Mazda World Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
77 Posts
Discussion Starter #1
I've been told around my way that a pulley will increase my HP dramatically on my 2k Millenia...i came across this site:
http://www.stillen.com/sportscars_detail.asp?cat=2&subcat=&id=13938&page=1 it was listed under a 2000 mazda millenia...can anyone give me good advice on a pulley, what EXACTLY does it do that SUPPOSEDLY creates so much horsepower? is it worth it?

1
 

·
Registered
Joined
·
77 Posts
Discussion Starter #3
I went to corksports.com and found the pulley, but it's listed for a 2.5 Millenia...i have a 2.3 S...does anyone know if this pulley will still work even though it's stated for a 2.5L Millenia?

1
 

·
Registered
Joined
·
105 Posts
It's easy to understand how these "under-drive" pulleys work...

The alternator, power-steering, air-con, etc are connected to the engine by a belt, which runs from the engine's crankshaft pulley (the lowest one) around the devices. As the engine spins the main pulley, it moves the belt and turns the devices.

Each device draws power from the engine (if they didn't draw power, they wouldn't need to be driven by the engine). The faster that you turn the pulleys (drive the main belt) the more power that the device gets, and the better it works.

Under-drive pulleys are smaller than a standard main pulley, so for each turn of the engine (rev) they do not move the belt as far. Therefore, the ancillary devices do not spin as fast... so they do not draw so much power from the engine.

So, by under-driving the ancillary devices you do not waste as much engine power... However, the factory designs the engine (including the pulley sizes) pretty carefully so that everything works properly for all operating conditions. They carefully calculate that the average driver needs (say) a certain amount of alternator power to recharge the battery after each start, and to run headlights, etc.

If you under-drive (say) the alternator, the battery doesn't get charged as fast as normal. This might be OK if you only start the car once a day then drive it a long distance, and not at night with the headlights on. It also might be OK if you rev your engine much harder than a "normal" driver, for example if you are racing most of the time.

Yes, under-drive pulleys give extra (nett) power, but they do not make the ENGINE make more power (although some claim to... think about it carefully and you'll work out this is a crock of s#@*t)- they just send less of that power to the ancillary devices. You would have to assess your driving style and usage and decide if that is an acceptable compromise....

IMO an extra 5 hp is not really a great deal of power anyway - especially for US$200 plus the cost of fitting the pulley - in a S you'd get much bigger HP from using octane booster or really good quality petrol in it, and making sure the engine tune is optimised !

JohnC
 
1 - 4 of 4 Posts
Top