Water pump flow numbers
Team Owner
Joined: Jul 2004
Posts: 40,370
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From: Redondo Beach, California
There's a fundamental difference in the way a mechanical (belt driven) water pump and an electrical water pump run.
Basically, an electrical water pump runs at a constant speed. (As far as I know). A mechanical water pump speed varies over a large rpm range.
I believe most mechanical water pumps are designed to provide adequate coolant flow at low engine rpms. When the car is engineered by the factory, I well imagine they size the water pump to provide enough flow so that someone driving on a hot day, with the AC on, in stop and go driving (low engine) rpm will get adequate flow. This means at higher engine rpms, the water pump will probably try to flow too much and become a drag on engine power. (Don't some dyno's use a water pump to put a load on the engine?)
An electrical water pump will run at a constant rpm, independent of engine speed. I think that because the electric pump doesn't get overdrivven at high engine rpms, this savings in drag on the crank is why racers install electrical pumps.
Basically, an electrical water pump runs at a constant speed. (As far as I know). A mechanical water pump speed varies over a large rpm range.
I believe most mechanical water pumps are designed to provide adequate coolant flow at low engine rpms. When the car is engineered by the factory, I well imagine they size the water pump to provide enough flow so that someone driving on a hot day, with the AC on, in stop and go driving (low engine) rpm will get adequate flow. This means at higher engine rpms, the water pump will probably try to flow too much and become a drag on engine power. (Don't some dyno's use a water pump to put a load on the engine?)
An electrical water pump will run at a constant rpm, independent of engine speed. I think that because the electric pump doesn't get overdrivven at high engine rpms, this savings in drag on the crank is why racers install electrical pumps.
Pro
Joined: Nov 1999
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From: Front Range
Originally Posted by Z-man
what alternator are you running? I'd like to up the power in mine also...
Here's a good page from MAD electrical that explains about modified alternators: MAD electrical tech
And here's a link to the unit I'm running:
Summit Racing
Note the MAD site recommends not going with 100+ amp internals in 10si casings due to heat buildup issues... fried rectifiers, burnt windings, etc. Personally, I haven't had any problems, and the thing keeps my voltage at 13.5+ volts, even with dual spals, lights, fog lights, coil, and accessories... AT IDLE.
I'm waiting for this alternator to die or one of my components to fail because sometimes it's putting out 16 volts, but so far it's running like a champ.
Burning Brakes
Joined: Dec 2004
Posts: 1,020
Likes: 1
From: Nederland Texas
While we're throwing opinions at this, here is one from my "circle-track racing" business partner.They use a slower gph water pump instead of a HV unit in order to slow the water flow down so it doesn't pass throught the radiator so fast it doesn't have time to transfer the heat out. HHHMMMM.
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Pro
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From: Lantana TX
Originally Posted by pef427
While we're throwing opinions at this, here is one from my "circle-track racing" business partner.They use a slower gph water pump instead of a HV unit in order to slow the water flow down so it doesn't pass throught the radiator so fast it doesn't have time to transfer the heat out. HHHMMMM.
This is why we have this forum.
I can't believe the multitude of different responses and pro's and con's of each.I am now back on the saddle regarding an elec vs mech version.
Z-man, Pef427, and others have open up a lot of new areas to consider.
However, I still can't believe there is not a published number for GPM on a mech water pump?????
Does it make any sense to put a switch in the drivers pit to manually controll the activation of the elec water pump simular to an elec fan set up? Probably not, but I figured I would ask....maybe that is a stupid question, I do not know.
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From: Lantana TX
Originally Posted by Z-man
Mezieres are made to run full duty, not just drag strip. Don't forget, when you need cooling the most (idling or slow speed), belt driven pumps are putting out the least flow. Their rating is only at top speed. Electrics put out full flow all the time...
If it gets hot in TX and you drive in traffic where you might come to a stop, you might reconsider an electric.
iNdigo - what alternator are you running? I'd like to up the power in mine also...
If it gets hot in TX and you drive in traffic where you might come to a stop, you might reconsider an electric.
iNdigo - what alternator are you running? I'd like to up the power in mine also...
Z man... you make a very strong arguement here. I will likely see many days driving in 90-100 temps and likely stop and go city driving. If what you say is true and I think it is, this may be a good idea (elec). Also, when I am at the strip itwill continue to cool down even if the engine is off. This with a dual spal system I might be Okay??
Do you know what the avg miles or hrs you get out of a elec water pump. Lets say it is the Mezierre?
Is anyone running one of these?
Race Director
Joined: Nov 1999
Posts: 10,643
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From: Foxfield CO 1970 Convertible
Originally Posted by 76 sting
Z man... you make a very strong arguement here. I will likely see many days driving in 90-100 temps and likely stop and go city driving. If what you say is true and I think it is, this may be a good idea (elec). Also, when I am at the strip itwill continue to cool down even if the engine is off. This with a dual spal system I might be Okay??
Do you know what the avg miles or hrs you get out of a elec water pump. Lets say it is the Mezierre?
Is anyone running one of these?
Do you know what the avg miles or hrs you get out of a elec water pump. Lets say it is the Mezierre?
Is anyone running one of these?
Yes - I can sit with the car off in the driveway with a hot engine. When the pump and fan are on (key on but engine off), I can watch the temp come down on my laptop so I know they're working...
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From: Lantana TX
Originally Posted by Z-man
As I remember, they advertise 2000 hours warranty. At 8 hours / week, that's 250 weeks or about 5 years if you commute 1/2 hour each way with one. For fair weather drivers like me, that's about 10 years...
Yes - I can sit with the car off in the driveway with a hot engine. When the pump and fan are on (key on but engine off), I can watch the temp come down on my laptop so I know they're working...
Yes - I can sit with the car off in the driveway with a hot engine. When the pump and fan are on (key on but engine off), I can watch the temp come down on my laptop so I know they're working...
So, I do not see a real down side to this avenue. Since both elec and mech have an impact on how much HP they each use. Either way, anything less than 5HP I am not going to worry about as I will just turn up the NOS a little more
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Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
OK - I found some info just FYI
These might be better than standard issue, but they probably are comparable to stock units.
http://www.edelbrock.com/automotive/waterpump_dyno.html
The SB Chevy pumps flow from about 14 gpm at 2000 to 37 gpm at 5000 rpm...
These might be better than standard issue, but they probably are comparable to stock units.
http://www.edelbrock.com/automotive/waterpump_dyno.html
The SB Chevy pumps flow from about 14 gpm at 2000 to 37 gpm at 5000 rpm...
Thread Starter
Pro
Joined: Jun 2004
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From: Lantana TX
Originally Posted by Z-man
OK - I found some info just FYI
These might be better than standard issue, but they probably are comparable to stock units.
http://www.edelbrock.com/automotive/waterpump_dyno.html
The SB Chevy pumps flow from about 14 gpm at 2000 to 37 gpm at 5000 rpm...
These might be better than standard issue, but they probably are comparable to stock units.
http://www.edelbrock.com/automotive/waterpump_dyno.html
The SB Chevy pumps flow from about 14 gpm at 2000 to 37 gpm at 5000 rpm...
So the question I have now is why don't more folks use elec pumps? Unless they are everyday drivers or course.
There are 2 versions of elec pumps a 35 GPM and 55 GPM. 35 sounds on the money, but you would think the 55 is better? However, your earlier comments mentioned the thought of moving the water too fast and not allowing the radiator to do its job?? what do you think?
Melting Slicks
Joined: May 2003
Posts: 2,387
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From: Meriden CT
Originally Posted by iNdigo
well, i'd certainly have to see this in a controlled experiment to believe it... i'm not about to disconnect my alternator output terminal while the engine's running.
i'm assuming the reasoning behind your statement is that the electromagnetic field changes intensity depending on load or RPM, and when the field becomes more powerful it produces some sort of magnetic resistance to the direction of rotation?
I still don't see how this could make a significant difference. Then again I'm running a 140A alternator, so maybe I just don't notice the difference.
intriguing to say the least. do you have some references you can point us to, i'd like to read more about it.
i'm assuming the reasoning behind your statement is that the electromagnetic field changes intensity depending on load or RPM, and when the field becomes more powerful it produces some sort of magnetic resistance to the direction of rotation?
I still don't see how this could make a significant difference. Then again I'm running a 140A alternator, so maybe I just don't notice the difference.
intriguing to say the least. do you have some references you can point us to, i'd like to read more about it.
lets say you have a backup generator on your house.. is that generator going to suck down more gas when its supplying 100 amps, rather than 10 amps? you bet your *** it is.... the mechanical load on the generator is proportional to the electrical load. I could give you some exact equations, but i dont have my books on me at the moment.
I say go with a mechanical pump... no sense in wasting an extra 100 bucks on an electric pump when a quality mechanical pump will adequatley suite your needs.
Burning Brakes
Joined: Dec 2004
Posts: 1,020
Likes: 1
From: Nederland Texas
Originally Posted by JoeRags
any electric power engineering book will point you in the right direction... think about it... if you have a constant current draw of 10 amps or 100 amps, you alternator is going to make up that power somehow.. only place its coming from is parasitic drag off the engine. the battery is simply a storage bank along the way.
lets say you have a backup generator on your house.. is that generator going to suck down more gas when its supplying 100 amps, rather than 10 amps? you bet your *** it is.... the mechanical load on the generator is proportional to the electrical load. I could give you some exact equations, but i dont have my books on me at the moment.
I say go with a mechanical pump... no sense in wasting an extra 100 bucks on an electric pump when a quality mechanical pump will adequatley suite your needs.
lets say you have a backup generator on your house.. is that generator going to suck down more gas when its supplying 100 amps, rather than 10 amps? you bet your *** it is.... the mechanical load on the generator is proportional to the electrical load. I could give you some exact equations, but i dont have my books on me at the moment.
I say go with a mechanical pump... no sense in wasting an extra 100 bucks on an electric pump when a quality mechanical pump will adequatley suite your needs.
A home generator is designed to ramp up under load. We were Hurricane Rita refugees for 3 weeks without power so I became intimate with my generator. I feel it is way more complex in it's operation than an alternator.
I know there are guys on this forum who can set us all straight about this question...
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From: Lantana TX
Originally Posted by pef427
OK. I'm not an Eletrical Engineer but I play one on TV. With that disclaimer in place, I don't think you can compare a home generator to a cars alternator. The alternater is only able to put "X" amount of drag on the engine no matter what load is drawn from it by your electrical components. It's not like it can tighten down on the belt under load!
A home generator is designed to ramp up under load. We were Hurricane Rita refugees for 3 weeks without power so I became intimate with my generator. I feel it is way more complex in it's operation than an alternator.
I know there are guys on this forum who can set us all straight about this question...
A home generator is designed to ramp up under load. We were Hurricane Rita refugees for 3 weeks without power so I became intimate with my generator. I feel it is way more complex in it's operation than an alternator.
I know there are guys on this forum who can set us all straight about this question...
An alternator is generating current whether there is a load or not. If the electrical load becomes too much for the alternator to handle, things will start to go wrong. However, if only 25% of the alternators load is being consumed the alternator is not intelligent enough to lower its charged amperage rating to supply just what it needs.
I am no expert, but an alternator (for the most part) puts out”x” average amperage it will continue to put out that amperage under normal driving conditions. Yes, I do realize the slower you go or stopping will decrease this rating, and the faster you go will increase it, but I do not believe it will be substantial decrease or increase.
Just my 2 cents
Burning Brakes
Joined: Feb 2006
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From: AL
For Power, P (in watts), Current, I (in amps), Voltage, V (in volts):
P = IV [DC circuits]
multiply Power in watts by 0.001341 to obtain horsepower (U.S.)
So if the electrical system is set up properly to run the large current users off of the alternator, a junction block, etc., and not the battery terminal, then increased current requirement equals increased horsepower requirement assuming voltage is constant, along with everything else. With a properly sized alternator in good condition, the voltage will be a nearly constant 14 volts at the junction.
Remember converting energy always involves inefficiencies or loss.
i know this will not close this discussion! it seems like a bonehead move to install an electrical water pump unless it is used on a drag car-no belt drive, or if there is speed control. With speed control, less current can be called upon as reqd resulting in an overall hp savings.
V-belts are also inefficient. Consider a more efficient belt drive.
P = IV [DC circuits]
multiply Power in watts by 0.001341 to obtain horsepower (U.S.)
So if the electrical system is set up properly to run the large current users off of the alternator, a junction block, etc., and not the battery terminal, then increased current requirement equals increased horsepower requirement assuming voltage is constant, along with everything else. With a properly sized alternator in good condition, the voltage will be a nearly constant 14 volts at the junction.
Remember converting energy always involves inefficiencies or loss.
i know this will not close this discussion! it seems like a bonehead move to install an electrical water pump unless it is used on a drag car-no belt drive, or if there is speed control. With speed control, less current can be called upon as reqd resulting in an overall hp savings.
V-belts are also inefficient. Consider a more efficient belt drive.
Team Owner
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From: Reno Nevada
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http://superchevy.com/technical/engi...s/0408sc_pump/
http://superchevy.com/technical/engi...s/0408sc_pump/
Race Director
Joined: Jul 2004
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From: Scottsdale Arizona
Originally Posted by JoeRags
any electric power engineering book will point you in the right direction... think about it... if you have a constant current draw of 10 amps or 100 amps, you alternator is going to make up that power somehow.. only place its coming from is parasitic drag off the engine. the battery is simply a storage bank along the way.
lets say you have a backup generator on your house.. is that generator going to suck down more gas when its supplying 100 amps, rather than 10 amps? you bet your *** it is.... the mechanical load on the generator is proportional to the electrical load. I could give you some exact equations, but i dont have my books on me at the moment.
I say go with a mechanical pump... no sense in wasting an extra 100 bucks on an electric pump when a quality mechanical pump will adequatley suite your needs.
lets say you have a backup generator on your house.. is that generator going to suck down more gas when its supplying 100 amps, rather than 10 amps? you bet your *** it is.... the mechanical load on the generator is proportional to the electrical load. I could give you some exact equations, but i dont have my books on me at the moment.
I say go with a mechanical pump... no sense in wasting an extra 100 bucks on an electric pump when a quality mechanical pump will adequatley suite your needs.
I've never seen anything (other than a few posts on the Forum) that demonstrates that the output of the alternator varies with the electrical load. If the output is constant at a given RPM, then so is the mechanical load.
Race Director
Joined: Jul 2004
Posts: 12,696
Likes: 329
From: Scottsdale Arizona
Originally Posted by 76 sting
An alternator is generating current whether there is a load or not. If the electrical load becomes too much for the alternator to handle, things will start to go wrong. However, if only 25% of the alternators load is being consumed the alternator is not intelligent enough to lower its charged amperage rating to supply just what it needs.
I am no expert, but an alternator (for the most part) puts out”x” average amperage it will continue to put out that amperage under normal driving conditions. Yes, I do realize the slower you go or stopping will decrease this rating, and the faster you go will increase it, but I do not believe it will be substantial decrease or increase.
Just my 2 cents
Melting Slicks
Joined: May 2003
Posts: 2,387
Likes: 2
From: Meriden CT
bottom line here is were talking miniscule amounts of power loss for either electric or mechanical water pumps.... were getting WAY off topic here. either way, its going to cost a few HP to cool your engine.... but whats just a few when you've got a few HUNDRED to burn them tires up?
I still recommend a mechanical pump.
I still recommend a mechanical pump.
Thread Starter
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Joined: Jun 2004
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From: Lantana TX
Originally Posted by JoeRags
bottom line here is were talking miniscule amounts of power loss for either electric or mechanical water pumps.... were getting WAY off topic here. either way, its going to cost a few HP to cool your engine.... but whats just a few when you've got a few HUNDRED to burn them tires up?
I still recommend a mechanical pump.
I still recommend a mechanical pump.
Money doesn't matter, I am willing to spend close to 700-800 ($350 elec pump & $400 dual fans) just to clean up the engine bay in this specific area even though my mech cooling system works perfectly.
I am not worried about loosing or gaining HP.
Melting Slicks
Joined: May 2003
Posts: 2,387
Likes: 2
From: Meriden CT