mpg gains with underdrive crank pulley?

[IsaacCarlson]

so you might wear your alternator out sooner....

[redpoint5]

Originally Posted by IsaacCarlson

so you might wear your alternator out sooner....

Not likely. You are reducing the number of revolutions that parts making physical contact have to endure by 20%. The load on the alternator will be reduced since it is running a lower RPM, but it will have to run under load for a longer duration to make up for the reduced output.

[ecofreak]

Could you replace your alternator with a brushless motor?

[redpoint5]

Originally Posted by ecofreak

Could you replace your alternator with a brushless motor?

I have not heard of brushless alternators for a car, but I suppose it's possible. As far as efficiency goes, I don't think a brushless design would help very much.

[ecofreak]

Originally Posted by redpoint5

I have not heard of brushless alternators for a car, but I suppose it's possible. As far as efficiency goes, I don't think a brushless design would help very much.

I just have always thought one is better than none. Road trips are hell if you run a deep cycle, especially with chargers pounding and the stereo up. Of course, an aero tonneau cover with a huge solar panel would be incredibly useful, if not indispensable. Could you make an alternator attach to an auxiliary source of power, like a Sterling engine? A hybrid running on a sterling engine during the day would be fantastic.

[Uncle Dave]

If you want to increase the MPG on the electrical system how about doubling the Voltage from 12 to 24 volts? Power is Power I x E = P. If you double the Voltage E, and keep the P Power constant, then you Half I, the Current. All the wiring can be of a thinner gauge and the weight can be reduced. We keep hearing, "Take the weight out of the Trunk." The use of Plastics because they are lighter.

Other countries use 240 Volts? Less Grid losses. Thinner wires.

24 volt batteries for the Trucks and Diesel engines.

They have gone from 6 to 12V. Why not 24? or 48?

[serialk11r]

Originally Posted by Uncle Dave

If you want to increase the MPG on the electrical system how about doubling the Voltage from 12 to 24 volts? Power is Power I x E = P. If you double the Voltage E, and keep the P Power constant, then you Half I, the Current. All the wiring can be of a thinner gauge and the weight can be reduced. We keep hearing, "Take the weight out of the Trunk." The use of Plastics because they are lighter.

Other countries use 240 Volts? Less Grid losses. Thinner wires.

24 volt batteries for the Trucks and Diesel engines.

They have gone from 6 to 12V. Why not 24? or 48?

Because the industry has no motivation to change. They've been talking about 42V electrical systems for a while since luxury cars are using more and more electricity and 12V alternators are having a hard time keeping up.

Another issue is that all the switches in the car would be less durable at higher voltages due to arcing. So you'd need a 12V system anyways.

A stopgap measure could be having alternators be designed for higher voltage outputs and then have an efficient means of stepping down the voltage. Higher specific power, lower losses.

[Piwoslaw]

78 volt systems?
Auto voltage...24 , 32 , 48?

[redpoint5]

Originally Posted by greasemonkee

Might buy a set of rod bearings to go with your underdrive crank pulley, especially if the factory had an isolator in the oem unit.

Since this thread was dragged back to life, I'm wondering if there is evidence to support this claim? My OEM crank pulley had a rubber isolator, but I couldn't see it really doing anything.

Are aftermarket pulleys known to be hard on rod bearings? I would think the lighter weight alone would make them more gentle on the engine and related bearings.