Underdrive pulley

what pulleys did you buy?

How much hp difference does a pulley make anyways ?

Aftermarket^^

I didn't do a before/after dyno run, so I have no idea. If someone else has the dyno runs that would be cool to see. I expect they add less than 5 RWHP.

First off you'll need to remove the water pump bolts (should be 4 of them) this can be tricky because the pump spins very easily. Might be easier to remove before you remove the serpentine belt and it would help to have someone give you a hand holding it in place. I was able to wedge a wrench between two bolts to hold the pulley in place while I loosened it.

Next you need a pulley removal tool to pull the crank damper off of the crankshaft.

Finally, you need an impact socket to remove the alternator pulley bolt.

Reassembly is fairly easy for the alt and water pump. Again, it can be tricky to get the water pump bolts tightened up.

I assume the underdrive crank pulley is the piggyback style. Therefore I'd recommend soaking the summit piggyback pulley in hot boiling water for at least a few minutes before bolting it to your stock crank pulley. This part was by far the most difficult for me. The damn powdercoating on the pulley made it really tough to get over the oxidized crank damper. Good luck, let us know if you have problems. Also, it helps to post pics if you do happen to have trouble with the install.

I have the Steeda pulleys and they are a great product(approx. $200). They are not piggyback style... stay away from those. I felt the difference on take-off and on freeway passing.
The air-impact drill is a must,otherwise you will struggle: You need the air-impact drill to take off the crank pulley bolt (12mm socket) and the alternator pulley nut (15/16 socket). The water pump bolts can be done by hand using a 12" long screwdriver at an angle on two bolts in front of pulley to prevent it from turning and a ratchet to loosen the 10mm bolts. It took me 30 mins max.

vipes1 said:

I have the Steeda pulleys and they are a great product(approx. $200). They are not piggyback style... stay away from those. I felt the difference on take-off and on freeway passing.
The air-impact drill is a must,otherwise you will struggle: You need the air-impact drill to take off the crank pulley bolt (12mm socket) and the alternator pulley nut (15/16 socket). The water pump bolts can be done by hand using a 12" long screwdriver at an angle on two bolts in front of pulley to prevent it from turning and a ratchet to loosen the 10mm bolts. It took me 30 mins max.

Click to expand...

Do you have actual first hand experience with the piggyback pulleys being problematic? I doubt it.

I've had piggyback pulleys on my car for about 80K miles and haven't had any issues. In fact, I don't know anyone personally who has had issues with the piggyback pulleys. Of the reported errors on the internet most were related to stock crank damper failure that likely would have occurred regardless of the presence of the piggyback pulley the remaining failures were likely due to an install problem.

I actually timed myself for the heck of it.
Took just over 18 minutes without rushing - used air tools for all of it. You can use a strap wrench on the water pump pulley and it is no sweat.
Don't know about actual gain in hp but seems to rev up faster.

My advice:

Alternator pulley. Use an impact gun. Simple as that. I don't think there is another way.

Water pump pulley. I use a big flat-head screwdriver (because the shaft is square) or a pry-bar through the bolts to hold the pulley in place while you remove the bolts. It's a little tricky, but one you figure out one of them, the other 3 will come right out.

Dampener. If you have a small impact gun, you can use that to take the bolt off, but my IR won't fit between the pulley and fan/radiator. So you'll have to do it with a breaker bar (socket size is 18 mm, btw). If you have a 5-speed, you can put it into gear to hold the crank from turning. If you have an automatic, you'll have to hold one of the bolts on the torque converter (should be a 14 mm) with a wrench or small ratchet through the access plate on the front of the bell housing.

When re-installing the dampener, be sure to put a small dab of RTV in the keyway to keep oil from leaking out of it. Also, the bolt isn't going to reach initially. It's best to use a rubber hammer to tap it on, or a wooden board over top of it to keep from breaking the dampener.

And technically, the crank bolt is a TTY (torque to yield) bolt that should be replaced, and torqued to spec. I have reused mine several times with no problems, but I have always torqued it to spec (which is 60 ft-lbs + 1/4 turn, IIRC).

The motor will rev up MUCH faster with the UDPs. I think some of the old 2-valve guys recorded gains of around .1 and 1 mph in the 1/4 mile. Hey, they came on the '01 Bullitts stock, so they must be of some gain if Ford was willing to put them on some of their cars.