GSlender's Track Beeotch!

gslender · Postby **gslender** » Sat Jan 10, 2015 10:34 pm

Btw - not sure of the facts by Davies Craig.... 10kW returned by removing a mechanical pump ? What kind of engine was that! That's a massively powerful water pump that needed 10kW of power to push water !!!!!! Only a little unbelievable yeah. --- oh, and replaced by a 12V electric pump with what, a 30amp fuse.... So how does that make sense!

Magpie · Postby **Magpie** » Sat Jan 10, 2015 10:49 pm

Grain of salt stuff. That fact is for people to use if they don't understand the why

Actually it will ADD weight to the car so this will off set the 'power' gains. Plus people may need to consider the alternator limits as adding the 30 amp draw of the pump, SPAL fans (20 amp draw each) and a 480w electric heater may cause other issues... Stock NA alternator output is around 60 amp!

gslender · Postby **gslender** » Sun Jan 11, 2015 4:24 pm

My point is that much of that FAQ is bollocks... it just can't be true that 10kW was found by removing the water pump. If it was, then the electric pump would need more than 360 watts to equal what a mechanical pump was drawing if it really was stealing 10,000 watts of power. Even if the mechanical pump was 10x less efficient than the electric pump (and it wouldn't be) then it would still be 1,000 watts vs 360 watts so something isn't right.

The science on that FAQ is screwed up and I'm betting so is lots of other so called facts on that link!

Postby **NitroDann** » Sun Jan 11, 2015 4:31 pm

You are wrong. Let me get to a PC in 2 minutes to explain.

Postby **NitroDann** » Sun Jan 11, 2015 4:40 pm

You aren't just replacing a pumping device, you are replacing a system.

The mechanical pump and thermostat has a bunch of shitty design issues for the sake of simplicity, price, and reliability.

The pump pumps against a closed or mostly closed thermostat much of the time, the pump needs to flow enough at idle, yet at redline is flowing many many times more, and the friction increases as a square of speed just like aero friction (drag).

I 100% believe 10kw with a mechanical pump at 8000rpm+ pumping against a wall. (With a cold engine remove the thermostat, take the radiator return hose off and put a garden hose into the radiator cap opening to keep it full of water, now start the car and give it a 3 or 4000rpm rev, the engine will literally completely empty itself of water shooting it right across the yard in a single rev, the mechanical pump is stupidly stupidly overpowered at high revs).

With the electic pump, although the alternator only has X amp supply the battery has hundreds and the pump does NOT run full time, it maximum duty cycle might only be 20% on any particular setup.

One more point is that weight will possibly be reduced on some setups with the complete removal of the water pump assembly and replacement with a plate.

Dann

Magpie · Postby **Magpie** » Sun Jan 11, 2015 4:41 pm

Irrespective of the 10kw using an electric pump allows greater control over the whole cooling system. The electric pump can be varied in speed whereas a normal water pump runs off the engine. The electric does not need a thermostat as again the pump could be set to 2% duty cycle and just circulate water and then go to 100% at the desired temp. Linking the duty cycle to speed you could have the pump at 100% duty cycle when the temp is about say 72 deg when speed is zero. The same logic can be applied to controlling cooling fans. Using the duty cycle maps on the DPO output will maintain full torque of both the pump and fans.

Spent the day doing some more reading up on if the PS1000 should control the pump/fan or use the DC controller. I'll be going with the PS1000 controlling and using generic output duty cycle maps to control the pump and fans. Need to look at the alternator though.

NitroDann looking forward to reading your post explaining the calcs.

ndragun · Postby **ndragun** » Sun Jan 11, 2015 5:38 pm

NitroDann wrote:With a cold engine remove the thermostat, take the radiator return hose off and put a garden hose into the radiator cap opening to keep it full of water, now start the car and give it a 3 or 4000rpm rev, the engine will literally completely empty itself of water shooting it right across the yard in a single rev

I would SOOO love to do that... words cannot describe

gslender · Postby **gslender** » Mon Jan 12, 2015 7:35 am

You guys are missing the point.

How can a mechanical pump consume 10,000 watts of power but an electric pump only 320 watts? The electric pump would need to be over 1000x more efficient or the mechanical pump is 100x or more over engineered.

I'd accept 4x or as much as 10x difference, but 1,000x ??? Really!?

If electric motors are that good, we'd have Davies Craig building electric supercharges!

You're believing they're marketing bullshit too easily!

I'd believe removing the mechanical water pump might make 1kW difference (at best) and that brings the entire linked page into question. Thermostats restrict the water for a purpose and speed of liquid or gas does change the effectiveness of thermal transfer.

Whew... The laws of physics are preserved!

G

Postby **NitroDann** » Mon Jan 12, 2015 8:29 am

Grant, please actually read my post. It isnt simply a pump replacement, its a system replacement. Please read it and think about it, you are missing how each system works.

sailaholic · Postby **sailaholic** » Mon Jan 12, 2015 8:33 am

G, I think the argument IS that a mechanical pump is stupidly inefficient due to being designed to pump sufficient water at idle.

They say UP TO 10kw. Not 10kw on every engine. So I'd guess they are getting that figure from some big capacity high rpm engines such as the ferraris that used to race Bathurst 24 hour which used DC water pumps.

I think someone here reported 4 kW increase on a turbo race car when they swapped to a DC and a retune.

Are their figures high, probably a bit, but that's sales.

Sent from my iPhone using Tapatalk

Postby **NitroDann** » Mon Jan 12, 2015 8:38 am

The mechanical pump/thermostat combo is stupidly stupidly inefficient.

Also grant you are typing as if you believe that the electric pump is simply replacing the mechanical pump with no other changes and that it suffers the same, different speed with RPM and thermostat restriction, and that it will run 24/7 like a mechanical. This is not the case.

gslender · Postby **gslender** » Mon Jan 12, 2015 10:00 am

NitroDann wrote:Grant, please actually read my post. It isnt simply a pump replacement, its a system replacement. Please read it and think about it, you are missing how each system works.

I fully understand how it works. I am reading everything.

All I'm calling out is that the Davies Craig web link was mentioned as a credible bit of research on how thermostats are not needed because they did some test that showed that slowing the water has zero effect on the cooling system - that you can rush water past at any rate and its all good etc..

I'm calling out that the Davies Craig page is full of suspicious non-facts that you'd want to be very, very careful assuming is correct.

The original post (in my build thread) was that removing the thermostat was a good thing to do as it isn't needed at all.

My claim is that it serves the purpose of keeping the flow rate of the water down to an effective rate. Those that think the mechanical pump absorbs 10kW would want to keep it as even if that was 1/10th true it would be pushing water past at such a fast rate, that it would have a diminished effect of the cooling system.

We seem to have floated (pun) way past the original posts and points... so let's get back on topic.

If you still think removing the thermostat is a sensible option (because it only serves a purpose for warm up) then let's meaningfully discuss that.

If you want to think that installing an electric water pump will return heaps of HP then start a new post and we can discuss the "science" there... not sure that demonstrating how fast it can empty a bucket is a measure of the watts used, nor do I believe that all OEM's for countless years actively agreed to over engineer something to the tune of 1,000x what is needed, but hey, will make for an entertaining discussion.

G

toppertee · Postby **toppertee** » Mon Jan 12, 2015 10:01 am

From a person who works with pumps day in day out....

If you dead head a pump, power draw doesn't increase much at all, (just heats the water in the closed loop), i.E. it's quite happy to set there dead heading, but just starts to get bloody hot, I've also found when you resrict flow it tends to decrease power draw. You tend to over load the pump with head hight. ( I would take a guess the oem engineers sized the pump correctly,Normally fair smart bunch of people)

I.M.O. all you are doing is instead of driving to pump mech you are changing it to electrical power.

By taking a guess most electrical motors are around the 90% mark, but if you are controlling the speed of the pump that changes as well. Mech motor 20-25%.... I would find it unlikely there would be more than a couple of horse power diff..... If you ran the same car down the 1/4 mile one with mech and one with elect, little no diff in speed.

With electrical set up, I.M.O. you are bringing a heap of controller, electrical isusse that are just not needed on a car.... I would go with K.I.S.S.

As with fluid, temperature dynamic engineering is well above my IQ levels.....

gslender · Postby **gslender** » Mon Jan 12, 2015 10:23 am

There is heaps of science being overlooked here... there is a considerable difference between the effectiveness of heat transfer from a laminar flow vs a turbulent one... so if you just increase the flow rate of a cooling system (to the point where it is now mostly turbulent) then the effectiveness of that system is reduced. In addition, cavitation can harm and damage metal due to the formation of air bubbles.