Have I sacrificed performance for unintended induction roar?

Discussion in 'Mech Tech' started by Spacecowboyuk, Sep 21, 2021.

  1. When I fitted my ict34, I initially used the skinner pancake filters. However during the tapping process for the engine and fuel breather they were damaged so I used a slightly deeper set I had on the shelf.

    Whilst sounds great from an induction roar pov, I do wonder if they are letting in too much air when the bus is travelling at speed. In other words, is it possible that with the side air intakes gulping down air that the air filters themselves are taking in too much air leaning out the mixture beyond that intended which the jets are unable to obviously compensate for?

    In anticipation of responses I'm going to partially cover them up and take it for a spin later. Could explain why it feels like it dies off at certain speeds. Pic to follow.
     
  2. Size of your filters is unlikely to make a difference.
     
  3. Dubs

    Dubs Sponsor supporter extraordinaire

    If anything, taller filters are better. Something to do with how the air enters the carb. Flat filters belong over the fence of shame...
     
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  4. docjohn

    docjohn Supporter

    More likely that your old filters were choking the carbs. New ones, provided they fit properly, should be fine as the engine will draw the air that it needs; the filters can't force excess air in. However, you should check the timing and jetting to suit the new set up, and make sure any vacuum lines are still in place.
     
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  5. mikedjames

    mikedjames Supporter

    You have changed the way the engine draws in air - probably leaner running now at high RPM, so get out the AFR meter and re-jet or watch the CHT.
     
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  6. The jets are all as per wayoutwestie and we checked timing and put the afr on them at techenders so that must all be right now. Maybe this is how the 2.0l type 4s run then.
     
  7. Zed

    Zed Gradually getting grumpier

    At full load?
    Tis true that leaner is louder than richer.
    What certain speeds does it die off at?
    What exhaust?
     
  8. ^this. The engine consumes the air it needs.
     
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  9. Stock exhaust. Around 75kph to 100kph it feels a bit flat.

    Sorry I didn't mean an actual AFR I meant the air flow meter i.e. the snail dealie thing.
     
  10. Fair enough I'll remove this from the equation then. I'm now thinking the jetting isn't quite right then.
     
  11. Chrisd

    Chrisd Supporter

    I have slightly different sizes than Wayoutwestie in my 2ltr type 4 and I think a few others have done the same. AFAIK (and that is not a lot)...this set up runs well for me.

    Mine
    Main jet 155, Air 175

    Wayout westie
    Mains 165, Air 185
     
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  12. yep, me too and also @Gooders . Originally jetted by mike as per his spec above, overfuelled at full throttle/high rpm, tried 160 first, now 155 main. Now that i have AFR gauge i will do some proper testing and see if it can be improved (however not all engines are the same so what works for one may not be right for another).
     
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  13. Zed

    Zed Gradually getting grumpier

    In English? :rolleyes:
    Just kidding. :)
    I assume you're in 4th?
    40-55/60mph in 3rd is where it's at for acceleration.
     
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  14. I believe it was @Chrisd who said the same at Techenders. Feels like I'm gunna blow something up in third at that speed! I'll try it (it's a 6 rib).
     
  15. Chrisd

    Chrisd Supporter

    I know nothing.......:easter:
     
  16. Chrisd

    Chrisd Supporter

    Wow...I've never taken mine up past 45mph in 3rd AFAIK. I'm taking it for a drive tomorrow and I'll experiment
     
  17. CollyP

    CollyP Moderator

    Yup. 45+ (indicated, but with smaller wheels) in 3rd. No worries.
     
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  18. Zed

    Zed Gradually getting grumpier

    More revs = more horses as you know.

    2L with 6 rib...
    Changing into 4th at 40-45mph is fine for cruising about but won't do much if you put your foot down.
    40mph in third is where it's just starting to perform. 60mph in 3rd is ok now and again, it's below the red line.
    It'll sing at 60mph in 3rd - all smooth and nice...or it should. By 60mph the HP won't be increasing though so you may as well give up there.

    1700 type-4 with 3 rib is also good for 55-60mph in 3rd - type-4 engines can rev to 5,400rpm

    Type-1 1600 with 3 rib...
    I think 50mph in 3rd is about your lot. Type-1 engines red line is 4,600rpm.

    This is a typical type-1 - the numbers are different, but the idea is the same - lots more power up the revs.

    [​IMG]
     
  19. Chrisd

    Chrisd Supporter

    Cheers Zed (ders...!)
    Maybe it's down to my driving style...more laid back than boy racer. I'll give it a blast tomorrow and see how she feels and sounds.
     
  20. CollyP

    CollyP Moderator

    Eg, I know mine will keep pulling at 60 / 65 in 4th but that’s where the supposed heat issues kick in. Indicated 55 / 60 is where I stay.
     
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