Thought I would start another post about cooling a 500+ BB in an A body. Still not sure which way I'm going with the radiator,but as this point I could go A or B body down flow.
I would like to cool this with a 440 source mechanical 40gal water pump and a flexi-lite 6 blade fan with a full rad. shroud.
Can this be done or do you think it would be easier to cool with electric fans?
Heres the fan.

Mechanical fan on a clutch or electric. Never a direct drive fan.

Mechanical can move a lot more air, but the advantage of electric is you can cool the radiator while the engine is off. If you are over heated, kill the motor, let the fan run a minute, then fire it back up to circulate water, and repeat till you're cool.

I like electric because it's only on when you need it. Not turning the clutch/fan when you don't need it. I kept a 500 hp big block cool with a properly sized fan and clean, well maintained radiator

A clutch hub is not gonna fit in there. it was very cramped with my electric fan and water pump when I had the small block in it.

I ran into that problem too with my 451 A-body. Even with the shortest clutch available (Hayden 2947) there would have been less than 1/2" clearance to my radiator core...

If you don't run a fan clutch, a direct drive has two problems - lots of wasted hp at higher RPMs, and possibly more importantly, high fan RPM that could result in a catastrophic explosion.

I installed a Contour dual electric fan. Remains to be seen if it's enough to keep it cool in a hot Missouri summer.

I understand. The theory is the blades are said to straighten out at high rpm minimizing hp losses. This fan does move a ton of air at idle or low speeds. I may just have to use electric fans. still trying to figure what works best all around. Maybe someone has done this with good results.

El decapitate..........those things are dangerous and I run the HHR chevy fan w/a Moroso w/p. and they work well together and the new pump cools a bit better. Street car, desert heat.............

Dom, what size is that pump? I was looking at the summit pumps earlier and i think they are 35gal pumps. Would that be enough flow.

never say never.

Yep. I ditched the clutch in favor of direct. Best way to move air if that's your goal.

Those flex fans are notorious for losing blades and hurting people. Get a good electric fan setup. I use the fan and shroud setup off a 2003 dodge Viper.

What you propose would be the way I would go, ( Simplest, least costly, best cooling capability, no additional amp draw issues to contend with ) especially for the street. I would lean more to electric for race only application.

A flex fan costed me 15 rwhp on a chassis dyno. And that was on a 370 rwhp car.

I like the electric fans and pump, for street or strip in my big block A-Body. On the street, if you would run into a problem with the car running hot because of traffic on a hot day. You can just stop and let it cool down. Same when you at the track between runs. But that's your own choice.

Then fan you posted is the fan I use.

I can tell you that a quality mechanical pump and fan with the correct pullies (I overdrive my WP 6% and would have done 10 I'd I could have found pullies).

I have a hard time getting heat in the engine without a Tstat.

The WP, speed you turn it and the area of the radiator is what counts. Most guys don't run enough pump or pump speed. Flow is what cools. The fan pulls air at idle and low speeds.

I dont know which one you had, but i read a shootout on mechanical fans about 15yrs ago and my fan cost 7hp in that study. With 700 hp im not too disappointed in that.

Cool and good to hear that. This fan moves a sh!t ton of air at low speed. If i do decide on electric fans i will do the fans and shroud radiator combo. Easy, just drop in and done.

If you are over heated, kill the motor, let the fan run a minute, then fire it back up to circulate water, and repeat till you're cool.


Even if your not overheated, leaving the ele. water pump and fans goes a long long way in the life of cast iron heat cycles.

Ive tried a mech fan in the past just to try to keep a oem look, things can get ugly at 6k plus shifts, plus if its a normal v belt ive always tossed them and then as well ive burnt up so many alt. bearings.

I have a serpentine pulley system. I had the electric pump and fan on last sb combo. They do have benefitts for sure. I already have the mech. Pump and fan. Just need the radiator at this point. Its good to get other ideas or opinions. Thanks

I have a serpentine pulley system.

I was thinking that was the case, im too cheap to pop for the serpentine setup.

BTW Dave im getting ready to go at my good 360 block again, the one Im so fond of that I mentioned to you.

Cool. Whats the plans for the block?

Cool. Whats the plans for the block?

Some old school domed pistons and a nice pair of iron J heads.... going back to stone age stuff on it but its still fun.

http://www.network54.com/Forum/215655/message/1066184641/Car+Craft+Cooling+Fan+Dyno+Test Flex fans scare the crap outa me

'nother http://www.carnut.com/ramblin/dyno.html

electric fan & electric pump. can cool down fast with engine off, can warm up fast with fan off. if its a bracket car its the best you can get.

Looks like the same article. 1308 looks closest to mine. Shows 20hp loss.

Word of warning, we bought an Ebay unbranded chinese electric fan to supplement the stock fan on our mild small block a body build, just in case we needed it. Never had to use it. During a burn out, the stock fan pulled enough air to exceed the electric fans safe working RPM and it promptly exploded taking out the radiator and part of the grill. Messy
Another point of note is we noticed the car would pick up on et and mph if the fan belt slipped those stock 8 bladers must take some power to turn at high (ish) rpm.

Hey Dave,
Over here with 95 deg F plus and 90% humidity, a Flexalite nylon fan, matching shroud on an aluminum radiator with 160F thermostat cools a 600hp big block in an A body. Idling in traffic sees 175-180F. Does get better than that.

Nothing wrong with the flex fan, if you don't have enough room for a clutch fan. My brother has had one on his car for years and street drives it and races every weekend and it cools good and has not flown apart. I have had both electric and mechanical fans on cars over the years. Electric fans are nice, but more complicated and need a good electrical system to support them. My wife was driving my car to work on time and the electric fan died= major overheat. After that I went back to stock shroud and fan setup. Really are you going to notice a few hp loss to turn it on a street car.

Remember you will be putting an additional 25 - 30 amp draw on your electrical system - at idle, which could necessitate an alternator change. If you have to run the fan with the engine off because of an over heat, you got "other" cooling system problems that you sure don't want to deal with on the street. Some of the HP losses quoted with a mechanical fan are way on the high side (IMO) and usually don't take in to consideration the HP loss caused by the additional 25-30 amp draw that the alternator has to supply. Due to clearance issues with my street rod, I have to run a 16" electrical fan. Draws 24 amps and I can actually watch the rpm drop when it kicks on. Unless it has been damaged, Flex fans are as reliable as any metal fans. Mine sees 7K at the track all the time.

I'm not afraid of this flex fan coming apart. had it for 18yrs now, was on my 340 for maybe 4yrs. iv heard the stories since the 80's about them coming apart ,but have never experienced it myself. when I switched the flex fan for the electric I could not tell any seat of the pants improvements.
so, as of now I'm leaning toward the A body down flow with 1.25 2 row with shroud and flex fan. should be pretty much drop in and if the car goes into the 9's with this set up it stays, if not then it gets the electric fans and pump. project wont be finished til about 4 of july.

I run the same flex fan you posted as I cant fit a factory clutch fan in mine and I have also run flex fans for years and never had any blades come loose. I check them every so often when the hood is up. I have used this one since 2006 and its still tight and not loose at all. I dont race alot as my son dont either and we still have the factory flex fan on his Dart which we always check and has also never had a problem. I did install an electric pusher fan for back-up as when I sit in traffic for a long time (about 1/2 hr) it creeps up to 200 and then I hit the toggle switch I have the electric fan on and it keeps it from going over 200 when sitting still in traffic.
Factory clutch fans work on eng temp as if you are racing and the eng heats up enough before you launch the factory style clutch fan can engage some and rob some hp going down the track. To me you need to be sure you leave the line below 180 to be consisdent with a factory clutch fan to be sure its not engaging any when you make a pass. I have heard some aftermarket clutch fans work on rpm only and just slip at high rpm and engage at idle but I have never used an aftermarket clutch fan. Ron

Ron, what radiator and shroud set up do you have?

Dave its an Afco aluminum rad I bought from Mancini as I just told them it was a 63 Sport Fury and they new which one would fit. I did not want to spend the money most places wanted for a good shroud to fit as most wanted over $200 for a shroud ! So I went to the salvage yard and got a shroud from an early 90's Dakota and modded it some to fit. It works pretty good and was alot cheaper then the good ones they sell. Ron

30 amps at 14 volts is 420 watts. 1 hp = 746 watts. Allowing for alternator efficiency, belt frictional losses, etc. that's less than 1 hp to drive the electric fan. Even if that 45 hp from the magazine article is double what your experience is, I'll take 1 hp over 20 hp loss any day.

The reason the RPM drops when that little load kicks on is that your idling engine is only making a couple of hp just to turn itself over, so the alternator load is a significant change... same thing happens on a non-computer-controlled car when the A/C compressor kicks in.

Thanks Ron

The newer Morose say bet. 35-37 gpm and should be more that the old ratings based on what Moroso told me............The HHR fits perfectly on my 26" tank to tank Griffen..............

I am soon going to install the updated Moroso pump and an electric fan on my 318
Moroso says 30-37 gpm, way more than the one they sold years ago that I used on my old car. And that one even worked decently on the street on a 9 sec car.
Btw, my brother and I years ago swapped on electric water pumps and fans on our cars. Both were sorted out cars and we both picked up a tenth with zero other changes.

Thank you doctor.

For that post I was wearing my engineer hat instead of my doctor hat

On my 505" stroker, I run a 318 poly radiator from a manual trans car. No lower tank for the A/T. I run the Hayden short "Jaguar" 2765 clutch on a Mopar fan. I had them move the saddles back 1/2 inch when they rodded out the radiator. It not only keeps it cool at the track but in stop and go traffic as well. Surprised the heck out of me it works so well! No shroud either. I have friends with high dollar aluminum radiators, electric fans and water pumps that shake their heads...

For a water pump I used the 440Source pump and housing. NO thermostat!

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?

OEM dual fan setups often just turn on the one fan at a certain temp, and when under hi load, AC on, hot weather, towing etc will turn on the other to rapidly pull heat from the rad/system.

For our cars, its the idle temps that usually are the issue, this is where the right elec fans shine.

If elec fans were crap - OEMs would not use them. They have already spent a fortune doing the R&D, the secret is to adapt the right ones, wire them correctly and make sure the Alt has enough beans to keep the system topped up.

In other words match your parts so that they work as a system

my alt is a 100A from Toyota 4runner. works good, but dual fans may be taxing.

Oh yeah, forgot, I use a 440Source wp pulley and a Moroso underdrive pulley on the crank was worried about it with the underdrive pully but no problem on even the hottest days!

Those #'s are "SLIGHTLY" high - IMO. I won't quote any numbers, but most electric fans actually run slower at idle and how much slower will depend on just how much your alternator is up to the task at idle, where it supplies much less current. A flex fan actually works just the opposite from your explanation. There is much less HP loss at speed ( higher rpm's ) where the blades flatten out -( reads "FLEX" fan). No one on this site really cares what the HP loss is at idle. They're just concerned with cooling. And as I said, todays cars are designed from the ground up for electric fans. They have well over 100 amp alternators with a very fast current rise curve ( very small pulleys, serpentine belt driven ) and they are cooling sewing machine motors that seldom see 5K rpm. - Apples and oranges. Flex fans don't use ( or need ) a fan clutch. Stick with your Doctor's hat.

I've run flex-fans on a few cars, all with good success. I've read the horror stories, but never had an issue nor ever met anyone who had one come apart. My current setup is a summit 7-blade flex fan and a homemade aluminum shroud on a summit radiator. Water pump and housing are 440-source units, and I run a 160 stat. My car stays nice & cool on the street, and is generally plenty cooled down by the time I get back to the pits after a run.

Just last year my buddies chevelle started getting real hot between runs at the track one day. We thrashed between rounds to find that electric water pump relay had crapped out. We had to bypass it. Turned out okay , but he almost missed a call. I know the OP is about fans, not pumps, but my point is I like simple & reliable.

I agree with you. I'm gonna need a upper hose just like the one in the pic. original # part?

which makes sense in theory, BUT, that fan speed, and type, make all the difference. my fan, at idle, pulls MUCH more air than all the electrics i tried. my combination didn't work until i bumped the fan/water pump speed up. it only took a little. i ran before/after at the track, and it ran EXACTLY the same e.t., regardless of which fan i ran. i did try a 7 blade, and it did slow about a half a tenth. it didn't run any cooler. as far as my definition of "hot lap", it was a 100 degree plus day at my home track in central oregon. i had gon out in the first round, so i bought into the "gamblers" bracket, which i won, because the last two opponents were unable to make it to the line. i made three passes in 10 minutes. THAT IS HOT LAPPING, methinks. flame on... i can take it...

Making use of the vacuum advance could also help in keeping it cool on the street.

Most guys try and save a bit of HP by slowing the WP down. I'd rather run it a bit faster. I run my at 6% faster than OE.

vac dist. wont fit with victor heads. I bought a vac pertronix which I now have to resale.

Yes, if you have a properly designed electrical system, it won't slow down. That only happens when your alt can't keep up with the demand and maintain 14 volts.

And once again, a flex fan takes less but not "much less". The flex fan, especially without a clutch, consumes a lot more hp at high rpm than you think. Look at the tables.



You can stuff that attitude. I may not be as much of an old-timer as you (built my first big-block A-body around '83) but I know what works and what doesn't.

Picture is current as it sits (on jackstands with all sorts of things unhooked). New HP carb doesn't have provisions for vacuum advance. I'll have to plug it, just haven't plugged it yet.

I've had it for years, don't have the part number handy. All I did was go to the local Napa, and start rifling through all of their hoses until I found one that I though would work. Had to get a sleeve to step down the size of the radiator side.