UDP Face off

[roswald0511]

What about an Underdrive Pulley face off.

FRI
PPP
SLP

Anyone else I am missing?

[tank8289]

you could do ATI

[roswald0511]

you could do ATI

Good call.

BIG BUMP

[CoolVanilla]

In theory it shouldn't be too hard to measure relative differences; pull the nose and swap parts...

But, I think the real measure of an under drive pulley/harmonic balancer is something we'll never be able to test: how well it stays together and how well it protects your motor.

I'm fairly certain there have been a handful of guys who have directly compared "stock" diameter to "under drive" diameters already. I don't recall the performance benefit being dramatic though. A few ponies? Can't remember...

But in my opinion, and again this is something we can't test, the ATI is the only one out there that is designed to actually protect the motor by dampening the harmonics of the crankshaft. The others are copies of the stock design (or are very similar). They do have some dampening affect, but I'm not convinced that effect is worth anything at higher power numbers (and none at all on a stroker), nor am I willing to subject my motor (nor anyone else's under my control) to a part I think will not prevent major damage over time (thinking about us real high power guys who NEED a dampener for protection purposes, and not power purposes).

The second point is the SFI certification; to my knowledge, the only one NOT SFI tested is the FRI unit. All others are. So without actually running an SFI style test ourselves (and taking out the side of a building, probably) this is just something we have to accept as having been done, or not.

So again, I'm not against the long term idea of running stock, swapping in the extreme overdrive and then the extreme underdrive, but I'm pretty sure this has been done indirectly and the results just arnt there. Also, when considering which to go with, IMHO SFI is a must as is an actual attempt at dampening... those two together make the ATI the only current choice, and therefore "it is what it is", regardless of the power benefit (or lack there of).

[stevesrt8]

nice points, but there are many more advantages from these. At least on other cars I've used them on.

Assuming you don't blow the engine to smithereens, of course.

One is smoother A/C engagement as the system cycles the compressor clutch on/off.

Another is snappier throttle response, extremely subjective, I know.

Lastly, I can imagine they may affect life of compnents favorably due to reduced speeds, especially in "enthusiastic" use, like road course. If you are a rev junkie this may really positively affect the life of the components driven by your serpentine belt.

I can't believe anyone would even consider these if there not certified and correct dampeners as well.

[Mike @ New Era]

Just FYI , SLP and Powerbond equal the same thing , Powerbond actually makes them for SLP .