Test Setup:I built a small test fixture with a wind tunnel type measuring section in front of the radiator. (see photos) I needed to be able to accurately measure the air that actually flows through the radiator of the SSR, along with a few other parameters. Although I did not have an A/C condenser mounted to the front of the radiator, I feel that the comparative data speaks for itself.
The parameter list is as follows:
• Voltage (Volts) – Power input to the fan measured with a digital voltmeter. This is a pretty straightforward simulation of the installation. Measurement variability is estimated to be +/- 0.4vdc from vehicle installation. Data recorded is an average of at least 5 tests.
• Running Current (Amps Continuous) – The continuous running current measured with a clamp-on current loop and a digital voltmeter on the main wire to the fan. Possible measurement variability is +/- 2 amps. Data recorded is an average of at least 5 tests.
• Inrush Current (Amps Max) – The peak inrush current measured with a digital storage scope, using the same clamp-on current loop. Possible measurement variability is approximately +/- 5 amps. Data recorded was typical for at least 5 tests of inrush current.
• 1 Second Current (Amps 1 Sec.) – The inrush current value (as it is decreasing to continuous current) after power applied for 1 second, measured with the same digital storage scope. Possible measurement variability is approximately +/- 5 amps. Data recorded was typical for at least 5 tests of inrush current.
• Airflow – calculated in CFM by a digital anemometer in the measuring section of the test fixture. The anemometer had an internal calculation of duct airflow, using the square footage of the measuring section as an input variable. Measuring section area calculated to be 1.918 square feet. Measurement variability estimated to be +/- 10%. Data recorded was an average of approximately 15 seconds of data.
• Decibel level – measured with a hand-held meter approximately 3 feet aft and 3 feet left of the fan exhaust. Although not representative of the installation, this provides a comparative measurement of sound between the fans tested. The meter was set on fast response and used the “A” weighting scale. Data recorded was an average of approximately 15 seconds of data.
Please note that my variability estimates are based on my “best guess” of how the test system compares to the actual vehicle installation. All of the measuring devices were calibrated to their original specs.
Fan diameter, motor speed, airflow area, radiator coverage, shroud (or lack of), air leaks and all the other physical characteristics of the fans are considered unimportant when comparing installed performance.
The test was accomplished “back-to-back” on three fan systems:
1) OEM – This is a stock GM P/N 15816298. It is a single speed motor with an internal voltage dropping circuit to provide two speed operation.
2) Simple Engineering MFK-1 – This is fabricated using a “Flex-a-Lite 180 Extreme” as the core with a replication of the OEM internal dropping circuit for two speed operation.
3) Simple Engineering MFK-2 – This is fabricated using a GM P/N 15819952 made by Delphi as the core. This is the fan that is supplied from GM on the 2005 and newer Corvette family and the Cadillac XLR. It has been modified using the same dropping circuit as the MFK-1 to provide two speed operation. Also added to the system is an “on-board” 100 amp relay with separate 8 gauge wiring and a 60 amp slow-blow fuse for connection to main bus power.
Findings: MFK-1 Radiator airflow is 30% higher than the OEM on low speed and 32% higher on high speed. Fan efficiency and low power consumption (lower than OEM in all aspects) is an advantage. Full shroud is a significant advantage at very low vehicle speeds. This is the recommended replacement for the OEM fan for stock SSRs.
MFK-2 Radiator airflow is 20% greater than the OEM on low speed and 50% higher on high speed. Power consumption is greater on high speed and is above the commonly accepted 30 amp limit for 10 gauge wiring. Direct connection to the power source and an optimum ground using 8 gauge wire (both without going through a disconnect) is critical for long term reliability. The half-shrouded fan housing is less efficient than a full shroud at very low vehicle speeds, but offers less restriction at very high vehicle speeds. This fan is the recommended replacement for the OEM fan for modified SSRs.
Notes:The MFK-1 will continue to be the fan recommended for the greatest percentage of SSRs. The low speed performance gives it the advantage over the MFK-2 with only a slight compromise in high speed performance. The overall performance of the fan is substantially better than the OEM unit. It is also still a "drop-in" replacement for the OEM fan that uses all of the standard SSR electrical system without adding any additional system stresses and does not require any additional connections.
The MFK-2 is the fan I am now recommending for the small percentage of SSRs with modified engines. Although it moves slightly less air on low speed, the high speed performance gives it the advantage over the MFK-1. At sustained high vehicle speeds (well above legal limits) with very high heat loads (uphill in the summer) the half shroud has the advantage of less restrictive ram air flow and will offer slightly better cooling than the MFK-1. This is especially important for supercharged trucks that have an additional restricion (S/C intercooler) in the airflow path. The MFK-2 fan kit is complete and includes everything necessary to drop into an SSR without drilling any holes or splicing any wires. The design of the Simple Engineering fan control system eliminates any possible stresses on the SSR electrical system and provides redundant power to the cooling fan.
The data for the GM 15819952 only applies to the Delphi fans sold through General Motors and modified to two speed operation by Simple Engineering.
This should answer a lot of the questions about fan speeds, airflows and sound levels.
My Best Regards,
Mike
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Looking at the airflow data in the first post, you can see that the fully shrouded MFK-1 has a very high efficiency (amount of air moved for electrical power consumed), compared to the other two fans. The explanation is simple....... It has a full shroud and a rubber seal that nests softly against the radiator core. There is no wasted air around the sides of the fan shroud.
Looking at the pictures, it's easy to see why the OEM fan pulls so little air through the radiator. It's also really easy to see why the half-shrouded Delphi fan performs like it does.
You will also notice the three different blade shapes. Lots of technology in blade design. The thickness of the three fans is quite similar..... OEM is 3" deep, front to back. The MFK-1 is also 3" deep. The MFK-2 is 3.75" deep at the motor, but 3" deep at the rest of the shroud. The MFK-2 does not have a fitment problem in our trucks.
A couple observations........ Decibel level seems to be proportional to the work being done by the fan. The more air that is moved, the louder the fan is. Seems to be a linear relationship. hdflstf..... where are you buddy?
Regards,
Mike
Last edited by Mike in AZ; 12-13-2010 at 05:56 AM.
I will be using all three fans on a comparison test with the OEM radiator, Ron Davis single row racing radiator and a Ron Davis double row racing radiator. I expect to find that the three fans perform a little differently when forced to pull air through a thicker radiator core. That testing will take palce in the coming weeks and I will post the comparative data in a radiator thread.
Oh yeah...... I forgot to show my power source for the fan testing. It's a 3hp electric motor that drives a 100 amp alternator and charges a car battery. Makes a nice "stiff" bus for doing testing.
There is a step change in the current trace on the digital storage scope at about 0.95 second on the MFK-2 test. This is where the 3hp motor drew too much juice and kicked off the 20 amp breaker on my compressor outlet and left me with just battery to run the fan. After the first couple times, it was no surprise when I heard the motor drop off line. No biggie....... just looking at the data it's still evident where we are at the 1 second point.
Special thanks to my engineer buddy for the loan of his power cart.
Mike
Last edited by Mike in AZ; 12-13-2010 at 12:09 AM.
Damn, since my truck has been blessed by the run-cool fairy, and the factory fan is humming along, I've put off installing the Simple Engineering MFK-1 which is living in my spare bedroom.
But looking at the results of the mad scientist's tests, it looks like spending 15 minutes to drop the MFK-1 in, would do my electrical system a big favor. Whoda thunk it?
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Mike,
Thanks for providing the answers to what I, and sure many others, were wondering! This detailed analysis will surely help many of us choose better and know more what the expected results should be.
Damn, since my truck has been blessed by the run-cool fairy, and the factory fan is humming along, I've put off installing the Simple Engineering MFK-1 which is living in my spare bedroom.
But looking at the results of the mad scientist's tests, it looks like spending 15 minutes to drop the MFK-1 in, would do my electrical system a big favor. Whoda thunk it?
The more air that is moved, the louder the fan is. Seems to be a linear relationship. hdflstf..... where are you buddy?
Regards,
Mike
Sounds reasonable. At least until the fan tip speed starts getting close to the square root of gamma R T...
BTW you may want to add an intercooler (or simulator) in front or the radiator for some of the tests to see what that does to your performance numbers.
I have a dual spal fan setup you can test if you want to make a comparison to another one of the 'competitions' fans. ... or maybe just for the sake of more data..
Sounds reasonable. At least until the fan tip speed starts getting close to the square root of gamma R T...
BTW you may want to add an intercooler (or simulator) in front or the radiator for some of the tests to see what that does to your performance numbers.
Thanks Art. I'm always open for more "playing with toys" in the garage. All I have to do is find an A/C condenser and an intercooler that I can use...
I have a dual spal fan setup you can test if you want to make a comparison to another one of the 'competitions' fans. ... or maybe just for the sake of more data..
If you're talking about the Colvin setup....... Yes, I'd love to test it.
My SSR: UV SSR My other SS is a 64 Malibu LA built Black Plate Car
Mike "The Wright Brother"
Mike is the long lost "Wright Brother" even though he isn't near old enough. How about the Right Bro."
Thanks Mike for being there for us
The wind tunnel you built is amazingly close the one at the Wright-Patterson AFB Museum in Ohio, the size is similar.
Click for the picture of the Wright Brothers Wind Tunnel http://www.nationalmuseum.af.mil/sha...-1234P-002.jpg
Thanks for answering our questions. The low amp draw on the ducted fan is a healthy thing for our SSR's electrical system.
JimBob
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JimBob
My SSR: 05, Silver Auto, Line-X Bed, X-Member and Plate
Variable Speed Control - MFK-2
Quote:
Originally Posted by Mike in AZ
Thanks Art. I'm always open for more "playing with toys" in the garage. All I have to do is find an A/C condenser and an intercooler that I can use...
Mikey
For the effort you have put into this project the GM fixed 2 speed MFK-2 strategy is less than ideal in my view. I'm thinking you have the CFM, current and load temps so a nice electronic variable current speed control module will work brilliantly. The max current draw is limited and better controlled because there is no instantaneous high draw on the battery and alternator. Also, the radiator/engine temp is stabilized/controlled in the region between speed 1 and 2. This will reduce the temp under and overshoot that is inherent in fixed switching. This temp swing is exagerated in the MFK-2 as your data shows (comparing version -1 and OEM) so it is really suited to an electronic setup.
Great work Mike, either way there is documented fix for high load engine temp conditions.
Whew....and this is why there are so many Mikey parts on my truck!!
Great job Mike and we missed you Saturday.
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2006 FPR Black
MikeinAZ's: Big Main & Aux fans, Tranny Cooler, Spare Tire Kit & Crossmember Plate, LC32 Kit, etc...and the list keeps growing and growing...
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