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alleneagles

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I was thinking about getting underdrive pulleys. Are they really worth it? About what gains would I see and where would I go about purchasing them?
 
I installed UDPs in my V6 a few years back. It was an easy install except getting the alternator pulley off. I needed an impact gun for that one. It took about an hour or so to install.

Back on track, the UDPs will free up about 10-15 HP, not a big gain in itself. I noticed a little better performance, but that might be attributed to the CAI I installed at the same time. I did get better fuel economy as well, about 3-5 mpg.

As far as "worth", it is your car & your money, do what you want with it, we are here to give advice and try to help.
 
I wouldn't mess with the engine's balancing. Not a mod if you're

what do you think heads/cam does? changes the engines "balance"
 
1onebadfox said:
what do you think heads/cam does? changes the engines "balance"
That's not what was being asked. I, myself am uncomfortable changing the balance of an engine, especially at the lower most part...

As for heads and cams... I know nothing about them, so I can't comment on that.
 
I wouldn't mess with the engine's balancing. Not a mod if you're going to keep the car for a long time, but that's my .02.
Underdrive pullies do not change the engine's balance one bit.
 
Underdrive pullies do not change the engine's balance one bit.
These engines aren't balanced with the crank pulley? It's not a harmonic balancer?

This was the issue with 6G72 engines (3000gt/stealth)... They were externally balanced and the crank pulley was the harmonic balancer.

For the OP:
http://www.miracerros.com/mustang/pulley_tech.htm said:
Some Commonly Expressed Concerns about Underdrive Pulleys

1. Lowering the alternator speed will cause the battery to run down.
That may be true for some people. If your driving style includes idling the car for long periods, or if you have a high end audio system that requires constant power from the alternator, underdrive pulleys may not be for you. The hot idle speed for a 2000 Mustang 3.8L V6 engine is 700-800 RPM. ASP claims that with its 25% underdrive set the alternator will provide a full charge when the engine is turning over at 850 RPM. I don't expect any problems in this area.

2. Lowering the water pump speed will cause the car to overheat in traffic.
If your cooling system is in marginal condition, that could become a problem. An underdrive pulley will remove some of the margin of safety that Ford builds into its systems to account for clogged radiators, slipping belts, etc. If you keep your cooling system in good shape, it should not be a problem. I live in Southern Arizona where it gets HOT in the summer. I haven't had any overheating problems.

3. Lowering the power steering pump speed and the A/C compressor speed will result in decreased power steering and A/C efficiency. The people I've talked to who have installed 25% underdrive pulleys don't seem to notice any difference in A/C or power steering performance.

4. Installing a smaller crankshaft pulley can cause the crankshaft to fail. The people who say this always seem to be talking about the (stupid) practice of removing the harmonic damper and not replacing it when installing a smaller crank pulley. The damper is there for a reason, and removing it probably will result in damage to the crankshaft over time. Manufacturers of underdrive pulleys for the V6 Mustang agree. Their underdrive crank pulleys either piggyback on the stock pully/damper, or they come with a new harmonic damper to be installed along with the new pulley.

5.
Underdrive crank pulleys are not compatible with superchargers.
True. You don't want to underdrive a belt driven power adder. If you have any plans to install a supercharger at some later date, don't waste your money on underdrive pulleys now.

UPDATE August 2003: It's been ten months and 7,000 miles since I installed this pulley, I've had no problem with overheating, even when sitting in Tucson traffic in 110 degree weather. My battery has not run down. And I haven't noticed any difference in A/C or power steering performance.

UPDATE February 2006: More than three years and 40,000 miles with this pulley and still no problems.
Jason
 
Regardless of "balance" or some other immeasurable skip underdrive pullies, they make your car run hotter and your charging system run lower...both BAD...trust me, I've had them...spend your money on something else..any minimal gain is not worth the problems they cause.
 
These engines aren't balanced with the crank pulley? It's not a harmonic balancer?

This was the issue with 6G72 engines (3000gt/stealth)... They were externally balanced and the crank pulley was the harmonic balancer.

For the OP:


Jason
Sigh...

Anyhow, if you buy the correct kit for your Mustang it will come with the correct crank pulley. 94-98 are a pulley only change while 99-04 require a pulley/balancer (which is one piece) to be changed.

A proper kit that is made to proper specs will not change the balance of the engine one bit. I personally would not install one on my car as well, the gains are not worth it.
 
Sigh...

Anyhow, if you buy the correct kit for your Mustang it will come with the correct crank pulley. 94-98 are a pulley only change while 99-04 require a pulley/balancer (which is one piece) to be changed.

A proper kit that is made to proper specs will not change the balance of the engine one bit. I personally would not install one on my car as well, the gains are not worth it.
+1 b1lk1...

if your charging system and cooling system are healthy, you won't have any problems. i've had mine for 2 years now, my car's battery never dies, nor does the engine run hot. also, my a/c works fine, as does my power steering.

also, changing the circumference will not affect the engines balance one bit. the harmonic balancer behind the crank pulley is replaced, but it is the same exact weight/design. (provided you purchase the correct kit).

in response to the OP:
unless you can find a good quality (name brand) set for less than $150, skip this mod.
 
WOW..... U really got me thinking now. My next mod in mind was getting a set of UDP's. The kit I saw has the water pump and crank (with armonic balancer) pulleys and a new shorter belt. It's from motoblue and it costs 300 dlls at RPM Outlet. Here in Culiacan it gets really hot in the summer, but te cooling systems runs very good, it almost never even gets close to the center of the gauge. I just ordered a no-name CAI, Accel Coilpack, and Tyler Spyro 8mm wires from AM. My next step was the pulleys and after that a t-lok and 4:10 gears (it's an auto) and then a tuner (SCT X3). So, should I skip the gears or what ?! Any help would be really great !! THX
 
I wouldn't skip the gears. I love my UDPs and would recommend them, but If I had to choose between the two, I'd go with gears.
 
Oops, sorry. My bad. I meant skiping the UDP's and going straigth to the gears.
 
Yeah there would be nothing wrong with that. you will feel more much more out of those gears that for sure. However, IMO, everything counts. If possible do both.
 
so i have a 98 mustang gt. how much off a difference would i notice while driving?
 
so basically a waste of money. but replacing the a/c compressor with a pulley does that increase power at all or just weight reduction?
 
no power increase(cuz the compressor has a clutch and freewheels when the system isnt on) just weight reduction especially if you get rid of all of the A/C system.. all lines and everything
 
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