically and understand why people install them (avoid cornering leads to oil pickup sucking in air) and the side benefits of lower center of gravity if you have a way to lower the engine, reduce the possibility of oil swishing around the corner changing your swaying, ability to route through an oil cooler, reduce oil splashing at high rpm, eliminate possibility of crank splashing up oil in some scenario, reduce crankcase pressure and improve ring sealing / allow the use of lower tension ring thus increase Horsepower, etc.

I understand most of them except the part about increase Horsepower.

If the increase in Horsepower come from reduce crankcase pressure, would a bigger PCV valving (unless forced induction) and baffle still be able to do that? Wouldn't the belt driven root type pump use more Horsepower and therefore cancel out the gain?

If the increase in Horsepower come from preventing oil splashing, a well designed pickup low position and baffle should be able to reduce a lot of that even in a wet sump system.

Regardless of the Horsepower gain, is it true that a dry sump system will still use more fuel and thus reduce mpg?

 

[ka9mnx]

If the increase in Horsepower come from preventing oil splashing, a well designed pickup low position and baffle should be able to reduce a lot of that even in a wet sump system.

The same reason racers use windage trays in the oil pan.

 

[wwillson]

A friend of mine who was a brilliant engineer and engine builder that held many patents on engine and transmission modification. He told me that the oil contacting and clinging to the crankshaft effectively increased the rotating mass. He used dry sump systems and built the windage trays such that they had very little clearance between the crank and the tray. The tray was effectively an oil scraper that scraped oil from the crank on the starting line. His calculations showed that he got faster torque from keeping the crank free of excess oil and which more than made up for the additional weight of the windage tray being build as a scraper.

 

[PandaBear]

Seems like what I though was called baffle is really more of a windage tray. I see them in a lot of non race car but they are not as aggressive as the race engine one.

I guess you can have them without going dry sump as well too? How much extra HP is used to pump away the oil and does the reduced crankcase pressure (not the windage tray aspect but the reduced crankcase pressure only) improve HP enough by reducing blow by?

 

[JackWildfeuer]

Yes you gain 50HP over wet sump. Most of that is due to increased ring sealing and the reduction of the ring tension. Part of it is do to reduced windage losses. Most governing bodies limit the size of the pump you can run to limit the amount of vaccum you can create in the system. For examples of that read NASCAR's rule books.

It took a long time to get low tension rings right and get them to last and seal well. If you put a piston with say 1980's high tension rings and piston design into say a Chevy Small Block and then put a racing piston with almost no skirt, with low tension rings postioned as close to the piston crown as you dare and hooked a fishing scale to the under side of the pistons and then draged them through the bore you could see a 50% to 75% reduction in the force required to push and pull that piston up and down the bore. None of that matters if you can not get good ring sealing for 500+ miles at 7500-10,000 rpms. When knife edging a crank and adding a windage traw gave you an easy 25HP or more adding the dry sump with vaccum was another 50+ you could pick up and most of that was reduced pumping loses from friction.

The air in the bottom end of the block is violent and so much so that most modern engines have windows on the crank webs to allow for the violent nature of the air in the bottom end swinging big throws around at high rpm.

Drag is the free power if you can reduce it. Imagine if every time you went for a walk, run or drive you had to walk, run, drive into an 30MPH head wind and then one day you find a way to get rid of that 30MPH head wind. It would be like finding more HP even though you and your car where un modified. Every time you find a way to reduce drag inside the engine it is much the same so long as you can seal everything that needs sealing and you can combust the fuel the same. This is also how going from a 20W50 or SAE 60 to a 0W8 gains power and fuel ecconomy.

 

[PandaBear]

Yes you gain 50HP over wet sump. Most of that is due to increased ring sealing and the reduction of the ring tension. Part of it is do to reduced windage losses. Most governing bodies limit the size of the pump you can run to limit the amount of vaccum you can create in the system. For examples of that read NASCAR's rule books.

It took a long time to get low tension rings right and get them to last and seal well. If you put a piston with say 1980's high tension rings and piston design into say a Chevy Small Block and then put a racing piston with almost no skirt, with low tension rings postioned as close to the piston crown as you dare and hooked a fishing scale to the under side of the pistons and then draged them through the bore you could see a 50% to 75% reduction in the force required to push and pull that piston up and down the bore. None of that matters if you can not get good ring sealing for 500+ miles at 7500-10,000 rpms. When knife edging a crank and adding a windage traw gave you an easy 25HP or more adding the dry sump with vaccum was another 50+ you could pick up and most of that was reduced pumping loses from friction.

The air in the bottom end of the block is violent and so much so that most modern engines have windows on the crank webs to allow for the violent nature of the air in the bottom end swinging big throws around at high rpm.

Drag is the free power if you can reduce it. Imagine if every time you went for a walk, run or drive you had to walk, run, drive into an 30MPH head wind and then one day you find a way to get rid of that 30MPH head wind. It would be like finding more HP even though you and your car where un modified. Every time you find a way to reduce drag inside the engine it is much the same so long as you can seal everything that needs sealing and you can combust the fuel the same. This is also how going from a 20W50 or SAE 60 to a 0W8 gains power and fuel ecconomy.

Thanks for the detailed explanation. I have heard about what you said as well.

What I am curious of is how many hp of running the dry sump pump need and whether the gain is going to make up the loss in the dry sump. Also is there any particular crossing point in rpm between the hp loss to the pump is not worth it to being worth it?