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Re: Old air filters for R1100S needed

> Ben is looking at experimenting with other air filters:
> Hi Ben -- have you seen Don E's air filter test somewhere on his web site?
> http://www.eilenberger.net/
> If I understand correctly, his measurements show that the stock filter, even
> when 50% blocked by plastic wrap, flows enough air to not degrade
> performance as measured by a dyno run.  His conclusion seemed to be that
> even more flow from a K&N type filter could not be used, so the choice comes
> down to which filter traps the most particles and that looks like the stock
> filter.
> Best of luck, though.
> Wendell Ponder
> Grapevine, Texas

Many thanks, Wendell, first I've seen Don Eilenberger's curves. Many more
curves and quite a lot of discussion can be found at Moto One


Reading dyno curves takes some care. The eye is easily fooled and sometimes
dramatic vertical increases (in HP or torque) are not eye-balled right or
not recognized in proportion. In other words, large practical changes at low
and lower rpm (which matters most to most of us) are overlooked.

Because the time course of the runs is not known and couldn't be much
controlled in any case (I have some experience with /7 dyno testing), it is
not clear how the curves really relate to ECU performance apropos the O2
sensor or, for that matter, how surging arises as the bike settles into
steady-state when on the road or how the two really relate to one another.

Although I thought it would be uncivil earlier to offer my baleful opinion
on K&N filters, I would now like to comment with the following well-known

1. you can't make a change to any single thing in your stock aspiration and
ordinarily expect an improvement,

2. paper filters are a pretty good compromise practical solution from the
point of view of manufacturers and

3. all things considered from the point of view of do-it-yourselfers, oiled
foam such as Uni (not K&N  which is oiled gauze) breathes well, cleans well,
provides hands-on feedback on your machine and keeps you in control, and is
far cheaper.

In the test you mention, Eilenberger blocked 50% of the air intake (which is
a pretty meaningless thing to say) and expected 50% reduction in power.
That's plain nuts. I feel you are wrong to take his point seriously.

What he did find, but did not interpret, was a large reduction in power and
also, oddly, a fairly clear reduction at lower rpms...which you'd never
expect. That certainly suggests that the front-end breathing is impaired (or
at best, marginal) in the stock form but the degree of impairment and the
benefits are hard to guess.

Moto One are quite enthusiastic about improving the intake path with
megabuck bits of plastic but others definitely are not. For sure, the intake
is often part of the tuning (although I personally view intake or exhaust
"tuning" to be unsound outside of racing). So changing the front-end
breathing is likely to make some changes somewhere, given the typical tuning
logic of modern bikes. Sometimes even introducing restrictions can be
beneficial to some part of the curve.

Having said all that, would somebody PLEASE let me know if the ECU corrects
for changes in filter resistance (other than the obvious if just occasional
presence of the O2 feedback)?


- -- 
Ben Barkow, Toronto... 39 seasons on Beemers, 44 as a biker,
1961 R69s/rod, 1967-1999... really sup'ed up and fast
1984 R80RT/rod, 1998- 5 extra peak ponies in a wider flatter power band,
  much modified 2-into-1 exhaust, CR 9.5, Keihin PJ 34mm oval carbs,
  Uni filter, dual-rate springs with cartridge emulators,
  BT45/S11, Saeng fairing
1999 R1100S, 2004- Leo Vince exh, JetHot coatings