datsun280zx Posted December 6, 2010 Share Posted December 6, 2010 Well my fan needs to be replaced so i wanted to switch to electrical fan. I know it may not be the best but i prefer the electrical. What im wondering is how many CFMs do i need to keep the engine cool? and should i run a single fan or dual fan? The only things i have done to it is a intake and exhaust so its basically stock. tried to search and couldn't find any other than for built engine. Thanks in advanced for the help Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted December 6, 2010 Share Posted December 6, 2010 Well, from my perspective, if the only info you have found is for a built engine, why not go with that setup, then later if you do get bit by the bug and build your engine up, then you won't have to redo the fans to manage the extra heat from the extra power generation. Quote Link to comment Share on other sites More sharing options...
datsun280zx Posted December 6, 2010 Author Share Posted December 6, 2010 Well this one is just my daily driver im having working on building a v8 260z. The most ill do to this is a very mild cam for a little more power. Quote Link to comment Share on other sites More sharing options...
nash542001 Posted December 6, 2010 Share Posted December 6, 2010 3200 cfm should be good! Quote Link to comment Share on other sites More sharing options...
bjhines Posted December 6, 2010 Share Posted December 6, 2010 I have the FORD 2 speed fan in my build. It is one hell of a powerful fan. The problem is, it draws as much power as the ENTIRE 240Z electrical system. It will consume normal relays with arcing and heat. You will have to invest in specialty, high-power relays that are not available in local stores. I have used the typical 14" aftermarket fans in several flavors on other cars and found that they are not powerful enough to cool the car in gridlock on a hot day. I used the quick and easy mounting method for these fans and was disappointed with the way they fit. If I were to do it again. I would use a DUAL FAN system with a fan shroud that sealed to the back of the radiator. Two independent fan motors that draw ~20 amps each are much easier and cheaper to operate than the 3-wire/2 speed FORD fan. Quote Link to comment Share on other sites More sharing options...
datsun280zx Posted December 7, 2010 Author Share Posted December 7, 2010 Ok so im thinking of using the ford 2 speed now. Think i could use something like this http://www.sonicelectronix.com/item_7324_Kinetik-HC-600-KHC600-HC600-KHC-600.html and maybe connect my amp to not drain out my battery? Also what specific fords did that fan setup come in? Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 7, 2010 Share Posted December 7, 2010 The area of the radiator is approximately 1ft X 2 ft. That means 2 Sq Ft. At 60mph, thats 5280 F/M, meaning 2Sq Ft X 5280 F/M=10,560 cuft/Min Slow your car down to 30 mph, and below that you start to see temperatures rise on a 100F day, so my assumption is that a potential flow of 5,280 CFM would support the car at speeds/heat input similar to driving at 30mph on a hot day. Going by that rule, I have not had an electric fan that failed to cool the car, or cycle in stop-n-go traffic on even the hottest desert days (110-120F!) 1 Quote Link to comment Share on other sites More sharing options...
hoov100 Posted December 7, 2010 Share Posted December 7, 2010 I have the FORD 2 speed fan in my build. It is one hell of a powerful fan. The problem is, it draws as much power as the ENTIRE 240Z electrical system. It will consume normal relays with arcing and heat. You will have to invest in specialty, high-power relays that are not available in local stores. I have used the typical 14" aftermarket fans in several flavors on other cars and found that they are not powerful enough to cool the car in gridlock on a hot day. I used the quick and easy mounting method for these fans and was disappointed with the way they fit. If I were to do it again. I would use a DUAL FAN system with a fan shroud that sealed to the back of the radiator. Two independent fan motors that draw ~20 amps each are much easier and cheaper to operate than the 3-wire/2 speed FORD fan. Ford uses a regular 70 amp relay in most of the cars you can get the two speed fan. I use the lincoln mark8 fan in my autox car and the taurus fan in my z32 with those relays and they don't even get warm after running for several hours. If you are killing relay's then you are not running the correct size. The taurus fan draws 35 amps on low and 40 on high and surges on initial start up to 43 amps on low and 47 amps on high. As a general rule of thumb, 3k CFM minimum with the fan sealed to the radiator and the radiator sealed to the core support and the airbox sealed to the radiator. Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted December 7, 2010 Share Posted December 7, 2010 Coverage matters more than cfm, make sure you get a shroud for it or buy one that has a shroud. Quote Link to comment Share on other sites More sharing options...
Miles Posted December 8, 2010 Share Posted December 8, 2010 Try a Flex-A-Lite 180 fan. It fits the JTR radiator pefectly. 3300 CFM. Draws 18 amps. http://www.summitracing.com/parts/FLX-180/ Quote Link to comment Share on other sites More sharing options...
bjhines Posted December 9, 2010 Share Posted December 9, 2010 (edited) MILES, Don't take this personally. I like the fit you get with the shroud, but that is not going to do it with summer weather in the SE USA on a V8 powered car. You Left Coast guys must not see 98 degrees with 98% humidity much. WOW!!!! $300 for that POS flexalite. It only uses 255 WATTS. That is like the LOW SPEED wire for the FORD fan. LOW speed is not enough to cool my V8 rig on 90 hot days. That fan is nothing like modern factory cooling fans. Even small cars have ~500 WATTS of cooling fan power with dual fans running. Even the Flex-a-lite "MONSTER" dual fans only draw 28 amps and they cost $550 with shroud. That is 4ucking rediculous $$$ and noodle armed weak. Flex-a-lite is total BS and WAY! overpriced. Their crappy little relay with temp probe is $100 for crissake. I call complete bullshavit on all the advertised ratings for fan CFMS. You want flow you need power. The CFM flow AND ultimately the current draw depend on airflow through the fan. Hoov100, Your AMPerage numbers are off. I don't know how you tested, but I did this properly and I used perfectly capable relays for my rig. I would definitely use DUAL FANS the next time around. I got a Dorman Taurus fan for ~$150. I found one at the JY for $40. I remember why I went that route now. I tested current through the FORD TAURUS fan on both speeds. I placed the fan on the radiator that it is to be used with to make the tests. Low speed draws 16.5 Amps @14.2V (235 WATTS) High speed draws 38.7 Amps @ 14.2V (550 WATTS) Here is my set up with the FORD fan ... Edited December 10, 2010 by bjhines Quote Link to comment Share on other sites More sharing options...
bjhines Posted December 9, 2010 Share Posted December 9, 2010 (edited) There are more problems than just relay current capability to deal with. You need surge/spark supression to make the relays last a long time regardless of their current ratings. The 3-wire, Dual-speed fans make that much more challenging than using a PAIR of 2-wire fan motors. I am not even going to get into methods of suppression until we are all on the same page here. I attempted to use a PWM DC speed controller on the low speed wire and switch over to a relay for the high speed wire. This turns out to be complicated because the MOSFETs would fry when switched over at full power. Besides the commonly availble DC controllers all switch the ground side(current sink). That is very frustrating considering the ground is common on the Ford fan. Edited December 9, 2010 by bjhines Quote Link to comment Share on other sites More sharing options...
kj280z Posted December 9, 2010 Share Posted December 9, 2010 I like having 2 1600 CFM fans - plus this gives you redundancy if one fails. Also, you can stage them, with one fan coming on at lower temps and the other coming on at higher temps or when the AC compressor is on... Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 10, 2010 Share Posted December 10, 2010 Try closing the main contactor before the PWM is complete. It should jump the fan to full speed before the driver circuit is running at maximum capacity. This is how industrial soft-starters work, though usually the SCR's will take it all the way up to speed and then use MUCH reduced size contactors to bypass the VSD ramping circuit. In the old days they had full size contactors...someone figured out if it's up to speed or near to it, you don't need a big inrush capability just maximum amperage holding. As for the comment 'coverage is more important than CFM'---I'll call BS on that one! I had twins at X CFM on mine, and it overheated. I replaced it with a larger single leaving FAR more uncovered surface and it cooled just fine with X+ CFM. Later I went back to a dual fan setup for 'staging' of the fans and kept the same CFM as the single...still no problems to date and that was years ago! You can cover the entire radiator, if that fan does not move sufficient air it WILL overheat. If you don't cover the entire radiator, but have sufficient CFM it WILL NOT overheat. Been there, done that. Like BJ says: CFM=AMPERES no way about it. If someone advertizes a 5000CFM fan that runs on 5amps my advice is call BS on it and steer clear! Quote Link to comment Share on other sites More sharing options...
bjhines Posted December 10, 2010 Share Posted December 10, 2010 (edited) In order to allow switching between wires, the output devices would need to be a current source, not a current sink like the SPAL PWM controller. The real deal would be to design a PWM that could provide the currrent needed to run the high-speed wire. There are DC motor controllers available for 50 AMPs continuous, but they cost more than the fans and require an entirely separate controller to monitor temps and respond accordingly. Remember that MOSFETs are DIODES so they self protect unless you open the circuit. Then they self destruct. As far as relay protection goes, we need to remember that these are high power devices. Protection requires high power parts. A diode would be king, but the freewheeling fans can generate enough current to fry most diodes without a limiting resistor. The more resistance, the more arcing at the contacts. A capacitor and relatively low resistance ~might~ do the trick, but determining the optimum values will require experimentation. AC pulses from the unused wire can overheat this type of supression. I should hook up the scope and get some data... Soon maybe. Edited December 10, 2010 by bjhines Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted December 10, 2010 Share Posted December 10, 2010 You guy's seem to know yerr stuff with fans. Can you please give me your opinion on if this fan has a chance in heck at keeping my engine cool? FAN specs Quote Link to comment Share on other sites More sharing options...
bjhines Posted December 10, 2010 Share Posted December 10, 2010 http://www.summitracing.com/parts/RNB-620-101/ is the Taurus fan I am talking about. It costs $170 from Summit and is 3 times as powerful as most aftermarket 15" fans. RB26powered, That SPAL fan is at least 400 watts and should do the job of cooling a big engine. It is a small dia. though and should be used with a shroud. Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted December 10, 2010 Share Posted December 10, 2010 http://www.summitrac...ts/RNB-620-101/ is the Taurus fan I am talking about. It costs $170 from Summit and is 3 times as powerful as most aftermarket 15" fans. RB26powered, That SPAL fan is at least 400 watts and should do the job of cooling a big engine. It is a small dia. though and should be used with a shroud. bj, I looked for the "watts" spec but do not see it. Are you coming up with the watts of all these fans in another manner? Quote Link to comment Share on other sites More sharing options...
hoov100 Posted December 10, 2010 Share Posted December 10, 2010 Hoov100, Your AMPerage numbers are off. I don't know how you tested, but I did this properly and I used perfectly capable relays for my rig. I would definitely use DUAL FANS the next time around. If you are picking the correct relay's then why are you burning them up? I'm not trying to start an argument here, but I have been using the ford 70amp relay for high on every taurus/mark 8 fan I have ever installed and any one of my friends installed and have yet to have one even come close to burning out or malfunctioning, and these fans are used only on high and used on a daily basis. Like I said though, I am not trying to start an argument, but you're being a little hippocratic in that statement. (as for the amperage ratings my friend tested it, I'll ask him the next time I see him and see how he got them) Quote Link to comment Share on other sites More sharing options...
calpoly-z Posted December 10, 2010 Share Posted December 10, 2010 Watts = Volts x Amperage. That fan listed pulls about 33 amps with no load at about 14.6v which means it is putting out about 480 watts. Add some restriction to flow, ahich decreases current draw, and you'll probably end up with about a 400W fan. Quote Link to comment Share on other sites More sharing options...
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