Since you seem to know Ohm's law, How long can his 650 CCA trunk mounted battery sustain a 25 amp draw with the engine off @ zero ambient temp before he can't start his car - causing him to miss his Doctors appointment?

Zero degrees and he's overheating so badly he has to shut down but keep the fan going to cool the radiator? Sounds like the worst case scenario. At that point, I'd walk away from the car.


No need to run the fan any longer than 90 seconds with the engine off to fully cool the radiator. I've tested this. From scalding hot radiator to cold to the touch. If the engine is overheating, that's the time to start it up, give it 2500 RPM to add amps back to the battery and circulate the water.

If his battery can't supply power for 90 seconds with the engine off, again, he has other problems.

25 amp draw is huge. Without the math, probably about two hours.

That's what's nice about the mercedes fan. With the fan running at idle (25%), the ones I've tested pull less than 10A if I recall correctly. It might have even been around 5a Certainly nothing near the 30-40a it will draw at full speed.

Around 1986 a guy in auto shop was showing off by revving up his mom's car. Well needless to say it shot a fan blade through the fender right next to where he was leaning on it. I will never forget coming around the corner into the shop and seeing a hole in his fender then looking over and seeing part of the fan blade stuck in the wall.

I still contend that if you are running a large HP motor, mostly on the street, a large flex fan and good shroud are the way to go. It will move more air than most electric fans where you need it, Big improvement in street reliability ( no wires, relays, controllers, switches to contend with ), less than a quarter the cost, no additional burden on your existing electrical system. Trade off for the above will be a small amount of HP.
Most cars today run electric fans. They were designed from the ground up to run them and only have to deal with cooling engines that are less than 1/2 the HP we are working with. "Yesterdays" cars only used mechanical fans - what they were designed for.
IMO, it's really all about the application, as are many threads on this site. Both types have their +'s and -'s. Want reliability on the street, mechanical fan. Want that last bit of HP for the track, electrical.

I agree as this package might make a 400 mile trip to a car show in the u.p. of michigan.

400 miles with a full fill of Hard blok You are a very brave man Mopar Dave. I had a 7 blade 18" flex fan in my Challenger for years when it had a 440 in it however when I installed the 505 my cooling problems started big time. The fix was a Smiths 2 core aluminum radiator with my old 7 blade flex fan from my previous set up. The motor cooled down quite a bit but still got too hot for my liking last year on Woodward ave during dream cruise. The fix was installing the factory original 7 blade clutch fan. The car has sat in traffic running in temps exceeding 80 degrees for over 20 min without even coming close to overheating I guess those Chrysler engineers knew what they were doing back in the day.

I'm running an old Direct Connection 5 blade clutch fan and stock repro pulleys from 440 Source on my 493 and it runs nice and cool at any speed. I'm running an older factory water pump that has less clearance to the Mancini housing. Later model pumps were designed with more clearance to run hotter for emissions purposes.(just a theory I share with a few other engine guys)
Gus

where did you find that shroud?

The hard block may or may not cause any cooling issues from the responses I received on here. some good and some not so good. I took another look in the block yesterday and the fill is 2 1/2" from the deck. Once up and running and tuned I will start venturing out around town then a trip to my fathers about 80 miles and if theres no issues with the cooling at that point it can be driven any where. I figure since I have the fan and pump, why not try them before spending anymore than I have too. If it wont cool, then go for the electric fans and maybe water pump. seems like the smartest thing to do. If ya have the parts already why not try them first.

Got an oil temp gauge? If not, I would install one. You won't have a water coolant problem. Shroud can be found on any 77 - 79 Cordoba. Pic is of my 79. It's the stock shroud on a Griffin aluminum Rad. Actually ran that shroud with multiple engine and fan applications. Pic is of a NA small block (street application) making about 350 - 400 HP. Same shroud as in other pic but with a 16" electric fan bolted to the outer edge of the shroud. You can see the Capillary tube ( going in to the upper rad hose ) and the on off fan controller in the lower left of the pic. New, but stock rad. Not totally trouble free, but did ok on the street at that power level ( barely ) and car ran high 11's. No way it was going to handle a 650 HP blown application on the street. This is just my experience and there is a lot more than just the fan ( mechanical or electric ) to making the system work in any given application. I don't have a hard on for electric fans, just think they are over portrayed as the end all to be all - with no down sides - and they aint. Please don't get me started on electric water pumps. I do like Ewectwic Gitars.

oil temp gauge equipped.

i run a flex-a-lite 19" 6 blade on my junk. i don't even have a shroud. my fan (and pump) are slightly overdriven (pulley size can make or break the combo). i have NEVER heard of, or seen, a flex-a-lite throw a blade. ever. their fans are rated at 8 to 10,000 rpm, depending on size. i tried every electric fan on the planet. wasted a lot of money, but learned a lot. the big dumb fan, and appropriate pulleys were the answer in my case. nothing fancy. the fan is quiet, and moves a preposterous amount of air. yeah, the electric freed up a couple of horsepower, but what good is that when you're stuck in a traffic jam, or hot lapping, and the temp is ratcheting upward? i'll gladly trade 10 hp for stonewall reliability. i actually won a race once because my competition couldn't make it to the line (it was a very hot day).

I think mine is a 16" fan. I thought that I might be able to reuse my march pulleys from the small block, but the water pump pulley does not fit, too deep. I will need another wp serpentine pulley. 440sourse has them. How do you figure over/under driver percentage? this would be the time to get the sizes right.

My setup never goes above 210 in the August heat..

A body , Rb , 12:1 , half filled , griffin alum rad. , 2007 HHR fan trimmed to fit , and stock water pump .

car trimmed to move the rad forward 1" .

I have around 1" from fan motor to w/p pulley .

Heres a link to the fan :


http://www.ebay.com/itm/Apdi-6016144-Engine-Cooling-Fan-Assembly-/361557605754?fits=Year%3A2007%7CModel%3AHHR&hash=item542e833d7a:m:mYc7ccvZDdaj_Sp_fQsp80Q&vxp=mtr

185 max.

Griffin rad, OEM GM dual fans snug/sealed to core and pulling air from the WHOLE core, relayed wiring, triggered by temp sensor with manual overrride locked out timing, 120A alt.

In a 572 Hemi A body, not well known for cooloing for for radiator width/room.

Most down here always use OEM dual fans for cooling and wire em the same way the factory did.

They're cheap, reliable, designed for the long haul and pull a truckload of air.

ok, will keep that in mind.

The electric fan moves the same amount of air whether idling or high rpm. However, the mechanical fan is moving MUCH less air at idle, which is exactly when you need it the most. Fan clutches help by slipping at higher rpm but now there's another source of reliability problems.

What kind of "hot lapping" are you referring to?Any time the car is moving over about 20 mph the fan only gets in the way. If you're overheating while moving, either the airflow through the core is insufficient, or you don't have enough radiator. The type of fan won't matter here.

Finally, it's not "a couple" or even "10 hp", didn't you see the fan test article (and other similar tests)? Would you gladly give up 30 or 40 hp?