If UNDERdrive pulleys are so great, why aren't they factory/OEM?

[fixizin]

I mean they're smaller, require less material/money to produce, and do ALL SORTS OF WONDERFUL things, including, allegedly, better EPA/CAFE mileage numbers, more butt dyno, etc... yet Ford decided to forego all these "curb appeal/showroom" benefits?

There must be some DOWNSIDE to having your water pump or fan or alternator or P/S pump or A/C compressor turning too SLOWLY...?

 

[Big Jim M]

I mean they're smaller, require less material/money to produce, and do ALL SORTS OF WONDERFUL things, including, allegedly, better EPA/CAFE mileage numbers, more butt dyno, etc... yet Ford decided to forego all these "curb appeal/showroom" benefits?

There must be some DOWNSIDE to having your water pump or fan or alternator or P/S pump or A/C compressor turning too SLOWLY...?

Yup!
Big Jim

 

[Wicked_Sludge]

when a car manufacturer designs an engine, they have to make into account thousands of different variables. your stock pulley set was designed to perform under ALL conditions. your underdrive pulley will only perform under most conditions. this may or may not become a problem for you later in the future, but it might be a problem if grandma was driving your truck, or if Mr. businessman was driving it, or what-have-you.

slower turning accessories mean you have reduced your cooling capacity, power steering capacity, electrical capacity, ect.

 

[fixizin]

slower turning accessories mean you have reduced your cooling capacity, power steering capacity, electrical capacity, ect.

Right, but I'm wondering if there's a THRESHOLD rpm, below which some accessories work erratically, and/or suffer damage...? Just curious, underdrive pulley NOT on my to-do list.


PS: There's no way to change the idle speed on a 3.0 w/ EEC-V system, right?

 

[Bob Ayers]

Right, but I'm wondering if there's a THRESHOLD rpm, below which some accessories work erratically, and/or suffer damage...? Just curious, underdrive pulley NOT on my to-do list.


PS: There's no way to change the idle speed on a 3.0 w/ EEC-V system, right?

You are exactly right!!! The UDP manufacturers, as well as the aftermarket air filter & intake manufacturers will try and make you believe that vehicle manufacturers don't know what they are doing, to make a buck off of you!
In reality, you are correct, vehicle manufacturers design their vehicles to be
as efficient as possible for CAFE reasons!

 

[red2003xlt]

The tooling for the 3.0 and it's accessories was paid for years ago(amortized I believe in the correct term). It's wouldn't make financial sense for Ford to develop and then retool a plant to make the underdrive pulley.


Good question about the threshold......

 

[Big Jim M]

So, a factory must retool for a PULLEY that they purchase from outside sources?
Big JIm

 

[krugford]

Yeah, pullies are cheap. The only reason they wouldn't change is because you have to make a business case for it. An underdrive pulley on the alternator isn't going to do any good. It's a regulated system, if you decrease it's speed, it'll increase the torque to meet the same power requirements. Running the water pump at a lower speed than what it was designed for is retarded. In order to keep the engine happy and cool, you need to meet a minimum heat rejection to prevent it from overheating, especially overheating in localized regions like the head deck, cylinder walls, valve seats, etc. Also keep in mind that a smaller pulley on the crank will not be able to transmit the same amount of power as a larger pulley without an increase in slip because of the decrease in belt length on the pulley.

As stated above, and underdrive pulley may work fine in some operating conditions, but not all. That's why it doesn't come from the factory that way.

 

[red2003xlt]

I looked at the underdrive reference elsewhere; Underdrive on the crank, overdrive on the alternator, stock size elsewhere.

 

[mhughes165]

You are exactly right!!! The UDP manufacturers, as well as the aftermarket air filter & intake manufacturers will try and make you believe that vehicle manufacturers don't know what they are doing, to make a buck off of you!
In reality, you are correct, vehicle manufacturers design their vehicles to be
as efficient as possible for CAFE reasons!

headers are 99% of the time better all around for a vehicle....yet they dont come factory, if the automakers tried to do everything the aftermarket is there for, then the aftermarket would disappear.....

 

[Bob Ayers]

headers are 99% of the time better all around for a vehicle....yet they dont come factory, if the automakers tried to do everything the aftermarket is there for, then the aftermarket would disappear.....

Headers normally help the high RPM range for HP, but they do reduce torque at the low RPM range. And since most people don't run in the high RPM range, there is more advantage to low end torque.

 

[Robin Hood]

The underdrive pulleys are worth it though right?

 

[shadetree]

Headers normally help the high RPM range for HP, but they do reduce torque at the low RPM range. And since most people don't run in the high RPM range, there is more advantage to low end torque.

It depends on the system design. The system can be designed for low end torque. The idea is to keep the system sized so as to keep gas flow velocity high at the lower engine rpm where the vehicle is normally operated.

Factory systems/designs,pulleys , timing, and many other factors are a tradeoff, more of an average due to the many conditions in which the vehicle may possibly be used. Tweaking and tuning here and there will give some gains, but there us usually a tradeoff somewhere else. You don't get something for nothing.

Many vehicles come with headers from the factory, including Rangers.

Aftermarket pulleys don't add power, they just free up power the engine already has. shady

 

[Will]

I don't know about headers. The heads on my wife's Honda Pilot have a huge oval exhaust pipe coming straight out of them. There is no 3 into 1 manifold or header. All the secret shit is done in the cylinder head--which is huge. It moves enough air to make 255hp out of 3.5 liters at only 5,750rpm. I think the stereotypes we grew up with can be safely shitcanned.

 

[Mutant Pony]

Everything done on a factory vehicle is a tradeoff. Stock vehicles are like A/T tires, They may do everything but, not good at most of them.
That is why a 19 second stocker can be turned into a 7 second drag car. The seven second car isn't much good for picking up groceries.
In HIGH rpms the water pump "cavitates". Which basically means the water in the pump in not going anywhere. An underdrive pulley will slow the pump down so that it doesn't cavitate. The down side is that at idle you are not pushing as much water so, you may need to upgrade the cooling system to keep from overheating.