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Radiator Designing

Radiator Designing

Radiator Designing

I am quite new to this subject and I really need some advice. I only know the power and torque of the engine. The water pump pressure. How do I calculate the area of the required radiator. I need some references and some methodology to tackle this problem. Kindly help

RE: Radiator Designing

You go to the engine dealer and get the technical data for the engine, which includes heat rejection to the engine's surroundings and to the cooling system.

Many such engine application manuals also give you more help with sizing radiators and exhaust systems, like worked examples of certain problems.

Mike Halloran
Pembroke Pines, FL, USA

RE: Radiator Designing

The said engine is of Ktm DUKE 390.I just have the basic engine data.Can you tell me about some reading material for radiator Designing.

RE: Radiator Designing

The KTM DUKE 390 is a very nice liquid cooled single cylinder motorcycle, not a loose engine.
KTM already put a radiator on it, so there's no need for you to design one.
You can probably learn a lot from the factory shop manual, and it's always a good thing to have, so invest in one of those. It won't tell you a lot about radiators.

I don't know much about designing radiators as a component; any useful design information that's known would be too commercially valuable to disseminate far.

If you want to know about _selecting_ radiators that someone else designed, go to an engine dealer, not a motorcycle dealer, and get the application handbook for an engine, e.g. a generator engine. I know that Caterpillar publishes such a document for each of its engine series, and John Deere and Cummins publish similar documents.

As for modifying your motorcycle, you can surely make it louder, but I doubt you can make it better. Keep it stock, keep it clean, and enjoy riding.

Mike Halloran
Pembroke Pines, FL, USA

RE: Radiator Designing

One aspect that seems to have been glossed over is that when you are at the point of having an existing engine that cannot be changed, there is no "design," only selection of the least worst alternative. A proper "design" is a whole-system analysis and synthesis that balances competing factors to provide the best compromise solution.

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RE: Radiator Designing

Perhaps the original poster could explain to us, why he wants to use anything but the standard radiator that came originally with the bike, in which someone else has already done all the work.

I have one motorcycle in which the standard radiator proved inadequate on track days in hot weather on tight tracks that have relatively lower speeds (not enough airflow). I removed the standard radiator (for the 400cc engine) and installed a bigger radiator (from a similar bike that has a 600cc engine) and adapted the mounts and the hose to suit. No engineering, just "make bigger to make problem go away". Solved.

I have another (different) motorcycle in which the standard radiator proved to be inadequate after going through the engine and installing higher-compression pistons, tightening up the squish band, and using non-standard camshafts. More power, more heat.

After making careful measurements, I bought the biggest automotive oil-cooler that I could fit in an available space underneath the standard radiator, and re-routed the coolant hoses that originally led to the (coolant-cooled) original oil cooler, such that the bypass coolant loop that originally went from the water pump through the bike's original coolant-cooled oil cooler and then to the radiator, now went through my extra cooler then to the bike's original oil cooler, with the hope that I could get the temperature of the coolant going to the bike's original coolant-cooled oil cooler down a little. It has helped.

But it's not really an engineering exercise ... simply a matter of fitting in the most additional cooling capacity that I could get and hoping it's good enough.

I have been hearing through the grape vine that the original cooling system on the RC390/Duke 390 might be a bit marginal. Perhaps the original poster could explain to us if that's the problem and if so, to what extent.

RE: Radiator Designing

I have to design a new radiator for a custom built car that is using the said engine. I wanted to know how to design a radiator. I want to learn how to calculate the apt radiator size
Rather than just try different radiators till I find the right one. Wanted to know what kind of approach I should take.

RE: Radiator Designing

IF KTM sold a version of the Duke engine for use in small automobiles, they would have an application handbook that would answer nearly all possible questions about putting their engine in an arbitrary vehicle.

I don't know if KTM does or does not sell the engine separately, because I haven't spoken to anyone at KTM.

Have you spoken to anyone associated with KTM?

The answer to that question, and every other tidbit of information that you have dribbled out so far, should have appeared in your first message. ... just so you know, for your next project.

Mike Halloran
Pembroke Pines, FL, USA

RE: Radiator Designing

Sounds very Formula SAE to me. The kind of engines those guys & girls choose for their entries.

- Steve

RE: Radiator Designing

Why don't you just re-mount the stock radiator from the bike?

If that's not viable for whatever reason, why not ruff-calc the total area of the fins of the radiator from the bike, and make/buy something that does fit, that has at least that much?

Not everything needs to go back to first principles. Not everything needs to be analysed to the Nth degree. Sometimes it's better to just use something you know is going to work and put it out of your mind.

Every car that I've owned from the last twenty years has overkill for radiator capacity. Fewer complaints that way.

RE: Radiator Designing

I was going to say pretty much the same thing as BrianPeterson.
I would measure the rad, find the closest one I could erring to the bigger side.
As long as the motor has a thermostat it won't be any issue running a slightly bigger radiator.

RE: Radiator Designing

The heat exchanger used on the donor MC is designed for different conditions than you will have on your car. The engine loads and speeds in your car will be different than those of the MC. The airflow over the heat exchanger core will also be far different. The MC radiator and water pump are designed for operation at mid-high engine rpm, low engine load, and mid-high road speed. Your heavier car will require the engine to operate at higher load and lower rpm. So you need to make sure the OEM coolant pump design is adequate for your application.

You can likely use a more compact heat exchanger on your car since you can design a more efficient air duct arrangement than the one used on the donor MC. If you do a good design job of the air ducts and heat exchanger it will not produce much drag penalty. If the pipes on your car connecting the heat exchanger and the pump/engine are substantially longer than those on the donor MC, you should do an analysis of the flow conditions in the coolant circuit to see if they affect the pump performance.

As noted by others, it would be a good starting point to reverse engineer the heat exchanger and coolant pump impeller used on the donor MC.

Good luck to you.

RE: Radiator Designing

Thank you Sir.I am going to design the new radiator by reverse engineering from the stock radiator. I am going to use the E-NTU method for designing.

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