Idler and Pulley Question

[04-VENM]

I am going to order the 4 piece billetflow idlers, and 2.76 ns billetflow pulley.
I have heard some of you say that you want a 2-4-6-8 lb lower pulley, is that part of this idler kit or is it something serperate?

If it is sepertate which lower should I go with 2-4-6-8? Looking to port the eaton, plenum, tb at stiegs.

What boost should I expect with the 4 piece and 2.76?
What boost with the lower pulley with either the 2-4-6-8 lower?

Any help would be apprecitated...

 

[Wings65288]

yes i would like to know, good questions

 

[badboy]

You increase your boost by increasing the blower speed. You can do this with a smaller blower pulley or a larger crank pulley or a combination of both. The "lower" is the crank pulley. Has nothing to do with idlers. The problem with a smaller blower pulley is belt slip. You can minimize this with a snub idler which increases the belt wrap around the blower pulley. A better solution is to go with a larger blower pulley and a larger crank pulley (2,4,6# lower) to produce the desired blower rpm (boost).

The lower pulley install is a major project and expensive (but I think its worth it). You also need to change the alternator pulley as well to maintain its design rpm with the larger crank pulley.

The stock lower pulley OD is about 7.63".
4# is 8.75"
6# is 9.25"
8# I don't know. I think its too large to fit easily.

You can calculate which lower/upper combo will give you the rpm you want. With my 6# lower/3.1 upper I get about 16# of boost.

 

[04-VENM]

You increase your boost by increasing the blower speed. You can do this with a smaller blower pulley or a larger crank pulley or a combination of both. The "lower" is the crank pulley. Has nothing to do with idlers. The problem with a smaller blower pulley is belt slip. You can minimize this with a snub idler which increases the belt wrap around the blower pulley. A better solution is to go with a larger blower pulley and a larger crank pulley (2,4,6# lower) to produce the desired blower rpm (boost).

The lower pulley install is a major project and expensive (but I think its worth it). You also need to change the alternator pulley as well to maintain its design rpm with the larger crank pulley.

The stock lower pulley OD is about 7.63".
4# is 8.75"
6# is 9.25"
8# I don't know. I think its too large to fit easily.

You can calculate which lower/upper combo will give you the rpm you want. With my 6# lower/3.1 upper I get about 16# of boost.

What boost will I get with just a 2.76 Upper? Why is it so expensive or hard to change the lower crank pulley? Is it that much different than a fox body?
What will give me the most boost that is not going to blow up in a week? Can you achieve 17-19 boost with a eaton?

 

[badboy]

Too many questions. Try the search function and do some research.