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pod filters....

Discussion in 'Modifications and Projects' started by nice2Bnaked, Apr 27, 2007.

  1. just took my airbox off my spada, and am thinking about using pod filters... it just so happens i have 2 filters, presumadly off a dirtbike/small car, about the size of a soup can (x2) they are foam, probably washable and need to be oiled...

    -what are the pros/cons of pod filters? do they add performance if coupled to my racing exhaust?

    -will they increase engine wear?

    -do the connecting tubes (carby to filter) need to be the same length, or will tuning the carbs eliminate the difference?

    -will riding in the wet be a problem?

    -should i get the carbs tuned or do anthing else to the bike ounce done, and will it damage the bike if not tuned?
  2. Gonna depend a lot on the type/quality of the filters you're planning on using but:

    -what are the pros/cons of pod filters?
    Pros: They may allow more air into the engine which should increase power slightly. They're also reusable.
    Cons: Can allow more dirt into the engine and tend to "choke up" faster
    Edit: Oh and they're also very much illegal in Victoria (can't have any oiled filter unless in an unmodified factory airbox).

    -will they increase engine wear?
    Potentially yes, if they allow more dirt in and/or they're not cleaned often enough

    -do the connecting tubes (carby to filter) need to be the same length
    To be honest dunno for sure, different length tubes will affect air pressure but don't know if this can be tuned for

    -will riding in the wet be a problem?
    If the foam gets wet yes, very much so

    -should i get the carbs tuned
    Yes, if you don't tune it for the extra air (if any) you won't get any advantages. Not tuning shouldn't damage the engine - but could cause it to become sluggish at certain rpms.
  3. Are they they different lengths as standard?

    If so they will have been setup for flow situations within the airbox, this can make significant differences to the fuelling if left unchanged. Generally with pod filters the velocity stacks should all be the same length, although this length may be different from the standard setup. Their length will significantly alter the power characteristics at given rpm's.

    I would be willing to bet that the bike won't make as much power with the pod filters on compared to the original airbox setup...but the improved induction noise may be worth it to you.
  4. I have pod filters on my Ducati. They were fitted by Vee Two engineering in Perth, directly to the carby mouths with no tube between. In order to get maximum benefit they also had to build new tuned length inlet manifolds to mount the carbys. My point being that changes in inlet tract length before the carby, also affect the airflow resonance behind it. Without an airbox, each carby will resonate differently creating turbulence. In general, unless the intake flow is properly designed throughout, losing the resonance smoothing of the airbox will usually mean less power, in spite of the greater airflow provided by the pod filters.


    Note the custom inlet manifolds in the picture. You can't actually see the pod filters. but you can just see the clamp holding the RH one to the carby mouth.
  5. Is ur airbox pressurised?
    From what i have read.
    If u put pod filters u will lose the pressure of a airbox, resulting in not enough air entering the carbs. THus problems
  6. from the mods read about being done on a cbr250. when they installed a higtht flow air filter that allowed more air in they also rasied the height of the needles allowing more fuel. and put in slightly bigger jets

    The rule of thumb was keep raising needles till u get rid of the flat spots. which is as easy as adding more washers and the needles or turning them depending what if they are adjustable or not
  7. allright, great advice...
    Ive just been to Repco to ask more qns and look at other stuff.
    I brought home 2 types of filter, and will post pics this arvo. I'll probaby test them out tonight and see how i go, but watch this space for pics...

    The only effecting factor would be restricted airflow. Im guessing the airbox is pressurised, and will take photos of that too...
  8. OK, got a bit mod-happy and chopped up my velocity stacks to fit the pods.. My only concern is that they may restrict/create more suction as they dont breathe as easily. I have oiled them (there a foam type) with FUCHS filter oil. They are an oil breather unit from a car... will post pics when i get off my ass.
  9. Ok, all went bad last night...

    The foam filters were too restrictive and choked the bike... I cut the filters down, but still too much suction (they were going to suck the foam into the carbies :shock: )

    Im going to slap the box back on. I might toy with the idea :idea: of using Pod filters (papar type) inside the airbox instead of the panel style original filter, that way airflow would be regulated inside the vaccum box. For now i might cut my losses and convert back to standard... I just hope supercheap doesnt notice that the filters have been used when i return them, or my time was wasted cleaning them up last nite... :oops:
  10. so how do u get past this. basicly ur saying pod filters will decrease efficency/power. Id like to hear more on the subject.
  11. No I'm not. I'm saying pod filters simply stuck on after losing the airbox, without properly designed inlet tracts can easily lose you power. This is particularly true with smaller displacement engines. Manufacturers spend huge amounts of money making engines as efficient as possible. What is it with people who think they can do better at the local Supercheap Auto? Generally you cannot just change one thing in isolation and expect an improvement, because what you gain on the swings you lose on the roundabout. The whole system has to be properly thought out and designed. The pod filters on my Ducati significantly increased power, but not on their own.
  12. well.
    do u think i would get a power increase with
    debaffle-pod filters-raised needles-bigger jets on a 250,

    are u suying just make the inlets longer
  13. I simply wanted to change to pod filters to match my open ended race pipe.. my understanding is that you have to change both ends? I also am going to get slightly bigger jets too, later when the project is finnished. you might say this is a waste of time on a 250, but im on restrictions till 2011 :shock: ... dont ask, or i'll tell you. :wink:
  14. on restrictions till 2011 haha
    geussing u lost ur license and gota redo from scratch
  15. What Inci said. :)

    Intake and exhaust design, matched up with camshafts, cam timing, ignition timing and engine design, is pretty heavy-duty as engineering goes. ;)

    The general rule is that shorter, wider diameter intake tracts are better suited to high RPM. They will flow high rates of air (for high rpm) efficiently, but you will lose your low and midrange torque. The wider diameter reduces the pressure loss due to boundary layer frictional losses at very high flow rates.

    Conversely, a longer and thinner tube will increase torque in the lower rpm, but will choke the airflow at high rpm. The thinner diameter increases the air velocity through the tube, so that the air has greater momentum and can help push additional air into the cylinder.

    Similar rules apply to the exhaust headers and muffler.

    But you really need to sit the bike/car on the dyno and Experiment to be sure, and the entire system needs to be approached as a whole, ideally.

    Best example of SuperCheapAuto vs Automotive Engineers was with the Honda Integra Type R. 140kW from factory out of 1.8 litres. The months after it came out, the car modding magazines were rife with stories of people losing 10-15kW because they got rid of the "restrictive" stock airbox and slapped on an 'free flowing' intake they built themselves. Similar story on the exhaust end too. :)

    As an aside, the foam airbox filter replacements flow the same or very slightly less air than than the paper disposable filters. But on the other hand, the oil-soaked reusable ones don't have to be replaced so often, just cleaned out.