So iv been looking at getting more power out of my tj sports I have a full exhaust with extractors and Im getting 380 Cams without turbo charging or supercharging how else could I get more power? My friend suggested under drive pulleys since a lot of people do.it with there falcons but I can't find anything about it for magnas anyone know anything about emr have one installed?
Cheers Rick

You just bolt a smaller pulley onto the end of the crankshaft. It's supposed to cut down on power loss when you rev the engine. without dyno figures, it's hard to tell how effective it is, donno if the smaller pulleys are available for Magnas. You would need smaller drive belts too. They are used commonly in race oriented applications where you don't want to over rev components like the steering pump, alternator etc and blow them up.

I did hear of a guy who was running one on his 3rd Gen. Lived around the Eastern Creek area I think?

His Magna was written off (I think) about a year and a half ago.

I don't know if he was a member here though, and I never heard exactly how successful it was.

Trying to put some figures onto things - your alternator puts out 130 amps maximum. At 14.4 volts, that is 1.8 kW. Allowing for some inefficiencies, this is probably 2 kW - if the power draw is 130 amps. The actual power draw is probably only 10 to 15 amps, so it is more like 0.3 kW maximum. The only other things run off the crankskaft pulley are the power steering and the air conditioner. If the A/C is not on, the power draw will be minimal (friction from the A/C pulley bearings and the idler pulleys). I don't know what the power draw from the Power Steering is but it won't be very much. Compared to 150 or more kW that the engine puts out, the power draw from the engine accessories is really minute and not worth chasing.

The power steering pump is circulating the fluid through an open circuit when your not turning the wheel, creating friction and heating the fluid, so you could gain a bit there at high RPM. The number of cars using electric power steering proves that there are gains to be had. The alternator will draw whatever power it needs to maintain 14.4v so in most situations it won't make any difference as even at idle speed with headlights on and stereo/heater etc it stills maintains 14.4v.

You could try finding a bigger pulley for the steering pump to slow it down, might be able to get it off a different car. Finding a smaller crank pulley could be hard, but there will be small gain to be had by reducing the friction of the drive belt and the bearings/brushes of the alternator and bearings of the air-con pump clutch.

Jimbo:
I think that you will find that the P Steering pump operates against a pressure relief valve ie it will be pumping its full output against the full pressure = maximum power absorbed. Even so, the amount of power absorbed will be small - true the Europeans are going to electric pumps these days, but it is still small loss compared to the available power developed by the engine. The alternator power is 14.4 Volts times whatever the current is (maximum 2 kW) - still miniscule relative to the engine's output. If you are chasing changes to that degreee, take the wing off the rear of the car - it will generate more than 2 kW in losses, providing "downforce" to the rear wheels in a front wheel drive car. If you want more acceleration, fit tyres with a smaller rolling radius.

The steering pump will only really lift the relief valve if you hold it on full lock. That would be when the pump is putting maximum load on the engine (power=flow X pressure). Flow rate is a fixed amount per revolution of the pump. Pressure when not turning would be minimal as its just circulating the fluid, there is no great restriction.

Surely someone has put there car on a dyno with belts removed to see the difference? Might be worth goggling.

When car is idling and you turn the wheel rpm drops doesn't it? Could this show how much power is being taken from the pump? Or is my car the only one that drops a few 100 rpm when I turn the wheel when the cars not moving?
All up it still seems like it might not be worth the hassle. Interesting thread though.

Only really worth the trouble if you have a race engine that spends all of its time in the upper rev range. It will stop the belts or alternator from flying apart or the power steering pump from overheating/frothing the fluid. A few Kw extra is just a accidental benefit of this increased reliability, but as usual the wannabe racer boys have it wrong. lol

just like an unenclosed pod will give you 50kw more ATW :D ah, wannabe racer boys.

just like an unenclosed pod will give you 50kw more ATW :D ah, wannabe racer boys.

yes, well?

Honestly, finding an undersize crank pulley or getting one made up for the Magna isn't worth the trouble. But feel free to prove this idea wrong.

You may be able to find a steering pump pulley from another car.