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Inline Vs V

Discussion in 'Technical and Troubleshooting Torque' started by FALCON-LORD, May 2, 2007.

  1. I was reading through Doonx thread on buying a New VFR and read this quote from N2BN

    And it got me to thinking...
    I understand that number of cylinders and flywheel size will effect power delivery lots... But why does the cylinder layout actually effect the vehicle? It changes the Cam shaft length, but when it comes to timing of the cylinders that can be changed no matter what the engine geometry.

    so can someone explain to me the difference (Not better or worse but actual "why is it so") between an Inline Vs a V
  2. V-4 and inline 4's both use "planar" cranks (the centerlines on all journals are in the same plane.) On the inline 4, like a CBR crank, you get an "even" firing order with one cylinder firing every 180 degrees of crank rotation. With the V4, the cylinders are at an angle and two cylinders share a common rod journal. This gives an "odd" firing order. Think of the V4 as two inline 2 cylinder motors that are 90 degrees out of sync. That is what give the VFR motors that distinctive sound. This is also where the low end torque comes from, having two cylinders fire very close to each other. The net power output is about the same.

    By using an "offset" journal crank (with each rod having it's own journal) you could make the V4 an "even" fire motor that behaves just like the inline 4 motors. However, that would weaken the crank & rods because they would have to be thinner to allow room for the offsets. The down side to the V4 is it's complexity and weight. The inline 4's have been getting more compact by re-arranging the cam drives to the point that an inline motor is not much wider than the same displacement V4.
  4. Great post incitatus - nicely explained!
  5. So in short...

    You cna change the firing pattern any way you like.
    But changing the crank that is effected by the firing pattern is not a viable option.
    So by changing the relative angle of the pistons you change the available firing pattern without having to make some wiered shapped crank.
  6. incitatus You MIGHT want to add that this is not your ideas but you only :google: Googled the answer and that this is a direct quote from Curtis Martin at https://www-auth.cs.wisc.edu/lists/vfr/1996-March/msg01300.shtml
    This is unless you are Curtis Martin and wrote that in 1996. Give credit where credit is due mate. Just put quote tabs in next time or say where u got the info from. FALCON-LORD you can read a more full version of what incitatus copied.

    FALCON-LORD you might also want to try looking at this site too
    Ive had at look at both sites and they have both very good info, so rather than quote any of them i'll just let you read them fully for yourself.

  7. This is only applicable to V4's with a 180 degree firing order (VFR750/800's).

    The V4's ride very like a cross between an inline 4 and a twin.

    Many other V4's use a 360 degree firing order, with essentially 2 pistons rising and falling 90 degrees after the first, similar in theory to a 'big bang' engine.
  8. [quote='92_Ducati_900_SS]Just put quote tabs in next time[/quote]

    Fair point, and if you look at my two years of post history you will find I normally do, obsessively so. When you have been here more than 5 minutes you may have a better picture. I had the unpleasant task of laying two people off this morning, and in my distraction simply forgot the quotes...mea culpa..Incidentally, I didn't Google the answer, I took it from a collection of such material I have compiled into a sort of electronic 'mega text book' for my own reference....
  9. I'll just add that inline fours CAN be tuned to get some midrange and low end torque, Kawasaki did it with the Ninja engines in the GTR by reducing cam overlap and using slightly smaller carbs, and smaller diameter header pipes. Mind you, it still revs to 10.5k!
    So it's not just all about cylinder layout, any type of engine can be targeted at any part of the rev range if so desired, but the general fours for top end twins for grunt is true.

    Regards, Andrew.
  10. It's good that some manufacturers still use something different to a parallel-4. Now if only someone would bring back the square four (Kawasaki ER-12 perhaps :-k ;)).
  11. It would be even more impressive if someone tried to bring back the radial-5 !
  12. From memory the early VF750S's were built this way - V4 shape but basically an inline 4 firing order - evenly spaced out.

    As incitatus suggests it weakened the strength of the crank and rods and they were beset by bottom end failure.

    The VF750F were better in the bottom end - they survived to have spectacular camchain failures instead :p

  13. Yes, and no.

    There are some designs that are more harmoniusly balanced than others and dont shake themselves to pieces. For instance V4's work at 180 degrees or 360 degrees. You dont find 300 degree ones.

    Some wierd arrangements do exist - eg the Volkswagen V5 Bora. Then you get V10's, W12's etc.

    Twins can be made balance nicely in a few different ways. Triples need to be really 180 degrees for best effect. Combine a Triple with a twin and you can have a good v5.

    There's a primary and secondary harmonic that engines are normally designed around one of. Hence a R6 has very good primary balance and a 90 degree ducati has a good secondary balance. Effectively you're trying to offset the motion of the pistons and crank off against each other - both in the stored energy and the kinetic energy.

    The better the balance the smoother the engine and the less rock.

    Compare a harley with a ducati for engine shudder.

    There are ways it can be faked - despite the dimension of an upright twin the TRX is basically a 90 deegree vtwin in all but external dimensions. The cam and the crank are designed to replicate the 90 degree v twin ducati feel, although the idea was initially made for better traction in loose sand for paris dakar on the tenere 750....
  14. simply explained.... like seriously.... F*** angles etc makes no sense to me... does a v motor have a distinct sound because at any given time you have 2 cylinders firing closer together... close enough that the human ear doesn't hear 1,2,3,4(5,6,7,8) but basically a 1,2. 1,2. 1,2. 1,2. at a rapid rate???
  15. That's it I think, just like a V8(on most anyway, some exotics have the 180 degree crank), you hear two exhaust pulses close together then a skip, which gives the burble on a V8 and V twin.

    Regards, Andrew.
  16. Closer firing angles make the different noise. Yes.
  17. Oh yeah, and certainly having seperate exhaust per cylinder on a twin versus a 4-2-1 makes a huge difference to the sound as well.