Underdrive Pulleys - Thoughts????

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

NoCaDiver

FRF Addict
Joined
Mar 4, 2010
Posts
1,274
Reaction score
12
Any thoughts on underdrive pulleys? Nobody makes them, kind of wonder why.

Question is wouldn't they make the engine theoretically "spool" up faster, or increase throttle response?

Just thinking of things I could do to get rid of the lag from the time I punch the gas and the time the truck takes off.

Had them on an '01 Integra and the thing "spooled" real quick vs. stock pulleys, that's my only experience with them.

I understand they reduce weight, less rotations (I believe), which reduces alternator output (not an underdrive pulley - I know) which may have me worried if I have 6 Rigid dualies and a 40" running at once (don't know the draw or stock alternator output). That's the only drawback I can think of. Less parasitic drag IIRC on the drivetrain with the underdrive pulleys or pulley kits.

Forgive my ignorance if I am on the wrong track here, I'm no expert.
 

The Tank

FRF Addict
Joined
Mar 14, 2010
Posts
1,877
Reaction score
50
Location
McMurdo Station Antarctica
The lag is a built in delay from the factory in the ETC. The only way to get rid of it is to get a tune. Also underdrive pulley don't give real world gains. What you pick up in power you'll lose in the transmission and rear end. If you want to decrease the load on your engine an electric water pump is the way to go.
 

SVTRay

FRF Addict
Joined
Jul 1, 2011
Posts
1,780
Reaction score
134
I've never used pullies but don't they tend to slow down the water pump causing the vehicle to run warm?

Anyhow, as Tank said, the Lag is from the ETC, most of your modern vehicles now days use what is called a "drive by wire" stem. This basically isolates the driver from the said vehicle by controlling the throttle electrically. You have to get a tune in order to adjust it. I'm sure you will see more real gains this way first than anything else.
 

MarkT

FRF Addict
Joined
Mar 4, 2010
Posts
1,202
Reaction score
26
Snip- The only way to get rid of it is to get a tune. -Snip

I agree that the "lag" is largely due to the way the computer is tuned.

Snip- Also underdrive pulley don't give real world gains. What you pick up in power you'll lose in the transmission and rear end. If you want to decrease the load on your engine an electric water pump is the way to go. -Snip

I think the gain from using underdrive pulleys would be insignificant on the 5.4 which is probably why nobody makes them.

I don't agree that the gains would be lost in the trans and rear end. I can't see how changing the pulleys to reduce the load on the engine slightly would adversely affect the trans and rear end efficiency.

Electric water pump? Hmmm... on a drag car where you use a "constant loss" electrical system and charge the battery between runs, yes. But power isn't free so on a vehicle running an alternator the overall power gains would be negligible. Maybe a little quicker revving though (which is what you wanted) and you'd have more water flow at idle. But blow a fuse or fry a relay and you can easily blow a motor before you know the electric pump quit.

The BIG drag is the radiator fan which Ford already went to electric on the Raptor.

As far as the Rigid lights? They use flea power compared to regular lights so even if you managed to find underdrive pulleys, you'd be fine.

I think even if you managed to reduce the "mechanical" drag slowing down engine response, you'd still notice the built-in computer delay more.
 

The Tank

FRF Addict
Joined
Mar 14, 2010
Posts
1,877
Reaction score
50
Location
McMurdo Station Antarctica
I don't agree that the gains would be lost in the trans and rear end. I can't see how changing the pulleys to reduce the load on the engine slightly would adversely affect the trans and rear end efficiency.
I think you misunderstood what I meant. Say he goes with the Steeda pulleys. Steeda Underdrive Pulley Kit for 2005-2010 Ford Mustang 701-0005A They claim a 10hp gain but that 10hp is going to get used up in normal drivetrain loss and so you've gained nothing.
 
OP
OP
N

NoCaDiver

FRF Addict
Joined
Mar 4, 2010
Posts
1,274
Reaction score
12
If the delay is actually due to electronics and not mechanical then I would not put the pulleys on. The goal was not to actually gain HP, though it would be nice, but @ Tank's quote of 10 HP with a 15-20% through the drivetrain that would leave a minimum of an 8 HP gain. Again, not my goal. It's really the hesitation that I don't like. When I punch the gas the truck should go THEN not a second later. Acceleration is lackluster but that may be my perception due to the hesitation that I am encountering (or due to the boat anchor of an engine).

I don't know what gears we have in the rear but I imagine that would be another option as well but that would kill cruising speed rpm on long trips.

I didn't think the Rigid lights would pull that much, but again I don't have much electrical/mechanical background knowledge...just enough to get in trouble.

Maybe a tune is the only option, I don't know. I do know I hate all of these electronics and crap and this is one reason I love my Landcruiser, a '91 with very limited electronic "restrictions."
 

SVTRay

FRF Addict
Joined
Jul 1, 2011
Posts
1,780
Reaction score
134
If the delay is actually due to electronics and not mechanical then I would not put the pulleys on. The goal was not to actually gain HP, though it would be nice, but @ Tank's quote of 10 HP with a 15-20% through the drivetrain that would leave a minimum of an 8 HP gain. Again, not my goal. It's really the hesitation that I don't like. When I punch the gas the truck should go THEN not a second later. Acceleration is lackluster but that may be my perception due to the hesitation that I am encountering (or due to the boat anchor of an engine).

I don't know what gears we have in the rear but I imagine that would be another option as well but that would kill cruising speed rpm on long trips.

I didn't think the Rigid lights would pull that much, but again I don't have much electrical/mechanical background knowledge...just enough to get in trouble.

Maybe a tune is the only option, I don't know. I do know I hate all of these electronics and crap and this is one reason I love my Landcruiser, a '91 with very limited electronic "restrictions."



Ya, I went from a non "drive by wire" truck to drive by wire truck. There is a huge difference in acceleration. That is the only reason I'm really even considering a tune my self. If it's anything like the Stangs, it should free up a lot more power and allow the truck to take advantage of future mods.
 

The Tank

FRF Addict
Joined
Mar 14, 2010
Posts
1,877
Reaction score
50
Location
McMurdo Station Antarctica
Call up Mike Troyer at Troyer Performance and he will set you up with a good set of tunes. Also just something to consider from the factory at WOT the throttle blade is only open 80% and goes to 95% above 5K RPMs IIRC.
 

SVTRay

FRF Addict
Joined
Jul 1, 2011
Posts
1,780
Reaction score
134
Also just something to consider from the factory at WOT the throttle blade is only open 80% and goes to 95% above 5K RPMs IIRC.

Yes sir, I remember reading about it with the new mustangs when they made the switch to drive by wire. The cars wouldn't respond to typical bolt on mods due partly to the throttle blades not fully opening at WOT.
 
Top