Horsepower vs Filter Restriction

[camrydriver111]

A lot of people have speculated why OEMs use such low efficiency filters.

Could it be due to CAFE? If a filter has high restriction, it will place an extra load on the oil pump and the engine.

For maximum performance, you will have the lowest resistance to flow, so you need to sacrifice efficiency.

I think the same principle is used in racing oil filters. I believe the companies selling them always advertise low resistance.

Has anyone tested how much extra horsepower you can gain by going to a low resistance oil filter?

 

[fantastic]

A lot of people have speculated why OEMs use such low efficiency filters.

Could it be due to CAFE? If a filter has high restriction, it will place an extra load on the oil pump and the engine.

For maximum performance, you will have the lowest resistance to flow, so you need to sacrifice efficiency.

I think the same principle is used in racing oil filters. I believe the companies selling them always advertise low resistance.

Has anyone tested how much extra horsepower you can gain by going to a low resistance oil filter?

That isn't always true. There are premium filters that use superior media to have excellent flow along with great efficiency. OEMs are going to favor flow more than efficiency bc of cost and the obvious person that doesn't change their filters like they should.

I'm not aware of performance testing and perhaps others will post

 

[mbaker]

Another thought... I don't think it all about media type but about the size of the filter itself. With any given media a smaller filter will be more restrictive than a larger one, especially as it starts to get contaminated. If engine compartment packaging dictates a certain size filter then the manufacturers will have to balance filter efficiency vs airflow to get the output numbers they need so I dont think you always have to sacrifice flow to have good effeciency if you have the space.. Also could depend on expected use of a filter, a car expected to serve mostly highway miles would not need the same filter a truck used in construction of offroad in dusty conditions might. OEM isn't always concerned with max performance or max filter effeciency, as long as it meets the minimum standards they set forth including their budget. They aren't going to spend 5$ more on an excessive filter for millions of cars and hurt the bottom line.

As far as racing oil filters go, the old saying is dirty oil is better than no oil. Even if the oil does start to become contaminated allowing extra oil to flow freely through the engine is more beneficial short term than trying to get every small particle filtered out. Plus these engines are probably serviced more frequently with fresh oil and filter vs a street car that someone runs 10k miles between oil changes. In most cases street cars will have a bypass if the filter becomes restrictive to prevent starvation, most race engines will not.

 

[oil pan 4]

A lot of people have speculated why OEMs use such low efficiency filters.

Could it be due to CAFE? If a filter has high restriction, it will place an extra load on the oil pump and the engine.

For maximum performance, you will have the lowest resistance to flow, so you need to sacrifice efficiency.

I think the same principle is used in racing oil filters. I believe the companies selling them always advertise low resistance.

Has anyone tested how much extra horsepower you can gain by going to a low resistance oil filter?

OEMs want cheap. The air filter they spec only has to make the engine last till its out of warranty.

Absolutely under no circumstances should you run a low resistance race oil filter. They're basically trash screens and and seem to have fallen out of favor.
The reason why they were used was the race engines ran external belt driven oil pumps that were driven just fast enough to produce the right amount of oil pressure for the engine and not waste a bunch of horse power sending oil through the oil pump high pressure bypass.
The high flow oil filter helped the low volume pump maintain pressure.
Any on road vehicle is going to is going to use an oil pump that provides plenty of volume at idle rpm and provides probably 10 times the oil volune the engine needs a max rpm. Even running at say 2,000rpm the oil pump is providing anywhere from 2x to 4x more volume than what the engine can use.

The same results can be achieved by simply running an oversized, known higher flow oil filter such as a wix xp.
If I run a ph8a or wix 51515 size oil filter it's like 50% bigger than stock and the wix xp 51515 flows something like 28gpm which is probably about 20 more GPM than my Dodge 5.2L could ever need.
The wix xp catches down to 30mu pretty good so it's efficient enough to make your engine last several hundred of thousands of miles.

 

[dnewton3]

What little "restriction" exists from filter media is a minute pittance compared to the parasitic drag of viscosity as the oil moves through the various engine passages. Pumping losses are the reason the US OEs are using thinner lubes; the filter has pretty much nil consideration in that regard.

 

[BMWTurboDzl]

OEMs want cheap. The air filter they spec only has to make the engine last till its out of warranty.

I'm still looking for roadways littered with dead engines which failed just out of warranty. How in the world are people keeping these 10-12 yr old cars on the road. Magic?

 

[ZeeOSix]

If you want to see the difference in required HP between two oil filters that have for example a 3 PSI difference in dP, then run the hydraulic HP equation.

The oiling system as a whole determines how much total HP is required to move the oil flow through the system. The oil filter is a very small resistance in the system compared to the whole system. The oil filter is typically around only 1/15th the restriction (pressure drop) of the whole oiling system. So if Filter A has 3 more PSI of dP at high flow than Filter B, the difference in required HP is going to be minuscule.

Example
Case 1: Oil flow through the oiling system is 10 GPM and it takes 80 PSI at the pump outlet to move that oil volume. The filter has 5 PSI of dP. Assume the PD oil pump is 90% efficient.

Case 2: If a different oil filter is used on the same engine that has 8 PSI of dP at 10 GPM of flow, then the pressure at the pump outlet is now 83 PSI due to the more restrictive oil filter.

Case 1 HP = (10 GPM x 80 PSI / 1714) / 0.90 = 0.519 HP

Case 2 HP = (10 GPM x 83 PSI / 1714) / 0.90 = 0.538 HP

Delta HP due to the different oil filter = 0.019 HP

This is a minuscule difference ... not even measurable on an engine dyno. When the oil flow rate is lower (10 GPM in this example is huge), the required HP is lower, and the difference in HP with different oil filters is even more minuscule ... basically non-existent in a practical sense.

 

[dnewton3]

There you go again, Zee ... Using facts, data and clear formulation to come to a concise and accurate answer. How dare you?
Whatever happened to good ol' fashioned shade-tree rhetoric and mythology?

 

[oil pan 4]

I'm still looking for roadways littered with dead engines which failed just out of warranty. How in the world are people keeping these 10-12 yr old cars on the road. Magic?

In most of the country a k&n rock catcher is fine. Even in tatooine county new Mexico a car running a k&n will likely still drive somewhat after breathing dirt for 10 years. As a bonus you'll never need to change the oil, just add a quart every fill up.

 

[oil pan 4]

If you want to see the difference in required HP between two oil filters that have for example a 3 PSI difference in dP, then run the hydraulic HP equation.

The oiling system as a whole determines how much total HP is required to move the oil flow through the system. The oil filter is a very small resistance in the system compared to the whole system. The oil filter is typically around only 1/15th the restriction (pressure drop) of the whole oiling system. So if Filter A has 3 more PSI of dP at high flow than Filter B, the difference in required HP is going to be minuscule.

Example
Case 1: Oil flow through the oiling system is 10 GPM and it takes 80 PSI at the pump outlet to move that oil volume. The filter has 5 PSI of dP. Assume the PD oil pump is 90% efficient.

Case 2: If a different oil filter is used on the same engine that has 8 PSI of dP at 10 GPM of flow, then the pressure at the pump outlet is now 83 PSI due to the more restrictive oil filter.

Case 1 HP = (10 GPM x 80 PSI / 1714) / 0.90 = 0.519 HP

Case 2 HP = (10 GPM x 83 PSI / 1714) / 0.90 = 0.538 HP

Delta HP due to the different oil filter = 0.019 HP

This is a minuscule difference ... not even measurable on an engine dyno. When the oil flow rate is lower (10 GPM in this example is huge), the required HP is lower, and the difference in HP with different oil filters is even more minuscule ... basically non-existent in a practical sense.

View attachment 247518

At normal driving speed it matters even less since most of the oil that the oil pump moves is just being blown out the oil pump pressure relief valve.
The only time what you described happens is in a race engine where the engine oil requirement and oil pump are carefully balanced to not waste horsepower power pumping oil through a bypass.

 

[ZeeOSix]

At normal driving speed it matters even less since most of the oil that the oil pump moves is just being blown out the oil pump pressure relief valve.

On a street car at "normal driving speeds" (which is pretty low engine RPM), there really isn't much oil pump bypassing going on when the oil is hot.

But the calculations I showed was for the oil that's actually going through the oiling system, regardless if any or none is being bypassed at the pump. It shows that a small flow vs dP difference between oil filters has no real effect on the required HP to move the oil through the oiling system. The oil filter's flow resistance is typically around 1/10th to 1/15th the flow resistance of a whole oiling system. So a filter with 3-5 more PSI of dP isn't going to have much impact on the HP required to pump the oil through the oiling system.

The only time what you described happens is in a race engine where the engine oil requirement and oil pump are carefully balanced to not waste horsepower power pumping oil through a bypass.

Even on a race engine, you are not going to win or lose a race based on the oil filter you're running and it's dP difference effect between oil filters on the HP to the wheels, lol ... but maybe on what oil you are using. As shown in the calculations, the difference in required HP between filters is so small it won't make any real world difference.