Real Fiero Tech

anyone run an electric water pump or know someone who does? any recommendations? I'm thinking about going with one, I plan to run it off of a relay, and piggyback the relay on the fuel pump relay circuit so that anytime the fuel pump is running, so is the water pump. thoughts?

They're most useful to cool the engine off in the staging lanes when drag racing. Is that why you want to run one?

They're also useful to ensure that you always have the optimal flow rate regardless of engine RPM, and don't cavitate at high RPM.

BTW, many modern BMWs (most 2007 and up) use electric primary water pumps (and no mechanical secondary!). Many of these look like good candidates for a retrofit.

Here's a good link to check out: http://www.miataturbo.net/engine-perfor ... ler-69420/

My 3 series runs an OEM electric water pump, without a mechanical pump at all. The benefits are lengthy, higher flow, full flow regardless of RPM, variable water temps, cool down after shutoff, and lower parasitic draw. The downsides are cost and reliability.

The BMW water pumps fail regularly. However they rarely if ever fail catastrophically, much like a mechanical pump they usually just start leaking, which gets progressively worse. They genuinely last about 50,000 miles.

I believe the newer N55 3 series cars went back to a mechanical water pump if I'm not mistaken. They went backwards in a bunch of ways unfortunately. Innovation just isn't the name of the game when you're BMW aiming to be Toyota.

I wouldn't wire it to the fuel pump but you could. I would wire it on a separate circuit with a switch so you can run it with the car off to cool it faster. If you aren't worried about that sort of thing, then I would do as you suggested and wire it to the fuel pump switch. You could also wire it to a thermo switch that kicks the pump on after a specific temperature to promote quicker engine warm ups in colder weather.

Series8217 wrote:They're also useful to ensure that you always have the optimal flow rate regardless of engine RPM, and don't cavitate at high RPM.

BTW, many modern BMWs (most 2007 and up) use electric primary water pumps (and no mechanical secondary!). Many of these look like good candidates for a retrofit.

Here's a good link to check out: http://www.miataturbo.net/engine-perfor ... ler-69420/

As you note, there's a big difference between a basic racer's electric waterpump and an OE level electric waterpump with a variable speed, RPM and temperature sensitive controller.

Aaron wrote:My 3 series runs an OEM electric water pump, without a mechanical pump at all. The benefits are lengthy, higher flow, full flow regardless of RPM, variable water temps, cool down after shutoff, and lower parasitic draw. The downsides are cost and reliability.

The BMW water pumps fail regularly. However they rarely if ever fail catastrophically, much like a mechanical pump they usually just start leaking, which gets progressively worse. They genuinely last about 50,000 miles.

I believe the newer N55 3 series cars went back to a mechanical water pump if I'm not mistaken. They went backwards in a bunch of ways unfortunately. Innovation just isn't the name of the game when you're BMW aiming to be Toyota.

What exactly is "full flow"? One of the points of OE electric waterpumps is to be able to vary the pumping speed with engine heat output in order to keep coolant temps constant. However, I suspect that the engine still requires recirculating flow when it's cold for all the same reasons that an engine with a belt driven pump does. It also needs to provide enough volume for the heater core... unless there's yet another pump in the system for that.

I guess that came out wrong...

The pump still flows when cold, just slowly. The car warms up quicker than my other cars, despite the OE air/oil cooler mounted up front. However it does not get up to temp crazy fast, the aluminum LSX still holds that record for me. I cannot believe how fast a 2002 LS1 Camaro has a warm heater. 2 blocks at sub 2000rpm.

By full flow, I meant the ability to give 100% coolant flow at low rpm. Probably not a huge deal, but for a car that makes 500wtq at low rpm with inefficient turbos, there's a lot of heat produced at very low engine speeds, and subsequently traditional water pump speeds. However, on the other hand, with a small car and 512wtq, not much time is spent at low rpm.

Some cool things about the tech:

Coolant temperature is varied by up to 60*F depending on driving conditions. For example at highway cruising the car usually sits at 240* in the name of efficiency.

After engine shut down the EWP continues running, including pushing water through the turbo, for several minutes for more controlled and equal cool-down. I can't even hear it unless I open the hood and intently listen for it.

After engine shut down the driver can continue to operate the heater, and the EWP will continue running coolant through the core. Obviously the water will cool down eventually, but it lasts quite some time when you consider it's circulating the entire system still.

To bleed the coolant system, you hook up a battery charger, turn the ignition on, and hold the throttle for 10 seconds. It does the rest, usually takes 5-15 minutes.

When they leak, you get to replace them! I've heard it's not that bad, but the part is of course expensive, I want to say around 300-500.

Signs of OEM level engineering.

It sounds like that's probably the pump to use, if one wants to use an electric pump.

However, as Steven said and as BMW has demonstrated... the controller needs to be pretty smart to get the maximum benefits from the system.

Simply turning one on at constant speed whenever the fuel pump's on probably wouldn't produce good results.

It'd be a good option, but I doubt you'd get it controlled to do everything it does factory, as that is integral to the ECU.

It is a remote mount, as in it'd be easy to adapt to any engine, just hook up a couple hoses and find a way to strap it down. It uses a rather large 2-plug connection, probably just 12v and ground.

Davies-Craig also makes a controllable EWP.