What do ya know about this?, Horizontal electric for 914 engines? Options

[JPB]

Aircooledclassics has an electric horizontal fan set up for 914 engines. My question is has anyone ever seen one in use or used one? It looks like a good idea but wonder if it would be good for street applications since they imply for "racing". 1200 cfms is not much wind compared to stronger fans on the market that can even push 3500+CFMs. If it does save HP from the power plant, then its worth it and it will give the engine a stead air stream compared to the belt/fan deal which will only supply higher CFMs at higher REVs. (IMG:http://www.914world.com/bbs2/html/emoticons/popcorn[1].gif)

[Joe Bob]

I tried a dual electric fan set up once and it was less than adequate.

The DTM by Jake, the upright 911 fan or the current T4 that are belt driven tend to be the best bet.....too easy for a failure on the electric.

[rhodyguy]

more continous current draw for our puny alternators to deal with. the idle falls off plenty on my car with the lights and everything else on, as it is.

k

[Jake Raby]

Do searches...You will find a lot.

Email to ask them how much pressure the system creates in the upper plenums, I'd like to see if they have any data and if so if it matches what I measured when I tested the arrangement against the 914 DTM.

It's all about pressure and those axial fans make about 1/2 as much pressure as the stock cooling system does on it's most effective side of the engine (right side, 1-2 cylinders)

As for being efficient, taxing the alternator and etc that much more robbed 3 more HP from the engine than we saw with the same test without the arrangement in place, with the alternator only supporting the engine...

It's fine if ALL you do is Auto-X, load the engine up in a stock 914 and see what happens in 5th gear. I have data.

[JPB]

I guess what you are saying is if you need air cooling from the belt or the alternator, its all costs HP's from the engine right and its better and safer from the original setup (IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif) ?

[rhodyguy]

and money better spent on other items.

k

[brant]

I've seen plenty of them..
used on -4s and on -6s..

strictly a racing item.
NOT a street fan

brant

[JPB]

Cool and informative. It sounded so good at the time and yes an oil cooler would do the trick instead of modifying something like that. THNX. (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

[jd74914]

Of course, if you are into the horizontal thing you could always go with a Tangerine-type setup .

(IMG:http://www.tangerineracing.com/images/EnginePics/RACE_ENGINE.JPG)

[Joe Bob]

Yeah that 90 degree bend worked wonders for the Corvair....

[alpha434]

QUOTE (Jake Raby @ Mar 25 2006, 07:35 AM)

As for being efficient, taxing the alternator and etc that much more robbed 3 more HP from the engine than we saw with the same test without the arrangement in place, with the alternator only supporting the engine...

Be specific. According to my data, the #1 HP robber is the fan. Not the alternator. So are you saying that you have a net loss of 3 HP with an electric system as opposed to the stock setup, or to no fan at all?

[lapuwali]

The power loss from the alternator scales with the amount of demand on power from the alternator. The stock alternator can put out 55A at peak, but usually only puts out 10A or less. Given typical efficiency of 50%, that means the normal power loss from the alternator is 1/3hp, but the loss at a peak load is over 2hp. Two 1500cfm electric fans would draw about 40A, or 560W, doubled to 1.1kW loss at the crank, or about 1.5hp, just driving the fans. That assumes the alternator really is 50% efficient (a common rule of thumb, but only that). If it's only 25% efficient, that's 3hp (and that also means the normal alternator loss is closer to 2/3hp).

The belt drive to the alternator also causes some conversion losses, though that's usually only 2-3%.

Given that centrifugal fans are more efficient than axial flow fans, and that the fan is direct drive on the Type 4, it's very likely to be much more efficient than this.

[alpha434]

I already knew all the stuff in regards to calculating alternator hp loss. Or sometihing close to what you said. The fan has to push a lot of air into a high pressure system and maintain that pressure system. There is a huge loss with the fan. Much greater than with the alternator at full draw. You would be surprised.

The advantage of a belt drive system is being able to set a ratio for the pulleys specific to the amout of air you need, the amount of air you can provide before starving the fan, and your average RPM range.

And then you loosen the belt to give you that extra oomph.

[lapuwali]

Energy in = energy out - unavoidable thermal losses. Plain, simple thermodynamics.

If pushing a fixed amount of air, then you have to expend a fixed amount of energy to push it.

If you use a system with a fan that's attached directly to the crank, or you use a system that has to drive an alternator through a v-belt (small power loss), then the alternator has to convert this to electricity (big power loss), then you have to convert the electricity back to mechanical energy with a motor (another big power loss), which one is going to end up drawing more power from the engine to deliver that fixed amount of energy?

[alpha434]

QUOTE (lapuwali @ Mar 26 2006, 11:19 PM)

Energy in = energy out - unavoidable thermal losses. Plain, simple thermodynamics. If pushing a fixed amount of air, then you have to expend a fixed amount of energy to push it. If you use a system with a fan that's attached directly to the crank, or you use a system that has to drive an alternator through a v-belt (small power loss), then the alternator has to convert this to electricity (big power loss), then you have to convert the electricity back to mechanical energy with a motor (another big power loss), which one is going to end up drawing more power from the engine to deliver that fixed amount of energy?

But with an electrical fan, you have constant output at all rpms. Unless you want to change that. The advantage would be at high revs, where the attached fan has the most power loss, and is borderline starving all the time. With a properly setup electrical fan, the hp cost would be constant, since the fan will always need the same amount of energy to turn the same speed.

[dstar]

I own an ACC electric fan and made the mistake of trying to breakin
an engine with it.

Head temps went to 400 in less than 5 minutes of run time....with 55 degree ambient air.......
(IMG:http://www.914world.com/bbs2/html/emoticons/mad.gif)

Had to switch everything back over to stock cooling to run the engine in.

Strickly a race only fan, unless you have ducted/forced air.......then pray
you don't get caught in *traffic*!
(IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif)

Don

[rhodyguy]

looks like the only way to find out is for you to buy and install one chris. strap the car to a dyno, give it a run or 2, switch back to stock, 2 more runs, and report with your readings.

k

[brant]

I would like to add that when these electric fans are used in RACING applications...

The reason for doing so is entirely about the HP.

and they are used with a 2nd battery at a 100% loss

so there is no question in that application that the acceleration HP is benefited.

brant

[lapuwali]

QUOTE (alpha434 @ Mar 26 2006, 11:26 PM)

QUOTE (lapuwali @ Mar 26 2006, 11:19 PM) Energy in = energy out - unavoidable thermal losses.  Plain, simple thermodynamics. If pushing a fixed amount of air, then you have to expend a fixed amount of energy to push it.   If you use a system with a fan that's attached directly to the crank, or you use a system that has to drive an alternator through a v-belt (small power loss), then the alternator has to convert this to electricity (big power loss), then you have to convert the electricity back to mechanical energy with a motor (another big power loss), which one is going to end up drawing more power from the engine to deliver that fixed amount of energy? But with an electrical fan, you have constant output at all rpms. Unless you want to change that. The advantage would be at high revs, where the attached fan has the most power loss, and is borderline starving all the time. With a properly setup electrical fan, the hp cost would be constant, since the fan will always need the same amount of energy to turn the same speed.

High RPM also generates more friction, so requires more cooling, so more airflow is needed, so the fan has to be spun faster.

As Brant says, if you run the car and an electric fan off batteries in total-loss mode, as is commonly done when racing, then you'll see a significant benefit, as you get to recover both the fan and alternator losses. This beneift only lasts as long as the battery does, and that's likely to be little more than an hour per charge. Perfectly fine for many racing uses, pretty useless on the street.

One *could* devise a setup where the alternator is clutched out of the system at WOT, and just run off the battery (or batteries) during full throttle. This may even work on the street.

[dstar]

@ 7000 RPM, the stock 914 cooling setup is using around 10-12 hp.
Cooling is NOT where you want to find HP!
(IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif)

But if you guys got enuff cabbage to piss away, have at it!
(IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif)

Stupidity usually ends up costing someone, something, in the end......
(IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

Again, this setup wasn't even usable for AXing, in a wide open 356......
with head temps in the 450 range.........
(IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif)

Don