KTM500EXC water pump

[mohab atef]

hi,
we were considering using a single-cylinder KTM500EXC on our first car and i'm trying to design the cooling system , i searched the internet for the engine's water pump model and water pump manual to help me know about the different flow rates but i couldn't reach it , so if anyone has any suggestions to get to reach it , i'd be grateful or it's just a dead-end and i have to change the track ??

---

Mohab Atef
cooling guy
CURT 2015

[GTS]

Well dude, you could ring KTM in Austria and ask - and they won't give it to you

You could buy parts of an engine and test it - which would be intelligent

You could decouple the problem from the choice of engine and run different water pump (e.g. electric) - which would be smart

(Clue: the competition's about being smart )

[paul_mh]

Hey Mohab!

We have been using the KTM EXC engine for 3 years now here at TU Graz Racing, but since I am a Chassis and Aero guy all I can tell you is:

The water pump is driven off the balancing shaft on the right side of the engine
The impeller is made from black plastic and the asembly looks like this (altough i suppose you have seen this image)

http://fichefinder.ktm.com/Page.aspx?catalog_page={%22Model%22:{%22ItemNumber %22:%22F8503O9%22,%22EngineNo%22:%22089550O%22,%22 ModelName%22:%22500%20EXC%22,%22Variant%22:%22EU%2 2,%22DisplayName%22:%22500%20EXC%20(EU)%22,%22Icon Typ%22:%221%22,%22ModelYear%22:%222015%22,%22Custo merName%22:null},%22CatalogPageNumber%22:%22C12781 3510%22,%22ConstructionUnit%22:%2235%22,%22Catalog PageName%22:%22WATER%20PUMP%22,%22ImageSrc%22:null ,%22ItemType%22:1}

Regarding the flow rate: As far as I am informed, the flow rate of the water pump is absolutely sufficent for racing purposes (we did extensive testing in the windtunnel with lots of different radiators, fans and sidepod configuratons but the water pump was not subject to be changed)

Nevertheless it might be intelligent to use an external electric water pump since the KTM engine doesn´t feature a thermostat and with an electric pump you could implement such a feature (which will allow your engine to be at operational temperature quicker)

Regards, Paul

[JT A.]

Well dude, you could ring KTM in Austria and ask - and they won't give it to you

You could buy parts of an engine and test it - which would be intelligent

You could decouple the problem from the choice of engine and run different water pump (e.g. electric) - which would be smart

(Clue: the competition's about being smart )

Spending more money and adding more weight for a job the stock engine can already do is considered smart? Not to mention putting more demand on your charging system, leaving less available for a fan. Seems a bit counter productive.

[Mbirt]

Spending more money and adding more weight for a job the stock engine can already do is considered smart? Not to mention putting more demand on your charging system, leaving less available for a fan. Seems a bit counter productive.

Great point and something often overlooked when running a single until the car won't restart after the driver change due to a flat battery. Your watts must be budgeted wisely with a single.

[GTS]

Spending more money and adding more weight for a job the stock engine can already do is considered smart? Not to mention putting more demand on your charging system, leaving less available for a fan. Seems a bit counter productive.

Read my whole post, tiger, and have a good look at the OP before calling context.

In a direct sense;

Someone's seeking to evaluate the engine and getting stuck on pump performance, which is a small thing to get stuck on - bourne of a limited perspective - when evaluating integtration of a powertrain with many facets.

Point is to attack the problem with some intelligence and non-linearity to move the design along meaningfully to the next stage. Which sounds more like powertrain selection and acquisition. The suggestion in the answer is (spelled out, now): (1) You'd be reluctant to trust data on the internet without a complete understanding of test conditions and design intent (neither of which have presented themselves), (2) testing performance yourself is probably smartest and (3) at worst, there are ways around this, and if dedicating time away from this problem and onto more prescient matters (in a cooling system there are many) completes a baseline design faster - or gets one closer to a powertrain choice quicker - then pick battles.

In a broader sense;

- Properly done, you'd struggle to add a half kilo to a setup with an electric water pump.
- Properly done, there's a good deal of efficiency to be had in control alone.
- If (considering realisable electrical system efficiencies, FMEP gains in dropping the pump and what likely needs to be done to the alternator regardless) an EWP presents a dire electrical load issue, you've likely bigger problems.
- If your design is contingent on the half-hp it'd cost (properly done) at worst, there's something wrong with your design.
- If your design's performance is so clearly contingent, despite all other performance factors, on that same half hp... and you can prove this at comp, then congratulations, you're beyond FSAE.
- Etc

The point overall: good engineers choose battles wisely. Think smart.

[JT A.]

Using an electric water pump to "get around" the need to test your own flow rates doesn't make any sense. The data provided by the EWP manufacturer is probably just a flow test of pumping water through a straight tube of some length. That information doesn't get you any closer to knowing what flow rate the pump will produce through your engine and radiator. You'll still have to test the system yourself if you want to know the flow rate, regardless of whether you use the stock mechanical pump or an aftermarket electric pump. And it would be smart to measure the flowrate of the stock mechanical pump before choosing an electric one, so you can choose a pump that is at least as good as the stock one.

But if you're going to do that, you might as well just stick with the stock mechanical pump anyways since A) you will now know what it's flowrate is and you can design the rest of your system in accordance, B) It's free and already on the engine, and C)it was probably designed by people who knew what they were doing (a perfect opportunity to "choose your battle wisely" and not try to reinvent the wheel).

I completely agree with choosing your battles wisely. It's funny how we can have the same philosophy but completely different interpretations of what it means.

For about 3/4th's of the teams in the world (by my opinion) the "wisest" approach to powertrain design would be to get an engine that is well known to be reliable, and LEAVE IT THE HELL ALONE as much as possible. Don't get fancy, don't reinvent the wheel. The more you mess with, the more you can screw up. My team used electric water pumps for several years and 1/3 of them developed leaks, even when following the manufacturer's mounting recommendations. It's not the end of the world, you just have to buy another one. But why bother with that hassle if you don't have to? What are you really gaining from it?

You only gain half a kilo? That's still worse than gaining 0 kilos.

Sure you can gain some efficiency by using the EWP as a form of "thermostat" control. Or you could just run the engine til it's hot right before you go to fuel up for endurance, stick a sheet of cardboard over the radiator, and remove cardboard before you run endurance. Choosing battles wisely means think simple solutions before you jump to more complicated ones.

And the rest of your points about system efficiencies and 1/2 horsepower...I more or less agree with you. If the difference is 1/2 horsepower either way, who cares?

[MCoach]

I think if your caught up on the water pump not providing enough flow for your engine then you either you have some serious system inefficiencies or some serious power output. Engine water pumps are sized for their stock power output and in most cases that is not again achieved once the restrictor is in place. In the case of single cylinders and some twins you may be able to regain and surpass this power output. Fortunately radiators are very forgiving as are very big fans.

I'd honestly not base the engine choice on the flow rates of the engine and only assume that they are sized appropriately. As Matt points out, the charging system is much more sensitive to the auxiliary systems on the car. Using a big ass fuel pump and some electric water pump searching for that last .5hp is likely to leave you stranded on the restart when your effective charging rate ends up something like -40 watts.

Buy whatever engine you want, and if you are really inclined to exactly figure out the flow rate of the stock pump, get two large buckets and let the engine pump from one to the other and record time. Done. If you want to wow some people on how academic you can get in exploring your engine, do it over several speed points, fit a line, celebrate.

The American way would to just try to make as much power as possible and go racing. Good luck!

[GTS]

Using an electric water pump to "get around" the need to test your own flow rates doesn't make any sense.

It does if your project is stuck on something so basic.
Or if you can see opportunities in control/
Or opportunities in power draw.
Or opportunities in packaging.
Or....

The data provided by the EWP manufacturer is probably just a flow test of pumping water through a straight tube of some length. That information doesn't get you any closer to knowing what flow rate the pump will produce through your engine and radiator.

A highly speculative statement devoid of proof or science.

That information doesn't get you any closer to knowing what flow rate the pump will produce through your engine and radiator.

Unless you can calculate or otherwise simulate or intimate the differences, no it doesn't.

You'll still have to test the system yourself if you want to know the flow rate, regardless of whether you use the stock mechanical pump or an aftermarket electric pump. And it would be smart to measure the flowrate of the stock mechanical pump before choosing an electric one, so you can choose a pump that is at least as good as the stock one.

Sure... though consider that measurement without bias in this particular data species isn't easy, or inexpensive. Decoupling the problem to start with... isn't a bad place to start.

"At least as good" may imply that it should work the same way - it doesn't.

Probably a good place to start in this thread is to offer the OP some discussion around how to calibrate the system.

But if you're going to do that, you might as well just stick with the stock mechanical pump anyways since A) you will now know what it's flowrate is and you can design the rest of your system in accordance, B) It's free and already on the engine, and C)it was probably designed by people who knew what they were doing (a perfect opportunity to "choose your battle wisely" and not try to reinvent the wheel).

I see no science here and would accordingly be wary. The stock pump is designed around an installation different from your own, and to different cost, engine performance, vehicle load and integration constraints (all of which affects thermal). Free doesn't mean best, or smart.

A pump doesn't provide a flowrate, a pump by definition provides a pressure rise in a working fluid. Unless pressures and thermal loads throughout the rest of the cooling system are identical to whatever vehicle it came from, then the same pump will deliver a different cooling system margin in a different installation. Whether or not this margin is sufficient for an application is another matter that similar requires data, analysis and scientific rigour. This is a significant, nonlinear problem - try, for instance, running increasing an engine-coupled pump's coolant system flow rate at idle after a vehicle dynamic session - it's a significant usage mode not replicated in the original vehicle.

At least with an EWP the pressure rise can be adjusted indepdendently of engine load, which is a signifcant point.

I completely agree with choosing your battles wisely. It's funny how we can have the same philosophy but completely different interpretations of what it means.

IMHO discussions like these are what makes engineering a great career - it inherently welcomes robust scrutiny.

For about 3/4th's of the teams in the world (by my opinion) the "wisest" approach to powertrain design would be to get an engine that is well known to be reliable, and LEAVE IT THE HELL ALONE as much as possible. Don't get fancy, don't reinvent the wheel. The more you mess with, the more you can screw up. My team used electric water pumps for several years and 1/3 of them developed leaks, even when following the manufacturer's mounting recommendations. It's not the end of the world, you just have to buy another one. But why bother with that hassle if you don't have to? What are you really gaining from it?

The second a restrictor goes on an engine, it's no longer at design spec. "Reliable" is therefore relative.

There's a lot to gain from an EWP, though as a starting point to simply "rough in" a design, it's hard to beat.

You only gain half a kilo? That's still worse than gaining 0 kilos.

Get your drivers a gym membership and time with a dietician if you're super worried about half kilos... and 0.5kg is really a worst case.

Sure you can gain some efficiency by using the EWP as a form of "thermostat" control. Or you could just run the engine til it's hot right before you go to fuel up for endurance, stick a sheet of cardboard over the radiator, and remove cardboard before you run endurance. Choosing battles wisely means think simple solutions before you jump to more complicated ones.

Agreed, though see above - there are more significant issues requiring simpler solutions.

Cardboard isn't in the spirit of the competition - the car's meant to be a prototype autocross design!

And the rest of your points about system efficiencies and 1/2 horsepower...I more or less agree with you. If the difference is 1/2 horsepower either way, who cares?

Agreed.

Engine water pumps are sized for their stock power output

Coolant systems are designed for a stock installation - this is a broader definition than just the output.

Using a big ass fuel pump and some electric water pump searching for that last .5hp is likely to leave you stranded on the restart when your effective charging rate ends up something like -40 watts.

A poor statement. Add science and get a solution to that problem.

I'd add that in 15 years of being involved in FSAE, electrical system design is often a student afterthought... that alone doesn't make it right!

Buy whatever engine you want, and if you are really inclined to exactly figure out the flow rate of the stock pump, get two large buckets and let the engine pump from one to the other and record time. Done. If you want to wow some people on how academic you can get in exploring your engine, do it over several speed points, fit a line, celebrate.

There are better ways. This'd probably be a good space for a discussion.

The American way would to just try to make as much power as possible and go racing. Good luck!

For a US-initiated competition, FSAE is remarkably Colin-Chapman-esque in execution

[JT A.]

You seem to have a lot of knowledge but very little logic or common sense.

If the team is "stuck" because they don't know the flow rate of the cooling system, how does buying an electric water pump get them "unstuck"? They still won't know what the system flowrate is until they test it on their own engine & radiator system.

It basically just gets them "unstuck" by forcing them to make a decision, and commit to figuring out the details and making it work later on.

But they could just as easily (or more easily) get "unstuck" by committing to using the stock pump, measure its flowrate is once they get the engine, and figure out the rest of the system based on what they find.