an idea about alt cut

[jrok]

thought about cutting the alternator field wire @ wot then use a electric fan and water pump and possible p/s ...should gain a few hp at wot and charge all the other time .....any feed back would be good......

[84supra84]

thought about cutting the alternator field wire @ wot then use a electric fan and water pump and possible p/s ...should gain a few hp at wot and charge all the other time .....any feed back would be good......

How would cutting the alternator at WOT save any horsepower? Your still turning the pulley... :ugh:
All the other stuff should save something for sure though

[jrok]

the alternator when there is a field has way more draw than just turning the alternator cause it could be running a fan lights charging the battery.....

[Donn29]

http://forums.celicasupra.com/showthread.php?t=31361&highlight=alternator
I never got around to it.

Someone suggested that it would only be a few HP. Once I get my car on a dyno, I'm going to try it out.

[84supra84]

the alternator when there is a field has way more draw than just turning the alternator cause it could be running a fan lights charging the battery.....

O! i learn something everyday!

[Donn29]

Turn the headlights and heater fan on, then unplug the round 3 wire plug on the back of your alternator. Listen to the difference! however it only takes a few hp to run the engine at idle. I'm still unsure of the gains.

[jsn_ayers]

When you have a 100amp alt it takes about 2hp to push it. At most you will only push 60amps at one time. Thats about 1 hp loss. You lose more hp at the water pump than that. If you want all the ponies in your engine to reach the ground I would look at a electric water pump first.

[Donn29]

When you have a 100amp alt it takes about 2hp to push it. At most you will only push 60amps at one time. Thats about 1 hp loss. You lose more hp at the water pump than that. If you want all the ponies in your engine to reach the ground I would look at a electric water pump first.

Electric pump with alt. cut out! WOOT!

[jsn_ayers]

In other words dont waste your time on it to much.

[lechner]

This is a bad idea. Ideally, the battery should only be used for starting the car. And then the alternator should provide the juice for the ignition system and everything else. Using the battery to power everything during wot when the ignition system, fuel pump, etc. needs to be at peak capacity will require a large, heavy battery and you will still see a voltage drop to these critical components, which may damage them. Less spark energy, less fuel pressure, etc. will cost you more power than you gain. An alternator puts out peak current when it is needed most, and not as much at lower RPM.

[Donn29]

This is a bad idea. Ideally, the battery should only be used for starting the car. And then the alternator should provide the juice for the ignition system and everything else. Using the battery to power everything during wot when the ignition system, fuel pump, etc. needs to be at peak capacity will require a large, heavy battery and you will still see a voltage drop to these critical components, which may damage them. Less spark energy, less fuel pressure, etc. will cost you more power than you gain. An alternator puts out peak current when it is needed most, and not as much at lower RPM.

I disagree.

The battery in a normal system is only for starting and then gets recharged. However, using it 10% of the time(or less on a daily) to run everything is not going to make an impact.

Now if you use it all the time or very frequently on a car that has a weak battery/alternator, you might have problems. kdmfk (I think) had pics of a salt flat racer without an alternator!

The HP/$ is likely not there anyways, like previously posted. That won't stop me from maybe unplugging the alt for a before and after sometime though.

[Dave A.]

The sole purpose of the alternator is to keep the battery fully charged, which is why it is considered to be a part of the charging system. The more load you place on the battery (via accessories, etc.) the more load you place on the alternator. You can disconnect the field winding during a WOT run to disable the alt. but the battery will discharge during the run. Just make sure that you keep the WOT run short and you should be OK.

[lacrssgus14]

I have mine setup to shut off the Alt and Air Con when over 80% throttle, I have not noticed any ill effects from shutting down the alternator, but I also rarely hit over 80% throttle unless I am doing a pull, at which point I want less drag. I wish I had done the electric water pump, but o well.

[jrok]

This is a bad idea. Ideally, the battery should only be used for starting the car. And then the alternator should provide the juice for the ignition system and everything else. Using the battery to power everything during wot when the ignition system, fuel pump, etc. needs to be at peak capacity will require a large, heavy battery and you will still see a voltage drop to these critical components, which may damage them. Less spark energy, less fuel pressure, etc. will cost you more power than you gain. An alternator puts out peak current when it is needed most, and not as much at lower RPM.

race cars dont have alternators and the time you are accually wot is very little.......

[StanS]

60 Amps X 13.5 Volts = 810 Watts
735 Watts = 1 HP
Then allow for inefficiencies in generating the electrical power (belt flexure, i squared X R in the winding) and the best you could get is 1.5 to 2 hp gain, which, imo isn't bad at all for the cost of a microswitch and a relay.

EWP is claimed to gain 10-20 hp.

Alternatively, you could put a 100 Ohm power resistor in series with your alt output and have a normally closed relay bypass the resistor for normal operation. Have the relay open at wot and the alt current will be limited to 0.13Amps (or lots less), thus unloading the alt. This way you should avoid any voltage transients which the alt might generate when you power the field wire. Hi voltage (20V) transients might hurt the electronics. At least test/monitor the alt with an oscilloscope when reapplying alt voltage to make sure that no voltage transients are generated.

[silverton]

As far as I know, powersteering is cut off after 3000 rpms. Take your car into parking lot put it in first gear and get it over 3000, and move the wheel, you'll see.

[Tanya]

power steering isn't "cut off" at any amount of rpms. There's a term for how our steering feels after a dcertain amount of rms, I just can't recall what it is. Progressive maybe? A very early form of progressive power steering. At any rate, the power steering is ALWAYS there as long as the belt is on, there will always be that drag on the motor.

You want to go balls out with nothing attached, get an electric waterpump (if there is such a ridiculous thing for our cars) and take the alternator off for 1/4 mile racing, but leave it on for DD

[StanS]

EWP Google "Craig Davies"

[Dave A.]

power steering isn't "cut off" at any amount of rpms. There's a term for how our steering feels after a dcertain amount of rms, I just can't recall what it is. Progressive maybe? A very early form of progressive power steering. At any rate, the power steering is ALWAYS there as long as the belt is on, there will always be that drag on the motor.

You want to go balls out with nothing attached, get an electric waterpump (if there is such a ridiculous thing for our cars) and take the alternator off for 1/4 mile racing, but leave it on for DD



Power Assisted R&P Steering:

On the MKII, the amount of power assist (and the load on the PS pump) is controlled by the fluid flow control valve on the PS pump. During straight ahead driving, no assist is required so the PS pump basically just recirculates the fluid inside the pump. When you turn the steering wheel left or right, the PS fluid is pumped through the rack under considerable pressure (over 900 psi.) to assist the R&P in turning the wheels. IIRC, the flow control valve is calibrated by spring tension in such a way as to provide more assist during low vehicle speeds than high vehicle speeds (progressive assist). Also, the air control valve on the PS pump is used to provide more air to the intake manifold to help keep the engine RPM steady while the PS pump is under load. Straight ahead driving shouldn't place much, if any load on the PS pump.