173BHP from 1000cc

I'd like to see the figures to back that up - as bikes have terrible aerodynamics - it's actually incredibly hard to get a bike to crack

This is definitely wrong. Power to weight ratios only affect accelleration - top speed is entirely governed by power and drag co-efficients (which are incredibly poor for a bike).

I have a Triumph Daytona 1200 c1993. It goes *extremely* well and is not Japanese. Which is nice.

Great commuter =8-O

My Cosworth would only *just* crack 185... and that was with a *lot* of power, and some messed with gearing..

speaking of aerodynamics, geezer I know spent approx £40k on getting about

Frontal area of a small, wheeled, bungalow...

No, you don't.

And a GSXR 1000 engine built for racing is?

That's not entirely true, since the pistons move up and down i.e. when the piston is at the top of it's stroke your ratio would give a very large surface area for the volume.

Compression ratio, piston shape and combustion chamber shape also affect this.

-- James

When you use a bike engine at full throttle you very quickly end up going as fast as you want to go, i.e. a bike engine spends relatively little of its life at high % power outputs compared to a car.

-- James

Don't 'regulators' in racing claim that the Wankel engine's capacity isn't 1.3l (i.e. one 'chamber/rotor full) but infact 3 times that- in this case 3.9l?

Yes good point, except that the surge of power might be addictive :-)

Quite true. It may first seem paradoxical that there is both a need for avoiding heat losses in the combustion chamber and for engine cooling. But the power extracted in the process is related to the temperature difference.

If power is to be extracted in a heat engine, the temperature difference must be created by allowing the gases to expand. Heat loss into your engine cooling system is waste heat.

I remember it being talked about in F1 circles that they had moved their engines over to different piston rings which allowed them to run higher temperatures and made the radiators smaller i.e. less cooling was needed. This increase in temperatures was accompanied with an increase in power.

The only reason you would want to keep your cylinders / combustion chambers cool are to stop your piston rings welding up. Heating up your incoming charge is also a bad thing because it means less of it will fit into your cylinders and you have to compress it.

-- James

I'm sure bikes have a much worse coefficient of drag than cars, since the coefficient of drag is drag relative to the frontal area (it's an almost meaningless measure when trying to compare how slippery two things are) and bikes are not a very aerodynamic shape. I would hazard a guess that the actual drag factors are similar since bikes are so small.

Personally I feel the whole BHP per litre thing is so much pointless dick waving. What actually matters is power to engine weight, or power to cost, or power to fuel economy, or power to reliability. Any of those is more important than power to capacity, which doesn't matter at all unless you live in a country, or take part in a race, where engines are taxed or categorised by capacity, and even then it's completely arbitrary.

What was the peak torque, and what RPM was it at? Those numbers will show you why an engine that derives it's power from very high RPM and little torque is not overly suitable of lugging a vehicle that weighs, maybe 6 times as much as the bike?

What is the brake specific fuel consumption? I'll hazard a guess at it being considerably worse than a car engine of similar power.

Can the bike go 10,000 miles between oil changes and still last well over 100,000 miles?

Regards

Mike