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ideola
Joined: 01 Oct 2004
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Location: Spring Lake MI
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simsport
Joined: 06 Nov 2002
Posts: 573
Location: UK Warrington
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 Posted: Thu May 01, 2008 9:10 am Post subject: Cooling Mods |
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Maybe I can help explain.
The std pump 'draws water' from the back of the head via the outlet that also serves the heater matrix. It draws as against pumps because the pipe meets the pump housing behind the impellor.
Its a restriction but on a std car you need to take care as you dont want to stall the water flow.
If you fit a Davies Craig pump it sits outside the opriginal pump housing and hence pressurises it pumping to, rather than drawing from, the rear port. This of course is a stall again.
What you do (steve's idea) is you take a larger pipe out of that port at the back of the head and but it into the pipe out of the head/thermostat housing at the front. You then blank off the original port in the water pump housing and you get increased flow through and out the head and into the hot leg going to the radiator....phew...hope that makes sense!
Cheers
Simon
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bass gt
Joined: 02 Dec 2004
Posts: 971
Location: Johannesburg for now!!
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| Posted: Thu May 01, 2008 9:20 am Post subject: |
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| emoore924 wrote: | I'd be interested in hearing more about the BOTH (back of the head) piping change, with how-to, and pics if they're handy. I sort of understand what you've done, but I can't quite visualise it without some more info.
THANKS! |
OK, i found this picture of my previous iteration. You can see the blue pipe coming from the rear of the head, which joins to the pipe coming from the thermostat housing. This version used the stock flange on the rear of thehead. The item with both the large and small water pipe connections.
In my new version, i have machined a flange that bolts to the rear of the head in place of the stock item, nd has a single 32mm ali pipe welded into it. This flange/pipe has a 32mm Samco pipe connected to it which joins to the 38mm pipe coming from the thermostat housing. There is no point going larger than 32mm s the outlet in the head casting is no bigger than this. So i have effectively equalized the flow rates from the front and rear of the head, which makes the #4 cylinder a lot happier, especially when the boost is ramped up.
Now don't forget that i am running an electric water pump, with the stat removed, so i don't know how suitable this would be for a street car running a heater system. However, if you look at the stock pipe, it goes from 10mm to 30/40mm where it joins the stock water pump, so perhaps there is scope to upscale this pipe AND retain the feed to the heater. In theory, it should work, but as i don't have a heater, i can't vouch 100%
Also, i am due home next week, so i shall try and take some pics of the new arrangement and post them up. however, even this is not 100% finished as i need to route the pipes around the plenum, which has not been fab'd yet. Work in progress ect 
EDIT!! Check below!!
Steve
Sorry, i found this pic on my pc. you can clearly see the large pipe coming from the rear of the head and running along the engine bay where it joins with the main front pipe. I shall be improving this design by making a Y pipe, to ease the flow from the two pipes, rather than the T join you see here.
And Simon's description is spot on. I have welded shut the ports on the water pump housing, so water is drawn out of the bottom rad port, into the electric pump, and pumped into the water pump housing. It is then forced into the block, as the pump is totally gutted and all other pipe connections closed.And when i say gutted, i mean there is no impeller, no shaft, no nothing. All holes welded shut. The pump body is just that, an empty casting. So the water goes into the block, feeds up though the block to the head, where it exits both front and rear, at roughly equal flow rates, where the pipes are then joined back together and feed into the top rad port. It then goes though the rad, and the cycle repeats. Seems to be VERY effective, possibly too much so, as on a cold day, the engine temps can drop to 50deg C. I shall be trying the Craig Davies electronic pump controller, which allows you to dial in a desired temp, and the pump speeds up or slows down accordingly, hopefully stabilising the engine temps.
Questions on a post card please to- Steve B, somwhere in the Middle East, too hot for comfort. please enclose a cheque for $2500 for my consultancy fees. Happy to help!!
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Sat May 03, 2008 2:21 am Post subject: |
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Steve
Check is in the mail 
Thanks a ton for this very helpful photo and description.
One thing to point out...I did a bit of research on the C-D controller unit. It's gotten some bad press due to failures, and some of the posts I read in other forums indicated that C-D threatened to sue a magazine that ran an article with a less than flattering review of the controller. To be clear, everything I've read online indicates that the pumps themselves are brilliant and reliable, but the controllers seem to be problematic, and the word on the 'net is that the company is very aggressive about negative commentary on its products. I can't vouch for any of this personally, just passing along a heads up.
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Sat May 03, 2008 2:24 am Post subject: |
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Steve, one more question...is it safe to assume that you also welded shut the short connection on the bottom of the T-stat housing, the one that connects to the water pump?
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bass gt
Joined: 02 Dec 2004
Posts: 971
Location: Johannesburg for now!!
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| Posted: Sat May 03, 2008 2:27 am Post subject: |
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| ideola wrote: | | Steve, one more question...is it safe to assume that you also welded shut the short connection on the bottom of the T-stat housing, the one that connects to the water pump? |
yes, that was closed as well. Funny you mention the CD controller, as i had the original fail!! I was thinking of trying the new digital unit. Failing that, i really need to work out a way of doing it. It might be possible to use a PWM output of he ECU and run it through that, so that the ecu controls the pump according to the temps sen by the ecu.
Steve
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Sat May 03, 2008 2:41 am Post subject: |
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Yeah, maybe their second generation digital unit is better, but if I were in your shoes, I'd do some due diligence before plunking down the cash. In my case, I'm planning to keep it as simple as possible, and just run full on, along with a post ignition shutdown cycle to provide flow to my water-cooled hybrid turbo.
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bass gt
Joined: 02 Dec 2004
Posts: 971
Location: Johannesburg for now!!
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| Posted: Sat May 03, 2008 2:56 am Post subject: |
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Dan,
I hear what you are saying
I do have my pump on 100% at the moment, and although it works well, i have had instnces where i am on the start line at 80Deg C and as i come over the finish line, the engine is at 50deg C!! Obviously, this is not ideal. However, having looked into this a little deeper, and having read the DC website and tech info, they do nothing more than control the pump with a PWM supply.
My SQ6 ECU has numerous PWM outputs, several rated to 12A. So i am going to check if i can reference the output to the temp sensor, and control it this way. This would be a much more elegant solution, and would keep the cash in my pocket!!
D-C state that the controller provides no output up to 20deg below the target value. Then it cycles at 5v up to 10deg below the target value. It then uses a constant ramp up to 12v output at the target temp. i don't think it is beyond the wit of man to write a PWM table to mimic this.
Steve
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Raceboy
Joined: 01 Mar 2004
Posts: 2326
Location: Estonia, Europe
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| Posted: Sat May 03, 2008 4:23 am Post subject: |
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PWM controlling of some high-powered output is essential and is definitely present on Pectel. it's best and pretty much foolproof to let the ecu control things like this.
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bass gt
Joined: 02 Dec 2004
Posts: 971
Location: Johannesburg for now!!
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| Posted: Sat May 03, 2008 8:04 am Post subject: |
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| Raceboy wrote: | | PWM controlling of some high-powered output is essential and is definitely present on Pectel. it's best and pretty much foolproof to let the ecu control things like this. |
Raceboy,
Forgive my ignorance, but am i right in thinking that setting a 12v PWM output to 50% duty cycle will give an approximate 6v output? And 75% 9v ect ect?? If the Pectel does this by allowing me to link the PWM output to the water temp signal, then this is the perfect solution. having read the Davies Craig info, i would set the pump at 30% up to 50 deg C and the up the duty cycle to the max temp, and all values above at 100%. I could even do this with the cooling fans, and have them run by a PWM driver and set other logic conditions such as road speed ect. ie no fan above 25mph for example.
Steve
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!tom
Joined: 28 Aug 2006
Posts: 1931
Location: Victoria, BC Canada
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| Posted: Sat May 03, 2008 8:34 am Post subject: |
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| bass gt wrote: | | Forgive my ignorance, but am i right in thinking that setting a 12v PWM output to 50% duty cycle will give an approximate 6v output? And 75% 9v ect ect?? |
Yep.
Depending on the PWM output and what you're driving, you may want to protect the PWM output with a diode. The diode is used to protect the output from an inductive load. I have no idea if your system has such a diode installed in it already
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Raceboy
Joined: 01 Mar 2004
Posts: 2326
Location: Estonia, Europe
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| Posted: Sat May 03, 2008 1:45 pm Post subject: |
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Yes, it's correct as itom already suggested.
Diode is a good idea and although Pectel most likely have done it already, it wouldn't hurt to use it anyway
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
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bass gt
Joined: 02 Dec 2004
Posts: 971
Location: Johannesburg for now!!
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| Posted: Sat May 03, 2008 8:21 pm Post subject: |
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Tom, Raceboy,
Thanks, and yes i was aware of the diode, as a motor turns into a generator when the poer is removed and it is spinning!!
Well it seems this is the way to go.
Steve
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ideola
Joined: 01 Oct 2004
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Location: Spring Lake MI
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| Posted: Tue May 20, 2008 3:52 am Post subject: |
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| bass gt wrote: | | i have had instnces where i am on the start line at 80Deg C and as i come over the finish line, the engine is at 50deg C!! Obviously, this is not ideal. |
Steve
Can you (or anyone else for that matter) explain why the lower temp is not ideal? Is this due to the coolant temp sensors used as input to the ECU? Is it due to optimal temp range for the oil? Not sure I understand why lower temp isn't better...
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Tue May 20, 2008 4:52 am Post subject: |
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| ideola wrote: | Steve
Can you (or anyone else for that matter) explain why the lower temp is not ideal? Is this due to the coolant temp sensors used as input to the ECU? Is it due to optimal temp range for the oil? Not sure I understand why lower temp isn't better... |
Combustion efficiency.
Min
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