Electric Water Pump
Discussion
Right, bear with me as I've had a few beers.
I was reading in Professional Engineer (the IMechE mag) that an Aussie company has developed and are selling an Electric Water Pump for automotive cooling applications.
Apparently the system is the 3rd generation.
benefits include reduced power consumption (as mechanical water pumps are sized to work well in the mid range of an engines rpm at the top end they are simply wasting power and from what I hear, quite a bit of power)
Increased cooling capacity due the ability to run independantly of the engine speed (the advantage that springs to mind is cooling whilst stuck in traffic)
it seems like a good idea. the water system is electronically managed to optimise power consumption against cooling requirments.
Aparently the Ferrari team used it this year at Le Mans...
they've got 1000's of hours of testing and claim that fuel consumption can be reduced (slightly) as well as optimising the cooling.
Sounds good. It would be particulary useful for engines with large rev ranges as the water pump wouldn't have to spin like a bugger at the top end consuming god knows how much power.
the company also claim that studies have shown that above certain flowrates the water isn't in contact with the engine block surfaces long enough to conduct efficient heat transfer. Thus by optimising the flowrate cooling can actually be increased.
Just though I'd share it with you all
night.
Andy
I was reading in Professional Engineer (the IMechE mag) that an Aussie company has developed and are selling an Electric Water Pump for automotive cooling applications.
Apparently the system is the 3rd generation.
benefits include reduced power consumption (as mechanical water pumps are sized to work well in the mid range of an engines rpm at the top end they are simply wasting power and from what I hear, quite a bit of power)
Increased cooling capacity due the ability to run independantly of the engine speed (the advantage that springs to mind is cooling whilst stuck in traffic)
it seems like a good idea. the water system is electronically managed to optimise power consumption against cooling requirments.
Aparently the Ferrari team used it this year at Le Mans...
they've got 1000's of hours of testing and claim that fuel consumption can be reduced (slightly) as well as optimising the cooling.
Sounds good. It would be particulary useful for engines with large rev ranges as the water pump wouldn't have to spin like a bugger at the top end consuming god knows how much power.
the company also claim that studies have shown that above certain flowrates the water isn't in contact with the engine block surfaces long enough to conduct efficient heat transfer. Thus by optimising the flowrate cooling can actually be increased.
Just though I'd share it with you all
night.
Andy
Do not believe the technical explanations on the DC web site about the pressure/flow/cooling characteristics that (a) their pumps provide compared to mechanical pumps, and (b) engines require. These little electric pumps may be adequate to replace the mechanical pumps on some small unstressed engines but are not suitable for large capacity or highly stressed engines. If you are after more power, then compromising the cooling system and hence engine durability is not the most sensible approach.
Not a new idea at all (though you did mention third generation to be fair!). I converted a Yamaha RD400 to water cooling in 1983, and the conversion used a nifty little electric pump which worked a treat.
Before everyone rushes to source an electric pump for their Chim/Griff, bear in mind that water circulation is generally not the problem. Getting enough cool air in, and getting the hot air out, most surely is!
Before everyone rushes to source an electric pump for their Chim/Griff, bear in mind that water circulation is generally not the problem. Getting enough cool air in, and getting the hot air out, most surely is!
greenv8s said:
Do not believe the technical explanations on the DC web site about the pressure/flow/cooling characteristics that (a) their pumps provide compared to mechanical pumps, and (b) engines require. These little electric pumps may be adequate to replace the mechanical pumps on some small unstressed engines but are not suitable for large capacity or highly stressed engines. If you are after more power, then compromising the cooling system and hence engine durability is not the most sensible approach.
Er, so how come the Ferrari racing team use them?
Andy
andytk said:
Do not believe the technical explanations on the DC web site about the pressure/flow/cooling characteristics that (a) their pumps provide compared to mechanical pumps, and (b) engines require. These little electric pumps may be adequate to replace the mechanical pumps on some small unstressed engines but are not suitable for large capacity or highly stressed engines. If you are after more power, then compromising the cooling system and hence engine durability is not the most sensible approach.
Er, so how come the Ferrari racing team use them?
Andy
Engine durability isn't high on their list - outright power is higher...
Ok, coming from a different tack, a lot of Mini Miglia and Se7en racers use electric booster pumps, or complete replacement electric pumps.
The reasons expressed to me were two-fold.
Firstly the water pump on the A-series is designed for optimum flow at about 2000~2500(crank)rpm. Overspeeding the pump leads to cavitation with all the problem which arise from that, and increasing the pulley size only goes so far as now the pump doesn't work adquately at idle/paddock rpm.
Second having shut the engine down stinking hot there is a serious risk of head gasket failure due to no forced water circulation.
In both these situations an electric pump can help, as you can vary the flow according to temperature rather than engine rpm and you can run the pump post engine shutdown to help disipate some of the residual heat.
As the engine driven water pump on the A-series is a centrifical the booster pump will still be able to flow water past the stationary impeller when the engine is stopped.
The reasons expressed to me were two-fold.
Firstly the water pump on the A-series is designed for optimum flow at about 2000~2500(crank)rpm. Overspeeding the pump leads to cavitation with all the problem which arise from that, and increasing the pulley size only goes so far as now the pump doesn't work adquately at idle/paddock rpm.
Second having shut the engine down stinking hot there is a serious risk of head gasket failure due to no forced water circulation.
In both these situations an electric pump can help, as you can vary the flow according to temperature rather than engine rpm and you can run the pump post engine shutdown to help disipate some of the residual heat.
As the engine driven water pump on the A-series is a centrifical the booster pump will still be able to flow water past the stationary impeller when the engine is stopped.
I ran mine like that for about six months, but I took it off recently. It helped significantly at tickover and washed the heat out well after you switch off, but the problem is that the little Davies Craig pump doesn't flow enough for full throttle high rpm cooling. The mechanical pump tries to circulate far more than the EWP can handle and it becomes a significant restriction, dropping the flow (in my case) from 180 l/m to under 120 l/m. (For comparision, the cross section area of the pump outlet is roughly one tenth of the cross section area of the water hose it is plumbed in to. You also need to consider that the insides of the pump disturb the water flow considerably and the restriction is more than the relative area implies.)
Not possible for the RV8 since the main pump outlet is internal to the front cover. You could put a bypass with a one-way valve in parallel with the EWP, and this is something I might experiment with one day. But at the moment, given that the rest of my system is now substantially overspecced, heat soak is not a problem at the moment.
Bearded-lada-man said:
I though I read that using electric water pumps wasn't legal for road use..... I'm sure this was from the brochure of one of the suppliers.
I can't think of any reason it would be illegal, the only problem I can think of is your insurers might get stroppy if you didn't disclose the modification to them. But that goes for any modification.
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