14 May 2007, 19:43
Hi All,
Been looking into oil filters and came across this very well written site called the Oil Bible. On there is a few good reasons why you should not fit an oil filter that is smaller in volume than the standard one and even recommends fitting larger ones.
And I Quote
There's a school of thought which says that enlarging the oil filter on your car is A Good Thing.
Why is this?
The small oil filters fitted to engines these days run with quite a high back pressure, and the bypass valve trips at about 3500rpm. That means that your oil is not being filtered when the engine is spinning faster than 3500rpm. As the oil filter does its job and starts to clog up, that rpm value can be lower.
If you increase the size of the filter, this will raise the rpm at which the bypass valve will switch. With a bigger filter and lower back pressure, for the same rpm (prior to bypass valve operation) less engine power will be lost in the filter. Bigger filter means better filtering and more power at low to mid revs. Clever eh? But there's some things you need to be aware of if you're going to try this approach, all of which are relevant, and none of which I can confirm or deny
Bigger filter = more "dead" space = more oil. Remember you'd need to add more oil to the engine to keep the oil level at the correct mark on the dipstick. This isn't necessarily a bad thing - more oil doing the same job theoretically means less stress on the oil.
Oil may take a little longer to circulate around the engine after startup, as the pump may have to fill up the larger capacity oil filter. With modern filters this ought not to be a problem though because all but the cheapest filters have backflow preventers which keep oil in the filter when the engine is off.
What do you guys think. It looks like if you fit a smaller one then it makes sense that you will increase the pressure and the Bypass valve will open much earlier and so your oil wont be filtered once you engine gets to say 2000 rpm so the oil will almost never be filtered !!!
I have spoken to a few people in the know and they agree with the bigger filter. It makes sense to me. If you ever see the size of the oil filter on my Esprit you will understand why, It's huge !!!
Dan
Been looking into oil filters and came across this very well written site called the Oil Bible. On there is a few good reasons why you should not fit an oil filter that is smaller in volume than the standard one and even recommends fitting larger ones.
And I Quote
There's a school of thought which says that enlarging the oil filter on your car is A Good Thing.
Why is this?
The small oil filters fitted to engines these days run with quite a high back pressure, and the bypass valve trips at about 3500rpm. That means that your oil is not being filtered when the engine is spinning faster than 3500rpm. As the oil filter does its job and starts to clog up, that rpm value can be lower.
If you increase the size of the filter, this will raise the rpm at which the bypass valve will switch. With a bigger filter and lower back pressure, for the same rpm (prior to bypass valve operation) less engine power will be lost in the filter. Bigger filter means better filtering and more power at low to mid revs. Clever eh? But there's some things you need to be aware of if you're going to try this approach, all of which are relevant, and none of which I can confirm or deny
Bigger filter = more "dead" space = more oil. Remember you'd need to add more oil to the engine to keep the oil level at the correct mark on the dipstick. This isn't necessarily a bad thing - more oil doing the same job theoretically means less stress on the oil.
Oil may take a little longer to circulate around the engine after startup, as the pump may have to fill up the larger capacity oil filter. With modern filters this ought not to be a problem though because all but the cheapest filters have backflow preventers which keep oil in the filter when the engine is off.
What do you guys think. It looks like if you fit a smaller one then it makes sense that you will increase the pressure and the Bypass valve will open much earlier and so your oil wont be filtered once you engine gets to say 2000 rpm so the oil will almost never be filtered !!!
I have spoken to a few people in the know and they agree with the bigger filter. It makes sense to me. If you ever see the size of the oil filter on my Esprit you will understand why, It's huge !!!
Dan
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