Dave wrote:But I never made a single run up the strip without it wizzing away.
you could have turned it off.
Not without overheating. This is why drag racers only fire up their engines when they get to the start line. So the engine is cold. But on a hot race day it takes ages to get the engine cool enough to race again. Going around back to the fire up lane after a run at a hot Mopar Nats you usually find the block is still at or only just below operating temp by the time you get to the start line again.
Most modern cars run at about 220F I think? These old Mopars have to be kept down to 160-180 degrees to make any power and the more power your engine is making, the more heat it is generating.
I am not knocking electric fans. They are great. Just don't expect them to make more power. That is the only point I am making.
Dave wrote:
So it actually robs more HP from the engine to run an electric fan that moves the same amount of air as a mechanical fan.
You cannot create or destroy energy. You can only move it around and every time you change the type of energy there are losses.
thats the point i'm trying to make. move the losses to where it doesn't matter
also for drag racing why not fit a micro switch that shuts the fan down at full throttle? not needed when moving and comes straight back on as soon as the run is over
i always found on the rolling road 75 degrees C gave best power. the reason modern cars run much higher tempratures is to make sure the fuel is completly vaporised for a more complete burn improving emmisions and fuel economy .
As regards engine losses, I fully agree with you there. I'm not saying you can't get an electric fan to work, just trying to point out that the aftermarket types that most people go for aren't up to the job. When it comes to losses, viscous fans are quite efficient by all accounts. Factor in the additional weight of the "right" fan and the larger alternator needed to run it, did you really gain anything? I'm not convinced it's worth the effort, but as always I'm listening...
I would go with what Blue says, I have tried electric but all needs to be correct, like rad shroud , alternator etc. It looks much better I think with electric but then big blocks (RB) can have issues with keeping cool at the best of times.
Last edited by TW71 on Fri Mar 14, 14 11:25 am, edited 1 time in total.
This is my set up 2x12" fans Ali rad and shroud run off a thermo switch that has a temperature probe that sits in between the veins of the rad, I have a switch I can over ride it so it is on permanently if I want
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Petty Roadrunner 416 Stroker 4 Speed
*MMA-609*
"Built to be driven!"
Leccy fans, flex fans, desk fans - you name it, I have tried it......
I wanted to fit a viscous fan, however that requires cutting of the slam panel in an A Body / BB car. To overcome this I have fitted a Jag XJ6 viscous coupling. TrevD made a adaptor although I did have to search about a bit for a left hand bolt that secures the coupling to it.
