bmfIROC-Z

iTrader: (1)

just wondering if anybody could save me a hassle and tell me what size belt i will need for a 94 f body lt1 with an a/c delete pulley and a BBK underdrive pulley?thanks in advance.

ssean92

iTrader: (10)

GET RID of the pulley......LT1's do not like those at all. you will end up destroying your engine with that pulley. The little you gain is not worth it.

bmfIROC-Z

iTrader: (1)

BBK's underdrive pulley or underdrive pulley's in general?

drperformance

iTrader: (5)

I can not remember the part number but run a string around the pulleys with the tensioner tight and take that measurement to the auto store.

I ran the underdrive pulleys for years before I went with an ATI balancer that is still smaller then the stock pulley and never had any issues, how would underdriving destroy an engine? Underdriving just reduces the torque required by the crank to turn over the alternator or any other sh*t ran, which in turns frees up a small amount torque or horsepower. And yes horsepower can be expressed in terms of torque (horsepower=((torque*rpm)/5252)).

The only issue I have ever seen with underdriving anything is a remote chance of alternator premature failure.

drperformance

iTrader: (5)

I did not mean to come off like a **** but I hate when people respond without any supporting evidence. If underdriving an alternator could destroy an engine please explain and I am all ears and always open to learning.

If you ask me I would say do not always believe what people have to say, unless they can back it up.

People have been down talking the LT4 hot cam for years and yes it is not the best cam for the LT1. But some how I can run 10s with one and my car is 3300lbs+ with modified stock LT1 heads.

Firebat

iTrader: (7)

Its something with the underdrive pulley having no built-in damper like the stock one does. Supposedly, underdrive pulleys with built-in dampers exist but are expensive.

The other thing is setups with belt-driven water pumps see the most gain out of underdrive pulleys. Cam-driven water pump setup like the LT1 is not near the HP gain.

bmfIROC-Z

iTrader: (1)

anybody ever actually seen engine failure with an underdrive pulley on a lt1?cause my engine is brand new and id really hate for it to start knockin 100 miles down the road because of a pulley,so if anybody has any info on this please let me know,thanks

Klortho

I know that a buddy of mine that built a 383 LT1 put an underdrive pully that was actually made for an LT1, that bolted in place of the stock pully.....it was a neutral balanced underdrive pully, then had his blower pully in front of that. You might want to make sure that the pully us just neutral balanced before using it.

Here's a link to Thunder Racing's site which these are LT1 underdrive pullys

http://www.thunderracing.com/catalog...d=251&pcid=111

it's toward the bottom of the page for the F-body LT1 pullies

49-847600 ASP 34% Underdrive Crank Pulley, 1993-1997 LT1 V8 F-Body. Works with belt 11-595K6. $79.99

These are for the vette's but the alternator pully may work on the f-body alternator

49-945803 ASP Pulley 2 pc. Set, Late 1993-1996 Corvette LT1, 22% Crank pulley and 15% Underdrive Alternator Pulley; full charge at 800 rpm (will not work on LT4) $171.99

And I've been doing some reading, and alot of places are saying that you only get about a 3-5hp gain by using the underdrive pully on the crank, have to worry about the alternator, which you could fix by putting an overdrive pully on the alternator.