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Discussion Starter · #1 ·
I just got done installing a 6lb lower and 3.2 alt pulley. All i can say is WOW! Boost gauage pegs 17psi and holds untill about 6000 rpms! It wasnt a bad job at all. They arent kidding when they say the stock crank pulley bolt is a MO-FO! You better eat your Wheaties!!! The longest part of the install was finding a belt to fit. Tried so many combos, i finally ended up w/ a 80.25 in belt. It was a tight fit! I am running the 100mm idlers also. I definately need a chip reburned now. I do get a lil ping under a heavy load. But i got about 5 gallons of 110 octane to be alil on the safe side. I definately recommend this mod! Thanks for the space, now off to the dyno! Jamie
 

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That's awesome, man. Contrads! I too bought a lower pulley setup but backed off on it last minute when I made the decision to invest in a KB. I bet that lower pulley is awesome on our cars.
 

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Can someone explain the benefits/drawbacks of just switching out the lower pulley or the upper pulley, or both?

I want to make the most power I can while being "safe" - track time maybe once a month. This includes a custom dyno tune. Thanks.
 

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I am a big fan of the lower pulley. In fact it's all I run. I have a stock upper and a 6# lower. I make 13#'s with no drop off. I have no belt slip.

Drawbacks... With a 4# lower or more it is worth investing in the alt. pulley sold separately, alt. needs to be removed to install.

Positive: I saw more consistancy. On three back to back dyno runs, I lost no boost, and no more then 5 hp and 7tq. I account the loss due to heatsink.. the runs were 1-2 minutes a part.

You'll be "Safe" with a variety of combo's as long as the tune is there as insurance. If "safe" means blower limits that's different. I have seen guys run a 2.80 upper and make more tq., although the majority that I have seen have boost drop off to 11#'s after 5000rpm and the HP number is generally the same as mine.
 

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Z20_WHAT said:
Can someone explain the benefits/drawbacks of just switching out the lower pulley or the upper pulley, or both?
More boost baby :banggears :banggears

--Joe
 

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soap said:
More boost baby :banggears :banggears

--Joe
I'm not a moron, and this didn't answer my question.

However, BlownCobra - thanks for the help. Anyone else?
 

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simply: availability, cost, ease of installation, & slippage.

bigger lowers weren't offered initially (or at least i didn't know where to find them)
lower pulleys are much more expensive
upper pulleys are easier to change out (w/ proper tools)
my 2.80 alone slips

i've got a 6lb lower pulley in my garage waiting for me to find the time to take somewhere to have someone else put it on :(

since a 2.80" slips (for me) now, putting a 6 lb lower would most likely just make the upper slip even worse.

so, i may go with a 6lb lower & 3.2 upper combination to get me back to where i am now, but hopefully w/ no boost lost / slippage! :burnout:
 

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coleman said:
simply: availability, cost, ease of installation, & slippage.

bigger lowers weren't offered initially (or at least i didn't know where to find them)
lower pulleys are much more expensive
upper pulleys are easier to change out (w/ proper tools)
my 2.80 alone slips

i've got a 6lb lower pulley in my garage waiting for me to find the time to take somewhere to have someone else put it on :(

since a 2.80" slips (for me) now, putting a 6 lb lower would most likely just make the upper slip even worse.

so, i may go with a 6lb lower & 3.2 upper combination to get me back to where i am now, but hopefully w/ no boost lost / slippage! :burnout:
Ok, what about those new Metco and Amazon Racing idler pulley kits that supposedly eliminate ALL belt slippage with any pulley size? Also, is it ok to go with a bigger lower AND a smaller upper for even more boost? How far is that stretching it? I know a lot of people around here with just basic mods and a 2.8 upper and a good tune pushing 500 rwhp+.

Originally I plannign on just doing a 3.2 or 3.1 upper - and most people are getting around 450 - 475 rwhp with basic mods and just that pulley swap. But if I can go even smaller, AND perhaps use a upgraded lower pulley without any worries then I'll want to do that. Anyone?
 

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Z20_WHAT said:
I'm not a moron, and this didn't answer my question.

However, BlownCobra - thanks for the help. Anyone else?
Wow someone peep in your Wheaties huh.........I was just joking around :confused:

--Joe
 

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Discussion Starter · #11 ·
The alternator does not have to be removed to change the pulley. w/ the belt still attatched to everything, take a 1/2 wratchet and 15/16 socket and break the nut loose. The remove tension off the belt and remove belt and remove pulley. Voila! Then change crank pulleys.
 

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BlownCobra,
If you don't mind me asking, what other mods do you have on your car to make the numbers in your sig? I was thinking of going with the 6 pd. lower and alt. pulley and your numbers are great. Do you have any track times with the setup yet?

Thanks,

Kevin
 

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03Venom said:
The alternator does not have to be removed to change the pulley. w/ the belt still attatched to everything, take a 1/2 wratchet and 15/16 socket and break the nut loose. The remove tension off the belt and remove belt and remove pulley. Voila! Then change crank pulleys.
Well I guess you were lucky or I was unlucky.
 

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Obiefox said:
BlownCobra,
If you don't mind me asking, what other mods do you have on your car to make the numbers in your sig? I was thinking of going with the 6 pd. lower and alt. pulley and your numbers are great. Do you have any track times with the setup yet?

Thanks,

Kevin
I have not had it out to the track yet. I live in the snowy tundra of LI NY. :lol My mods are the 6# lower, JDM CAI, Accufab T/B and plenum, A/R tune, Bassani catted "X" into a Mac cat back. Very simple. I don't run belt wraps or over sized idler pulleys, even retain the use of my belt cover. What I like about the set up is it's consistancy. I dyno'ed 3 back to back pulls in a climate control area 1 to 2 minutes apart. We tested manifold temps, timing throughout the pull A/F you name it. I never lost more then 5rwhp and 7rwtq., and no boost drop off, Ricks tune was on the money. My A/F waves between 11.6 and 11.2, my timing is a steady 23 degrees. Pump gas happy :D

I admit I am no pioneer, I am not going for broke. There's nothing wrong with that. I wanted to see how far I could go before I fell of the edge.
 

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Thanks for the details! I appreciate it. I agree with you on the consistency angle. If you are not trying to go crazy and make 500+, then the lower is the way to go.

Take care,

Kevin
 

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Obiefox said:
Thanks for the details! I appreciate it. I agree with you on the consistency angle. If you are not trying to go crazy and make 500+, then the lower is the way to go.

Take care,

Kevin
Well that one way to look at it. But I will be testing a prototype 8# lower. The ring is 9.5" to give a total of 16#'s. I get it in a week, stay tuned. However I am not sure I will be keeping it.

I think if you talk to a few that are making 500+ and running on the street, there are some driveability issues. Whether it's stalling in traffic, or hard starts, or the need for C116 fuel... etc...etc. Then again there are people who have 500+ and drive everyday and don't mind or tollerate these issues and more. These are just my opinions ... Have fun
 

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So what kind of boost can these things make if you go with say, a 6# lower and a 2.93" or 2.8" upper? What kind of estimate dyno #'s?
 

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In theroy: 2.80 and a 6# lower would give you 13#'s of additional boost, for a total of 21#'s. The 2.93 and a 6# lower would give you 11#'s for a total of 19#'s. Nitrous Pete had experimented with these set ups before going over to the KB blower. He made terrific power. He used serious octane. Search this site for some of his old posts on dyno, or check his signature.

I feel, and have read in other posts, that anything more then 18#'s on 93 octane is pushing it, and even that is on the edge. I tested the 3.10 w/ a 6# lower, (10# additional for a total of 18#'s) and had a tip in detenation. We were able to fix in the chip, but that was too close for me. Oh and BTW, the boost gage never read more then 15#'s, which is why I say in theory.:)
 

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Anyone know the price of the alternator pulleys? Any other sources besides Metco?

TIA
 

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Discussion Starter · #20 ·
I bought the 3.2 alt pulley from Metco for 40-50 bux i cant remember which. I remember someone else saying another company is making them as well.

As far as boost pressure is, Befor w/ just the 2.8 uppper on cold days i would get maybe 13-14 psi and 11-12 on warmer days. Now w/ the 6lb lower i get no less than 14 psi on warm days and on cold days i have seen a max of 17 psi. I have the BilletFlow uppper idler and i have played around w/ diff size idler set-ups for better belt wrap and i am seeing no more than 1 psi lost and thats around 6000 rpms. It does drop a lil more on the warmer days though. Usually no more than 3 lbs. Ill have dyno numbers soon. the dyno numbers on my sig are before the 6lb lower and T/B. and so is the 1/4 time and trap. Ill keep you posted. thanks Jamie
 
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