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Old 05-31-2009, 03:07 PM   #21
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Originally Posted by JasonC SBB View Post
If the car is moving, the pump is running, there it no t-stat, and the fans are off, the engine can still overcool.

The electric pump is a lower power pump than the typical mechanical water pump. I'm not saying it's "inferior" - I'm saying it needs to run without a t-stat, and a consequence of this is the lower pressure in the cylinder head - which may mean Evans coolant would be needed to counteract this downside. I measured the actual coolant pressures years ago, and I found that when an engine is revved, the pressure rises significantly, even with a full open t-tat. If you look at the pressure-flow curves of the DC (I had to ask for the curves years ago), it can't build more than a couple of psi.

Second, I ran calculations of the required coolant flow given a certain amount of heat rejection, the DC pump cannot work with more than a certain amount of pressure head.
Over cooling is the least of my worries...running ~250HP in South Florida.

Lower power pump? Nonsense. Needs to run without a t-stat? Nonsense.
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Old 05-31-2009, 03:29 PM   #22
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Jason, the photo below speaks for the power of this pump (by the way it's not my photo).
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Reverse Flow/Electric Water Pump Cooling System-p002ct.jpg  
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Old 05-31-2009, 04:02 PM   #23
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mrtonyg, Jason's assertion is that the volume of water flowed by a pump in free space is much greater than the volume flowed against a restriction (such as a thermostat).

In order to satisfy him, you will need to post a picture of the pump throwing a stream of water while its outlet is restricted by something having approximately the same passage area as a fully open thermostat, such as an overdrilled fender washer or a partially closed ball valve. +1 for measuring the volume of water pumped per minute before and after, by measuring the time taken to empty a bucket containing a known quantify of water. +2 if you can figure out how to run the same test on a stock Miata water pump for comparison.
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Old 05-31-2009, 06:36 PM   #24
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Quote:
Originally Posted by mrtonyg View Post
Over cooling is the least of my worries...running ~250HP in South Florida.

Lower power pump? Nonsense. Needs to run without a t-stat? Nonsense.
how long have you ran this situation on the street?The ultimate test is running on the street(or track) in a heat soaked or winter time run.then you will KNOW whats what.In Albuquerque N.M.,Ive ran a coolant reroute that would not allow the engine to see full warm up,motivating me to return to stock.
-G-
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Old 05-31-2009, 06:56 PM   #25
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Originally Posted by Reverend Greg View Post
how long have you ran this situation on the street?The ultimate test is running on the street(or track) in a heat soaked or winter time run.then you will KNOW whats what.In Albuquerque N.M.,Ive ran a coolant reroute that would not allow the engine to see full warm up,motivating me to return to stock.
-G-
I agree with further testing, and is something that I intend to do. Like I said, this is a test mule setup, it is not a finished product. The basic design is solid, and at the most would need minor tweaking. The only major problem I foresee during heavy track use, is the small radiator might have a problem keeping up with the demands.

My claim is that reverse flow cooling has allowed me to run a more aggressive timing curve... nothing, more nothing less. It achieved my goal.
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Old 05-31-2009, 07:12 PM   #26
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Originally Posted by Joe Perez View Post
mrtonyg, Jason's assertion is that the volume of water flowed by a pump in free space is much greater than the volume flowed against a restriction (such as a thermostat).

In order to satisfy him, you will need to post a picture of the pump throwing a stream of water while its outlet is restricted by something having approximately the same passage area as a fully open thermostat, such as an overdrilled fender washer or a partially closed ball valve. +1 for measuring the volume of water pumped per minute before and after, by measuring the time taken to empty a bucket containing a known quantify of water. +2 if you can figure out how to run the same test on a stock Miata water pump for comparison.
Joe, at this point in the design, I doesn't make any sense for me to perform this test.

If you look at the design of the factory pump you being to wonder how it can circulate coolant. Factory pumps actually "pump" very little. If fact, almost all factory cooling systems that utilize mechanical pumps use gravity and the properties of hot coolant to help in circulation.
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Old 05-31-2009, 07:23 PM   #27
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Originally Posted by mrtonyg View Post
Joe, at this point in the design, I doesn't make any sense for me to perform this test.
I'm not the one arguing with you here.
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Old 05-31-2009, 08:30 PM   #28
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Originally Posted by mrtonyg View Post
My claim is that reverse flow cooling has allowed me to run a more aggressive timing curve... nothing, more nothing less. It achieved my goal.
Yes you showed that data and I did note it when I first read your post.

However, knock threshold has a lot of variability, thus the CHT measurement that Reverend Greg suggested would be a great way of double checking for improved head cooling. For example, IAT, fuel octane, and probably oil temperature, all would move the knock threshold around.

Now because you just dig your heels in and say "nonsense" to the stuff I investigated years ago, I will just patiently wait for other datapoints from you, such as temperatures at the track.
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Old 05-31-2009, 08:31 PM   #29
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Originally Posted by mrtonyg View Post
If you look at the design of the factory pump you being to wonder how it can circulate coolant. Factory pumps actually "pump" very little. If fact, almost all factory cooling systems that utilize mechanical pumps use gravity and the properties of hot coolant to help in circulation.
Now THIS, is nonsense.
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Old 05-31-2009, 08:48 PM   #30
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Copying myself from
MX-5 Miata Forum - View Single Post - Skunk2 trick: Electric water pump

I did some calculations and this water pump may flow enough to cool a turbo miata motor on the track:

http://www.daviescraig.com/main/display.asp?pid=8

note: the above link which I think was to the pump curve, is gone.

Mechanical water pumps are designed to be lossy, so that at low speed it flows enough to cool the engine, and at high speed have enough "leakage" so that they don't build too much pressure and draw too much power. They probably draw a few hp at high RPM. (Compare this to 100W for the Davies Craig 80 l / min model)

The Daviescraig pump draws ~8A and flows 80 li/min at zero pressure drop, and 50 li/min at 3 psi of pressure head.

At around 50 l/min flow rate, flowing water, it can carry away 50 hp of heat (average heat generated, not peak wheel hp) with a 10*C rise in water temperature. So far so good.

The real attraction is not the hp saved, but two things - you can get max flow at idle, possibly solving overheating at low speeds, and more importantly, being able to run your coolant in reverse as mentioned above.

Running coolant in reverse reduces temperatures in the head, all else being equal, helping prevent detonation. However, according to a patent by Evans (Evanscooling.com), you can get water vapor bubbles trapped in the head if you simply convert a conventional engine. His patent was violated by GM, according to his website, which shows using special little traps to get the vapor bubbles circulating. (I looked at the patent).

Another way to solve the vapor bubbles issue running coolant in reverse, is to use hi temperature coolant, NPG and NPG+, which have a 350*F boiling point. So, the combo of electric pump, reverse flow, and NPG seems synergistic.
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Old 05-31-2009, 08:51 PM   #31
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Quote:
Originally Posted by JasonC SBB View Post
Yes you showed that data and I did note it when I first read your post.

However, knock threshold has a lot of variability, thus the CHT measurement that Reverend Greg suggested would be a great way of double checking for improved head cooling. For example, IAT, fuel octane, and probably oil temperature, all would move the knock threshold around.
I took before and after measurements and yes, there was a drop in head temperature readings. I think there was an average temp difference of about 10deg. But since I was reading at the external surfaces of the head, and combustion temperature is the key in knock prevention, I don't know how meaningful those measurements were.

Obviously, there are many variables that affect the knock threshold, and those were kept to a minimum during my testing.
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Old 05-31-2009, 09:11 PM   #32
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Now THIS, is nonsense.
I am sorry you disagree.

Do you know that some of the early water cooled systems for automobiles didn't used water pumps at all? They relied on the temperature differential of the water to establish flow.

The colder water would sit at the bottom of the block, as it heated it would rise up as colder water would take its place thus establishing flow. The same basic system is still employed today.
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Old 05-31-2009, 09:55 PM   #33
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Quote:
Originally Posted by mrtonyg View Post
Joe, at this point in the design, I doesn't make any sense for me to perform this test.

If you look at the design of the factory pump you being to wonder how it can circulate coolant. Factory pumps actually "pump" very little. If fact, almost all factory cooling systems that utilize mechanical pumps use gravity and the properties of hot coolant to help in circulation.
Quote:
Originally Posted by mrtonyg View Post
I am sorry you disagree.

Do you know that some of the early water cooled systems for automobiles didn't used water pumps at all? They relied on the temperature differential of the water to establish flow.

The colder water would sit at the bottom of the block, as it heated it would rise up as colder water would take its place thus establishing flow. The same basic system is still employed today.
I would have to agree on these points,the factory pump more "stirs",than pumps.But also the ability for debate is what "pumps": the innovation in the HI Perf.Miata arena i.e.cops ignition.This could be the next step.
-G-
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Old 05-31-2009, 10:59 PM   #34
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Tony I don't disagree the reverse flow will result in reduced head temperatures, all else being equal.

The big question is whether or not the Davies Craig has enough flow/pressure to handle a turbo miata on a hot track day. I think it won't be, with a t-stat in place, and may be, if the t-stat is removed.
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Old 06-01-2009, 12:11 AM   #35
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I am using a Mezeire pump intended for SBC's it has more than enough to pump a swimming pool through a straw,plus I am fabbing an air bleed that will exit at the plugs in the head under the Valve cover.may take a week or so to get to,I am finding this a very helpful intercourse.Thanx to all.
-Greg-
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Old 06-01-2009, 12:35 AM   #36
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What's an SBC?
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Old 06-01-2009, 12:41 AM   #37
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SBC=Small Block Chevrolet
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Old 06-01-2009, 12:45 AM   #38
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Quote:
Originally Posted by Reverend Greg View Post
I am using a Mezeire pump intended for SBC's it has more than enough to pump a swimming pool through a straw,plus I am fabbing an air bleed that will exit at the plugs in the head under the Valve cover.may take a week or so to get to,I am finding this a very helpful intercourse.Thanx to all.
-Greg-
You are most welcome! And let's see some photos of the install and subsequent post-install feedback!
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Old 06-01-2009, 12:56 AM   #39
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Man I took my wifes camera to work to take a picture of my CNC lathe cutting the plug for stock water pump,and wouldnt you know it.Coolant splashed on it and it dont work no more.Im going to use my kids Toy digital next week and see if that will suffice.
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Old 06-01-2009, 12:58 AM   #40
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Quote:
Originally Posted by JasonC SBB View Post
What's an SBC?
Sorry I some times am misunderstood.On the HAMB forum it is common parlance,Im still kind of a forum noob.I cant even load pics to a post yet[]

Oh I figured it outIm kinda Clevah!
-G-

Last edited by Reverend Greg; 06-01-2009 at 01:32 AM.
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