Crunch! Battle Scar

Hey Guys,

Last Thursday I was out at Willow Springs with the Spring Fling crowd. I did a couple of morning sessions on the racetrack with the group and the car performed great. Then I went out for the High Noon drag races, and had a good time there too. Eventually lost a drag race to a Hellcat (big surprise), but I had him at the 60'!

Then I pulled into the pits for the car to cool down. I returned a few minutes later to find a small puddle under the radiator. It took 'till I got home to figure out what had actually happened, but when I got the fan and shroud off, I was able to see the following:



I am running a Wizard aluminum radiator and shroud with an engine driven fan and a standard Mopar fan clutch (removed in the photo). At some point during my track day, I believe during the drag racing, the fan clutch and the radiator came together, closing the 5/16" gap between them and adding an additional 3/32" dent into the radiator. I say it that way because I'm going to ask YOU to tell me what actually happened. Did the engine move forward enough that the fan clutch hit the radiator? Or did the radiator and core support move? (Seems unlikely but someone here besides me is the drag expert).

The engine is "tilted back" in the car compared to the core support and the radiator, which explains why the fan clutch touched the radiator "at the bottom of the circle" instead of in an even circular pattern.

Drag Race Experts: I get that the engine wants to rotate under torque, hence torque straps, chains, etc. But does it move FORWARD in the car under a hard launch?

Ouch!

If you bolted the fan assembly back on, how close is it to the radiator?

Is the scar on the radiator the same height as the clutch or higher than the clutch?

How old are your mounts?

The engine mounts are Mighty Mounts and were installed with the engine about 1,500 miles ago. They should be good, or as good as new anyway. The distance from the clutch, at it's lower edge (which is closer than at the upper edge), is about 5/16" from the radiator, and the scar is definitely from that - from the cooling fins on the clutch hitting the radiator.

That 5/16" was there both before and after the two came together, in other words, the engine moved, hit the radiator, and moved back to its original position. I was actually able to drive the car with no problem after the crunch, it just leaked a little.

Just my opinion, 5/16" is too close. Let's see who else chimes in on a safe distance from rad to clutch fan. I'm going that route on my '62. Just haven't made it to that point yet.

Much too close. Can't speak to drag racing, but I have experienced a ruined radiator due to a hard stop. No fancy mounts or anything like that, but I had at least 1" between the fan and radiator, and my fan blades flexed enough (standard fan, not flex) to completely core my radiator. After the incident, there was plenty of clearance between the fan and radiator (not counting the damage). It is surprising, but rubber mounts supporting 600+ lbs can flex a lot on a hard stop.

Ever think about maybe going the electric fan route?

Actually the electric fan route is exactly what i have been thinking. Only problem is that everyone seems to say that the mechanical fans pull way more air. On the one hand, i don't want to create a cooling problem on an engine that runs perfectly, and perfectly cool.

On the other hand, there is NO data which tells you how much air the mechanical fans DO pull, and we know that even if they pull more air at 6,000 rpm, they sure don't at 800 rpm sitting in traffic!

Everyone just puts on the biggest electric fan they can. Some guys are lucky and it's enough. Some guys have to go back to mechanical because it wasn't. Trial and error sucks. I want to spec a fan that I know will do the job, and if I can't fit that fan setup, I'll know I need to stay with mechanical.

But how do I know how many CFM I need?

I went the electric fan route several years ago. I found a website that had a lot of info on airflow but don't recall the website, maybe Flex-a-lite? I used one puller fan and figured if that wasn't enough I could add a pusher as well, turned out to be plenty of cooling for me. Good luck

Dont change what is already working. Get a shorter clutch and be done with it.. Hayden 2765 should give you the most clearance. A shroud might be a good idea too while youre at it.

good luck

I thought about electric fans, but after considering the electrical upgrades that are needed, I figured I should keep it simple, and stay mechanical.

".....the fan clutch and the radiator came together, closing the 5/16" gap between them and adding an additional 3/32" dent into the radiator."

MP book recommends 3/4" minimum fan to radiator clearance if that helps.

Depends on what mechanical fan & what electric fans your comparing

1) with a clutch fan set up it quits spinning basically when you get up-to
freeway speed, I don't remember where I read it, maybe it was
Mopar Muscle or Hot Rod mag tests art. (??)

2) IIRC the full mechanicals {not a clutch fan} move about 2500cfm,
far less efficient when they are at higher 4000-5000-6000rpms,
IIRC it also said they start to falloff higher they are spun
blades flatten out or just distort or just don't push/pull air the same...

3) I seem to remember reading also, again I can't remember where but it's stuck in my head now for over 20+ years now, the 1st 300-400hp you need like
IIRC 2200-2500cfm {depend in the effectiveness of your water pump
{OE is like 27gpm IIRC} radiator size & cooling system designs& about another 1000cfm for ever 200hp above that...

I like to be on the safe side, I have an Pro-Comp electric wp 37gpm
has a constant gpm flow not up & down like a mechanical pump is,
constant air flow from the electric fan too, not up & down
like a mechanical or clutch fan...
& 2 elec. fans 1 Perma-cool #19115 2950cfm 16" alum. blade
& 1 Perma-cool #19113 2650cfm 13" alum. blade pusher just in case, for in traffic etc.
both fans are reversible too, if need be to change puller to pusher etc.
{all ran thru each on a 30-amp Bosh relays & separate arming switches}
with a 4 core Mancini down flow 22" alum. radiator &
also a custom shroud for the inside puller fan...
No thermostat just a 3/4" hole washer in place for restriction
to keep water in the rad. a bit longer, I've ran this set up a couple times now...
I live in Calif. it's been driven in 95*-100* {traffic} serious heat, no issues of overheating,
180*-190* all day long {knock on wood} BUT; if it shows signs it may climb,
I do worry some then, especially when your beating on them...
I'll turn on the pusher fan, it drops temps almost instantly...

my 383/479ci engine makes about ballpark 600hp & about 600ft/tq



Don't believe all the naysayers, it revs far quicker far more responsive,
make more power not turning the water pump & fan either, another free
{well kind of} another 12-15hp, not running the belt, mec. pump & fan....

It works well for me, You success/results may vary...

good luck what ever you decide

sorry the dirty engine comp. & crappy photos,
it's ment to drive, not just look perty...

Before I spent any money, I would file down all those tabs down too about half there height and gain some clearance. That might be all you need too do.....

Grabinov911 said:

Actually the electric fan route is exactly what i have been thinking. Only problem is that everyone seems to say that the mechanical fans pull way more air. On the one hand, i don't want to create a cooling problem on an engine that runs perfectly, and perfectly cool.

On the other hand, there is NO data which tells you how much air the mechanical fans DO pull, and we know that even if they pull more air at 6,000 rpm, they sure don't at 800 rpm sitting in traffic!

Everyone just puts on the biggest electric fan they can. Some guys are lucky and it's enough. Some guys have to go back to mechanical because it wasn't. Trial and error sucks. I want to spec a fan that I know will do the job, and if I can't fit that fan setup, I'll know I need to stay with mechanical.

But how do I know how many CFM I need?

Click to expand...

I have the Wizard package with the Spal fans. Just give them a call and tell them your hp specs and how you use the car and they will set you up

Can check out cfr performance for electric fans, have some of the best flow numbers and their are kits to hook them up to a thermo switch. I have one for their fans soon to be two on my 72 satellite with a 440

Most aftermarket electric fans don't work very good on the street with heat and low vehicle speeds.

Those Champion radiators really push the core back.

Is the car a manual trans? Is it an Tremec and/or Keisler conversion?

Tom Quadrini mentioned engine movement under braking with his Cuda AAR and 70 Charger he built. IIRC he had a picture that showed the motor tilted looking at the headers underneath. It was tilted down on the drivers side, not up like on acceleration. I know you situation is the motor moving forward, but it shows that on a road course things are happening no typical than what most are used to.

2-11/16" is the Hayden 2765 clearance? How does this compare to your current fan clutch?

khryslerkid said:

Just my opinion, 5/16" is too close. Let's see who else chimes in on a safe distance from rad to clutch fan. I'm going that route on my '62. Just haven't made it to that point yet.

Click to expand...

I agree, the measurement I've commonly read is between 3/4" and 1 1/2". My fan clutch is too close as well, maybe 3/4". I've considered switching to a set of electric fans.

Why the contact? My guess is chassis flex. The lower radiator "support" is just 16 guage sheet metal. XV motor sports used to sell a square tube to replace that thin stock sheet metal. The additional support there reduced frame rail and chassis flex. I'm thinking about looking into that.

Go with the fore and aft limiter like is shown on the motor plates thread.

autoxcuda said:

2-11/16" is the Hayden 2765 clearance? How does this compare to your current fan clutch?

Click to expand...

The car is a 727 automatic. The fan clutch I had been using is about 3 1/8", so it looks like I could save 3/8" to 7/16" or so just by switching fan clutches. That's a lot.

I just put on a Flex a Lite flex-fan with a 1" spacer and it's just a hair too tight with the idler pulley shaft - it just barely touches. On the other hand, The 1 1/2" spacer I have puts the fan much closer to the radiator. I have been looking for an 1 1/8" spacer but that doesn't seem to exist.

I may just try that Hayden clutch. And I'm going to have to look into that fore/aft limiter idea...

Did the water pump let go?