Water Pumps - Mechanical Vs Electric

Magpie · Postby **Magpie** » Mon Jan 12, 2015 1:09 pm

Let the battle begin!

What we are discussing here is a forcing pump and not a lifting pump.

In the red corner - Electric.

Whilst electric MAY give more horsepower its main advantage is that is a complete system that does not rely upon the RPM of the engine and can be controlled/programmed separately. The separate control can either be via an aftermarket ECU or with a dedicated controller.

I ask, why would you use a mechanical fuel pump instead of an electric one?

rascal · Postby **rascal** » Mon Jan 12, 2015 1:16 pm

Magpie wrote:I ask, why would you use a mechanical fuel pump instead of an electric one?

Because the car comes with a mechanical one, and using an electric one means changing a lot of stuff.

If however you could choose mech or elec at time of car manufacture as a no cost option, that would change things..

Magpie · Postby **Magpie** » Mon Jan 12, 2015 2:01 pm

I made a mistake that I frown upon, gave an opportunity for people to focus in on something other than the real question. We are talking about modifications, not factory options.

If you had a car with a mechanical fuel pump and modified it to fuel injection would you leave it as a mechanical fuel pump?

The same as if you are seeking to gain an advantage in cooling why rely upon a system that is dependant on RPM to work?

If you have a system in place that can control cooling with some 'smarts' and not just rely upon a linear mechanical pump why not?

If you have a daily drive is there an advantage in mechanical or electric, probably not?

Any other questions that need to be focused on in responses

I should have left it as an open question and not ask a question (negotiations 101).

sailaholic · Postby **sailaholic** » Mon Jan 12, 2015 2:45 pm

Advantage electric - can be run after engine shut down to prevent post shut down boiling etc.

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ben wilson · Postby **ben wilson** » Mon Jan 12, 2015 7:23 pm

I ran an electric pump on a mr2 for a while and apart from the heater not working, it was great.

The car warmed up a lot faster, I could leave the water pump and the fans running after a hard run and (most importantly) I could crank up the supercharger belt tension without damaging the water pump.

Friends with rally cars have had no end of problems with them, so YMMV...

Postby **beavis** » Mon Jan 12, 2015 7:41 pm

Interested in where this goes..... paging Dann.

hks_kansei · Postby **hks_kansei** » Mon Jan 12, 2015 7:52 pm

Mechanical all the way.

An electric may be better for the reasons you mentioned, but a mechanical pump seems to have a lot less possible ways to go wrong.

An electric pump stops because of say an electrical gremlin causing a fuse to pop, or say a wire breaking, and you cook the engine. Same as if the electric motor buggers up (brushes or whatever breaks on them)

A mechanical pump will keep going as long as the engine does (unless the impeller corrodes, or the belt snaps)

Dan · Postby **Dan** » Mon Jan 12, 2015 8:00 pm

hks_kansei wrote:Mechanical all the way.

An electric may be better for the reasons you mentioned, but a mechanical pump seems to have a lot less possible ways to go wrong.

An electric pump stops because of say an electrical gremlin causing a fuse to pop, or say a wire breaking, and you cook the engine. Same as if the electric motor buggers up (brushes or whatever breaks on them)

A mechanical pump will keep going as long as the engine does (unless the impeller corrodes, or the belt snaps)

I agree with that.

Water pump failures are a pretty common thing on BMW's which use Electric Pumps. But they also make them easy to replace so it's not like it's a huge drama.

hks_kansei · Postby **hks_kansei** » Mon Jan 12, 2015 8:04 pm

Dan wrote:Water pump failures are a pretty common thing on BMW's which use Electric Pumps. But they also make them easy to replace so it's not like it's a huge drama.

The pump is easy to replace, but I'd be concerned about the car getting too hot and warping the head..... whihc is a bit lett easy to replace.

At least if you lose a belt with a mechanical pump it usually drives something else important, so the car will probably stop anyway.

Magpie · Postby **Magpie** » Mon Jan 12, 2015 8:24 pm

Again an electrical failure can be dealt with instantly. Using PDM's you can auto reset a fuse issue, as well as other smarts. Most aftermarket ECU's can handle an electrical failure and take action to protect the engine. If no aftermarket ECU then some simple electronics can provide immediate warning if pump stops. A belt failure takes time to recognise and time to act.

project.r.racing · Postby **project.r.racing** » Mon Jan 12, 2015 8:33 pm

Magpie wrote:I ask, why would you use a mechanical fuel pump instead of an electric one?

Cost.

Magpie wrote:I made a mistake that I frown upon, gave an opportunity for people to focus in on something other than the real question. We are talking about modifications, not factory options.

Meow!

hks_kansei wrote:Mechanical all the way.

An electric may be better for the reasons you mentioned, but a mechanical pump seems to have a lot less possible ways to go wrong.

An electric pump stops because of say an electrical gremlin causing a fuse to pop, or say a wire breaking, and you cook the engine. Same as if the electric motor buggers up (brushes or whatever breaks on them)

A mechanical pump will keep going as long as the engine does (unless the impeller corrodes, or the belt snaps)

Not really a good enough reason since you are already driving around a car full of all those things.

project.r.racing · Postby **project.r.racing** » Mon Jan 12, 2015 8:35 pm

Magpie wrote:Again an electrical failure can be dealt with instantly. Using PDM's you can auto reset a fuse issue, as well as other smarts. Most aftermarket ECU's can handle an electrical failure and take action to protect the engine. If no aftermarket ECU then some simple electronics can provide immediate warning if pump stops. A belt failure takes time to recognise and time to act.

Whether mechanical or electric. The temp gauge still works the same. So dealing with pump failure and increased temps is the same.

Apu · Postby **Apu** » Mon Jan 12, 2015 8:38 pm

hks_kansei wrote:Mechanical all the way.

An electric may be better for the reasons you mentioned, but a mechanical pump seems to have a lot less possible ways to go wrong.

An electric pump stops because of say an electrical gremlin causing a fuse to pop, or say a wire breaking, and you cook the engine. Same as if the electric motor buggers up (brushes or whatever breaks on them)

A mechanical pump will keep going as long as the engine does (unless the impeller corrodes, or the belt snaps)

Well...that's not really "fair" because if an EWP fails, it's not like temperature is going to suddenly skyrocket and boom, engine gone. Much in the same way as a mechanical pump failing, water temp will rise steadily and you will (or should) notice it.

hks_kansei · Postby **hks_kansei** » Mon Jan 12, 2015 8:54 pm

project.r.racing wrote:Not really a good enough reason since you are already driving around a car full of all those things.

True, but of the things that have had issues on my MX5 so far, most have been electronic.

Sam with household appliances and other stuff.

Magpie · Postby **Magpie** » Tue Jan 13, 2015 8:25 am

Since engine rebuild only electrical issue was a CAS failure, one environmental and no mechanical.

There have been a few other electrical issues (bad connections, sensor calibration) but these have not stopped the car.

Sensor issue was managed by having a backup system. Same thinking with using the ECU to make a decision to protect the engine rather than the driver who is concentrating on other things and does not see the temp go up.

If water boils a temp sensor no longer works hence the use of a coolant flow sensor. Wiring this into the ECU gives another tool for the ECU to make its decision.