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Why do triples (allegedly) have a unique sound?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Spots, Apr 1, 2008.

  1. Here's a 'fun' super-nerdy question. :grin:

    I've been pondering why different engine configurations sound different. And I'm stuck on Inline Triples vs Inline Fours.

    Some of it's pretty obvious, like how V-twins have their lumpy rumble because of interesting crank angles. And how V-fours sound like a pair of V-twins stuck together (again, crank angles). And then there's the famous WRX/Subaru Boxer sound because the exhaust headers are paired up 'wrong' for proper scavenging.

    But then we get to the inline triple and inline four. Triumph's marketting material talks up the unique sound of a triple. So do all the magazine writers.

    But... The piston crank angles are evenly spaced on both engines, unlike the 'lumpy' spacing on most V-twins. So an I3 should sound like a 1/4 slower I4 by all accounts. Supposedly they don't.

    3-1 exhaust instead of 4-2-1? Maybe?

    No idea. Anyone know, or care to discuss? :)
  2. Haven't heard one? They are truly unique and sound fantastic. Heard one on a triumph cruiser the other day, it took me a while to figure it out as they sound sportsbike-esque.
  3. Not in person, unfortunately. A video on Youtube of the new Tiger 1050 being wound right out (unlike all the city-idling videos) did impress me though. :grin:

    Testriding a Tiger this weekend I hope...
  4. If your keen on 120 deg triples usual spacing then at sometime you might listen for an early 180 degree Laverda,completely differant and sets the hair on the back of my neck up.
  5. Triumph triples, at least with standard pipes, seem to have a sort of "whistle" to them. It's odd.
  6. Triumph triples don't create sound at constant intervals like an inline four.

    They create sound as *pulse* *pulse* *pulse* PAUSE
  7. It's a fact and discussing it won't change anything! :)

    However, the first fourstroke triples I ever heard were the Triumph/BSA 750s from the early 70s. I can best liken the sound to something hardly anyone would have an idea of what I am referring to (unfortunately, maybe) and that is: a Bedford truck.

    There is a grumble to any 3 cylinder, four stroke engine - even the Diahatsu Charade we had in the 90s had that same "grumble" which reminded me of the Tri/BSA triples.

    The Kawasaki triple 2 strokes from the same era as the Tri/BSA 750s also had a "grumble" about the engine noise, but I don't remember ever hearing the same from the Suzuki 2 stroke triples.

    Some of the unique sound is possibly to do with gear design, especially the primary drive from the crankshaft to the gearbox input shaft. Some is also due to intake sound, and some to the exhaust.

    The current Triumph triples exhibit the same tendency - don't talk about it, get one!


    Trevor G
  8. I'd characterised it as a 'rasp' as in the woodwork tool (or possibly a tearing sound like fabric ripping), as opposed to the typical 'rasp-berry' or 'fart' of an IL4.
    I wonder if maybe ZRX1200R is right...
  9. my triumph i had as a young guy had a jet engine quality to it, with an underlying pulse of growls and roars, quite a unique sound.

    but my rotary engined triumph (triumph factory fitted norton rotary engine from the early 70s so efectivey its a triton triple) makes a sound like nothing i have ever heard, sort of like a banshee wail with a Ingve j Malmstien riff undercurrent, makes me soil my undies every time i hear it
  10. Don't say that too soon - I'll be testriding an R1200GS and Tiger 1050 this weekend, and my heart's already really set on the Tiger...
  11. I still reckon the old Triumph Trident had the best most spine tingling note I have ever heard. Apparently when they test ran it on the test bench in the old Meridan Triumph factory people came from blocks away to see what it was :grin: :grin:
  12. I had a quck round-the-block on a friends brand new Tiger and man it was sweet. Soooo much power compared my little VTR250 and like, twice the size...

    And to be a little more on topic; I think the triples sounds awesome and have no idea why, but I one on order, so yay for me... ;-)
  13. I just testrode a black ABS-equipped one today, and it confirmed all my fears. I must have this bike. :p

    Though, one wonders why they bothered to install a gearbox at all when 2nd pulls like a freighttrain from 5kph to 130kph. :eek:
  14. Vtwins fart, i4's scream :cool:

    But us Vtwin riders are polite, so we call it 'burbling' or 'grumbling', etc. :LOL:
  15. yeah ive noticed that. i think its a big intake noise. simmilar to suzukis just sounds a bit diff. i must say im not a massive fan of the whistle
  16. i would call it a sizzle, not a whistle. and no, not a fan.
    the sound is unique because of the stage at which each piston is at during its four cycles as detonation occurs. a v2 has a comfortable pause, and an i4 has no pause. an i3, on the other hand, has a slight pause, but is then on a strong power stroke. the power stroke is less "wasted" (by wasted, i mean that an i4 almost compounds, or piggybacks its power strokes) on a triple and this is why they generate good midrange when comparing to a similar capacity i4.
    a screaming i4 or a burbling v2 for me, though, any day.