Considering a lower ONLY Pulley set-up

[2001asp]

So when you weigh the cost of adding all the idlers and an upper pulley it seems like it would cost more, the same or close to just getting a lower. So my question is simple. How big should I go to match what a 2.80 or 2.76 pulley would produce? I understand I would need an alt pulley. So would I go with an 6LB or 8LB pulley and stock upper? How do the dyno results differ on a lower only pulley? Does the supercharger sound different with an upper only setup? I see the Metco and LFP? Any other inexpensive options? I have $800 to spend and the dyno tune costs $285. My current mods are JLT CAI, Pypes X pipe w/ welded in Mettalic cats, Borla Stinger exhaust, w/ a tune.

Cobra makes 421HP pre X pipe. Can anybody give me details in how this setup differs and what kind of numbers it can make. I am pretty handy in the garage and have access to a lift. Let me know..... Thanks in advance :beer:

 

[cobracide]

Lower is tougher, let's put it that way. Easier is upper. :read:

 

[04sleeper]

Unless you buy a lower with a crank support, don't waste your time. If you value your crank that is.

Also, you still need to buy all the idlers. You speed up the idlers with the larger lower so actually you need them more!

 

[Jefe]

Metco 4# lower here and stock upper. #s in sig. I got a hell of a deal on the lower swap/install though so thats why I went that route. Eventually you will want an upper like me...

 

[2001asp]

Interesting, This is the first I have heard of the crank support. I assume the metco does not come with one. If I did have to go with all the idlers, then I might as well just get the upper for now with full idlers, plugs, boost overlay, and billetflow diff. support. Posi port later and then a lower. BTW, Any reason Billetflow does not make a 2.81 pulley any longer?

 

[Posi]

There's a local guy here that's ran just a 6lb lower for years and his best time the last we talked was like a 11.21 or something close to it.

I run a lower and wouldn't think twice about putting one on the car all over again. What few cranks have broken we know of were either a large twin screw blower or something odd happening is the way I put it. There was one where the guy admitted the pulley ring was loose at some point.

I'm thinking one even broke and the guy posted he had a stock crank. Anybody remember?

 

[Emwun Garand]

After hearing both sides of the crank support argument, I chose to go with the upper pulley and idlers. My personal motto is better safe than sorry. Plus, the stock idlers are absolute trash once you start spinning them faster.

I'm about to install a Whipple 2.3 twin screw and still will be rolling the stock lower. Got myself a Reichard 2.5" Whipple pulley, should be more than enough to hit my 700rwhp goal on E85.

People have run lowers for years without issues, but, I'm not willing to add the extra "what if" risk if I don't need to.

 

[2001asp]

After hearing both sides of the crank support argument, I chose to go with the upper pulley and idlers. My personal motto is better safe than sorry. Plus, the stock idlers are absolute trash once you start spinning them faster.

I'm about to install a Whipple 2.3 twin screw and still will be rolling the stock lower. Got myself a Reichard 2.5" Whipple pulley, should be more than enough to hit my 700rwhp goal on E85.

People have run lowers for years without issues, but, I'm not willing to add the extra "what if" risk if I don't need to.

So what size upper Pulley did you end up going with? What kinda power did it make for you?

 

[Emwun Garand]

So what size upper Pulley did you end up going with? What kinda power did it make for you?

On the Eaton I have a 2.75" Reichard Racing pulley.
My power numbers are misleading though. I have no timing in the tune. I chose not to push it to the limit because I'm about to install the Whipple and switch to E85. I elected the safest route possible by pulling all of the timing out to avoid the off chance of damaging my motor before my build is finished.

Even so, with low timing, I picked up 29rwhp from the pulley. I would guess there's another 20ish in there somewhere.