Mike Ward

I thought this thread had died.

1) put engine on dyno, measure output with all accessories

2) disconnect all accessories= 5-10 HP increase

whether you disconnected them electrically (turn them off) or mechanically (remove the belt) makes no difference.

Now try driving your car with no water pump, fuel pump, alternator or fan and see how far you get.

Got it?

C3 Stroker

You're not seeing what I'm saying....the difference is not accessories vs. no accessories; it's alternator HP drain(w/electrical accessories on) vs. mechanical fan and WP drain on engine.

Simple - It takes more HP to turn the mechanical fans and WP than it takes to turn the alternator even under the full load of the added accessories. It's not a large net increase in power to the wheels by any means, but a small increase nonetheless.

Got it?

straub18045

by far the amount of horsepower needing to turn a mechanical fan especially 'locked' exceeds the amount that the load would be on a alternator to supply an electric fan

Mike Ward

I officially give up. You guys are just too smart for me. I have no idea how to defeat the laws of physics like you two apparently can.

68L71

Is Clem here?

BarryK

and you thought *I* was going to have a hard time in the Pertronix thread..........

...Roger...

No,and he won't.

68L71

I think you are not taking enough of the laws of physics into account...efficiency

Daffy2

I've seen this discussed many times. I'm involved with 2 cars running electric water pumps:
A V-8 Fiero conversion (my son's car) with a remote mounted CSR pump (37 GPM). This is a well built 350 based off of a ZZ3 and is making somewhere around 375 HP. It has never given us any problems and runs a regular Fiero alternator and has never exceeded 190*, the radiator fan never even comes on. The E-Pump was needed as there is no real estate available for a normal water pump. There are literally
100's of V-8 Fieros out there with various E-Pumps and I've never heard of a problem.
A good friend has a '65 Mopar with a heavily built 440 and is running a Meziere (55 GPM). He has run this setup for 3 years and the car has never exceeded 200*. He has never had a problem.
Having given you my personal experiences, I will add that I would not use an electric pump if I didn't need to - why complicate your life for a possible tiny HP gain.

Daffy

C3 Stroker

....Check out this article..13 HP added by switching to electric water pump. The biggest "drain" would probably be on the wallet...depends on how much it's worth to you.

http://www.vetteweb.com/tech/vemp_08...mps/index.html

straub18045

that was an excellant article! i guess its how much $$ you want to spend. fiqure i spent so much $$ on my vette so far why not keep going?

...Roger...

Can barely spell physics but I
Don't get me wrong I much prefer a mechanical setup for the street but with the right balance I believe mech.- electrical can prevail.Isn't that what a Hybrid car is all about?Gas engine,generator,motors and battery's.Extra power is there when its needed supplied in part by the battery's and then the rest of the time the battery's are being bulked back up for the next needed power surge.
Balance and knowing what the needs are are key.

NHRalph

People seem to forget there is rotational mass that takes power from the engines output. The more of a rotational mass, the more horsepower drain. An alternator that is large enough to charge the battery when peripheral items are turned on is constant. The alternator puts out a certain amperage at a given RPM.
The biggest power drain from the engine is the rotating masses and the drag from the fan. There will be a certain horsepower gain by eliminating the engine driven fan and the water pump, how much probably isnt much and not worth the money but it is there.

straub18045

NHRalph - i am on your side and believe there would be horsepower gained by eliminating mechanical fans and pump. sometimes every little pony counts.

JustinD

If you have not switched to an electric fan, that is where I would start. I swapped mine out for around 50 bucks. 15 for the fan, 25 for the relay and 10 for the wire and other misc crap.



Fan is from a 90's ford taurus. I run it on the low speed setting and it still turns on and off. The high setting just pulls way to many amps. It runs at around 27 amps on high and 14 amps on low.

Tim_Ko

Mike,
Do you have a chart on that that you can post where one of the manufacturers or rebuilders measured alternator output current at various loads from idle-6000rpm?

Tim_Ko

Stroker,
I think you have it right. You have my vote on this. Its not the law of physics, its simple arithmetic. It seems to be that it takes a lot more energy (power) to get a 16" diameter 5# metal fan to spin to 6000 rpm than it does to spin a 4/5/6" diameter rotor. If you then factor in wind drag, its seems obvious the cooling breeze generated by the rotor is significantly less that the radiator cooling wind generated by the cooling fan.

The only way the stamped steel metal fanblade wins ... is production cost. An alternator has a more moving parts in there that cost a bunch more. And then from a reliability standpoint, I bet you could find plenty of fanblades from 30's/40's/50's cars that still work as well as the day they were installed. I have a 68 alternator sitting that I kept only because of the casting date code - everything else in there is shot!

I would like to see a chart on alternator output current vs load and rpm.

NHRalph

I can give two good reasons for switching to an electric fan, maybe even an electric water pump.

1. When the auto companies switched how they rated horsepwer back in the early 70's. The SAE rating was just the block, no accessories, headers, four barrel carb, premium fuel and advanced timing. When they went to NET horsepower figuers, they put on the normal exhaust manifolds and all accessories. A BIG difference in horsepower ratings. An example is the 1970 LT1 at 370 hp, by 1972 the LT1 was listed as
255hp. Same engine.
2. If it did not increase power and efficiency, the new Vettes would still be using a fan, since they are a lot cheaper to install.
Point is, everything you take off the engine or anything to make it more efficient will free up power.

Z-man

The load doesn't matter. What matters is rpm...Here is a comparison of a stock '70s 10SI alternator (top) and a CS144 from a '90s Cadillac that most of us "modifiers" are using now.

Idle is about 2,500 rpm. My old 40 amp 10SI was putting out about 20A at idle and my "new" CS is putting out about 110A at the same speed! Plenty of juice to run my fan, water pump, ignition, fuel pump, and EFI system.

tshort

These threads about electric fans and electric water pumps always end up in the ditch like this. Why???
Let's throw out any possible gains or losses in HP (because they really are so small that a street car will never tell the difference) and discuss the other benefits/drawbacks of both.

I personally like electric on both of these and use them in my street/strip '69. I like the electric fans because they really clean up the engine bay and make working on stuff very easy. I also like the simplicity of the electric pump. But these are asthetic preferences. Not right or wrong. The other thing people seem to always fail to mention is that with electric, you can continue to run the pump and fans with the engine off to help cool the block on a hot day. Now if this is a stock or close to stock small block and you NEVER have heat issues then this is not an incentive. I have one of those motors however that likes to build up a little more heat. I also like to take mine to the track every now and then and between runs I can keep the fans and pump running and cool the block down very quickly.
Then there's this notion that electric pumps or fans are good for a street vehicle. Why? Go look at a lot of modern factory cars and many are making the switch. I guess these aren't really street cars. New products always seem to get a bad rap when they first come out and no matter how many improvements they make, people will still bash them.
When the electric pumps first came out, yes, they were made for racing and not good for lasting long on the street. But they have made big improvements in the newer pumps and last plenty long for our weekend cruisers.

See, there, no discussion of HP and still points to consider.