To underdrive or not? Pulley Sets
08-31-2003, 07:43 PM
#16
Guest
Posts: n/a
The stock pulley doesn't have a dampener, it is a big steel hunk of a pulley. If you go with to light a flywheel, you throw crazy cels from the crank position sensor. Choose your poison. Modern engines can talke alot; as long as the engine is tuned right, they are pretty hard to kill.
09-01-2003, 06:01 AM
#18
VIP Member
Join Date: Feb 2003
Location: 12.9 / 105+
Posts: 488
Car Info: black my03 5mt wrx s/w
Originally posted by BAN SUVS
Personally, I believe the risk of damaging your crank bearings outweighs what small gains are to be had with the pulleys. It's a better idea to save up and do it right with a new flywheel.
Personally, I believe the risk of damaging your crank bearings outweighs what small gains are to be had with the pulleys. It's a better idea to save up and do it right with a new flywheel.
the crank itself, i can see, but the bearings?
and, how does lightening the rotational inertia at one end of the engine differ from doing it at the other? in other words, how does a lightened flywheel cause no problems, whereas a lightened pulley does? (in fact, it seems to me that they should be/would be matched to each other.)
no vitriol here, just honest questions.
ken
09-01-2003, 01:38 PM
#19
Registered User
iTrader: (12)
Join Date: Nov 2002
Location: Reno, NV
Posts: 18,369
Car Info: 1993/2000/2001 GF4 mostly red
The small rotational vibrations of the crank, when they are not sufficiently dampened, cause small spots to wear in the crank bearings. They eventually wear down enough to get out of round, and cause even more problems, leading to excessive clearance between the crank and bearing. It's the bearings that actually take the punishment of the vibrations in question. The reasont the flywheel is better is that the typical lightweight flywheel is still 12 pounds, which is plenty for dampening the vibrations on that end of the crank. If you read Mike Shields' article that was linked to by Nate0125RS, you'll see why it's better to stick with the stock. The other reason is the siple fact that you are unlikely to be able to tell the difference between a 12 pound flywheel and stock pulley versus a 12 pound flywheel with a lightened pulley- it just isn't really worth the $100 at that point unless you are modded to the max and need every last hundredth on your E.T. While a lightened flywheel costs roughly 4 times as much as a pulley, it's WAY more effective at increasing throttle response, plus it is easier on your gears. The bang-for-the-buck is actually better with the flywheel than with a pulley.
09-03-2003, 09:22 AM
#20
VIP Member
Join Date: Feb 2003
Location: 12.9 / 105+
Posts: 488
Car Info: black my03 5mt wrx s/w
hmm...
well, i still have yet to hear of someone's engine failing from EITHER crankshaft failure OR bearing wear/tolerance... it seems the bottom ends of these boxers are pretty tough.
i just don't think the use of UD/LW pulleys is nearly as severe a problem as folks theorize it to be. if it were, SURELY we would have heard something by now, right?
imo, if you're looking to get 200k mi out of your original engine, drive it like grandma and don't mod it. otherwise, be aware that just about 99% of the mods you do to your car have a negative impact on longevity.
jm2c
ken
well, i still have yet to hear of someone's engine failing from EITHER crankshaft failure OR bearing wear/tolerance... it seems the bottom ends of these boxers are pretty tough.
i just don't think the use of UD/LW pulleys is nearly as severe a problem as folks theorize it to be. if it were, SURELY we would have heard something by now, right?
imo, if you're looking to get 200k mi out of your original engine, drive it like grandma and don't mod it. otherwise, be aware that just about 99% of the mods you do to your car have a negative impact on longevity.
jm2c
ken
Thread
Thread Starter
Forum
Replies
Last Post
QuickShift
Engine/Power - non turbo (All non turbo Imprezas)
1
12-13-2002 09:57 AM
