Underdrive pulley?

[Torrle101]

What will an aftermarket Forward Motion underdrive pulley do that a stock 3.0 liter pulley won’t do? They look the same except the aftermarket one looks like it has room for another belt on the end, and if that’s what it’s for what would it go to? How do they help increase power?

[MOPAR_TUNING]

The under drive pully is not the same size its smaller and if it comes with another attachment its probably for the air conditioning wich you prolly dont wanna have hooked up if youre trying to gain power from the under drive pully.

I see youre from kalamazoo Im from Portage Kalamazoo.

[Torrle101]

Wow your pretty close, what do you drive? It’s possible I might have seen you around before.

[MOPAR_TUNING]

Well i just got done doing an engine swap on my car. and im currently doing a complete rebuild on the old motor. I drive a Red with gray 1990 dodge daytona ES with a 1991 5speed 3.77GR and a 1994 6g72. i bought the car last summer took it to the track over at martin and blew the trans then got the trans swaped took it to the track the next week and i spun a berring on the crank. it sat for about the whole winter and i just got it running last week ive been driving it for about 3 days now all over portage on westnedge and stadium.

What do you drive?

[Torrle101]

I drive a red 93 Daytona IROC nothin special.

[MOPAR_TUNING]

cool..this is my cardomain check it out.

Dude what are you doing tomorrow? it would be cool to meet a TD fan all the other TD guys in michigan live like an hour away or more.

http://www.cardomain.com/ride/3150691

[c2xejk]

A couple years ago I dyno tested the UDP and found that it does not add peak hp, but does add ~4 off-peak whp. If you search the 3L section of the Forum, I am sure you can find all the results.

[Juggy]

the power gain is mainly from the weight savings, and not the actual underdriving.

[c2xejk]

One test I have toyed with doing is removing the belt altogether... I could also add removing the pulley completely.

A couple weeks ago I did notice that the timing mark is MUCH more stable without a belt on. To set the timing on my turbo 3L I removed the UDP and put the stock pulley on. Since I didn't have a stock belt, I didn't bother with it... The timing was rock solid and didn't waver jump like I normally see...

[mopar3.0]

i never found any seat of the pants power from the pulley but it did seem to make the engine rev quicker and smoother

[mightymulhern]

I just found that it made my headlights dim when idling at a stop light.

Then I upgraded to a 130A Jeep alternator... and they still dim when idling at a stop light.

Not my favorite mod.


BUT... I was with Ed when he did the UDP vs no UDP test. As he commented, there were marginal off peak gains and the peaks were the same.

[Ondonti]

Quote:

Originally Posted by c2xejk One test I have toyed with doing is removing the belt altogether... I could also add removing the pulley completely. A couple weeks ago I did notice that the timing mark is MUCH more stable without a belt on. To set the timing on my turbo 3L I removed the UDP and put the stock pulley on. Since I didn't have a stock belt, I didn't bother with it... The timing was rock solid and didn't waver jump like I normally see...

I would be interested to see a dyno pull with the belt off. Would you have to have a charger on the battery?

lets get some custom clutched crank pulleys that disengage @ WOT

I think the UDP makes a big difference when you lug around the motor at low rpms. Which I love to do. Probably a lot of power is eaten up by accessories around 1000 rpms.

[mightymulhern]

Here's Ed's van with and without an underdrive pulley. Green is with. Blue is without.

[MOPAR_TUNING]

Quote:

Originally Posted by Torrle101 I drive a red 93 Daytona IROC nothin special.

hehe its funny that i got to meet you today at 3 in the morning i keep looking for ricers but i can not find any in portage. its probably because of the economy they dont have money to drive their 30-40MPG civics and toyotas.

So how was that ride in my daytona? hehehehe. well if you want your daytona to be as fast as mine just let me get my hands on it.
It was a huge differance between a stock daytona and my daytona i dint think all those mods i did were going to actualy do anything but i gues i was wrong.

How did you like my ricer burn out at the stop light? hahaha now i got melted tire all over both doors.

[Torrle101]

It was a fun ride, It’s nice to know now from experience that a 5 speed can REALLY wake up the three liter. Although in reality most auto trans units out there tend to be “dogs” when it comes to power. I know she’s got more power than that, My old 88 NewYorker 3.0, with a blown head gasket, and two twelve inch subwoofers in the trunk could light up the tires from a complete standstill. It had a 3 speed auto of course, I swear that tranny was indestructible! I put that car thru so much abuse at the age of 18. It ended up down at LKQ this winter and someone took the tranny. But for Christ sakes I can just barely peel out on wet payment! Something’s definitely not right with it. I’ll eventually figure out why I’ve got an issue with power loss.

Quote:

Originally Posted by MOPAR_TUNING How did you like my ricer burn out at the stop light? hahaha now i got melted tire all over both doors.

You call that a ricer burnout? Nooooooo I beg to differ, besides there little 1.2 liter VTEC engines couldn’t even move a box fan fan blade if it was hooked up to it, no torque lol.