I've got an UDP on order at the moment. People have kind of discouraged me from wanting to get it. However i'm still going to get it, as I don't believe there is strong enough evidence against UDP's to not get one. But if anyone can enlighten me I would be more than grateful.
There is no "evidence" to say 100% an udp caused a particular failure. Buy one, fit it and forget about it.
I believe it would be an Over drive Pulley for the water pump. As the alternator and power steering work fine at low revs, though because the engine bay can get hot quickly it's better to get an Over driven water pump pulley to make up for the Power lost from the UDP. Hope that makes sense.
The stock pulley has a layer of rubber to assist in dampening torsional vibrations. You will lose that with a UDP. In an ideal world, your engine is perfectly balanced and there are no vibrations. In your engine - who knows ? You may not be able to feel any vibrations, but if severe they may shorten the life of your engine - again who knows ?
Stef was right about the rubber bit. though its like only a small amount of rubber. If it starts to rattle when I install the UDP, I'll consider taking it off. If it runs well i'll leave it. That'll be my final decision.
agreed, just put it in, it's the only way you're gonna know for sure. not every engine will be the same after 20 years so if there's a bit more crank vibration than others, it'll be more noticable after the UDP goes in.
It's been done too many times with no real winner on every occasion, the age of apathy is here. Less stressing, do it, then report findings.
I am curious, can you point me in the direction of any evidence that supports removing the harmonic balancer from your engine? I mean, there's heaps of info out there about potential cons, but what's the rationale for doing it?
Probably the numerous people that have removed the stock crank pulley and fitted a solid alloy UDP and not had a failure is evidence enough
Yes but what do you gain? I doubt very much that a before/after dyno would show a measurable increase in hp.
Well.. from what i've been reading. It apparently isn't a harmonic balancer, as the engine is internally balanced. So that would just mean its a heavy pulley? I mean I spose you can argue the stock one has rubber in it to stop torsional vibration and it's the way its meant to be etc.. however you could probably just as well say the reduction in weight means there is less weight to throw around, as well as having a smaller circumference therefore meaning if there were ANY amount of vibration occuring in the first place, wouldn't it be far less damaging to have the vibration occuring on something lighter weight opposed to something heavier? Also aluminum is a softer metal than iron or steel. Perhaps the aluminum absorbs vibration just as well as the small amount of rubber on the original pulley? Just some thoughts.... While I'm here. Do the aftermarket UDP's make use of existing belts? Or do the belts need to be replaced when you change the pulley to match?
Focus is on the the pulley causing engine vibration and thats not the real issue, because any brand name udp is well made and perfectly balanced, so if you get a vibration after installing a udp, its because the problem existed before hand, and because damper is gone it becomes appearant The real issue should be how the car behaves after the udp install, especially a manual zed. In an auto Z a udp should be standard equipment.
You may get a slight improvement in hp on the dyno due to increased engine acceleration but would be pretty small. The response is definatley better with one, but I doubt a dyno would show it up, maybe 0-60 times might. I know what you are saying Rob, but there are just too many people running them to say they are no good. One thing I don't like is an udp coupled with a lightened flywheel, the engine looses too much rpm between shifts imho.
Apparently the reduction in rotating inertia can add up to 20hp. An article in the tech section stated that... as well as the GFB UDP description on the Cazracing website saying that they "add more throttle response and power." I'm sure it has been tested on a dyno before to see how much power can be added and if ANY power at all could be added, before writing that into their ad. Otherwise it'd be false advertising I guess. Why make the engine work harder for HP if you can make it work easier? Seems to make sense to me
Once again, the posts from happy owners do the talking. From my own personal experience with these you do notice the engine is not as doughy down the bottom and other comments form owners with UDP's have similar comments. A lightened flywheel gives similar improvement but you don't really get an increase in power. Top end power is not the be all and end all of performance modifications Rob, you of all people would know that better than most I would hope!
i had one. took it off. Had a noticable amount of vibration. i kept looking at the tail shaft. almost had it rebalanced. took off the UDP and it was gone. it did rev up ever so slightly quicker. im glad its gone.
