JTSVP Gen III Underdrive Pulley

[AMS3]

I'm thinking of ordering one of their pulleys. Anyone have any Pro's and Con's about this, and what real gains would I get out of it?

 

[VIPR PWR]

My only con is that it slows the drag on the other systems to give you a few horse power ... can cause charging , running hot at idle in traffic or even overheating ... that’s my experience with changing pulley sizes years ago on my 340 duster .. they came off fast and power gains were not seat of the pants feel ..

 

[CaptnCrash]

Based on personal experience I would say go for it IF the truck is strictly used for racing. If you street it I wouldn't do it, especially in a hot place like GA where you need cooling and A/C. The few HP you get isn't worth the down side.

 

[Psycho1122]

My experience with the UD pulley is contrary to the above statements. I live in Phoenix metro area and the UD pulley did NOT effect the cooling. If anything, it slowed down the flow off coolant through the radiator just a touch to INCREASE heat exchange. If your cooling system is up to snuff and you have maximized your water ratio as I did, you will not have cooling or even charging issues. I always had a good system VDC even at idle. The voltage regulator in the system compensates effectively.
Seat of the pants? I would state that is works good as part of the whole "package". Proper custom tune, correct gap and indexed plugs, cool intake charge from the stock set up and a free flowing exhaust like a B&B. The UD pulley just allows the engine to rev though the range in a shorter amount of time.

Cheers!

 

[AMS3]

Thank you to all of you. I will consider your inputs before making a decision. I might wait until I install my B & B headers and exhaust before deciding. Worst case scenario, if I go with the UD pulley, I can always put the factory back on.

Psycho,
What tuner do you recommend?

 

[rottenronnie]

Do yourself a favour and have your headers coated.
BIG reduction in underhood heat!!

 

[rottenronnie]

U/D pulley will unlock about 10 horsepower and a five-inch won't bother anything else.
i've run one for years without issue.

 

[rottenronnie]

Our 5", through dyno-pulls and street-use evaluation, was the sweet-spot for diameter, and worked without penalty.
Smaller than that could provide a few more horsepower but it will slow things down considerably and might not be the answer for a vehicle used primarily for street-use.

 

[oldcolt]

I have used rottenronnie's underdrive pully for years, without issue.

 

[Psycho1122]

Psycho,
What tuner do you recommend?

I used the SCT and Torrie from Unleashed assisted with the custom tunes.

Cheers!

 

[AMS3]

Once again, you guys are a wealth of information. Thank you to all and have a Happy New Year!!!

 

[stealth78]

Riding the shirttails of the other comments... I have had a UD pulley on my 04 and 06 SRT-10's as well as my 06 and 08 Viper's and never had an issue. I'm not positive but I think most of the UD pulleys being offered for the GenIII's, GenIV's and GenV's are the same size, if so you should be safe. I think most people that mention that they have charging issues may have simply had a battery that was at the end of its life cycle, in-turn the UD pulley was the easiest to point the finger at.