Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Underdrive pullies for 2.5L Duratech.

torsional damper != harmonic balancer :rolleyes:

no harmonic balancer == kaboom very quickly

no TVD =? lower reliabilty maybe

46,000 miles and counting on my UR UDP (like 2.5 - 3 years)

the NECO guy reported scored cams as well, hard to think an UDP would stop oil from reaching your top end.

OK, different car, different engine, but the Saturn guys at SC Racing took the whole darn belt off for their first dyno run and gained a whopping 3hp. They figured the best they could do was about a 20% underdrive for a whopping gain of .6 hp on something that is probably detrimental to engine life over the long haul. Even if it isn't, it's hardly worth the money.

In their words, "In racing, horsepower talks and marketing bull$hit walks."

Yes, but they still had the heavy weight of the pulley on there. Yes the pulley radius is smaller than a flywheel, but there is still a 5 lb chunk of steel at like 4 inches off axis of rotation. That is roughly equivalent to taking 1-2 lbs off of an 8 inch radius flywheel.

It could if bits of bearing material clog the oil passages...

I would like the name of the person you spoke w/ at SVT.

I can say i've met two people with U/D pulleys and have had no problems for over a year or two....

I'm not doing it but just bringing up a interesting point.

I think the point here isn't when it happens, just that it WILL happen. Do as you wish

Yes it "could", but I know of a few people running top ends from fried 2.5's(spun bearings) on there 3.0's now. Most reported engine failures eat just the bearing, leaving most eveything else at least visually clean.

With the number of duratecs biting it naturally (ie with stock pulleys - and remember for crank whip the stock unit is just as bad as an UDP) it's hard to statisticly say how much an UDP may shorten life expectancy.

I suppose I could send my oil out for analysis by one of the labs to look for bearing material in it (similar to how aircarft predict time for complete overhauls).

Damaged main bearings = loss of oil pressure = loss of upper cylinder lubrication first = scored cams

That is a perfect example of what crank whip can do.

This is somewhat correct. The pulley can't be a 'harmonic balancer/damper' because it connects between two external systems (the crank and the accessory drive belt.) An harmonic damper would connect to an isolated ring of specific mass and size through a damping element. Changing the mass and shape of the ring or the shape and stiffness of the elastomer would change the tuning.

HOWEVER, Terry is correct to warn you to proceed at your own risk. The pulley does act as a broad, untuned damped coupling and will damp transient vibrations at the snout of the crank. How much fatigue damage these transient vibrations might cause has never been admitted (officially) by Ford.