Track Bike

Originally Posted by northwind

Didn't you do the minitwin-legal full cam swap though? Not quite the same.

Indeed (hence the like for like statement )

Ok, we are going in circles a bit here ... which when we both know where each other are coming from is a bit pointless!!

... and the conclusion is still the same as we both agree - if you had/wanted to chuck say £200 to at the bike, the cam swap is low on the priority list. However if you have sorted all the bouncy and stopy bits properly and have a few quid left - for the most effective/useful ENGINE/POWER mod per-buck is the cam-swap ... and if you can DIY and find a set of donor cams for reasonable money, the ... well why not!!

The real bonus is that if you are not running to minitwins spec* then you get more gain for the same money!!

*you can use later cams, but they have to be in the same place - the better (but MT illegal) mod is a combo of pointy and curvy inlets. Don't know what the actual HP difference is, but you will be getting ~1mm (I think it was ~1mm?!!? ) extra lift over the like for like setup!!

Seriously guys, all the nancy arguing aside, if you want a real performance increase in your speeds, get one of those fiberglass kits that puts the airflow vains on top of your helmet, directs airflow, reducing drag, an extra 0.02 to 0.04 % gain. Also, waxing you leathers can take a couple of 1/10ths off those times...

Originally Posted by ELR4ever

...

Although you are obviously joshing here , it does raise a good point (or spark off a new argument!! ) ... 5hp can easily be sucked up with air resistance ... or equally you can easily 'gain' (well not lose) effective power by making yourself/the bike more slippy (tuck in better, take mirrors off etc).

making the figures up* - by tucking in you probably need say 15hp LESS to get to 130 than sitting upright ... 20hp to get to 135 .... 30hp 140 etc etc

*as I don't now the real drag without a wind tunnel etc - but I know the numbers are not insignificant - so prolly in the order of this.

[quote=Blue_SV650S;1360761]Although you are obviously joshing here , it does raise a good point (or spark off a new argument!! ) ...

While this is making you dizzy:

Power
The power required to overcome the aerodynamic drag is given by:
Note that the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power.
It should be emphasized here that the drag equation is an approximation, and does not necessarily give a close approximation in every instance. Thus one should be careful when making assumptions using these equations

Work can be shown as:



So the cheapest and most effective mod ever for gaining power is dropping 25 lbs.

I've junked about 35 pounds of un-needed road going crap off my CBR trackbike, and I'm a bit of a whippet in stature...woohoo.

[northwind]

I love losing weight off mine, it's tricky with a street bike but with an angle grinder and a load of ally strip, and an eye to losing unneccesary components, you can still get some stuff done... Very satisfying too, frinstance you can knock 300 grams off the front subframe in 10 minutes without affecting its strength at all- how much would you have to spend on titanium bolts to do the same? Maybe a wee bit of a derail, but it costs you nothing but time, so even though the difference is pretty trivial in the grand scheme it's sometimes worth doing. (better on track to just lose the stock subframe, but it's all about cheap)

And before someone says "Just lose weight yourself" I weigh 63 kilos- I'm the perfect weight for stock SV forks

[quote=ELR4ever;1360777]

Originally Posted by Blue_SV650S

Although you are obviously joshing here , it does raise a good point (or spark off a new argument!! ) ...

While this is making you dizzy:

Power
The power required to overcome the aerodynamic drag is given by:
Note that the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power.
It should be emphasized here that the drag equation is an approximation, and does not necessarily give a close approximation in every instance. Thus one should be careful when making assumptions using these equations

Work can be shown as:



So the cheapest and most effective mod ever for gaining power is dropping 25 lbs.

You are not gaining any, you are just not losing/needing as much ... its reducing drag that gives the most significant gains in (high) speed ... not weight reduction ... why dig out a more in-depth explanation of calculating - power to overcome drag - then waffle on about weight?!!?

The gentleman in my avatar felt that as his skin would have less wind resistance than his leathers he could dump them and increase his speed from 148 mph to over 150. Apparently it worked. So you know what to do ...

[northwind]

If he drilled holes in his skin, like an old fireblade, he'd have even less air resistance. Not to mention being lighter.