Effectiveness of Underdrive Pulleys

[TCKTPLZ]

In my endless search for relatively inexpensive mods, I have come across underdrive pulleys. There was a post about a year ago in the New Products Section with West Coast Jason selling these:

http://vca2.viperclub.org/forums/showflat.php?Cat=&Board=UBB24&Number=373949&Forum=All_Forums&Words=underdrive%20pulley&Match=Entire%20Phrase&Searchpage=1&Limit=25&Old=allposts&Main=370309&Search=true#Post373949

At West Coast Viper's website, they claim about a 15 RWHP gain:

"Includes power steering, alternator, waterpump and crank pulleys. Average gains are about 15HP. Won't cause charging issues! $495.00"

Now my question is, has anyone bought and used this set, and more importantly, is it effective? If it is effective and produces more horsepower, where does it aid the Viper? On the road course or at the drag strip? I am looking for some inexpensive ways to add some more bottom end punch to my snake and perhaps the underdrive pulley set might help.

Thanks in advance!

 

[Russ M]

I have a 25% under drive crank pulley, did some before and after dyno testing seemed to have picked up maybe 5hp.

It is one of those mods that may be difficult to measure propperly without extensive dyno testing, which I was not willing to do. The gain I got was already more than I expected, I am sure if the before and after graphs were looked at closer there may have been more gain which was not seen at peak.

 

[Kiaser]

I don't have that set but I do have underdrive pulleys installed. Mine are really lightweight so less turning mass is always better but definetely shouldnt be invested in if you are looking for noticeable gains. But I have no problems with undercharging or overheating (I have excellent cooling upgrades).

 

[shelbynut]

Underdrive Pulleys

Just a note to let everyone know Unorthodox Racing is blowing out there Viper Underdrive Pulleys for $90...just got mine today, nice piece!

10 Left according to the web site...

Unorthodox Racing Parts Blowout Page

7-10hp for under $100 ain't bad!!

Jay

 

[VENOMAHOLIC]

Re: Underdrive Pulleys

I would consider it as an upgrade because it will free up a small amount of hp but throuougt the whole power band and because it is easily bolted on or off as needed.

 

[REDSLED]

Re: Underdrive Pulleys

Feels like 30 SOTP HP.....




























Big waste of money unless they are chromed out in which case you could justify the purchase by the upgraded "Bling" factor if you frequent car shows or drive around town with your hood off
Performance wise..NADA

 

[Tom F&L GoR]

Re: Underdrive Pulleys

It's a small benefit for two reasons:

1) slowing the speed of the power steering pump will greatly lessen the chances of overheating the fluid and causing the occasional fire, rack failure, etc.

2) the "power" effect shows more in transient behavior. If you measure power at a steady speed, the benefit is only is that from driving the accessories at a lower speed. If you measure the "power" effect during an acceleration, the engine also has less effort to spin an alternator from idle to 10,000 RPM (I'm sort of guessing at the number, but it's more than engine speed because the pulley is smaller) than from idle to 7500 RPM. And admittedly whatever the benefit is, it's probably small. It's the same argument as a lighter flywheel; you can change engine speeds more quickly, which is measured as "power" but it's probably better defined as "less power drain."