Dit zijn mensen aan het woord met meer KL-kennis dan onze club en de helft van probetalk bij elkaar genomen..
Ik zeg verder niks, probeer je alleen maar te adviseren en waarschuwen.
I don't believe there really are any gains. They just look cool! If you weigh the reduced rotating mass (very minimal) and reduced accessory load in one hand and then the possiblity of damaging bearings, oil pump or increased vibrational induced drag in the other hand. hmmm. let me think about that one for a bit.
You can use a UDP but if you do then be safe and use a IUD -oops I mean get your crank balanced!
just to add some random maths into the thread (as i do), assuming our alternators output about 120A (120A x 13.8V = 1.66KW) that means it can provide 1.66kw of electrical power, now take into account the alternators inefficiency (say 80%) and make it 2KW (2kw = 2.7hp), thats the MAXIMUM crank power the alternator can take from your engine at any given time.
what else is connected to the pully?
well the power steering pump which would take maybe 1.5KW max to run, and A/C compressor, assuming the compressor is off most of the time you can assume a loss of maybe 0.5KW (max) through rotational resistance so your typical power gain from removing the accessory belt completely would be about 4KW (5.36chp) assuming i haven't forgotten anything.
so under-driving these accessories by say 20% you could expect a proportional gain at the crank 0.8KW (1.07hp) (4KW x 20%), transfer that to the wheels and there's nothing left. Now obviously the reduction in rotating mass comes into some effect but im not going to bother with the maths on that unless someone can post the exact weight differences.
to sum up if your power steering and a/c compressor are working fine (as you assume they are) this would be the most expensive "bang for buck" performance mods available.
im not trying to talk people out of buying them, if you want one thats your choice. i would like people to understand this should be placed towards the far end of any mod list. just my opinion.
The moral of the story is that if you want to use a UDP then do yourself and your engine a favor and get the rotating assembly balanced so that you get more out of your engine. And if you do not care if it puts more wear on your bearings or pump then don't worry about the balancing. After all - there are some protesters out there who will say that they have never had a problem with UDPs. Wikipedia has an article on UDPs and I would suggest that it is worth reading. But it isn't anything that I didn't already know.
P.S. A well balanced engine makes more power by not losing it to parasitic vibrational induced drag.
