Mechanical Vs Electric Water Pump

[Ross_328i_sport]

Good morning,

Over the winter I am looking at completing some preventative maintenance on the race car and with this in mind am replacing the hoses and water pump. Currently the car is fitted with a mechanical water pump but was wondering what the benefits were of replacing this with a water pump? The car is a race / track car and is not road registered.

Is a electric water pump considered to be an upgrade over the mechanical water pump? I assume one benefit is the eCU can be programme after the engine is turned off to carry on pumping water through the engine until a pre determined temperature is met providing a more stable cooling of the engine preventing heat soak.

Appreciate the thoughts

Cheers

[BertBert]

I'd say no real benefit at all.
Bert

[Canuck7]

I seem to recall that using an electric pump, especially in a race car, has a few benefits.

The first, as with other engine-alternator-electric motor systems, such as railway engines and mining trucks and such, is that the electrical engines do a better job, and a more efficient job, such that it is worth running a 4000 Hp diesel just to make electricity for them. An odd thing to do, but torque and efficiency is high. Better if they could run them off huge battery packs, of course. So an electric pump will be more efficient at the same job.

The second, and is important for high-revving engines, is that you don't get cavitation from over-spinning the impeller and therefore bad coolant flow and damage. An electric water pump is always running at its most efficient speed, and, as the OP stated, can be separately run by the ECU. There may even be units that will run slower or turn off when engine is just warming up. *shrug*

So on a race car you get two things; less power loss than trying to pump water using the engine, and the most efficient cooling, even at high revs. Plus you aren't wearing out a stock water pump setup by spinning it a bit too fast... or spinning it too slow at idle if you have some underdrive pulleys. In an extreme engine, it makes a lot of sense. More power to race, and an happier engine temperature at both ends of the tachometer.
You'd have to look it up, but with a big engine, it might even save a truly measurable few horsepower. The cooling efficiency is worth it at both ends of the engine RPM range. Especially with well applied Man-maths. :-)

[gregpe]

hi electric pump has in race car few benefits i think but need to be properly controlled..

in short - OEM water pump - is design to work in low and mid range of rpm efficiently in some cases when not possible slowing down water pump (driven by chain) we had a cavitation problems at high RPM and in some cases to sort out this problem we end up to changing for custom rotor to copy with higher speed..

for me electric pump WITH controller which will control pump speed is the way to go in race car applications.. some power gain ( at least theoretical), better control of engine temperature - by removing thermostat is all programmable ... possibility of "predict" hi load so for example you can increase DC pump on full throttle so on....
obviously again is all depend of your application ...

[DCL]

You haven't said what engine but one advantage is that the whole cooling system can be made more efficient. That translates to a smaller and lighter system - smaller hoses, less coolant, and the option for no auxiliary drive (if alternator is not used). A significant weight and power saving for a race car, or sprint car.

On the down side is the loss of simplicity and reliability. On engines like the Duratec, the loss of re-circulation also needs to be considered.

Edited by DCL on Saturday 3rd October 11:06

[Ross_328i_sport]

Thanks for all the responses it sounds like there is a couple of benefits which are certainly worth it from my point of view.

The car is a C400 duratec running 220 bhp. I am looking at competing in the Mag 7's next year and complete around 10 track days a year in the car therefore the car does run an alternator. I would also like to understand what is referred to with the loss of re-circulation and the potential affects this may have if you would be so kind to explain?

[DCL]

Modern engines, such as the Duratec, are designed to warm up quickly and that's achieved, in part, by reducing the thermal mass (and amount of coolant) in the head and block. To ensure that it remains at an even temperature as it warms up, the coolant in the engine block and head is rapidly re-circulated via a by-pass pipe. This is controlled by the thermostat which is a two way valve and not just an on-off switch, as you might think. Ford (Mazda) placed it on the return side to allow more precise control of cold coolant entering the engine.

These pictures show the 'on' and 'by-pass' positions






Here's the by-pass pipe that is shut off when the thermostat is open



SBD have developed some electric systems that do away with the thermostat and by-pass pipe but you do need to 'manage' the circulation to prevent localised over heating. Simply turning it on when it reached temperature would not work for long and you'd probably start experiencing HGF.

Edited by DCL on Saturday 3rd October 15:53

[Ross_328i_sport]

I am looking at the SBD system and notice that is has a temperature sensor in the back of the head which will then provide temperature values to the ECU to control the speed of the water pump. I assume that providing the ECU is programmed correctly then this configuration should be find and there should be no worry of Head gasket failure?

[DCL]

I'm not familiar with how SBD control the pump but I would assume they've tried and tested it. Don't get me wrong, it's not a difficult problem to solve, just that you need to be aware that there is a problem in the first place.

For what it's worth, my experience when doing this sort of mod, is that engine specialists like SBD tend to be focused on their own top end development cars. Their understanding of durability may be very different from your own.

It's also worth finding out if your ECU is locked as that may add to the cost if you plan to use it to control the pump.

Good luck

Edited by DCL on Saturday 3rd October 18:15

Edited by DCL on Saturday 3rd October 18:30

[sam919]

You can run it in conjunction with the radiator fan to cool the engine once its stopped, nice especially when its baking hot after a race. If using OMEX, and I'm sure most ECU's will have the same function, on the pin outs there is a facility to ground a relay.......the relay can be used for the fan/ pump. This has top and bottom temperature scales to set to what your happy with and what the engine is best suited to.

Edited by sam919 on Saturday 3rd October 21:33