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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
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 :))
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
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.Quote:
Originally Posted by GTS
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.Quote:
Originally Posted by JT A.
Read my whole post, tiger, and have a good look at the OP before calling context.Quote:
Originally Posted by JT A.
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.
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?
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!
It does if your project is stuck on something so basic.Quote:
Originally Posted by JT A.
Or if you can see opportunities in control/
Or opportunities in power draw.
Or opportunities in packaging.
Or....
A highly speculative statement devoid of proof or science.Quote:
Originally Posted by JT A.
Unless you can calculate or otherwise simulate or intimate the differences, no it doesn't.Quote:
Originally Posted by JT A.
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.Quote:
Originally Posted by JT A.
"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.
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.Quote:
Originally Posted by JT A.
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.
IMHO discussions like these are what makes engineering a great career - it inherently welcomes robust scrutiny.Quote:
Originally Posted by JT A.
The second a restrictor goes on an engine, it's no longer at design spec. "Reliable" is therefore relative.Quote:
Originally Posted by JT A.
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.
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.Quote:
Originally Posted by JT A.
Agreed, though see above - there are more significant issues requiring simpler solutions.Quote:
Originally Posted by JT A.
Cardboard isn't in the spirit of the competition - the car's meant to be a prototype autocross design!
Agreed.Quote:
Originally Posted by JT A.
Coolant systems are designed for a stock installation - this is a broader definition than just the output.Quote:
Originally Posted by MCoach
A poor statement. Add science and get a solution to that problem.Quote:
Originally Posted by MCoach
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!
There are better ways. This'd probably be a good space for a discussion.Quote:
Originally Posted by MCoach
For a US-initiated competition, FSAE is remarkably Colin-Chapman-esque in execution :)Quote:
Originally Posted by MCoach
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.
The OP is getting terrific value here.
(This is going to be fun).Quote:
Originally Posted by JT A.
OK, I'll play. I'll happily contend you're wrong there.
It's the difference between not understanding whether the pump an engine is supplied with has the characteristics you require, which are themselves unknown - but committing to a pressure characteristic prior to designing your coolant system - and being noncommittal about what's required of a pump when there's little understanding about what's inherent in the broader system it supports.Quote:
Originally Posted by JT A.
I'd find it hard to believe that KTM designed this particular engine, the engine calibration, the coolant system and the like around the water pump. So why would you design an FSAE car around one? You'd have to have, as you suggest, "very little logic or common sense" to do this.
If a design lends itself to a place where an engine-driven driven pump is suitable - let alone the very same one that comes with the engine - then so be it. As this isn't a given, don't bet on it. Granted, the same assembly or parts thereof probably appear on a number of engines for reasons of resource rationalization and economy of scale (at the least). it likely works in a number of scenarios. Assuming it works in yours is silly. Insisting that it needs to... is stupid.
Let alone that you're betting on the characteristic the pump provides beign a best fit for use, all integration factors considered.
No, it fundamentally moves the design process beyond that particular decision by adding degrees of freedom (pick any pump you want to design what cooling system you need) vs an inherent limitation (design your cooling system around a given pump, which was designed around a different application and different constraints).Quote:
Originally Posted by JT A.
If at the end of this journey what's required can be met with the pump on the engine, so be it.
Designing a cooling system around a pump, when there's so much flexibility in choice at negligible penalty in so many areas... is illogical.Quote:
Originally Posted by JT A.
If you're still talking in terms of flowrate, you're fundamentally not understanding what a pump does and how to design accordingly. As an aside, if by chance you're planning on turning up to FSAE-A 2014 this much understanding about coolant system design, I'd revise a bit first.
The pump clearly cooled the bike just fine and can quite easily cool an FSAE car just fine with an appropriately sized radiator. Why the hell would you add the extra complexity of an electric water pump that's going to screw the power budget of your single's stator to design a cooling system to be absolutely 99% perfect amazing etc. Use the stock pump, it's simple it's there, it'll easily do the job you need. Run the engine with the inlet in a bucket and the outlet to another bucket to get an idea of flow rate.
Your cooling system design just needs to work it doesn't need to be the most perfectly designed thing in the world. Cooling systems don't make cars go fast, put your time into things that do. Chase the 20% gains before you chase the 0.2%. So long as the system can keep the car cool you'll be fine.
An electric water pump does not:
1. make your car faster
2. make your car more reliable
3. get the car finished faster
4. help your cost score
It maaaay potentially help your fuel efficiency score. Hey Kettering, how compromised was your award winning powertrain when you dominated fuel economy without an electric water pump?
It does open up some packaging options, that value is contingent on your car/team/goals.
Yes engineering is about finding the smart solution. Smart doesn't always mean technically best when weighed against the big picture goals.
To adequately design a cooling system you need a pump map and it is not a simple task to get that data. Advice to OP: Centrifugal pump calcs will get you close enough inputs to design your system. Leave room for more radiator, you will never cross the finish line and say "damn, that cooling system packaging really kept us off the podium!" Take an integral part of the cooling system that will not be changed and spend some time testing to generate a pressure drop curve for that part. Now install a couple pressure sensors on that part and log the data. You have now created a simple flow meter that will help you refine the system. Hey you could even use it to test an electric water pump if you choose!
Sure does cool the bike.Quote:
Originally Posted by Menisk
No guarantee of cooling every particular FSAE configuration.
Why would it necessarily screw your power budget?Quote:
Originally Posted by Menisk
What's the difference between "99% perfect amazing" and what it'd be for a given install? What'd be in effort?
Not the original question, and convention isn't a way to characterize an engineering problem.Quote:
Originally Posted by Menisk
C'mon, there's better ways to test than this - even at the undergrad level.Quote:
Originally Posted by Menisk
Cars need to finish events before they go fast, and judging by the rate of engine attrition in FSAE relative to the production configurations the original powertrains usually came from, statistically there's some weight to the notion that some added effort in design to a few ends (cooling included) could be of use.Quote:
Originally Posted by Menisk
Do you recommend such effort in all critical systems?
Understand engineering basics before wrapping assumed knowledge at speed into convention. The OP required flowrates, and this series of replies has been fun - the suggestion is far less about explicit solutions, and far more about challenging the question. Is the OP seeking an answer to the best question for the given need?Quote:
Originally Posted by Menisk
Correct.Quote:
Originally Posted by Menisk
Good integration means not doing this at any cost, however. Understanding the tradeoffs demands solid design principles... not reflected in the OP or in a few answers here.
1. It can.Quote:
Originally Posted by Mumpitz
2. It can.
3. It can.
4. No, certainly doesn't, though what compromises make the cut partly define integration.
It may do a lot of things.Quote:
Originally Posted by Mumpitz
Pulling one solution out of a complex space to fit out of context is poor advice. There's never been any suggestion that an EWP is a requirement, or that a built-in pump is an impossibility.Quote:
Originally Posted by Mumpitz
Me-too engineering works as research to head-check a base contention - should be more of it. Runs into limits as an ultimate replacement for fundamental knowledge.
The value of any advantages are so contingent.Quote:
Originally Posted by Mumpitz
Could argue "technically best" (whatever that means) to be to use the existing pump, select another pump, any number of things. Relative to the OP, the 'big picture' goals in engine selection shouldn't hinge around alleged flowrates.Quote:
Originally Posted by Mumpitz
Best advice in this thread so far (please take note anyone competing at FSAE-A 2014).Quote:
Originally Posted by Mumpitz
If you really think an electric water pump is going to make your car faster at the level FSAE teams are at there's no helping you.
If you really think this is what I'm suggesting, read again - quite far from it.Quote:
Originally Posted by Menisk
GTS, your unconstructive criticism is approaching troll level stuff here. Still don't see your EWP logic and reasoning as promised.
You claimed an EWP to be a smart option and have provided no logical explanation as to why. "it decouples the system" and "it can" isn't going to win any favor with design judges and isn't helping anyone here. Are you going to add any content here or just pick at others? If you want to get your rocks off trolling take it elsewhere.
EWP as one solution is well explained - the OP isn't necessarily asking for a specific solution - it's about robust processes to reach a good solution. To this end, there's been plenty of content added.Quote:
Originally Posted by Mumpitz
I'm pretty sure any reasoned approach will win favour with the design judges. Calling what doesn't gel with a given opinion "unconstructive"... won't.
I'm amused as your assertions of trolling - particularly given that where you made a solid contribution, it was highlighted and supported.
In 2013, we ran a WR450F engine (2012 MY, EFI stock) with the stock radiators mounted in the left sidepod. We made relatively minor engine changes internally (stock piston, new cams, etc.) and with intake/exhaust changes we reached 56hp peak (~42kw). We had no cooling issues ever, we had a hard time getting the car up to temp at MIS (it was a quite cold that day) and had to cover one half of the radiator at Formula North for the endurance to keep the car up to temp.Quote:
Originally Posted by Mumpitz
In 2014, we located radiator behind the intake (off the MHR braces), and had a hard time ducting air to it. We never had a cooling-related failure, but virtually all of our airflow came from the fan and we ran ECTs of over 100C normally (the hottest I measured was 113C).
The pump was definitely not the weak point of the 2014 cooling system. We do not know the flow data of the pump, but we have test data to show that the cooling system as a whole performs adequately, especially with sidepod-mounted radiators on the 13 car.
I will warn though that we have had several failures of water pump seals and shafts degrading in pure water. Using coolant when testing helps.
Edit:
Before we switched to the 2012MY bike (stock EFI) with a 3-phase stator, we had charging system issues with the 2011MY bike (stock carb, smaller 2-phase stator). We were usually running at a slight loss, with a small electric radiator fan and relatively small other loads. With the 2012MY bike charging system, we were able to run a larger fan in 2014 with a net power excess in most cases, with a larger ignition coil as well. Every watt does count, spend them wisely. If we could shaft drive more of our engine loads I would be happy.
Proud alumni chiming in to say "to the wheels".Quote:
Originally Posted by apalrd