UD Pullies & S/C

[Cartman]

Underdrive pullies free up horsepower and people that have them have reported that they can rev up quicker and get into their powerband. Okay well my question is would the 'effect' that UD pullies give be more dramatic on a supercharged engine because it would take more load off the crank and give more to the blower? And when you change the accessory pullies do you need a new belt or will the original one still be tight enough?

[FiveO]

I know on the Trilogy the UD Pulley's are not advised or even usable.

With a Eaton style S/C you don't need to rev up quicker because its screw driven off of the engine...and you spool up just fine without it. The boost comes on very quickly...and I mean very quickly.

I'm not sure on the vortec style. Never owned one.

My .02.

[Joe Walsh]

Underdrive pullies free up horsepower and people that have them have reported that they can rev up quicker and get into their powerband. Okay well my question is would the 'effect' that UD pullies give be more dramatic on a supercharged engine because it would take more load off the crank and give more to the blower? And when you change the accessory pullies do you need a new belt or will the original one still be tight enough?


Three things to consider....#1: UDPs slow down all the accessories INCLUDING the water pump. A S/C creates lots of heat in an engine, so it would be a good idea to run the Meziere electric water pump (which runs at full speed all the time).
#2: The smaller underdrive crank pulley would slow down your S/C and decrease boost, so you would have to "re-pulley" the S/C with a smaller pulley to get back to your original boost level.
#3: If the S/C you chose has a 'piggy-back' drive pulley that bolts to the OEM crank pulley, the S/C drive pulley might not fit onto the underdrive crank pulley.

[Cartman]

Okay so it's UDP + for N/A and UDP - for a S/C. But IF there was a turbo instead then it would still be a plus, right?

Thanks.

[BillyGman]

Okay so it's UDP + for N/A and UDP - for a S/C. But IF there was a turbo instead then it would still be a plus, right?

Thanks.This is my opinion on U/D pullies......

If you have a worthwhile form of any type of forced induction (S/Cer,Turbo, or NO2) then that modification will easily add over 100 HP to the wheels, which will transform your car dramatically (it sure has done that to mine!). And after receiving and experiencing the dramatic acceleration increase that comes from adding that much power, many people will not be all that interested, nor concerned about the possibility of the extra 10 HP that U/D pulllies offer. Because you're not going to feel an extra 10 HP when you put your foot int the go pedal. That's just too small of an increase to be noticeable. So if you're planning on a formadable means of forced induction, then why even worry about an U/D pulley set?

[Cartman]

I gotcha. When I thought of this I spaced that the point of them was to slow down accessories and that would negatively affect a supercharger anyway.

But BillyG, I think I read you did most of your mods before your Trilogy. If you could go back are there any that you would not have done if you had just put in the blower in the first place?

[BillyGman]

But BillyG, I think I read you did most of your mods before your Trilogy. If you could go back are there any that you would not have done if you had just put in the blower in the first place?
Yep, almost all of them. Here's a link to a thread about that same topic which I started shortly after I installed the Trilogy S/Cer on my car......

http://www.mercurymarauder.net/forums/showthread.php?t=9507