No engine driven fan for me, I wouldn't have guessed
10-11-2017, 03:50 PM
#21
Safety Car
That is the "5-6 horsepower" question.
I don't have any concrete answer.
The Delco Remy white paper linked below says "typical" alternator efficiency is 55%.
http://www.delcoremy.com/documents/h...ite-paper.aspx
I don't have any concrete answer.
The Delco Remy white paper linked below says "typical" alternator efficiency is 55%.
Electrical power on a vehicle is not free. It comes as a direct result of
consuming fuel within the engine to drive the alternator. With a typical engine
efficiency of 40%, a belt efficiency of 98% and an alternator efficiency of 55%.....
consuming fuel within the engine to drive the alternator. With a typical engine
efficiency of 40%, a belt efficiency of 98% and an alternator efficiency of 55%.....
10-11-2017, 04:42 PM
#22
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A modern alternator will easily be 50% or more efficient, so your 1.12hp for 60A becomes about 2hp at the crank.
A pair of decent electric fans won't draw over 60A when operating so they won't put more than a 2hp mechanical load on the engine.
A pair of decent electric fans won't draw over 60A when operating so they won't put more than a 2hp mechanical load on the engine.
10-11-2017, 04:48 PM
#23
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A couple of other links to testing;
http://www.carnut.com/ramblin/dyno.html
http://www.network54.com/Forum/21565...+Fan+Dyno+Test
http://www.carnut.com/ramblin/dyno.html
http://www.network54.com/Forum/21565...+Fan+Dyno+Test
10-11-2017, 04:51 PM
#24
Safety Car
10-11-2017, 04:53 PM
#25
Team Owner
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St. Jude Donor '05
Whatever happened to those white plastic fans that used clutches, seen other mfrs use them did Chevy ever do it?
Seems like the best of both worlds sure is less weight moving around
Dont mind clutches but every one Ive had except one blows apart at rpm;usually big blocks and takes the snout of the water pump with it
Seems like the best of both worlds sure is less weight moving around
Dont mind clutches but every one Ive had except one blows apart at rpm;usually big blocks and takes the snout of the water pump with it
Last edited by cv67; 10-11-2017 at 04:54 PM.
10-12-2017, 10:26 AM
#28
The engine driven fans consumed 25 to 30 hp at 6000 rpm which would mean they consumed 13 to 15 hp at 3000 rpm or 6 to 7 hp at 1500 rpm. A 60 amp alternator with its field fully energized will consume about 5 to 6 hp when the engine is spinning around 1500 rpm so the actual difference is very small.
10-12-2017, 10:45 AM
#29
Le Mans Master
I dyno tested this as well on my car. 7 blade fan with the Hayden 2799 extreme duty fan clutch killed 15 rwhp, Tests were 30 mins apart but temps were brought back up to match.
I had a thread here years ago about it with pics/vids info. I also tested air cleaners, hood open vs closed etc...
Playing on the dyno is eye opening for sure.
I had a thread here years ago about it with pics/vids info. I also tested air cleaners, hood open vs closed etc...
Playing on the dyno is eye opening for sure.
10-12-2017, 12:57 PM
#30
Melting Slicks
I dyno tested this as well on my car. 7 blade fan with the Hayden 2799 extreme duty fan clutch killed 15 rwhp, Tests were 30 mins apart but temps were brought back up to match.
I had a thread here years ago about it with pics/vids info. I also tested air cleaners, hood open vs closed etc...
Playing on the dyno is eye opening for sure.
I had a thread here years ago about it with pics/vids info. I also tested air cleaners, hood open vs closed etc...
Playing on the dyno is eye opening for sure.
I think it really depends on the fan tested. A good flex fan like Jim runs flattens out and doesn't use much power at RPM. Others could use quite a bit.
Mike
10-12-2017, 01:27 PM
#31
Team Owner
This discussion is dealing with power losses at Wide-Open Throttle and maximum engine power. If this is really important to you, you should definitely go to an electric fan system which (if engineered correctly for those specific needs) can minimize power losses to the cooling system.
For the rest of us who drive MOST of the time at low throttle conditions, this discussion changes considerably. At cruising engine rpm's, differences of power loss with these two methods of cooling become less important. BOTH systems can provide for adequate engine cooling...if they are properly designed.
So, if you would rather have a 'stock' cooling system on your "normally driven" car, there is little loss in doing so (and a lot less expense than re-engineering that system). If you frequently go to WOT conditions, make the change to electric.
Folks just need to do what's best for them depending on how they use their car.
For the rest of us who drive MOST of the time at low throttle conditions, this discussion changes considerably. At cruising engine rpm's, differences of power loss with these two methods of cooling become less important. BOTH systems can provide for adequate engine cooling...if they are properly designed.
So, if you would rather have a 'stock' cooling system on your "normally driven" car, there is little loss in doing so (and a lot less expense than re-engineering that system). If you frequently go to WOT conditions, make the change to electric.
Folks just need to do what's best for them depending on how they use their car.
10-12-2017, 03:28 PM
#32
Le Mans Master
I remember your testing Allan. If I remember you lost about 15 HP with the L88 ac with the top and screen on. I'm trying to figure out how to make that better. I am running the air chamber in my L88 hood.
I think it really depends on the fan tested. A good flex fan like Jim runs flattens out and doesn't use much power at RPM. Others could use quite a bit.
Mike
I think it really depends on the fan tested. A good flex fan like Jim runs flattens out and doesn't use much power at RPM. Others could use quite a bit.
Mike
Yep...I'd have to go back and look at the old thread for the exact numbers but... I think the little L88 lid and chicken wire killed like 6-7 hp. Hell just closing the hood killed a few.
After that I had the high rise hood made, run the L88 base and a 4" element and chrome lid... Its within 1 mph at the track of running just the air cleaner base alone.(which always makes the most power).
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10-12-2017, 06:18 PM
#33
Safety Car
By the way, here's a link to the video.
10-12-2017, 06:23 PM
#34
Instructor
Thread Starter
This discussion is dealing with power losses at Wide-Open Throttle and maximum engine power. If this is really important to you, you should definitely go to an electric fan system which (if engineered correctly for those specific needs) can minimize power losses to the cooling system.
For the rest of us who drive MOST of the time at low throttle conditions, this discussion changes considerably. At cruising engine rpm's, differences of power loss with these two methods of cooling become less important. BOTH systems can provide for adequate engine cooling...if they are properly designed.
So, if you would rather have a 'stock' cooling system on your "normally driven" car, there is little loss in doing so (and a lot less expense than re-engineering that system). If you frequently go to WOT conditions, make the change to electric.
Folks just need to do what's best for them depending on how they use their car.
For the rest of us who drive MOST of the time at low throttle conditions, this discussion changes considerably. At cruising engine rpm's, differences of power loss with these two methods of cooling become less important. BOTH systems can provide for adequate engine cooling...if they are properly designed.
So, if you would rather have a 'stock' cooling system on your "normally driven" car, there is little loss in doing so (and a lot less expense than re-engineering that system). If you frequently go to WOT conditions, make the change to electric.
Folks just need to do what's best for them depending on how they use their car.
Last edited by 2airtime2; 10-12-2017 at 06:23 PM.
10-12-2017, 09:34 PM
#35
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I did some testing on my car years ago. At the time it was making about 615 RWHP. I ran it with and without the fixed stainless steel flex fan using stock pulleys.
Back to back we could "maybe" see 3-5 or so RWHP. It was really almost within the normal run to run variations. Certainly a little better...but no where near what I had heard over the years. In fact, I had already bought an electric dual fan assy. and was looking for a larger alternator to run them. After the testing I took the fans back and have kept my mechanical fan for simplicity and weight savings.
I'm still running it and it's spinning just under 8000 RPM at the finish line in the 1/4 (stock PS pump too!) at 158+ MPH on every pass. I ran a similar fan on my 427 for 20+ years also. No issues. I believe these type flans flatten out pretty well. I've tried it at the track with it removed and could never verify a substantial enough improvement to make it worth the trouble to remove it. Again..I know electric IS better...but I'm not losing any sleep over it. Maybe someday I'll get around to it.
JIM
Back to back we could "maybe" see 3-5 or so RWHP. It was really almost within the normal run to run variations. Certainly a little better...but no where near what I had heard over the years. In fact, I had already bought an electric dual fan assy. and was looking for a larger alternator to run them. After the testing I took the fans back and have kept my mechanical fan for simplicity and weight savings.
I'm still running it and it's spinning just under 8000 RPM at the finish line in the 1/4 (stock PS pump too!) at 158+ MPH on every pass. I ran a similar fan on my 427 for 20+ years also. No issues. I believe these type flans flatten out pretty well. I've tried it at the track with it removed and could never verify a substantial enough improvement to make it worth the trouble to remove it. Again..I know electric IS better...but I'm not losing any sleep over it. Maybe someday I'll get around to it.
JIM
I also require that my car brake and corner well. My SS fan and 40A mini-alternator are several pounds lighter than an electric fan and a 100A alternator.
10-12-2017, 10:10 PM
#36
Team Owner
As always, do what's best for you and your machine...
P.S. I doubt that the stock clutch fan is advantageous anywhere but for normal city/rural driving. But it is still easier for me to retain the stock unit (at no additional cost) than swapping it out.
P.S. I doubt that the stock clutch fan is advantageous anywhere but for normal city/rural driving. But it is still easier for me to retain the stock unit (at no additional cost) than swapping it out.
Last edited by 7T1vette; 10-12-2017 at 10:10 PM.
10-12-2017, 11:38 PM
#37
Drifting
I had a bunch of dyno runs done with my mechanical fan in place. I removed the fan a couple months ago- think I'll have another run to see what I gained.
10-13-2017, 09:03 AM
#38
Burning Brakes
Hard to believe a fan would take 25-30 hp to drive it. if that were the case, my old chevette would have nearly double the power if I removed the fan!! :0.
I am curious as to how a motor on a dyno compares to a motor in a car going down the freeway compares. I would assume it takes less power to spin a fan that has air already pushing against it at 70mph than one sitting still in a room, unless they somehow account for that in the testing?
I am curious as to how a motor on a dyno compares to a motor in a car going down the freeway compares. I would assume it takes less power to spin a fan that has air already pushing against it at 70mph than one sitting still in a room, unless they somehow account for that in the testing?
10-13-2017, 09:51 AM
#39
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Hard to believe a fan would take 25-30 hp to drive it. if that were the case, my old chevette would have nearly double the power if I removed the fan!! :0.
I am curious as to how a motor on a dyno compares to a motor in a car going down the freeway compares. I would assume it takes less power to spin a fan that has air already pushing against it at 70mph than one sitting still in a room, unless they somehow account for that in the testing?
I am curious as to how a motor on a dyno compares to a motor in a car going down the freeway compares. I would assume it takes less power to spin a fan that has air already pushing against it at 70mph than one sitting still in a room, unless they somehow account for that in the testing?
10-13-2017, 03:48 PM
#40
Team Owner
Fan BELTS are only good for a few horsepower...no way can you get more than 10 hp out of a stock auto drive belt.