Center Tubes and Flow......

[WMSmotorhead]

I've been looking at lots of cutways and it seems that the most free-flowing designs are the Champ Ecore, but it can get weak. and the "Grater" style I've seen on Hastings/Baldwin and a few others... I thought I'd look it up.. and found this on some literature.

Louvered Centertube adds strength to resist pressure surges. The louvered design has 40% open area compared to the standard 15%, maximizing flow through, while maintaining strength.

Sounds good to me... but does that mean that most metal center tubes are really only 15-20% flowing? Makes me want to look at a few performance filters like KN to see how they did it.

 

[motorguy222]

What literature was this from?,it does not sound right.A typical filter is probably going to have around a 2psi pressure drop,depending on the filter.

If you only have around 20% of the oil getting through,it seems that you would be in by-pass quite a bit of the time,especially during cold weather.

 

[Shannow]

As long as the total area of your centre tube is greater than (say) the holes in the outer rim, or the drilled bolt that the filter mounts to, the centre tube will have nearly nothing to do with flow restriction.

 

[JimPghPA]

What about an extra long filter?

 

[ZeeOSix]

Originally Posted By: WMSmotorhead
.. and found this on some literature.

Louvered Centertube adds strength to resist pressure surges. The louvered design has 40% open area compared to the standard 15%, maximizing flow through, while maintaining strength.


40% and 15% of what? Numbers can be mis-leading if they are not used properly. As others have said, look at the total area of all the holes in the center tube compared to the total area of the holes in the base plate and the total area of the ID of the mounting fitting the filter screws to. You can do your own measurements and calculations and you'll probably find that the they are all close to each other.

 

[hofcat]

Oil pumps in auto engine are fixed displacement type pumps, not a centrifugal type like a swimming pool pump. Think of an oil pump as being more like a grease gun pump, the engine is going to push hard enough on the grease gun handle to ensure that grease is going to out or something will break. What this means is that at a given engine rpm the oil pump will discharge a given oil flow rate now matter how restrictive the oil filter is. If one filter is more restrictive that another the oil pump will build up a higher discharge pressure to drive the same flow of oil through both filters. A less restrictive filter will not allow anymore oil to flow, but it will lower the discharge pressure at the output of the oil pump. If the filter is way to restrictive then the pump pressure relief valve would open and discharge some flow directly to the sump. This would be a really abnormal conditions though.

 

[WMSmotorhead]

I got it here...

Hastings LF 115


I have used these for years, and I wanted to see how they compared to others... I have looked at cutaway diagrams, and real cutaway filters. The diagram matches the filter in reality. Regardless of the literature's truth or exaggeration, this is the best 3$ filter in terms of build quality I can get in this region.

I thought the description was too vague to really gain any real data.

 

[ZeeOSix]

Originally Posted By: hofcat
A less restrictive filter will not allow anymore oil to flow, but it will lower the discharge pressure at the output of the oil pump.


To add ... the only time a less restrictive filter will allow more oil to flow (vs a more restrictive filter) is when the oil pump is in pressure relief mode (ie, where it hits max discharge pressure and starts to shunt flow back to the sump). A more restrictive filter will also make the pump hit relief pressure (ie, max discharge pressure) sooner as you've also indicated.

Originally Posted By: hofcat
If the filter is way to restrictive then the pump pressure relief valve would open and discharge some flow directly to the sump. This would be a really abnormal conditions though.


The filter's bypass valve would probably come into play before the pump would go into relief if the restriction was in the filter's media or center tube. If the restriction was due to a failed ADBV that blocked flow, then the oil pump would probably go into pressure relief first. That would be a major oil starvation scenario.

I imagine if a filter's media was totally clogged and it was in full bypass mode, it's possible the filter's bypass valve might not be able to handle the total flow from the pump, which would then make the oil pump go into relief mode. That condition would starve the engine of oil flow to some degree.

It's good to have an oil pressure gauge down stream of the filter to indicate the actual oil pressure (after the filter's pressure drop) feeding the engine's oiling circuit.