Air filters or no?

[fj1289]

What are the thoughts on running with or without airfilters?  It's an older air cooled 4 cylinder motorcycle with partially enclosed bodywork.  Converted to EFI but no airbox.   Filters are dual UNI foam pods. 

Thanks,
Chris

[hotrod]

I think the general feeling is to run some sort of filter. Racers have reported engines ingesting quite a bit of salt dust, especially if the intake is a direct path with no air box or ducting that might pickup clean air in some sheltered location.

[ONEBADBUG]

Smokey Yunick said "Only 2 vehicles don't need air filters, planes that never land, and ships that never dock."

[wobblywalrus]

No filters were used on the Triumph for the first few years.  The pistons and bores were scratched up pretty bad when the first tear down was done.  Small oiled gauze pod filters were used on motor #2.  They did not work either.  Feelings are the filters were very close to the carb intakes and the pulsing air pressure pulled the salt through them.  Motor #3 has big oiled foam pod filters.  No problem.  The pistons and bores looked perfect during the last tear down.

Vizard, in his book "how to Build Horsepower" has formulae for sizing air filters.  Years ago when tuning desert racing bikes we learned the least restrictive air filter is seldom the best.  Usually what works better are some of the more restrictive ones that are adequately sized.  The filters feed intake tracts with valves at the ends that are closed most of the time.  It does not take a huge filter to be more than adequate.     

[fj1289]

Thanks all - filters it is then!

[Stainless1]

FJ, we have used un-oiled K&N filters on the Bockscar and bike with success.  We knock the salt out after every run.  The filter also helps "straighten" the air as it makes its way into the engine.

[Hot Rod Lincoln]

I figured this question has been asked before. Something we are trying to figure out before the car goes out.

this set-up cost us 80hp:


ended up with this set-up with wire mess screen to keep the birds out :





I think it's fine, dad wants to run a filter. I'm thinking I can find some foam from an Uni-air filter or something like that and wrap it.

[jh333]

Joel SR. will never notice if you tell him you have a new @$%# &*($# filter thats almost invisable.

[Hot Rod Lincoln]

you are probably correct .....   

[Stan Back]

Picture 2 looks like the filter is inside the mesh(?).

I think the turn was the culprit, but what do I know.

[jdincau]

If those are self tapping screws replace them with rivets. Your and everyone else's tires will thank you.

[Hot Rod Lincoln]

If those are self tapping screws replace them with rivets. Your and everyone else's tires will thank you.

rivets were the first choice.. ran out of time.

Will look into replacing them.

[Hot Rod Lincoln]

Picture 2 looks like the filter is inside the mesh(?).

I think the turn was the culprit, but what do I know.

no filter just the mesh

[hotrod]

Yep that sharp turn with no guide vanes or anything to help turn the air is probably the primary culprit for the power loss.

If you can't find foam that works you might try a loose fabric like a cotton tee shirt sewn into a sock that just slips over the screen then oil it like a K&N filter.

[tauruck]

Here's a tip.
Take it or leave it.
I may not have credibility here because I'm in Africa and don't have a car that runs.

Get this material and use it as an air filter. Cheap!!!
Try it and tell me.
Vacuum bagging breather layer available at companies that sell composites.