ESE's works engine tuner

[husaberg]

So you did mate. Did anyone ever do the sums to see how much would be required to deal with the waste heat energy involved in an average bucket race? Wouldn't surprise me if just a couple of litres would do the job. Getting the bloody stuff cooled in time for the next race might be interesting.

See that graphite whodackey increases the capacity by 570 times......

[Moooools]

So you did mate. Did anyone ever do the sums to see how much would be required to deal with the waste heat energy involved in an average bucket race? Wouldn't surprise me if just a couple of litres would do the job. Getting the bloody stuff cooled in time for the next race might be interesting.

I conservatively estimate 107 litres.

My reasoning:

30hp engine: 22.4 kW

For four stroke we run on the assumption that 1/3 goes to the crank, 1/3 goes out the pipe, and 1/3 goes to the water. That is all I know So I wills stick with it for now. Corrections welcomed.
That means if 22kW is getting to crank, 22kW is going into the cooling.

22kW of heat rejection for 10 mins is 60x10x22 = 13422kJ of heat.

I am running on the assumption that we don't want the water to get over 50 degrees C as that is what you all like to run your engines at. Also assuming that the water begins before race at ambient temp of 20 degrees C.
That is a change of 30 degrees throughout the race.

Specific heat of water at 20deg = 4.18kJ/kg.K
That means for 30deg temp change one kg of water can absorb 125kJ of heat.
We need to absorb 13422kJ

13422/125 = 107kg = 107l

***Assumptions***
1/3,/1/3,1/3 rule of thumb
No heat lost in to other systems
The engine outputs 30hp for the full race. (probably more like 50% for some tracks, even less for the likes of mt Welly)
Cp is constant.
**************

Even with less conservative numbers, the radiator looks pretty good.

[Frits Overmars]

In 1968... the Yamahas swept the championship, but Herrero left no doubt that the little Ossa was quick and dependable. He finished seventh in the championship and claimed a third place in the final race of the season at Monza.

So he did encounter the V-fours, although he didn't do battle with them. It escaped me.

Herrero friendly manner, super talent and mechanical skills made him an attractive proposition to the OSSA factory and Giró offered him a job developing the OSSA 250cc race bike. He worked harmoniously and effectively with Eduardo Giró on the development of the OSSA monocoque, which featured a 6 speed rotary valve engine and together they began to surprise the motorcycling world. On the OSSA 230 cc bike with no fairing and 30 HP, they won 250cc Spanish Championship in 1967.

Girós rotary brainchild did not start as a monocoque bike; here is the 1966 tubular frame version with Herrero in the saddle.

[Frits Overmars]

..has anyone tried blowing air thru a watercooled engine? I know the specific heat of air is a ¼ of water and that its thermal conductivity is far, far less, but the one thing going for it is that the volumetric flow rate is far greater, given a decent blower...
Maybe just a product of the too many top quality Australian beers I guess. Just can't wait for the response to this though

You should be careful what you ask for, Ken .
So the specific heat of air is a ¼ of water; I'll take your word for it. And for really good engine cooling we need 1 liter water per 1 crankshaft-Hp per minute.
Let's assume a modest 30 Hp for a bucket, then we'll need 30 kg water/minute. Or 120 kg air/minute.
The density of air is 1,225 kg/m³ so we'll need an air flow of 97,959 m³/minute.
The coolant hose pillars on a typical 125 cc cylinder have a 16 mm diameter, but let's be generous and assume 20 mm.
Then we'll need a flow velocity of 311813 m/minute, or 5197 m/s. That's a little over Mach 15. I'd like to see the blower...
I'm pretty sure that blower will absorb more than 30 Hp. Just as well, because air 'cooling' your cylinder at Mach 15 would melt it in no time at all.

OK, maybe we don't really need 30 liter water per minute; maybe the engine will survive at only 10 l/min. Switching to air will then only require Mach 5.
That's a little above the top speed of the SR-71 Blackbird spy plane that had to be made completely from titanium because alu couldn't stand the heat...

[Frits Overmars]

Yamaha withdrew the V-fours at the end of 1968.

I did wonder why I couldn't get a pic of a 1969 250 V4 that would likely be why lol.

here's something to comfort you Husa.

[Frits Overmars]

... And some more. Don't forget to zoom in.

[seattle smitty]

Just from looking at photos, and not from any but the barest familiarity with racing motorcycles, but it seems to me that even though some of you, and others throughout the sport, have fabricated air-scoops and deflectors, there is more that could be done in re-directing airflow. The front tire/rim is a truly awful barrier to having any kind of decent airflow to the radiator or the fins of an air-cooled engine, and could hardly be worse for creating turbulent eddies of air behind it. Whether the tire/rim could be any less bad aerodynamically with something like spun aluminum "full-moon" wheel covers (which would add some undesiralble unsprung weight), I don't know. But in my youth I got to ride on the radial-engine propliners of the day, including the L749 Lockheed Constellation, with its four 3350 twin-row Wright engines. Ten thousand take-off horsepower apiece, yet at the fuel-saving slow 230mph cruising speed, with nothing but ram-air, UN-obstructed ram-air, those engines went thousands of hours between overhaul.

I'd like to know if anybody has studied the ACTUAL air-flow entering the radiator or cooling fins on specific motorcycles, as opposed to the ASSUMED air-flow, because I don't think you can assume anything, given the turbulence-making front tire. An example of why you can't assume anything here is the (rather silly) controversy about how to reduce the ASSUMED drag of the tailgate of a pickup truck. Guessers will tell you that when your bed is empty, you can save a little fuel by dropping the tailgate. But such people don't understand what the air is doing as it comes over the cab . . . or that it changes at different highway speeds. Unsurprisingly to anyone who has some feel for low-speed aerodynamics, when a big consumer magazine did tests on a number of different pickup trucks, they found that some of them showed a small mpg gain with the tailgate down, some did better with the tailgate UP, and some showed no worthwhile difference with it up or down. To my mind this is sort of like the supposedly air-directing shrouds that Suzuki used to put over the fins of their old air-cooled 2-stroke street bikes; a good idea IF the air is ACTUALLY flowing fore-and aft, and it very well might not be. My point is that I don't think you can assume what's happening with the wake turbulence of your front tire, or how much air is blowing through your radiator or cooling fins, how much is burbling off to the sides, or whatever. And, that maybe with considerable attention to this area, you could get a lot better cooling.

(FWIW, when I make these long posts, I am ASSUMING that by CAPITALIZING key words I am improving readability. If this is more irritating than helpful to readers, say so and I will DESIST)

[Frits Overmars]

....To my mind this is sort of like the supposedly air-directing shrouds that Suzuki used to put over the fins of their old air-cooled 2-stroke street bikes; a good idea IF the air is ACTUALLY flowing fore-and aft, and it very well might not be.

That's an assumption, isn't it?
BTW, capitalizing whole words is considered shouting on the world wide web. Please don't shout, Smitty; I'm not blind.

[Dutch Fisher]

IF the air is ACTUALLY flowing fore-and aft, and it very well might not be.

Yes i think your right there Smitty.... in a 200mph side wind #Gulp #Aerodynamicsoutofthinair

[Ocean1]

I conservatively estimate 107 litres.

My reasoning:

30hp engine: 22.4 kW

For four stroke we run on the assumption that 1/3 goes to the crank, 1/3 goes out the pipe, and 1/3 goes to the water. That is all I know So I wills stick with it for now. Corrections welcomed.
That means if 22kW is getting to crank, 22kW is going into the cooling.

22kW of heat rejection for 10 mins is 60x10x22 = 13422kJ of heat.

I am running on the assumption that we don't want the water to get over 50 degrees C as that is what you all like to run your engines at. Also assuming that the water begins before race at ambient temp of 20 degrees C.
That is a change of 30 degrees throughout the race.

Specific heat of water at 20deg = 4.18kJ/kg.K
That means for 30deg temp change one kg of water can absorb 125kJ of heat.
We need to absorb 13422kJ

13422/125 = 107kg = 107l

***Assumptions***
1/3,/1/3,1/3 rule of thumb
No heat lost in to other systems
The engine outputs 30hp for the full race. (probably more like 50% for some tracks, even less for the likes of mt Welly)
Cp is constant.
**************

Even with less conservative numbers, the radiator looks pretty good.

Two significant difference between water and a designer-wax: #1: You're not allowed water.

#2: Cooling water isn't changing phase from solid/liquid/gas. The various thermal waxes are designed to phase change at a specific temp. Applying heat initially simply warms the wax up, but as the temperature approaches that required to change the wax from solid to liquid the temperature simply stops rising. And it'll remain constant as the wax soaks up the huge quantities of energy required to change phase.

So a wax designed to change at 50deg and absorb 13422kJ will only need a small portion of that 107 litres.

But I'm not a process engineer, which is why there's some numbers missing from the above.

[chrisc]

The rules say:

Solo motorcycles shall have two engine capacity classes:
F4 2 stroke 55-100cc
2 stroke 55-125cc air cooled
4 stroke 55-150cc

F5 2 stroke 0-50cc
4 stroke 0-100cc air cooled

Whilst there is anyway some interpretation to be had with rules, they do not say that the 125s are allowed anything but water-cooling, they say air cooled. Therefore, wax cooling or whatever other matter state changing cooling would seem to be against this simple rule.

[TZ350]

I am ASSUMING that by CAPITALIZING key words I am improving readability. If this is more irritating than helpful to readers, say so and I will DESIST)

I have been breaking my posts down into smaller bite sized paragraphs with the hope of improving readability.

[TZ350]

I'd like to know if anybody has studied the ACTUAL air-flow entering the radiator or cooling fins on specific motorcycles, as opposed to the ASSUMED air-flow, because I don't think you can assume anything..... like the supposedly air-directing shrouds that Suzuki used to put over the fins of their old air-cooled 2-stroke street bikes; a good idea IF the air is ACTUALLY flowing fore-and aft, and it very well might not be.

When I was looking at improving the air cooling performance on my bike I came across an article on motorcycle radiators. The assumption was that the wind blew through the radiator but this was not necessarily so, the bulk of air could very well be moving sideways across the radiator.

The only way to have air move through the radiator was to have a depression behind it and this was not always present, even when going fast. But there is always some sort of depression behind a moving motorcycle and the idea was to form a duct from the back of the radiator to the low pressure area at the back of the motorcycle. That way the air at the front flowed through the radiator to fill the depression behind it.

This thinking is influencing how I arrange the air ducting for my new bike.

[husaberg]

I conservatively estimate 107 litres.

My reasoning:

30hp engine: 22.4 kW

For four stroke we run on the assumption that 1/3 goes to the crank, 1/3 goes out the pipe, and 1/3 goes to the water. That is all I know So I wills stick with it for now. Corrections welcomed.
That means if 22kW is getting to crank, 22kW is going into the cooling.

22kW of heat rejection for 10 mins is 60x10x22 = 13422kJ of heat.

I
***Assumptions***
1/3,/1/3,1/3 rule of thumb
No heat lost in to other systems
The engine outputs 30hp for the full race. (probably more like 50% for some tracks, even less for the likes of mt Welly)
Cp is constant.
**************

Even with less conservative numbers, the radiator looks pretty good.

Two significant difference between water and a designer-wax: #1: You're not allowed water.

#2: Cooling water isn't changing phase from solid/liquid/gas. The various thermal waxes are designed to phase change at a specific temp. Applying heat initially simply warms the wax up, but as the temperature approaches that required to change the wax from solid to liquid the temperature simply stops rising. And it'll remain constant as the wax soaks up the huge quantities of energy required to change phase.

So a wax designed to change at 50deg and absorb 13422kJ will only need a small portion of that 107 litres.

.

that third third third rule Mooools used. The assumption that all the exhaust heat loss needs to included puzzles me?
Also as I pointed out there are other forms 570 times more efficient than paraffin wax, food for thought.
The rest Ocean covered with the phase change.

The radiator is good, but what I spit balled was just a dodge, a musing. The radiator works because it has plenty of cooling air and the water is pretty efficient.

[Grumph]

When I was looking at improving the air cooling performance on my bike I came across an article on motorcycle radiators. The assumption was that the wind blew through the radiator but this was not necessarily so, the bulk of air could very well be moving sideways across the radiator.

The only way to have air move through the radiator was to have a depression behind it and this was not always present, even when going fast. But there is always some sort of depression behind a moving motorcycle and the idea was to form a duct from the back of the radiator to the low pressure area at the back of the motorcycle. That way the air at the front flowed through the radiator to fill the depression behind it.

This thinking is influencing how I arrange the air ducting for my new bike.

When the factories started using pressurised airboxes I watched with interest the frame mods which were required - steering heads which were effectively box sections to allow air passage. If you're going to harness the low pressure wake air Rob, you may want to look at a box shaped frame - specifically a wedge shaped box, large open end at the rear,smaller inlet duct at the front. Maybe fold up a monocoque ?
Remember the Britten radiator is in the seat so as to use the low pressure wake to drag air through it.