[mechdb]

I have no accessories except the alternator, and even though this may sound pretty foolish, wouldn't it be more efficient to drive the alternator from the timing belt? I'm guessing the more belts there are the more places there are for energy losses from friction. Not to mention the extra pulleys, mounts, and etc. The only problem I could see with this is the difference in belts. I wonder which is more efficient. I read somewhere that chain is even more efficient than belts in terms of friction loss, but then the extra rotational weight of moving an entire chain kills off the benefit.

 

[Reaper1]

There are TONS of factors when talking about the efficiency of the drive system of the accessories. Not only do you have friction, but interta, thermodynamics, and when you thow in the alternator, now you have electrical losses too. There are also minor losses due to aerodynamics, bearings, tension, ect.

In practice there are two things that can help the efficiency of this system the easiest. #1, reduce the inertia by reducing mass of the pullies and nything else that rotates.

The #2 thing is the radius of those said pullies, but that has a muliple effects. It reduces intertia of the pullies by reducing the mass. It also will slow down the speed at which the accessory turns. In this case it will reduce the losses of the electrical system of the alternator, but there is a point of diminishing returns with that, especially at idle. With the reduction in speed you get less thermo losses due to friction as well as from the bearings ect.

Unless this system is VERY inefficient, then the best way is to simply reduce the mass of the pullies. The ONLY reason I run an underdrive pulley on my car is that I do a LOT of highway driving. I wanted to slow the accessories down to try and extend their life, and to possibly eek out a tad more fuel economy out of it.

 

[mechdb]

I run a 50% on my other car and I never had a problem with it. Those are quite nice, and I plan to put one on this engine soon as well (the stock gigantic harmonic balancer is ridiculous). However I was just theorizing about a step beyond though. But like I said, it would have too many other problems. However, pretty soon I'm also thinking about eliminating the water pump and replacing it with an electrical one. Although I've read a lot of negative things about them, the one I managed to acquire seems to meet normal flow requirements and do good for highway usage. I'll just make a plate out of aluminum to cover up the old one in the 2.4 engine. And in the worst case scenario I can always return the coolant system to the way it was.

 

[Reaper1]

The harmonic balancer will become ineffective if you alter its mass. The reason it is a certain mass is to deal with certain harmonic vibrations that occur naturally in the engine...hence its name. Back in 2001-2002 I was trying to get race-spec harmonic balancers made for the 3.0. They were going to be aluminum and smaller in diameter. However, their actual mass was going to be as much as the stock one. They HAVE to be. If you get rid if the balancer on an engine that is supposed to have one, you WILL see a decrease in engine life, especially on the main bearings. This point has been argued over and over with the Honda crowd. It is a fact.

I DO agree on a lighter pulley, though(IF that can be done...I don't know if the balancer and the pulleya re two spearte things like they are on the 3.0).

As for electric water pumps...I don't see an issue with them. For me it has always been finding one that can flow enough at highways speeds, or for long periods of WOT....

 

[speedyshelby16]

You guys know you can buy a bolt on electric water pump?

click the link then choose chrysler and Part # 922.

CSR Performance Products | Water Pumps | Simply the Best

 

[detobias]

The #2 thing is the radius of those said pullies, but that has a muliple effects. It reduces intertia of the pullies by reducing the mass. It also will slow down the speed at which the accessory turns. In this case it will reduce the losses of the electrical system of the alternator, but there is a point of diminishing returns with that, especially at idle. With the reduction in speed you get less thermo losses due to friction as well as from the bearings ect.

just to be clear, you would want to reduce the radius of your *crank* pully and / or increase the radius of your driven (e.g. alternator) pulleys

so certainly the best option is to reduce the crank pulley diameter that way you get BOTH benefits - slower accessory speeds AND lower rotating inertia

I'm contemplating lightening my cam gear, intermediate shaft gear, water pump pulley and certainly buying (or fabricating) an 'underdrive' crank pulley

PS - the 2.2/2.5s don't have any "harmonic balancer"

 

[puppet]

I have no accessories except the alternator, and even though this may sound pretty foolish, wouldn't it be more efficient to drive the alternator from the timing belt?

If I'm not mistaken the 200mph LeBaron did this. ... and used it to drive a oil pump for the dry sump system. (same belt run off a dual intermediate shaft pulley) Water pump was run directly off the crank pulley (single belt).

 

[Reaper1]

I think this guy is running a 2.4L guys...I read his side profile! :thumb:

If he is indeed talking about a 2.2/2.5, then I agree with the above posts.

BTW, good catch on the larger/smaller pulley diameter things. I actually thought of it, but I didn't want to get in to that becuase I don't know of any source currently offering a larger alternator pulley for either platform...