BMW M5 Forum and M6 Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
931 Posts
Discussion Starter #1
Here is a mod that should help the engine rev up quicker, cut some weight, and keep the rev's up between shifts. Get rid of the OEM mechanical engine fan and put in an electric fan. I used a Perma-Cool 16" High Perfomance unit from Perma Industries, Inc. Ontario, CA (www.perma-cool.com). You can find distributors via. web search (www.jegs.com is a good source). I also got their adjustable 160 - 210 F thermal switch/wiring kit. Removing the fan is easy, just remember the fan has reverse threads. A quick smack with a hammer on the wrench will break it free. The install is a bit involved as I had to remove the front bumber, radiator plastic, headlights, drain the radiator, lossen the radiator so it can be moved rearward to pass the plastic mounting ties thru the radiator core. Not for the faint of heart. I had to figure out how to wire up thing and pull power. I used the crimp connectors and heat shrink tubing to seal things up. Power is taken off of the Battery terminal at the engine. Wires are covered in corrogated tubing for the clean look and provide protection. I set my temp at 160 degrees, and have not had any problems at all.

The fan....



Fan support leg mounted to the radiator.



Close up of wires coming off the fan and secured to OEM fan bezel.



The power tap.



Many racing cars and high performance rigs use the electric fan so as not to use engine horsepower for cooling chores. If anyone decides to do this mod, let me know how it goes. Take your time, and do a good clean job. Good luck!

:M5launch:
 

·
Registered
Joined
·
2,817 Posts
That's a great mod, mr_bock. I've been through 2 summers now without the mechanical fan, without even adding a supplemental electrical fan. But it doesn't get very hot here in Michigan. A true no-cost, fast, easy mod that works.

When I picked up my car after Inspection I service, the SA said "Your fan is missing....but you probably knew that... yup :7:
 

·
Registered
Joined
·
1,346 Posts
Sounds interesting!

I live in Finland, and the winters are about 0 to -20 celsius, autums 10 to 0, springs the same, Summers 15-30 celsius. Close to Michigan?

Do you think I could remove mine?

If so, do I really have to take all those parts of?

And what is the gain? hmmm
 

·
Registered
Joined
·
12,398 Posts
You're using HP for engine cooling- can't get something for nothing.

You're pulling it from the battery- which gets it from the alternator- which gets it from the engine. Doesn't the alternator requre more HP the higher the current draw?

What am I missing?

ard
 

·
Registered
Joined
·
2,817 Posts
bayerischemotor said:
Sounds interesting!

I live in Finland, and the winters are about 0 to -20 celsius, autums 10 to 0, springs the same, Summers 15-30 celsius. Close to Michigan?

Do you think I could remove mine?

If so, do I really have to take all those parts of?

And what is the gain? hmmm
Climate sounds similar. You might want to remove one or both of the intake pipes to gain better access to the fan. That's it.

If you try it, just keep a close eye on your temp gauge. My electric fan came on maybe twice this summer.

Regarding power gains, there's a thread that claims 8HP or so. Don't know about that, I'm just happy with how quiet the motor idles.


:cheers:
 

·
Registered
Joined
·
7,514 Posts
The stock fan has a viscous clutch that engages progressively with increasing temperature during idling or slow engine speed conditions. Once on the road with sufficient air flowing through the radiator (i.e. 25mph), the clutch is free-wheeling with extremely low drag (i.e. you could easily turn it with your hand) even in very hot ambient conditions. For the most part, this modification will likely result in no measureable difference in power to wheels at engine speeds over 4k rpm with 25+mph road speed radiator air flow. Even when the termperature is such that the viscous clutch is engaged, if you rev the engine you'll see that it starts free-wheeling around 3.5k rpm or so (you can hear it disengage).

Now if it was hard locked to the engine, it would be a different story of course ;) .
 

·
Registered
Joined
·
931 Posts
Discussion Starter #7
ard said:
You're using HP for engine cooling- can't get something for nothing.

You're pulling it from the battery- which gets it from the alternator- which gets it from the engine. Doesn't the alternator requre more HP the higher the current draw?

What am I missing?

ard
The fan is being powered by the battery (stored energy). The alternator is always powered, battery is being recharged as required, no real change in usage. Incidently the electric fan only comes on when higher temp comes up. If you live in a cool area, you don't need the electric fan. I live in Virginia, our summers can get hot :eek: On cool days, I suspect that the fan does not even come on.
 

·
Registered
Joined
·
12,398 Posts
I always thought the electrical system balanced the alternator output to the power draw... As you turn on more power sinks (lights, radio, etc, etc) the excitation voltage to the aternator is increased and the alternator generates more current to supply the demand- hence a balanced system. It is virtually impossible to pull the battery down and PREVENT the alternator from resonding. As the excitation voltage is increased the alternator's internal swept magnetic field is increased, creating more of a drag on the motor. (The hp required to move the alternator increases as more current is generated).

If the only argument is that you can keep the fan off if not needed, I agree- but if you need the cooling it is a zero sum game.

I remember a co-worker who determined that adding an electic motor (powered by the car's battery) to 'assist' his Karman Ghia and reduce gas consumption would be a perfect solution...

ard

PS Hey, is one HP equal to 746Watts? (Remember that physics??) I suppose we could look at what a fan draws and infer the HP required.... 12V x60AMPS = 720 Watts of course the fan is not 100% efficient..and it doesn't draw 60AMPs. I remain skeptical of the HP gain. Don't get me wrong- nice work on the mod.
 

·
Registered
Joined
·
2,817 Posts
Another reason to ditch the fan... it's heavy :crying2:
 

·
Moderator
Joined
·
10,445 Posts
mr bock, can you post any pics of the thermostat? Does it tap into the cooling system (ie. splice into a hose) or is it one of the ones that measures radiator core temp? (or maybe provide a pn from the jegs site)
Thanks,
Mike
 

·
Registered
Joined
·
931 Posts
Discussion Starter #11
mottati said:
mr bock, can you post any pics of the thermostat? Does it tap into the cooling system (ie. splice into a hose) or is it one of the ones that measures radiator core temp? (or maybe provide a pn from the jegs site)
Thanks,
Mike
I searched PermaCool.com to make my selections, then search the web for suppliers. #19115 16" High Performance Electric Fan and #18905 Wiring Kit (Adjustable 160 - 210 degree F Thermal Switch). This sensor is set in between core tubes in the radiator. I selected a spot that was easy to reach and away from any moving parts. I also selected the adjustable switch as I did not know what temp I would need. I have mine set to the 160 F setting.

Good Luck to ya :2:
 
1 - 11 of 11 Posts
Top