People With 8 lbs. Lower Pulley Change Only

[adrenaline rush]

What made you only change the lower instead of the upper or a combination?

 

[Antex]

Ratfink on another board did it - very little ,if any belt slip...

 

[bender460]

At the time I didn't want to use a 2.93 upper "too much with no tune". So trying to work around the warranty I chose a 4lb lower, a wideband O2 set up and a MAfterburner EFPC. Was a great combo. Was time for more boost so just went with a 8lb ring and an alternator pulley. And still no need for idlers and looks stock to everybody else.

 

[mosconiac]

I'm of the opinion that you should maximize your lower pulley before moving on to upper pulleys. Belt slip is the reason why. I run an 8# lower (with stock upper) and it holds boost all the way to redline. I don't need to run bandaids like idlers or belt dressing and hope it doesn't slip the next time I race someone...peice of mind so to speak.

 

[Antex]

I'm of the opinion that you should maximize your lower pulley before moving on to upper pulleys. Belt slip is the reason why. I run an 8# lower (with stock upper) and it holds boost all the way to redline. I don't need to run bandaids like idlers or belt dressing and hope it doesn't slip the next time I race someone...peice of mind so to speak.

Did you change the altenator pulley? If so what size?

 

[Special Blend]

I'm of the opinion that you should maximize your lower pulley before moving on to upper pulleys. Belt slip is the reason why. I run an 8# lower (with stock upper) and it holds boost all the way to redline. I don't need to run bandaids like idlers or belt dressing and hope it doesn't slip the next time I race someone...peice of mind so to speak.

I like the sounds of this. Looks stock and much easy to put back to stock. Anyone else with any experience with this combo?
About how much boost are you see with the 8# lower?
And do you run the same size belt that is needed with a 2.93 upper?

 

[mosconiac]

Did you change the altenator pulley? If so what size?

Oops, I forgot. I run a 3.2" alt pulley which returns the alt speed back to stock (within like 2%).

About how much boost are you see with the 8# lower?

I can't tell you exactly how much boost I see, but I estimate at 15psi in 80* weather. The needle pegs sideways as shown in the photo below so it should be about 5 psi above the 10 psi mark.

And do you run the same size belt that is needed with a 2.93 upper?

Absolutely not. The crank pulley gets HUGE so the belt length goes up accordingly. The stock belt is around 74-1/2". With my setup (8#/3.2/3.65), I run a 83-3/4" belt!

 

[soccer8888]

^^ Nice CF background. Got any more pics of the setup?

 

[Antex]

Oops, I forgot. I run a 3.2" alt pulley which returns the alt speed back to stock (within like 2%).

How did you figure out the 2% alt speed. I remember you saying with the 4lb lower the alt speed is 8% slower than stock.

So the 8lb lower is like having a 2.93 upper....have you found what the other combos give - 3.10/8lb or 2.93/8lb? (not that I'm thinking of doing this..lol)

And this is without the auxilary idler right?

 

[Special Blend]

Sweet man. I like the looks of that boost gauge....hehe. I am really liking the idea of switching that alternator pulley and just running a 8# lower.

 

[mosconiac]

How did you figure out the 2% alt speed. I remember you saying with the 4lb lower the alt speed is 8% slower than stock.

Its all a matter of pulley ratios. Just divide the lower pulley diameter by the alt pulley diameter to get alt speed relative to engine speed. I wrote the following up several months ago...you might find it helpful...

Per METCO, the stock alternator pulley is 2.6”. The lower pulleys Metco sells are 9.55”(8#), 9.10”(6#), 8.6”(4#), and 8.0”(2#). OEM is 7.6”.

The alternator pulley ratio is 1.231 from 3.2” to OEM (2.6”).
The stock lower pulley ratio is 1.257 from 8# (9.55”) to OEM (7.6”).

That means the 8# with 3.2" will spin just a bit faster (2%) than an all OEM system. Looking at it another way, the alternator pulley will spin 2.846 times per lower pulley revolution with all stock pulleys and the alternator pulley will spin 2.984 times per lower pulley revolution with the 8# and 3.2” pulleys.

So the 8lb lower is like having a 2.93 upper....have you found what the other combos give - 3.10/8lb or 2.93/8lb? (not that I'm thinking of doing this..lol)

And this is without the auxilary idler right?

You're in luck...check the following thread for just about every pulley combo out there.
http://67.15.62.79/forums/showthread.php?p=2480889#post2480889

I don't run any aftermarket idlers.

 

[mosconiac]

^^ Nice CF background. Got any more pics of the setup?

 

[mosconiac]

From this photo of the boost overlay (which most believe is very accurate), my 8# lower puts me at 14 psi when the needle is flat.

 

[badctcobra]

How did you do that to the boost gauge. It looks awesome!!! Does a company make that?

 

[BlackMachWon]

How did you do that to the boost gauge. It looks awesome!!! Does a company make that?

Here ya go
http://www.billetflow.com/Boost-Overlays.htm

 

[adrenaline rush]

I'm starting to really like the lower pulley change more than an upper. What have your TQ & HP numbers been looking like?

 

[heywaitfourme]

i'm goin to bump this up since i am interested also

 

[03YellowVenom]

Im running a 2.76 with a 4lb lower.The torque is unreal gotta luv it. I hold 19 to 20lb's of boost all the way to red line. :rockon: