Best engine design for a motorcycle?

[grampi]

Originally Posted By: ZGRider
Best sounding motorcycle I have ever heard was a Yamaha V-Max with an aftermarket exhaust -- It really sounded like a small-block Chevy V-8 on steroids. Awesome bike. Had a cool tribal green flame paint-job and my buddy bought it for $3000 off Craigslist.


You got that right! I had an '89 V-Max that had Supertrapp exhaust on it and it sounded like a top fuel funny car when I got on it! That leads me to my pick for best overall engine design; the V-4. They produce all the bottom end torque of a v-twin, and all the high RPM HP of an inline 4. The best of both worlds! A co-worker of mine had a 1500 Vulcan at the time and he wanted to do a comparison. He wanted to ride side by side and put the bikes in high gear at 30 MPH and see which one pulled the hardest when the engines were doing little more than lugging. Suprisingly, the Max, which gave up a 300ccs to the Vulcan, stayed dead even with the Vulc until we hit about 50 MPH, then the Max just started to walk away. I wish I could get that enigne, only in an 1800-2000cc version, in a true cruiser style bike (something like the M109R). That would be a rockin' bike!!!!

 

[expat]

Why would a V4 have more torque than an inline 4 ?

 

[grampi]

Originally Posted By: expat
Why would a V4 have more torque than an inline 4 ?


Not more torque, more torque at low and mid RPMs. And don't know why, they just do.

 

[Redline955]

Different pulses from the V four firing order transmit more grunt.

 

[ZGRider]

Originally Posted By: expat
Why would a V4 have more torque than an inline 4 ?


Same reason V-Twins tend to have "better" torque than other twins. Think Ducati V-Twin VS BMW Boxer Twin - No contest on torque.

For the BMW faithful, no offense, but don't think for a minute that a Boxer twin could compete with a Ducati V-Twin at the race track.

As successful as the Ducati V-Twin has been, even Ducati can see the writing on the wall and has released a V-4. The Desmosedici. Aprilia has also released several V-4s and Honda is ready to produce the "killer" V-4 is the guise of the VFR1200.

Even Harley toyed with producing a V-4 with the help of Porsche in 1979. It was termed the Nova V-4. The cylinder heads resembled Laverda heads.

Most manufacturers have seen the advantages of the V-4 design.

 

[expat]

Hmmmmmmm.....I think I should take this to a General Forum,
Honestly I don't see why. To ME Torque is a result of Volumetric efficiency, Thermal efficiency, and Mechanical efficiency of each individual cyl REGARDLESS how each cyl lays in relation to others pushing a crank.
Sure sound a vibration characteristics will differ, and some cyl layout will offer better induction possibilities than others, But...

 

[grampi]

Originally Posted By: expat
Hmmmmmmm.....I think I should take this to a General Forum,
Honestly I don't see why. To ME Torque is a result of Volumetric efficiency, Thermal efficiency, and Mechanical efficiency of each individual cyl REGARDLESS how each cyl lays in relation to others pushing a crank.
Sure sound a vibration characteristics will differ, and some cyl layout will offer better induction possibilities than others, But...


So are you saying it's nothing but pure coincidence that v-4s make lots of low end grunt AND produce lots of high RPM HP?

 

[Cujet]

My vote is for liquid cooled, 4 valve, v-twin engines in various displacements. The wide torque curve works very well with motorcycles.

Anything from a SV650 to a big Ducati works for me.

 

[KernelK]

Originally Posted By: ZGRider
Originally Posted By: expat
Why would a V4 have more torque than an inline 4 ?


Same reason V-Twins tend to have "better" torque than other twins. Think Ducati V-Twin VS BMW Boxer Twin - No contest on torque.

For the BMW faithful, no offense, but don't think for a minute that a Boxer twin could compete with a Ducati V-Twin at the race track.

As successful as the Ducati V-Twin has been, even Ducati can see the writing on the wall and has released a V-4. The Desmosedici. Aprilia has also released several V-4s and Honda is ready to produce the "killer" V-4 is the guise of the VFR1200.

Even Harley toyed with producing a V-4 with the help of Porsche in 1979. It was termed the Nova V-4. The cylinder heads resembled Laverda heads.

Most manufacturers have seen the advantages of the V-4 design.


As regards the torque of the Ducati v-twin versus the BMW flat twin, I don't really think there is that much of an inherent superiority. In a given displacement range of the 4 valve models, the Ducati's advantage lies in in being able to tune to a higher level because it is liquid cooled and consequently is able to cool more efficiently as compared to the BMW flat twin. The 4 valve Ducati can be tuned to rev higher and give more power through the high revs. A better comparison would be to compare the air cooled Ducati to the BMW.

All BMW flat twins are shaft drive motorcycles and as such are handicapped with the extra weight of the shaft as well as the added weight of of the paralever paraphernalia necessary to make the BMW a little more "conventional" in its handling. The motorcycles are simply not in the same class.

Returning to the thread topic, how many Ducati V-twin motor cycles have you seen with over 100,000 miles. Not many I would wager, but there are quite a number of BMW flat twins with hundreds of thousands of miles, which, I admit, speaks to the use the motorcycles are put to. Compare servicing a flat twin to 4 valve Ducati with 6000 mile valve adjustment intervals and 12,000 mile cam belt changes.

The V4 Ducati desmosidici is raced in Moto GP only. Their superbike racing efforts continue to employ the V-twin 4 valve configuration. It will be interesting to see which way they go when Moto GP returns to production based 1000cc engines.

BMW currently races World Superbike with an inline 4 chain drive bike.

 

[Geonerd]

As I see it, a motorcycle should be a sensual, slightly decadent indulgence. As such, engine center of gravity, primary balance, weight (to a point), fuel efficiency, blah, blah... are all largely irrelevant.

Possibly the most wonderful engine was the CBX straight 6. It looked awesome and made the most beautiful noise.

Those big Guzzi pots look and sound pretty sexy too! (Second place.)

 

[Geonerd]

Originally Posted By: grampi
Originally Posted By: expat
Why would a V4 have more torque than an inline 4 ?


Not more torque, more torque at low and mid RPMs. And don't know why, they just do.


IMO, that's largely due to marketing. The manufacturers have pushed the 'V4 torque' angle for years, to the point that it's an accepted 'fact.' As others have mentioned, there is no inherent reason a V4 should produce more torque at lower RPMs. AFAIK, most all of an engine's torque/power characteristics are determined by cam timing, exhaust/intake tract tuning, etc. Where the cylinders happen to be is largely irrelevant.

 

[Silk]

Originally Posted By: ZGRider

For the BMW faithful, no offense, but don't think for a minute that a Boxer twin could compete with a Ducati V-Twin at the race track.


I don't think for a minute that BMW has ever built a flat twin to compete with Ducati on the race track.They tune their motors for ride ability,not top end power....the torque curve tends to be flatter.

How about a V twin that was actually built to go head to head with BMW? The Honda XLV750 was made to run against BMW 800GS bikes in Paris Dakar....I had one,and now have an airhead.The Honda V twin had some grunt for sure,but it was really a rev head,wanting to run at the redline....which was 1,000rpm over max hp revs.An airhead isn't happy at all at 8,000rpm,but use in the meat of it's power curve makes it an easy bike to ride fast....faster than it feels.

A V twin is just a twin...all twins make more bottom end grunt than a 4 cyl of the same capacity....unless the designer had other plans.

 

[ac_tc]

The obly thing that produces torque is cylinder volume(combined on multi cyl engines) and the efficensy it can be filled with.
But who would accept a rowfour at 1200 cc and making 60 hp-no one, but if it was a 12oo v twin its gorgeus.

 

[grampi]

Originally Posted By: Geonerd
As I see it, a motorcycle should be a sensual, slightly decadent indulgence. As such, engine center of gravity, primary balance, weight (to a point), fuel efficiency, blah, blah... are all largely irrelevant.

Possibly the most wonderful engine was the CBX straight 6. It looked awesome and made the most beautiful noise.

Those big Guzzi pots look and sound pretty sexy too! (Second place.)


I had a '79 CBX, and while I thought it was the greatest thing since sliced bread at the time, I've realized there has been better engine designs produced since. The inline 6 was smooth as glass, and with an aftermarket exhaust system it sounded like a Ferrari, but that engine made absolutely no power whatsoever below about 5K RPM. It couldn't even get out of its own way in the lower RPM range. That engine HAD to be revved in order to make power. Even though V-4s aren't quite as smooth as the inline 6, I'd take them any day of the week and twice on Sundays ove the 6 because of their flat torque curve from idle to redline. Now if someone were to develop a v-6, that could be very interesting...

 

[grampi]

Originally Posted By: Geonerd
Originally Posted By: grampi
Originally Posted By: expat
Why would a V4 have more torque than an inline 4 ?


Not more torque, more torque at low and mid RPMs. And don't know why, they just do.


IMO, that's largely due to marketing. The manufacturers have pushed the 'V4 torque' angle for years, to the point that it's an accepted 'fact.' As others have mentioned, there is no inherent reason a V4 should produce more torque at lower RPMs. AFAIK, most all of an engine's torque/power characteristics are determined by cam timing, exhaust/intake tract tuning, etc. Where the cylinders happen to be is largely irrelevant.


I'll ask you the same question I asked expat (which he never answered BTW); if there's no inherent reason v-4s should produce more torque at low RPMs than other engine types, then why do they? I have personally owned two models of v-4s; an '83 Honda V-65 and an '89 Yamaha V-Max and I can tell you with certainty these two bikes made more low RPM power than any other motorcycles in their size range. v-4s also have a much broader power band than other engine types. Inlines tend to make all their power at high RPMs while they make almost nothing in the lower RPM range. V-tiwns are just the opposite, they're all bottom end torque, but most of them have such a long stroke they simply can't rev and therefore can't produce any high RPM HP. v-4s do it all. Massive low end torque, and massive high RPM HP. If someone can explain why this is purely coincidence, I'm all ears. Until then I have to believe it has something to do with the v-4 design.

 

[grampi]

Originally Posted By: Silk

A V twin is just a twin...all twins make more bottom end grunt than a 4 cyl of the same capacity....unless the designer had other plans.


Not true. I can't think of a single 1200cc v-twin that produces as much low end grunt as the v-4 of the V-max.

 

[boraticus]

The flat six Valkyrie engine makes some serious low end power. It also revs up like an in-line four. However, the red-line is around 6500 rpm which is low by comparison to most modern motorcycle engines. The thing just jumps to max rpms with very little throttle input. Despite it's power and super smooth running characteristics, this is not the engine I'd choose as the best for a motorcycle application. A four stroke, transverse V-4 similar to a Guzzi configuration, but fuel injected, liquid cooled with SOHC, and more compact with a shaft drive would be close to ideal for a street bike in my humble opinion.

Or, a simple but modern 500-750 cc, fuel injected, liquid cooled, two stroke twin in any configuration would also be sweet.

 

[grampi]

Originally Posted By: boraticus
The flat six Valkyrie engine makes some serious low end power. It also revs up like an in-line four. However, the red-line is around 6500 rpm which is low by comparison to most modern motorcycle engines. The thing just jumps to max rpms with very little throttle input. Despite it's power and super smooth running characteristics, this is not the engine I'd choose as the best for a motorcycle application. A four stroke, transverse V-4 similar to a Guzzi configuration, but fuel injected, liquid cooled with SOHC, and more compact with a shaft drive would be close to ideal for a street bike in my humble opinion.

Or, a simple but modern 500-750 cc, fuel injected, liquid cooled, two stroke twin in any configuration would also be sweet.


I'd like to see how the Valk compares in terms of top gear roll-on with my 109. I bet they'd be pretty close despite the the Valk giving up about 300ccs to the 109.

 

[ZGRider]

Originally Posted By: grampi
Originally Posted By: boraticus
The flat six Valkyrie engine makes some serious low end power. It also revs up like an in-line four. However, the red-line is around 6500 rpm which is low by comparison to most modern motorcycle engines. The thing just jumps to max rpms with very little throttle input. Despite it's power and super smooth running characteristics, this is not the engine I'd choose as the best for a motorcycle application. A four stroke, transverse V-4 similar to a Guzzi configuration, but fuel injected, liquid cooled with SOHC, and more compact with a shaft drive would be close to ideal for a street bike in my humble opinion.

Or, a simple but modern 500-750 cc, fuel injected, liquid cooled, two stroke twin in any configuration would also be sweet.


I'd like to see how the Valk compares in terms of top gear roll-on with my 109. I bet they'd be pretty close despite the the Valk giving up about 300ccs to the 109.


Well, it ought to....it's a 6 cylinder engine. It's also one of the most technically complex motorcycle engines ever put in to mass production. It is a huge engine that weighs substantially more than a comparable V-4 engine. Yes, its weight is low, but it is expensive to build and doesn't perform substantially better than a V-4.

Remember, Honda dumped the Valk, and redesigned the VFR (for the 6th time) -- they ought to know best which is superior. They are also the only company to ever make an oval-piston engine and it was a V-4/8.

 

[grampi]

Originally Posted By: ZGRider
Originally Posted By: grampi
Originally Posted By: boraticus
The flat six Valkyrie engine makes some serious low end power. It also revs up like an in-line four. However, the red-line is around 6500 rpm which is low by comparison to most modern motorcycle engines. The thing just jumps to max rpms with very little throttle input. Despite it's power and super smooth running characteristics, this is not the engine I'd choose as the best for a motorcycle application. A four stroke, transverse V-4 similar to a Guzzi configuration, but fuel injected, liquid cooled with SOHC, and more compact with a shaft drive would be close to ideal for a street bike in my humble opinion.

Or, a simple but modern 500-750 cc, fuel injected, liquid cooled, two stroke twin in any configuration would also be sweet.


I'd like to see how the Valk compares in terms of top gear roll-on with my 109. I bet they'd be pretty close despite the the Valk giving up about 300ccs to the 109.


Well, it ought to....it's a 6 cylinder engine. It's also one of the most technically complex motorcycle engines ever put in to mass production. It is a huge engine that weighs substantially more than a comparable V-4 engine. Yes, its weight is low, but it is expensive to build and doesn't perform substantially better than a V-4.

Remember, Honda dumped the Valk, and redesigned the VFR (for the 6th time) -- they ought to know best which is superior. They are also the only company to ever make an oval-piston engine and it was a V-4/8.


I'd take it one step further and say the flat 6 wouldn't perform as well as a v-4 of the same displacement. The v-4 would likely produce more low end grunt and more high RPM hp.