water pump UD pulley

[BoostJunki3]

is it worth it? have one? like it?

[Bio248]

i dont think underdriving the water pump is ever a good idea.

[neel2008]

get an electric water pump if you are worried about it that much....then get an ac bypass pulley and rip all ur ac crap out, that will help more than silly UD pulleys

[TheOtherNick]

Buy an electric pump. I would never undrive my cooling system.

[mechguy]

It depends on your desired outcome. An electric water pump (EWP from here on) can use less engine power compared to a crank-driven pump. The reason the electric pump is able to do this is because it can operate off of the battery (essentially a power reserve). This is advantageous for heavy accelerating, where the engine is temporarily relieved of "water pumping duty" by using the battery power.

It should be noted that an EWP should decrease your MPG because of the inherent energy conversion process. You are converting mechanical power from the crankshaft into electric potential at the generator and back to mechanical power at the EWP. No energy conversion will be 100% efficient, so there are energy losses. In real-world situations, I suspect that the difference in MPG will be negligable between the two pumps.

Of course there are other factors to consider such as whether the electric pump can shutdown when water circulation is not needed. Also, the actual pump (not motor) has an efficiency rating that may be greater or less than the stock unit.

Why do I make such a detailed stink about everything? I'm a mechanical engineer.

[matt5112]

It depends on your desired outcome. An electric water pump (EWP from here on) can use less engine power compared to a crank-driven pump. The reason the electric pump is able to do this is because it can operate off of the battery (essentially a power reserve).

No...

It runs off of your alternator.

This is advantageous for heavy accelerating, where the engine is temporarily relieved of "water pumping duty" by using the battery power.

Again, alternator power. Not battery.

It should be noted that an EWP should decrease your MPG because of the inherent energy conversion process. You are converting mechanical power from the crankshaft into electric potential at the generator and back to mechanical power at the EWP. No energy conversion will be 100% efficient, so there are energy losses. In real-world situations, I suspect that the difference in MPG will be negligable between the two pumps.

The alternator spins regardless.

They're 50% efficient.

But the pump draws 6-7 amps according to manu.

Thats 100 W.

Thats 0.26 HP draw from the engine.

ZZP claims it frees up 7 hp.

Of course there are other factors to consider such as whether the electric pump can shutdown when water circulation is not needed. Also, the actual pump (not motor) has an efficiency rating that may be greater or less than the stock unit.

Why do I make such a detailed stink about everything? I'm a mechanical engineer.

And not an electrical engineer.

[mechguy]

No...

It runs off of your alternator.




Again, alternator power. Not battery.



The alternator spins regardless.

They're 50% efficient.

But the pump draws 6-7 amps according to manu.

Thats 100 W.

Thats 0.26 HP draw from the engine.

ZZP claims it frees up 7 hp.



And not an electrical engineer.

Please try to read my posts a little more carefully.

Notice that I said "depends on your desired outcome" followed with "can use less power compared to a crank-driven pump...."

Clearly, I was stating this in the most general sense; disconnect your alternator when racing. That's why I called the battery a power reserve. I once drove my Olds Alero for over 50km without knowing that I had a broken serpentine belt (no alternator charging). The car did not stop until I turned off the ignition at my destination. That aside, disconnecting the alternator is something I will never do, for many reasons, but I will re-iterate that the aforementioned quote was clearly in the most general sense.

Your response of "The alternator spins regardless" is an interesting one. Very obviously, the energy conversion process I talk about is occurring. Again, you will want to notice some of my wording: "...an EWP should decrease your MPG..."

Nowhere do I give quantitative reference, simply qualitative.

You go on to mention some numbers and statistics which I don't care about because I was only providing theory between the two types of pumps. What the manufacturer claims is their claim and real-world testing sometimes provides unexpected results. Notice that I mention "real-world situations" in my second paragraph.

There are many reasons why ZZP claims that the stock WP is using almost 7 HP more than the electric version. Removing the the stock WP deletes one pulley and the associated friction, bearing losses, windage, etc. Also, how do the maximum flow rates compare....and there are many more reasons. The main point is that the theory I have provided is correct.

Again, read my posts more carefully.

Awaiting your response....

[blueguy]

You go on to mention some numbers and statistics which I don't care about because I was only providing theory between the two types of pumps.

Again, read my posts more carefully

I read your post carefully...and if your going to debate something...you NEED numbers and statistics...saying you don't care means just that...you lost.

Done.

[mechguy]

I read your post carefully...and if your going to debate something...you NEED numbers and statistics...saying you don't care means just that...you lost.

Done.

Nice try. I gave you 100% correct theory about these pumps. If you cannot comprehend that's fine.

[matt5112]

Please try to read my posts a little more carefully.

Notice that I said "depends on your desired outcome" followed with "can use less power compared to a crank-driven pump...."

Clearly, I was stating this in the most general sense; disconnect your alternator when racing. That's why I called the battery a power reserve. I once drove my Olds Alero for over 50km without knowing that I had a broken serpentine belt (no alternator charging). The car did not stop until I turned off the ignition at my destination. That aside, disconnecting the alternator is something I will never do, for many reasons, but I will re-iterate that the aforementioned quote was clearly in the most general sense.

You'll run through batteries quite quickly. Generally the battery light comes on with the alt fails.

Your response of "The alternator spins regardless" is an interesting one. Very obviously, the energy conversion process I talk about is occurring. Again, you will want to notice some of my wording: "...an EWP should decrease your MPG..."

Nowhere do I give quantitative reference, simply qualitative.

You go on to mention some numbers and statistics which I don't care about because I was only providing theory between the two types of pumps. What the manufacturer claims is their claim and real-world testing sometimes provides unexpected results. Notice that I mention "real-world situations" in my second paragraph.

There are many reasons why ZZP claims that the stock WP is using almost 7 HP more than the electric version. Removing the the stock WP deletes one pulley and the associated friction, bearing losses, windage, etc. Also, how do the maximum flow rates compare....and there are many more reasons. The main point is that the theory I have provided is correct.

Again, read my posts more carefully.

Awaiting your response....

In a nice short summary:

The power being used by the water pump pulley appears to be greater than the already existent load created by the alternator which is also more than sufficient to power an electric pump.

I never said thermodynamics were wrong.

Nor does my napkin math suggest it.

It merely suggests you'd find similar or improved fuel economy by utilizing the wasted power that the alternator is drawing as well as reducing the mechanical load on the crank thus the engine itself by removing the mechanical water pump.

I see you're trying to take a fine line here and stick to your precise wording.

But whats interesting to note is your emphasis.

Note this section here:

It should be noted that an EWP should decrease your MPG because of the inherent energy conversion process.

Its on the decrease which implies you are assuming that logic says the decrease is more likely.

But..... The logic is this:

The alternator provides a load on the engine. Full load on the engine is 4 HP. (105 A output at 14.4 V, 50% efficiency)

The WP does the same. Full load is 7 HP (Debatable, but still >0.26 HP)

Remove the WP entirely and add a .26 HP additional load via the alternator.

Even if an EWP is only good for a single HP you've minimized losses.

And to the guy who suggested hammer time..... You don't ban people who you dont agree with. That's childish.

[BoostJunki3]

In a nice short summary:

The power being used by the water pump pulley appears to be greater than the already existent load created by the alternator which is also more than sufficient to power an electric pump.

I never said thermodynamics were wrong.

Nor does my napkin math suggest it.

It merely suggests you'd find similar or improved fuel economy by utilizing the wasted power that the alternator is drawing as well as reducing the mechanical load on the crank thus the engine itself by removing the mechanical water pump.

I see you're trying to take a fine line here and stick to your precise wording.

But whats interesting to note is your emphasis.

Note this section here:



Its on the decrease which implies you are assuming that logic says the decrease is more likely.

But..... The logic is this:

The alternator provides a load on the engine. Full load on the engine is 4 HP. (105 A output at 14.4 V, 50% efficiency)

The WP does the same. Full load is 7 HP (Debatable, but still >0.26 HP)

Remove the WP entirely and add a .26 HP additional load via the alternator.

Even if an EWP is only good for a single HP you've minimized losses.

And to the guy who suggested hammer time..... You don't ban people who you dont agree with. That's childish.

/thread

[neel2008]

ur waterpump is always running when ur car is running.....i would assume you would just run a thermostat like a motor driven pump....If you like to drag race, I would rather run an electric pump money permitting.

[TheOtherNick]

The alternator has the same drag no matter how much it is charging on theses cars. So adding more electrical load will not put more load on the engine.

[mechguy]

The alternator has the same drag no matter how much it is charging on theses cars. So adding more electrical load will not put more load on the engine.

No offense intended, but I would be happy to explain the fundamentals of this concept if you wish.

[QwikGT]

ive had mine from zzp on my car for 5 years now. it runs cool, never had an overheating issue. the stock pulley weighs a lot compared to the zzp one so less rotating mass is good i guess.

[addzradd]

Changed mine to ZZP's UD pulley, temps stay right near 180 still, the difference in weight is about a lb, but alot of that is in the middle where moment of inertia is changed the least. Over the next 3 tanks I noticed a .2 mpg increase, which is within the realm of being statistically insignificant, but I can see how it would be a real change.

But for 30 bucks used on CGP I have to say I think it was worth it.

[neel2008]

yea when I do an alternator test, you can deff hear the difference in the motor when the tester puts a load on the alt.....

[neel2008]

engineers are worse.......cause they think they know everything.....lol which we have just seen here....

[Bio248]

im an engineer. i do know everything.

[blueguy]

im an engineer. i do know everything.

Proven.

4 times.

3 times here...once when God told him he was a liar.