ESE's works engine tuner

[TZ350]

Think how big the fan at the dyno is and thats just for short runs.

Yes the dyno fans are big but they need to throw a lot of air some distance. My plan is ducted air and possibly a battery powered leaf blower.



https://www.ryobitools.com/outdoor/products/details/580

Suitable Leaf blowers range from 150 to 300 cubic feet of air per minute.

This is where I am a little unsure but I think 1m3 of air absorbs about the same amount of heat as 1L of water for 1 deg C temperature rise. How many litres of water a minute pass around the cooling system of a Honda RS125? probably not even a 50.

Its all about carrying waste heat away quickly and sure water gets into very small areas around the combustion chamber, we just have to think of clever ways of doing that with air.

One idea is to have a number of 3/8" copper tubes running through the critical parts of the head and blowing cooling air through them. The beauty of this is that the length of warmed copper tube will expose a greater surface area to the cooling air than the head could by itself.



The fan could force feed air through a group of pipes stacked together like this. The pipes could then be routed to where cooling is needed.

[husaberg]

Yes the dyno fans are big but they need to throw a lot of air some distance. My plan is ducted air and possibly a battery powered leaf blower.

Suitable Leaf blowers range from 150m3 to 300m3 of air per minute.

This is where I am a little unsure but I think 1m3 of air absorbs about the same amount of heat as 1L of water for 1 deg C temperature rise. How many litres of water a minute pass around the cooling system of a Honda RS125? probably not even a 50.

Its all about carrying waste heat away quickly and sure water gets into very small areas around the combustion chamber, we just have to think of clever ways of doing that with air.

One idea is to have a number of 3/8" copper tubes running through the critical parts of the head and blowing cooling air through them. The beauty of this is that the length of warmed copper tube will expose a greater surface area to the air than the head by itself.


The fan could force feed air through a group of pipes stacked together like this. The the pipes could then be routed to where cooling is needed.

70 litres per minute rings a bell for the RSA
http://www.pit-lane.biz/t3173p80-gp1...-part-2-locked

Later oh hell no golly

Compare two cooling systems, A and B. In system B the water flows three times as fast and picks up only half the amount of heat per liter, compared to system A.
Then system B removes 50% more heat than system A! And provided your piston clearance is OK, you just cannot have too much cooling. In the Aprilia RSA125 the water pump circulates 160 liter per minute. That is 3 liter per HP per minute!

Nowadays we have a fine solution for avoiding corrosion; it's called plastic. Saves weight too.

I don't know exactly how the NZ dollar is doing, but that sum will probably buy you two of these:
http://www.hvg-engineering.com/index...id=127&lang=NL

160 liters per minute

[TZ350]

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RS125_compilation.doc

While looking for info on Honda RS125 cooling systems I found this handy little gem on setting up RS125's and how to get the best out of a small race bike. Also a RAD air chart for setting up carbs.

[TZ350]

70 litres per minute rings a bell for the RSA
http://www.pit-lane.biz/t3173p80-gp1...-part-2-locked

Later oh hell no golly

Aprilia RSA125 the water pump circulates 160 liter per minute. That is 3 liter per HP per minute!

Thanks Husa, thats what I need, a handy rule of thumb to work to.

I am aiming for 40hp so 120m3 a min of air, sounds possible with a leaf blower combined with conventional air cooling. With the leaf blower for the critical areas.

[TZ350]

Specific heat explained:- http://www.iun.edu/~cpanhd/C101webno...cificheat.html

Turns out that the specific heat of air is a quarter that of water.
So 300+m3 of air is required, well still doeable but getting difficult....

[husaberg]

Specific heat explained:- http://www.iun.edu/~cpanhd/C101webno...cificheat.html

Turns out that the specific heat of air is a quarter that of water.
So 300+m3 of air is required, well still doeable but getting difficult....

Scooters use engine driven fans and shrouds just saying........ kiss

[Muciek]

Maybe snowmobile fans? They are big and move a lot of air (talking from what I have seen here when I was repairing sleds).

[TZ350]

Scooters use engine driven fans and shrouds just saying........ kiss

Yes and it allows them to get away with quite small fin areas for their power output. Because the power absorbed by a fan goes up by the square of its speed ie double the speed = four times the power required to drive the fan. To keep it simple and the power absorbed to a minimum I prefer the idea of a constant speed electric fan to the variable power drain (and output) of a fan attached to the crank.

[husaberg]

Yes and it allows them to get away with quite small fin areas for their power output. Because the power absorbed by a fan goes up by the square of its speed ie double the speed = four times the power required to drive the fan. To keep it simple and the power absorbed to a minimum I prefer the idea of a constant speed electric fan to the variable power drain (and output) of a fan attached to the crank.

Granted but..... wouldn't the electric power to power the electric fan also need to be generated or carried. I would also propose the engine power loss to drive a engine driven fan would be nullified when compared the power loss caused by thermal overload power losses as it is at present.

Then again I am no physicist...........

[TZ350]

Granted but..... wouldn't the electric power to power the electric fan also need to be generated or carried. I would also propose the engine power loss to drive a engine driven fan would be nullified when compared the power loss caused by thermal overload power losses as it is at present. Then again I am no physicist...........

Struggling to get my head around it to, all this talk about m3 of air required, for instance I don't see 300m3/min of air squeesing through a typical RS125 radiator, do you? Thinking 300m3, I have obviously got something wrong.

The specific heat talks about how much heat is required to raise something 1 deg C, well I guess there must be a reasonable difference between radiator inlet and outlet temp.

So, say the air temperature gets raised 20deg C as it passes through the radiator, then 1m3 of air raised 20 deg C = 20m3 raised 1 deg C.

So when I was thinking 300 m3 of air to do the job, I really only need 30/20 = 1.5m3 of air if its temperature is raised 20 deg as it passes through the cooling system.

Intuitively, we only need the same amount of air that passes through a Honda RS125 radiator to pass through the air cooling system and it will carry away the same amount of waste heat if its discharge temperature has been raised to the same level as it would have been passing through the RS radiator.

The trick is to effectively apply the air cooling to the essential parts like the combustion chamber shell and the underside of the exhaust duct.

[Yow Ling]

Yes the dyno fans are big but they need to throw a lot of air some distance. My plan is ducted air and possibly a battery powered leaf blower.



https://www.ryobitools.com/outdoor/products/details/580

Suitable Leaf blowers range from 150 to 300 cubic feet of air per minute.

energy/specificheat.html[/URL]

Turns out that the specific heat of air is a quarter that of water.
So 300+m3 of air is required, well still doeable but getting difficult.... [/QUOTE]


if 300m3 of air is required then 300 x 35(cfm per m3) = 10500 cfm or about 35 300cfm leaf blowers , might be more convenient to run a duct back to the pits

[TZ350]

Granted but..... wouldn't the electric power to power the electric fan also need to be generated.

True but the drain on the motor would be constant as the fan speed would be constant.

I have a small generator, and after the ignition and EFI it has about 5 amps to spare.

[husaberg]

True but the drain on the motor would be constant as the fan speed would be constant.

I have a small generator, and after the ignition and EFI it has about 5 amps to spare.

5 amps drain at 12 volts equal 60 watts which has to be drawn from somewhere.
re the rad, the air does have to flow through it it just has to be exposed to it. Air is pretty abundant.

I found this remember how big a fan is on a bus
http://johnmaherracing.com/tech-talk...e-cooling-fan/

flex fan blades also fatten as speed rises....... so as the they flatten the power consumption curve required to drive it lessens.
either way I think I like water

[TZ350]

... if 300m3 of air is required then 300 x 35(cfm per m3) = 10500 cfm or about 35 300cfm leaf blowers , might be more convenient to run a duct back to the pits

Yes you're right, I don't think towing a trailer would be all that easy, so it needs to be a big fan running off three phase power back in the pits. The ducting would not be a problem unless I actually pass someone, which is a bit of an unlikely event on a normal day.

35 leaf blowers!!! clearly something wrong with my initial assumption of the volume of air required. Because that much air does not pass through a Honda RS125 radiator or even a turbocharged Mac trucks radiator.

[TZ350]

5 amps drain at 12 volts equal 60 watts which has to be drawn from somewhere.

True but the power drain on the motor does not increase by the square of engine speed like it would with a crank driven fan.

I found this remember how big a fan is on a bus
http://johnmaherracing.com/tech-talk...e-cooling-fan/

Interesting about the bus tests.

An alternative is to use a Turbocharger to blow air through selected ducts in the head and cylinder.



A side benefit of a turbo would be using the waste gate for varying the expansion chambers internal pressure like Frits moving gate.