Visual comparison of underdrive pulleys

Sharing just for general interest. This is a stack of pulleys. - the bottom is stock 996.1, the middle is Mantissport and the third is Torque Solutions. I find the differences in size interesting.

Wow! That’s quite a difference!

Was the Torque Solutions only available for the 3.4? Don't find it on their site for an 04 C4S. Was cosidering the RSS one but am wondering if it is actually "worth" it

If you track your car, an UDP relieves a lot of stress on ancillaries like power steering pumps etc. If you don’t track, don’t bother. IMHO.

I went with RSS and really happy, it has been on for a few years now, no issues. Is pretty good quality, a little bit of weight reduction, but not enough to weaken. Beware of purchasing a brand with many holes machined in it, they have a tendency to break Make sure you buy a new crank bolt.

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it is not a tack car. Its a weekend play toy. I have no intention on it being a track car. But will admit that once i get the suspension upgrades done and some other things i do plan to join PCA and try some of the track events.

The theory behind them is they create less parasitic drain and let more horsepower get to the wheels. Not a lot, some claim maybe 5hp, but for some, every bit counts.

So i guess we are saying it is a waste for street cars?

Do you like more horsepower to the wheels? I do... Then not a waste.

I have a cargraphic one, seems well made. Don't have a baseline to compart it to - was done by the PO. Good to see your tape measure is in centimetres!! :-p

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You would have to show me evidence of this hp gain. I track my car and I have found that the UDP has saved me a lot of grief with an over-revving power steering pump and the like (and I do have experience with this type of problem). I think that any power gain is psychological. I could be wrong, it wouldn�t be the first time.

Just to clarify, it doesn�t add any horsepower. It just reduces the amount of parasitic loss, so more horsepower gets to the wheels.

I understand the benefit while at the track, reducing the rpm's going to the ac, alternator, water pump??, etc.is a good thing, I don't think these components like to be at above 6k rpm for an extended period of time. But how do these components deal with the slower rpm while on the street?

There is a ton of information about underdrive crank pulleys all over the internet - for all cars, but many specific to the 996. The bottom line is that they work, put more horsepower to the wheels, and (according to experts like Jake Raby) the solid ones (where the center is not machined for lightness) are durable. Many have reported sustained long term use on street and track. Here are a couple of examples: https://www.ebsracing.com/articles/l...pulley-9x6-9x7 http://www.pedrosgarage.com/Site_2/TechnoPulley.html And if for some reason you don't believe them, even Jake Raby has posted in the past: "Time and time again this install gives us the largest net power increase of any other bolt on.. I've installed a 3,000 dollar muffler and set of headers in the past and haven't gained as much power as this pulley provides. Glad install went smoothly. The Dremel is the tool for this job when doing the work in-car." and "Despite any actual values, this mod is one of the few that can be felt in the driver's seat. I see 5-7 HP at the wheels and a torque increase of generally 5 lb/ft after the installation on my dyno. What should be more considered is this mod creates more power across the ENTIRE RPM range, so the average HP is increased and thats a much bigger gain on a stop watch or in the driver's seat than just a peak HP gain." Both at: http://986forum.com/forums/performan...ve-pulley.html

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From what I've read, anything over 1800 rpm and you are fine. Unless you are in stop and go traffic constantly, or drive like a grandma, I can't imagine how that would be an issue.

The only difference I notice with my Tarrett UDP is that my AC doesn't get as cold as it did with the stock crank pulley (except when driving on the highway). I've never had a problem with the charging system, cooling (I do have a third radiator though) etc...

Well, I won’t argue with Jake! As for regular street driving, I haven’t noticed any disadvantage.

Just ordered the RSS version. Hope its worth it

What are you all doing for TDC pinning for cam timing/maintenance?

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I thought about that before ordering it. I figured i would save the old one for when its needed.

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I asked RSS what size theirs was and they said, "under 5." (<127mm) I was hoping for a more accurate measurement.

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That was my plan as well. I might swap out just for track days. That way I could DD my car. My commute consists of LOTS of stop and go traffic, and perfect working AC is a requirement during the summer. I'll have to order a dozen crankshaft bolts. Luckily they're cheap.

don't overthink folks, it's just like riding a bike. literally. easier to pedal on the smaller front chain ring, yes? but don't go as fast. ditto the udp; less power lost to turning the smaller pulley, but accessories - water pump, alternator, power steering pump, air conditioning compressor - don't turn as fast. issues? power steering seems to like the slower speed better. air conditioning? it's on an electric clutch, so presume compressor just runs longer to meet required load. water pump? if cooling were an issue you wouldn't see these things on track cars where heat management (tires, brakes, engine, driver) is priority #1. alternator? apparently there is an issue here if you are running a lot of big loads - subwoofers, hair dryers, microwave ovens, etc. - at the same time. i've not encountered it myself, and i run the smallest - 4" - pulley. of course, the only electric accessory on my car is intermittent wipers, so ymmv.

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I purchased and installed the RSS Pulley and it was well worth the money. I have installed these on Mustang Cobras in the past and the RSS version seems to be one of the best. As others have said stay away from the units with multiple slots or holes they can fatigue and break. While your in there might as well replace the belt http://roadsportsupply.com/6pk-conti...-kits-601-608/

I've been running an RSS pulley for years with no ill effects. If I recall correctly it came with a new bolt and a pulley wrench and original belt still fit. 03 C2 MT

I think another important point that I did not see addressed was that the RSS units are both smaller in size (Underdriven) but more importantly they are Harmonic Dampers not just a pulley wheel. This has many positive effects not just the lessening of parasitic losses of the belt driven engine accessory components.