electric cooling fan

[rablack21]

Also Aberegg005, contrary to what you were told on the "other site", getting the coolant passages milled out some will NOT drop the coolant temp 20-25°F. This is just BS. The radiator barely accomplishes that, and some probably don't. All that would help with is if you had issues with seizures on the exhaust side of the cylinder, it would not drop the overall coolant temp by 25°F. If that were true then big bore manufacturers would do that already. The only time this has been an issue is with non pv cylinders that happen to have too much solid mass around the front of the exhaust and the temp around the exhaust getting a bit too hot. This option would do you no good if the engine's cooling system is overheating.

[aberegg05]

I think I'm going to try the afco radiator first.

[Tbone07]

Also Aberegg005, contrary to what you were told on the "other site", getting the coolant passages milled out some will NOT drop the coolant temp 20-25°F. This is just BS. The radiator barely accomplishes that, and some probably don't. All that would help with is if you had issues with seizures on the exhaust side of the cylinder, it would not drop the overall coolant temp by 25°F. If that were true then big bore manufacturers would do that already. The only time this has been an issue is with non pv cylinders that happen to have too much solid mass around the front of the exhaust and the temp around the exhaust getting a bit too hot. This option would do you no good if the engine's cooling system is overheating.

I wonder if that service is done in house just like the clutch covers? Lol. But i'd definitely agree with you on this one

I think I'm going to try the afco radiator first.

Got a link for this radiator? I'm also looking at the one from ESR

[rablack21]

I wonder if that service is done in house just like the clutch covers? Lol. But i'd definitely agree with you on this one



Got a link for this radiator? I'm also looking at the one from ESR

Bahahaha!!!! I bet they are!

Here you go sir. http://www.afcodynapro.com/store?search_api_views_fulltext=80260n

[Bio86]

I have the cure to your overheating...  Methenol!! haha  

Also doubles as a mosquito killer.  :ride:

[atvcrazy]

Kinda interesting topic.  I never had a problem with Pro-X big bore cylinders getting above 150 at the dunes but the last couple CP Inc cylinders I have had including this 363 cc sphinx seem to run hotter running a stock radiator.  Was at the dunes this past weekend and running the crap out of it got me 170-180 degrees which isn't bad but what's funny is on my jetting which is pretty close to spot but have a little dead spot (rich) in that 1/4 throttle range that gets worse as the motor runs hotter.  I can leave the bike sit and take off throttle response in that area but as the motor heats up, that little spot in the rpm range must get richer or something.  Seems like these cylinders should run cooler being all aluminum but maybe not?

I do still have the stock radiator and radiator cap from 1986 but its a real clean radiator without any fins messed up.  Exhaust is a big bore, LED Large intake system which helped on power by the way so I'm wondering if these all aluminum including the sleeve run a little hotter than a steel sleeved motor.

[Jerry Hall]

When fuel burns 20 to 30 %, of the heat is turned in to crankshaft power, 30 to 40% of the heat leaves in the exhaust and rest of the heat leaves HAS TO LEAVE THOUGH THE COOLING SYSTEM.

The stock 250Rs made about 32 to 34 hp @ the rear wheels on my dyno.  A lot of 330s and larger big bore kits will easily make 55 plus HP.  The percentage of waste heat going out the exhaust and into the cooling remains about the same on all engines.

A 55 hp engine has to get rid of approximately 1.7 times more heat into the cooling system (radiator) than a stock engine.  If we build a 60 to 70 HP engine the radiator must get rid of 2.2 times as much heat as the stock radiator to maintain the same coolant temperatures we would see riding  at the same speed, temperature and humidity as on a stock 250 R making 32 hp.  

There are only two ways that I know of to make the cooling system get rid of  more heat.  Increase the volume of air per minute that passes THROUGH the stock radiator or increase the number of square inches of fins in the radiator. Always strive to add more frontal area to the radiator.  Frontal area is much more efficient than increasing the thickness of the radiator.  There is a point where adding thickness will not increase the cooling capacity of the radiator.  This is because heat flow from hot to cold.  On a radiator that has many rows the 1st row gets rid of most of the heat.  The 2nd row has hotter air flowing over the  same number of fins but does not get rid of as much heat as the 1st row.  The last row of fins in a radiator will not transfer any heat if the temperature of the air flowing over the last row is equal to the temperature of the coolant inside of that row of fins.  

The amount of heat put into the cooling system is influenced by the power the engine is producing.  The brand of cylinder or type of material the cylinder and head is made of does not have much of an influence of how much heat needs to flow into the coolant from the cylinder and head.

There are some coolants that may be slightly more efficient in transferring heat from the engine into the coolant and then from the coolant to the radiator, but these expensive coolants are really just a band-air for an under-sized or inefficient cooling systems.

[rk88r]

Is the afco dual pass radiator more effective than another radiator of similar volume and frontal area?

[atvcrazy]

so it sounds like the best radiator to use would be the biggest single row radiator a person could find.  So does anyone know how much larger than stock the PWR single row radiator ESR sells is?

[aberegg05]

So which  radiator cools better the afco or pwr?

[rablack21]

So which  radiator cools better the afco or pwr?

I personally think that the Afco would due to it's dual pass design over the PWR. This is my expectation from my experience with heat exchanger design, but I haven't actually tested on to the other. If the companies know and would tell you the radiation capacity of each of the coolers, that would tell you which one cools better. It wouldn't hurt to call and find out. If they designed the cooler, they SHOULD have it's radiation capacity info or atleast the test data numbers where you could calculate it yourself.

[Jerry Hall]

so it sounds like the best radiator to use would be the biggest single row radiator a person could find.  So does anyone know how much larger than stock the PWR single row radiator ESR sells is?

YES!!    YES!!    YES!!

If you had a radiator that had 1 square foot of frontal area and was two rows thick and another radiator that was one row thick but had 2 square feet of frontal area, the 1 row thick radiator would remove a lot more heat.  


This simple idea is being used in the refrigeration and heating industry in the high efficiency units.  Using one row thick condenser and evaporator coils with huge frontal area has done more to increase the efficiency than just about all of the other changes made in compressor and control technology in the last 15 years.

[Jerry Hall]

I personally think that the Afco would due to it's dual pass design over the PWR. This is my expectation from my experience with heat exchanger design, but I haven't actually tested on to the other. If the companies know and would tell you the radiation capacity of each of the coolers, that would tell you which one cools better. It wouldn't hurt to call and find out. If they designed the cooler, they SHOULD have it's radiation capacity info or atleast the test data numbers where you could calculate it yourself.

The radiation and convective heat transfer rates are specifications that are provided by any company who designs and builds heat ex-changers.  I doubt that any of the Chinese companies that are building radiators for our industry or any of the USA companies that are buying Chinese core material and making radiators for our industry could provide these heat transfer specifications.

[rablack21]

YES!!    YES!!    YES!!

If you had a radiator that had 1 square foot of frontal area and was two rows thick and another radiator that was one row thick but had 2 square feet of frontal area, the 1 row thick radiator would remove a lot more heat.  


This simple idea is being used in the refrigeration and heating industry in the high efficiency units.  Using one row thick condenser and evaporator coils with huge frontal area has done more to increase the efficiency than just about all of the other changes made in compressor and control technology in the last 15 years.

^^^ I agree. This aligns with my experience as well.

The radiation and convective heat transfer rates are specifications that are provided by any company who designs and builds heat ex-changers.  I doubt that any of the Chinese companies that are building radiators for our industry or any of the USA companies that are buying Chinese core material and making radiators for our industry could provide these heat transfer specifications.

Very true. I was speaking mainly for the PWR and Afco radiators, which have better reputations, but still can't gaurantee they would have this information to share.