Amsoil Bypass Filter Mount...How's it Work??

[galaxy]

Just looking at the filter mount for the BMK23 kit (the one with the bypass filter and normal filter on the same mount), how does that thing work?? What I mean is, both the filters spin on that same mount...what controls the fluid flow (advertised 10%) through just the bypass filter without impeding fluid flow through the normal filter?

Looking at photos of the mount, the inside is plumbed so the filters are mounted in parallel, not series (oil doesn't have to go through one, then through the other). It seems to have a restrictor on the threaded part that the bypass filter spins on. Seems to me, the oil would just take the path of least resistance and go through the unrestricted, normal, full flow oil filter. I guess some oil would get pushed through the bypass filter, but just how much.

Obviously this mount has been successful so I'm quite certain it doesn't limit any normal oil flow in any way, it's just hard to picture how it works without putting my hands on one yet.

 

[slalom44]

They are in parallel, but there's a spring-loaded biasing valve (restrictor exposure in the diagram below) that increases inlet pressure to the full-flow filter.

There was an oil filter study years ago that showed how much pressure drop took place with various filters, as well as with the BMK-13 unit (Amsoil's previous version of the BMK-23). IIRC, most filters had a pressure drop of about 8 psi at operating temps, but the BMK-13 had a pressure drop of about 18 PSI.

I've had a BMK-13 on my car for about 150,000 miles without any problems, and my UOAs have been great. I was nervous about the backpressure when I installed it, which is why I also installed an oil pressure gauge. Since the gauge's pressure sender measures the pressure downstream from the filter, I was measuring the oil pressure the engine was receiving, not the pressure before the filter. Most oil pressure switches are located downstream from the filter.

 

[galaxy]

Thanks. For the info. That picture is from the web site but if you look at the new mount for the 23 kit, the full flow filter is first and the bypass is second from the oil inlet and doesn't have that "restrictor" in the mount itself. Meaning there should be little impact on flow through the normal filter and no need for any gadgets inside the mount to control flow/pressure through the filter....which is part of my reason for asking the question about the oil just taking the path of least resistance through the normal filter. Seems to me with this set up and the way the bypass side is restricted, oil wouldn't flow through there much at all, if any. And it is possible I'm just way overthinking this.

 

[slalom44]

I see what you mean. I didn't catch that. The testamonial photos are mostly BMK-13 setups which are different than the BMK-23. I'd be interested in knowing if there is some sort of biasing valve in the BMK-23. Maybe they've configured the porting to get a venturi effect.

 

[galaxy]

I finally got to look at a mount and I am still not convinced in this design...

The two passageways (in and out) in the filter mount are completely open between the two filter mounts...as we discussed before, the filters are in parallel. The restrictor screwed into the bypass side reduces the flow through that filter as you mentioned. However, it would appear to me oil coming out of the normal filter back into the manifold can either flow back to the engine or towards the bypass filter (where oil would be exiting the bypass filter into the manifold) filling that area of the manifold. With that small tiny hole limiting oil flow out of the bypass filter, it would seem oil from the normal filter would work against this and could actually limit very little oil, and possibly no oil at all from leaving the bypass filter. There's nothing in the manifold at all that prevents oil exiting the normal filter from entering the bypass filter through that tiny hole if the pressure was greater.

In fact, basic fluid dynamics would suggest to me that with that portion of the manifold pressurized from oil exiting the full flow filter, oil attempting to exit the bypass filter through that tiny hole would not be able to overcome the pressure on the manifold side of that tiny hole and would literally or potentially create a liquid lock at that tiny restrictor hole.

 

[slalom44]

I agree with your comments, Galaxy. Check this out:



The BMK-13 has always claimed to get 10% of the oil flow through the bypass filter with a warm engine. I can't see how the BMK-23 can get the same flow without that spring-loaded restrictor. I suspect that it's much less, but probably still effective.

 

[galaxy]

I've got an e-mail into Amsoil tech basically stating the same things stated here...see what comes out of that.

 

[Gary Allan]

I used an already mounted dual Permacool setup by exchanging the threaded nipples. No restrictor/biasing valve involved. The (at the time) Bp110 got locally warm when first installed (like oil passed more easily through it) and progressively totally warm as the full flow got some age to it. It wasn't long into the 12.5k OCI. I haven't used that setup with the newer EaBp filters, but I imagine it would be the same.

 

[deeter16317]

I would expect the EaBP to just warm up since its nothing more than a really efficient pleated filter, whereas the BE-series was a "stacked plate" design with stacked discs of what looked like felt. The EaBP's oil is discharged anywhere along the center support tube whereas the BE was discharged at the end and the oil flowed the length of the filter back to the threaded end. And before anyone says otherwise, I have cut both filters apart myself...they were completely different designs.

Probably what was happening was the BE's media was saturated with oil...and it flowed closest to the center tube early because the oil there was warmed by the center tube (less viscosity)...after a while that portion (the center closest to the center tube) of the media becomes plugged with contaminants and the oil's path slowly moves outward to the can.

Another thing to consider is the EaBP mounts flow more oil than the older BE mounts...the size of the orifice is significantly different.