Pearls of wisdom from Kevin Camerons...

[shilka99]

'Classic Motorcycle Race Engines'

In case anyone is interested in a readers digest version of this book, I just finished reading it for the fourth time. Each time I took notes on what I considered the most interesting facts and details.
I didnt include any details about riders or championships - this is easy to find elsewhere. Instead, I was most interested in the information pertaining to engine development.
I have another list of snippets from his other book which is a collection of his TDC editorials since the late 60's. I'll be posting this later, which will include more info on suspension tuning.
Each point has been quoted verbatim, unless additional information was required to clarify. ie none of this is my own assertion.

squish can generate turbulence but if it requires a long spark advance power is lost. Intake charge must flow effectively (turbulently) and also burn fast (indicated by short ignition advance.) Slow flame front requires more advance. Pancake combustion chamber slows flame front.

VE and combustion efficiency are inherently opposed. intake charge tumble = power.

The flatter the chamber and piston crown, the lower the engines heat loss

A flat crank has residual secondary vibration, but simplifies exhaust by not requiring connection between banks.

shortening header pipe length raises rpm of peak torque

A hemisphere has double the surface area of a disc the same dia.

Lower chamber surface/volume ratio reduces heat rejection to coolant.

reinforcing cases by adding material runs the risk of thermal cracking as the poured part cools

In WSBK, ducati reduced valve duration over time to gain mid-range torque

Acceleration requires compression. high top speed requires high flame speed which requires low compression

The four pulse desmosedici ran dual 2 into 1. The twin pulse ran four pipes

Liquid hydrocarbons expand 1cc per liter per Degree C.

All types of exhaust pipe have a positive and an anti-resonance. A virtual power band fills in the gaps.

7075 (Ergal) is a high strength aluminum with high zinc content developed in Japan by sumitomo in 1936

As turbulence is pinched out by higher bore/stroke, combustion must be initiated earlier. longer spark timing causes greater heat loss to combustion chamber/piston. this will still generate more power by revving higher with shorter stroke

throttle harshness in early versions of the RC211 was solved by driving fuel pump at engine speed

gear driven cams eliminate chain stretch and the inaccurate timing this causes, increasing available power at the end of a race.

popping and banging on throttle closure indicates increased valve overlap timing

deep chamber 2-valve heads originated in 1922 in fiat gp engines but compression was limited. tetraethyl lead for anti-knock allowed greater compression

The 1957 mondial 125cc single achieved the same piston acceleration (7000g) as a 2012 R6 thanks to a forged piston

a big end bearing is at maximum rpm at TDC, when the rod rotates opposite to the crank. Its at minimum RPM at BDC when rod rotation is subtracted from crank rotation.
Eye to eye length of the rod is ~4x length of the crank arm so the once per rev variation is approx. 24%.
Longer rod reduces variation. (like 19% in the guzzi V8)

detonation is a race between combustion speed rushing to consume all the intake charge and the pre-flame chemical changes that cause detonation.(prompted by heat and compression) in the early 50's, cooling the valves internally (with hollows filled with small amounts of sodium) helped. Detonation causes failure by progressively softening the ring lands which locks the ring causing sudden rise in piston temp.

Locating something heavy low in the chassis increases resistance to rapid roll.

Generally speaking, a smaller intake valve moves the torque peak down the rev range.

fuel injection generates pressure and velocity required to flow fuel. smoothbore carbs require small(er) bores to generate sufficient pressure delta. this reduces cylinder filling ability at high rpm. Fuel pump generates sufficient pressure at all rpm allowing large throttle bodies for ideal flow rates at any desired rpm.

larger valve included angle = deeper combustion chamber = greater chamber surface area. this thin orange peel combustion chamber slows combustion, kills top end power, increases heat loss and piston temp which affects kills piston durability.

wave supercharging allowed 2-strokes to eclipse 4-stroke power levels in 1972

high strength aluminum starts losing strength at the temp of boiling water.

[fixxervi6]

some really interesting factoids there!

[shilka99]

Snippets from Top Dead Center 2

a secondary function of oil is as coolant. Even a very accurate and efficient gear pair seldom exceeds 98% efficiency in power transmission. The lost power is consumed in shearing the lubricant film between teeth as they slide over each other and this lost power appears as heat. A gear pair transmitting 100hp at 98% efficiency will rid itself of 1,500 watts in heat - equivalent to 2 toasters. Oil in a transmission bathes the gears and carries this heat away.

Before rising rate suspension, multi-rate springs were used but they could be matched to a damper at only one rate. below that rate, the damper was too stiff for the springs soft initial rate. Above it, the stiffening spring was too much for the damper. A bike with suspension like this would be over damped when upright, under damped when loaded down in a corner.

a tire generates traction by continuously receiving the imprint of the road. the deformation of the rubber is called hysteresis

Every tire has a steering effect called Camber Thrust. This generates a steering torque on the footprint of the tire, steering it into the turn. This twist develops entirely in the carcass and takes place without any steering movement of the rim

Camber thrust must develop in concert at front and rear tires. Mismatched tires may develop unbalanced steering giving a feeling of understeer or oversteer.

The difference between designed trail and actual trail is called pneumatic trail. This varies with carcass stiffness and inflation pressure. In effect, the trail of your bike increases the more you deflect the front tire out of shape.

Fork dive is desirable. As a machine dives, the CG is lowered, permitting harder braking

[Fish R1]

Interesting read.

[111]

Some interesting facts there, especially the last one about fork dive.

I was reading through Tony Foal's book and one interesting fact it said was that tires have the greatest amount of traction when they are slipping at a rate of 10 percent or traveling 10 percent faster than the bike is moving. I will have to take some notes as I read through it. His book is a good 600 pages if you haven't read it.

[DarcShadow]

I'd need to see some math behind that. Slipping is the very definition of not having traction.

[111]

My thought too. If I remember right it pertained to cornering. I will try to go back and find it and maybe post up some details.

[111]

Sorry for the screen shot but the pdf I have is protected. Here is an excerpt. This is from the second edition published in 06

[Rhino]

I don't think that's saying you get better traction with slippage, I think it's saying that slippage is a fact of life for tire traction.

It makes sense when you think about it, it's not like the microsecond that your contact patch touches the road you have instant grip. The tire takes time to deform around the surface of the road and "bite in". Since that's happening constantly as the tire rotates and new parts of the tire come in contact with the road, you end up with the tire in a constant state of low-level slip. I don't think it's traction *loss*, I think it's the time it takes for that part of the tire to gain traction.