Amsoil BMK-11 vs. Amsoil BMK-13

[The Critic]

Which one filters better?

From what I understand, they both work roughly in the same way. In the BMK-13, the oil goes through the Bypass Filter then through the FF, then gets return to the system.

I'm not exactly sure how the BMK-11 works, but doesn't it filter the oil through the Bypass, returns it to the system, and then the oil just gets a final "filter" through the FF before going back into the oil pan?

Installation doesn't bother me, nevertheless, lets save that for another time. I'm interested in building my own kit, btw.

Michael

 

[slalom44]

The BMK-13 is designed to take all of the oil (through the filter adapter), filter it (with some of it bypass filtered), then return it to the filter adapter. The hydraulic attachments are a direct replacement for a regular spin-on full flow filter. The primary difference besides better filtration is a drop in pressure due to the spring-loaded restrictor valve. Since oil pumps are positive displacement, this means that your engine will likely see higher oil pressure upstream from the filter.

The BMK-11 is intended to tap into the oil system (either through a sandwich adapter at the oil filter or through the pressure switch port) and return the oil to an unpressurized area, such as to the oilpan or head cover. There is no increase in pressure associated with this setup, but there is a slight reduction in the flow of oil through the engine's galleries. With the BMK-11, you can use just about any full-flow filter you want.

 

[Gary Allan]

slalom44 just about said it all. Here's a visual

Here's a view of the dual ff/bypass mount. Note the upper channel to the full flow has a sprung biasing valve in it. This assures that there's an artificially created inducement for the oil to go to the bypass filter. Otherwise the flow through the bypass element would be greatly reduced until particles started blocking up the ff.

Without this valve ..you get very little flow through the bypass for quite a few miles.

 

[greencrew]

I agree, slalom44 about said it all.

In either case, the oil either goes through the FF or the BP. Both FF and BP filters output back to the engine in both the BMK-11 and BMK-13. The FF delivers 90% of the oil while the BP delivers 10%.

All specific details mentioned by slalom44 aside, the BMK-11 works with your current FF filter, and the BMK-13 is a compact package which replaces your FF filter. They both function the same way.

The filtering is determined by the by-pass element, which is the same in both, so I can't think of a reason to say one would filter any better than the other.