blue missile
Well-Known Member
I plan to be using an electric water pump. Muanufacturer yet to be determined. Do they all come with provisions for by pass and heater feed?
Andrew
Andrew
Electric Water Pump info please
- Thread starter blue missile
- Start date
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blue missile
Well-Known Member
So I take it that if you run one of these you cant have heat or run a thermostat. Am I getting this correctly?
Andrew
Andrew
C130 Chief
Mechanical Genius
You weren't thinking of running one of these on the street were you? Pretty much a race only item.
blue missile
Well-Known Member
C130 chief:
actually yes I was. Well the street is kind of a misnomer. I am building this for one to participate in the SSC. And yes it will see some street/cruise time, but mostly highway high speed use. I wanted to get rid of the engine drag and will be running a pair of electric fans.
Andrew
actually yes I was. Well the street is kind of a misnomer. I am building this for one to participate in the SSC. And yes it will see some street/cruise time, but mostly highway high speed use. I wanted to get rid of the engine drag and will be running a pair of electric fans.
Andrew
C130 Chief
Mechanical Genius
You'll only be transferring the load to the alternator, it still requires energy to run the pump. Consult the pump manufacturer about the life expectancy if you plan to run continuous.
As for the 2 fans, why? You say you will be doing a lot of high speed running. With a 60+ MPH breeze coming through the radiator the fans aren't needed In fact, they will be a resistance to airflow. Id run the smallest fan I could get away with without overheating at idle. Or no fan at all if I didn't have to deal with stop and go traffic, and was only going fast. NASCAR cars don't have fans.
As for the 2 fans, why? You say you will be doing a lot of high speed running. With a 60+ MPH breeze coming through the radiator the fans aren't needed In fact, they will be a resistance to airflow. Id run the smallest fan I could get away with without overheating at idle. Or no fan at all if I didn't have to deal with stop and go traffic, and was only going fast. NASCAR cars don't have fans.
fishy68
Tyr Fryr's Inc.
Hey Andrew Chief's right. I thought about switching to an electric fan to reduce engine drag and and clean up the look of the engine compartment but I found most any 16" fan draws 15-20 amps so your just transfering drag to the alternator which will in turn put more drag on the engine there. Same goes for the water pump. It'll add more drag on the alternator since it uses electricity. I bet in the end you loose power. Plus you load down a wiring harness that was just barely adequate in the first place.
blue missile
Well-Known Member
Thanks all
I guess the electric water pump is out, Im still on the fence about the electric fan though. There will be some cruise nights. And Im shure if I dont build it to put up with bumper to bumper traffic, I will encounter it the first time I take out on the street.
Andrew
I guess the electric water pump is out, Im still on the fence about the electric fan though. There will be some cruise nights. And Im shure if I dont build it to put up with bumper to bumper traffic, I will encounter it the first time I take out on the street.
Andrew
D-mailman
Well-Known Member
It is correct to say that the electric fans will add to the voltage requirment of the alternator. And will create more drag on the alternator than a belt driven fan and put more load on the cranshaft. But the water pump is another story. The water pump is a mini dyno and robs a considerable amount of hp by having it on the crankshaft. Electric water pumps will add voltage to the alternator also, but the increased drag of the alternaor is much less than the hp drag the water pump imparts on the crankshaft. 20 hp range in most cases. Install a field cut-out switch inside the car to allow 'removing' the alternator from the crank only when needed. Like when making a pass or making a point to another driver. Only needed for a few seconds during a run and then switched back on. The field wire is the green wire coming out of the alternator. Break this wire and switch it from the underside of the dash or anywhere you want to inside the car. Drag strip testing I have done shows a solid tenth and about 1 - 1 1/2 mph. For a 3 dollar switch. Good luck.
Terry
Terry
C130 Chief
Mechanical Genius
If a water pump uses less power to operate it is only because it is pumping less water. Work is work. All else being equal, the electric will draw more load (amperage NOT voltage) due to some energy lost to resistance in the electrical system.
So why do drag racers like electric pumps? A few reasons:
1. They run at a constant speed, equivalent to say 2000 crankshaft RPM so in the staging lanes you can keep the engine cool with a small light radiator because you have a lot more circulation than you would have at idle.
2. With an alternator cutout, you can remove the pumping load and all others from the alternator temporarily during the pass, 30 seconds or so.
3. As you idle down the return road, your pump is running at it's constant speed so you can cool off quicker.
4. Back in the pits, with the car plugged in, you can leave the pump running to cool the engine between rounds.
So for a typical drag car they make sense. If you plan to cool a high horsepower big block with a lightweight little VW or Honda radiator, an electric water pump is probably mandatory.
So why not run one on the street?
1. They're expensive.
2. They're constant speed, so you will tend to overcool (no thermostat remember) at idle and at low speed, and undercool at high RPM like highway driving or road racing.
3. They're added complexity. Sure would suck to fry a $5000 engine because a $0.15 fuse blew.
4. Most aren't exactly weatherproof. Ever wonder what it's like under your hood driving down the highway when it's raining? Hide behind a car radiator during a hurricane and see how dry you end up.
If it were me, I would spend the money on a good crossflow radiator, and then a set of March underdrive pulleys. That way you could slow the belt drive pump down during sustained high RPM running. Remember, as pointed out above, the faster you spin the pump, the more water it moves, but the more work is required.
For endurance running consider simple, reliable, proven technology even if it means giving up a couple horsepower. Think about airplane engines, an O-360 Lycoming is ridiculously simple for a reason.
So why do drag racers like electric pumps? A few reasons:
1. They run at a constant speed, equivalent to say 2000 crankshaft RPM so in the staging lanes you can keep the engine cool with a small light radiator because you have a lot more circulation than you would have at idle.
2. With an alternator cutout, you can remove the pumping load and all others from the alternator temporarily during the pass, 30 seconds or so.
3. As you idle down the return road, your pump is running at it's constant speed so you can cool off quicker.
4. Back in the pits, with the car plugged in, you can leave the pump running to cool the engine between rounds.
So for a typical drag car they make sense. If you plan to cool a high horsepower big block with a lightweight little VW or Honda radiator, an electric water pump is probably mandatory.
So why not run one on the street?
1. They're expensive.
2. They're constant speed, so you will tend to overcool (no thermostat remember) at idle and at low speed, and undercool at high RPM like highway driving or road racing.
3. They're added complexity. Sure would suck to fry a $5000 engine because a $0.15 fuse blew.
4. Most aren't exactly weatherproof. Ever wonder what it's like under your hood driving down the highway when it's raining? Hide behind a car radiator during a hurricane and see how dry you end up.
If it were me, I would spend the money on a good crossflow radiator, and then a set of March underdrive pulleys. That way you could slow the belt drive pump down during sustained high RPM running. Remember, as pointed out above, the faster you spin the pump, the more water it moves, but the more work is required.
For endurance running consider simple, reliable, proven technology even if it means giving up a couple horsepower. Think about airplane engines, an O-360 Lycoming is ridiculously simple for a reason.
blue missile
Well-Known Member
Chief;
I don't know if you are really a mechanical genius, But you do put forth a well reasoned and well organized point of view. Taking cost out of the picture,the limitations of running without a thermostat, take the electric water pump off the table.
I do intend to run a good cross flow rad. with a set of electric fans off a taurus. They move alot of air and I can pick them up all day long for about $50.
Thanks for the info
Andrew
I don't know if you are really a mechanical genius, But you do put forth a well reasoned and well organized point of view. Taking cost out of the picture,the limitations of running without a thermostat, take the electric water pump off the table.
I do intend to run a good cross flow rad. with a set of electric fans off a taurus. They move alot of air and I can pick them up all day long for about $50.
Thanks for the info
Andrew
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