Is there a better Air Filter for Kawasaki FR651V out there ?

Getting back to your earlier thread, the filter is quite heavy and requires some clever bracketry to hold it so it does not shake like a maracca and end up tearing a lump out of your blower housing , which ain't cheap
 
Good point Bert, I will have to factor that into the bracket fabbing.

The Donaldson Outer filter on it's own is said to be able to pull 95 cfm of air. Don't know if that is more or less than current oem paper pleated ?
 
7394 said:
Good point Bert, I will have to factor that into the bracket fabbing.

The Donaldson Outer filter on it's own is said to be able to pull 95 cfm of air. Don't know if that is more or less than current oem paper pleated ?
Click to expand...

A 651cc 4-cycle engine running at 3600 rpm needs about 40 cubic feet of air per minute.

The best thing you could do is put a restriction gage (Filter Minder) on your new air filter. Maybe you'll get lucky and it already has one. They're really the only accurate way to tell when your air filter element needs to be replaced.
 
Thank You cpurvis- Yes I planned to add a restriction meter to the intake elbow. No, it doesn't come with one. But familar with them from excavating equipment.

OK my Kaw engine FR651V is 726cc

Donaldson's site specs the outer filter # P821575 to be able to pull 95 cfm, while filtering out @ 99.9% efficiency.

And if I add the inner safety filter # P822858 that number drops to 86 cfm

Just curious as to how much diff the oem Paper pleated filter on my engine pulls or needs to be able to.

Reason I'm wanting to know is, I can't find any source if I need to drop the main jet down a size or two, to lean it out running the Donaldson set-up. Kaw makes them called High altitude jets. # 122 & # 120. My Toro Dealer won't even try & find them, he is a non-believer of modding.
 
Why would you need to lean the mixture when running the bigger air filter?

Smaller jets are needed when the density of air decreases from what the carb was calibrated for at the factory. Installing a higher capacity air filter doesn't cause a decrease in air density, like an increase in altitude does. Fuel needs to be mixed with air by mass, but carburetors mix it by volume. Putting on a higher capacity air filter doesn't change the density or the volume of air going into the engine.

I'm with bert. I think you can forget about the jets.
 
Thank you for the quick reply. My thought was the Donaldson Filters are so much more restrictive than paper pleated, & could cause a rich condition. But to yours' & Bert's point, I would be adding much more filtering media.

I just wanna line up all my ducks for winter, when I get on this up-grade.

PS: Thank you for the link, & the enlightenment as well (You too Bert.)
 
Now I have not done this , so I might very well be sinking my own ship here.
But if you check the jets for the commercial series engines that are supplied with a Donaldson against the residential jets me thinks you will find they have the same part number,
If not check the choke size and if the carbs are the same size buy the jets for the commercial engine.
Just because a filter can flow 100 cu'/min does not mean it will flow 100 cu'/min as the air flow is determined by the demand from the engine.
This demand is not static either.
Most of the time your engine will never be running more than 3/4 throttle
 
Bert- Good point, I looked into that, & every FX651V & bigger has a 2 barrel carb.

my FR651 has a 1 barrel carb. And in mowing I run it wide open (supposedly @ 3600 rpm).

Spoke to Donaldson today & the tech sent me some different ways they get an engines air intake max needs. 1 way is to measure the HP (in my case 21.5) x 2 cylinders= 43 CFM @ 8" H20.

I kinda got lost on the last part about the H20 ? , but he said the filters I listed here were way overkill for my set-up. That I could use filters 1/2 the size. I told the tech that I'd prefer to have oversized filters. He said that would make em last longer, & no negative effect 'cept to my wallet.

Plus he gave me the part # for the correct "Informer indicator") restriction gage for my engine.

Alternative Method
Engine Horsepower Formula
English Units
Airflow (CFM) = HP (SAE) x SA
SA = (Specific Airflow) per Horsepower
 
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