Any mechanical engineers in the haus? Help requested!

[Dare]

The one that fires all four together! (Actually, taht's a fourth firing order. And firing a two big twinbs would be a fifth) .

That sounds torquey. I wonder why it's not done... After all there are 4 valves to a piston these days.

[bogan]

That sounds torquey. I wonder why it's not done... After all there are 4 valves to a piston these days.

I'm guessing cos you would get massive pulsing on intake and exhaust flows which would create a big powerband by fucking the rest of the rev range.

[Dare]

I'm guessing cos you would get massive pulsing on intake and exhaust flows which would create a big powerband by fucking the rest of the rev range.

So.. Same as a normal thumper then :P

[bogan]

So.. Same as a normal thumper then :P

hmmm, good point, maybe not so much of a powerband then, perhaps the pulsing just rob power over the whole rev range as I can't identify anything but smooth power on the 4T bikes in below dyno


spot the two smokers

[motorbyclist]

all of them but the 400 yamaha and the 600 husky (IIRC)

good to see further evidence that honda engineering beats kawasaki

[bogan]

all of them but the 400 yamaha and the 600 husky (IIRC)

good to see further evidence that honda engineering beats kawasaki

yeh, I made it too easy leaving the names there. I would have put the KTM into the 4T just going by the curve, and fuck they rev'd the snot out of it, extra 2,500rpm after max power

[avgas]

all of them but the 400 yamaha and the 600 husky (IIRC)
good to see further evidence that honda engineering beats kawasaki

I see a believer, can i get an amen......AMEN!!!!!!

[Dare]

I see a believer, can i get an amen......AMEN!!!!!!

Goddamn threads lose track fast around here...

[bogan]

Goddamn threads lose track fast around here...

aren't you finished with it yet?

[Dare]

aren't you finished with it yet?

Point. Ok how many cylinders is best?

[bogan]

Point. Ok how many cylinders is best?

thats easy, two! in a V configuration though

[avgas]

Point. Ok how many cylinders is best?

0 cylinders
2 pistons
2 valves
and the most elaborate induction system known to man.

well you are making a bicycle...........(there you go dragged it back on topic for ya)

[jono035]

Lol, he was so adamant about it aswell

Yeah, but he was also right, whereas you were wrong. Actually it may have been Indy, in fact I think it was a few of us.

Crank angles ignored, firing order (for cars at the very least, not 100% on inline-4 bikes) is always 1342 except for a couple of random old ford pushrod engines...

[schrodingers cat]

0 cylinders
2 pistons
2 valves
and the most elaborate induction system known to man.

well you are making a bicycle...........(there you go dragged it back on topic for ya)

What is the total efficiency of a bicycle - calorific input to power source (rider) to output power * efficiency of vehicle?

[Dare]

What is the total efficiency of a bicycle - calorific input to power source (rider) to output power * efficiency of vehicle?

A human being traveling on a bicycle at low to medium speeds of around 10-15 mph (16-24 km/h), using only the power required to walk, is the most energy-efficient means of transport generally available. Air drag, which increases roughly with the square of speed,[4] requires increasingly higher power outputs relative to speed, power increasing with the cube of speed as power equals force times velocity. A bicycle in which the rider lies in a supine position is referred to as a recumbent bicycle or, if covered in an aerodynamic fairing to achieve very low air drag, as a streamliner.


Racing bicycles have dropped handlebars, a narrow seat, and minimal accessories.
On firm, flat, ground, a 70 kg person requires about 30 watts to walk at 5 km/h. That same person on a bicycle, on the same ground, with the same power output, can average 15 km/h, so energy expenditure in terms of kcal/(kg·km) is roughly one-third as much. Generally used figures are
1.62 kJ/(km∙kg) or 0.28 kcal/(mi∙lb) for cycling,
3.78 kJ/(km∙kg) or 0.653 kcal/(mi∙lb) for walking/running,
16.96 kJ/(km∙kg) or 2.93 kcal/(mi∙lb) for swimming.
Amateur bicycle racers can typically produce 3 watts/kg for more than an hour (e.g., around 210 watts for a 70 kg rider), with top amateurs producing 5 W/kg and elite athletes achieving 6 W/kg for similar lengths of time. Elite track sprinters are able to attain an instantaneous maximum output of around 2,000 watts, or in excess of 25 W/kg; elite road cyclists may produce 1,600 to 1,700 watts as an instantaneous maximum in their burst to the finish line at the end of a five-hour long road race. Even at moderate speeds, most power is spent in overcoming aerodynamic drag, which increases with the square of speed.[4]

According to google: 100 hp = 74 569.9872 watts (74.6kw)
Compared to say, 5 w/kg * 70kg = around 350 watts or 0.47 hp

I'd say bike wins efficiency stakes, fun stakes... Not so much.