Metco resized their pulley rings!

[BOOOOST]

Hopefully this isn't old news yet.

Anyhoo, in talking with Metco yesterday, they redid the size of their pulley rings, so for all those who bought the 6 # lower more than about a month ago, you really got about a 4.5 # :uh oh:

The size of the old 6 # ring was approx. 8.625". The new one is 9.02" (they measured it right on the phone for me). Their new 8 # ring is 9.2somethinganother.

You wanna know just how much blower rpm difference that is between their old 6 ring and new 6 ring? Try approx. 703 at 6500 engine rpms. That equals about 1.5 #'s less boost.

Thoughts, complaints, praises?

 

[coleman]

so, the 6# lower pulley that i bought wasn't a 6# lower pulley!?!
that sounds like false advertising... i want my 6# lower pulley that i paid for!!!

 

[ltv1]

The whole lower I looked at was pricey, so I looked at alternatives. I have only heard good things about Metco, a lot of guys I know run lowers and the system is great. I am sure they will work it out for everybody. Why hasn't anyone posted < boost if the pulley is way off? Just curious.

 

[fiorefiveoh]

god damn, can you say 2.70 upper/8lb lower? just a slight overspin.

 

[Silver 03 Cobra]

Sure that wan't a salesperson that didn't know what he was talking about? You don't measure the O.D. of the pulley. It is the pitch diameter that determines the size of the pulley. That diameter is near the middle of the groove below the surface of the pulley. I put a 6# on my buddies 03 and I don't remember exactly but it was right up against something. I don't see how it could have been much larger.

 

[toofast4u]

Cool thanks. I am looking at getting the new 8#.

 

[ALA G8R]

A 9" lower will cause the SC to spin at the same speed as a 3" upper. Both are worth about 4.5lbs of extra boost. It would take a ~9.6" lower to give you 6lbs. The lower pulley ratings are slightly off. You can never believe all of what you read. Verify.

Do the math.
7.9in lower pulley is worth 2lbs. same as a 3.4in upper.
8.5in lower pulley is worth 3.5lbs. slightly more than a 3.2in upper.
9in lower is worth 4.5lbs same as a 3.0in upper.

 

[lethal]

Originally posted by toofast4u
Cool thanks. I am looking at getting the new 8#.

Brian-

Thought you were going with the KB blower? Trying to stay warrenty friendly? =)

John

 

[toofast4u]

Ok lets look at it another way.

The attached chart is a breakdown of what different pulley's should produce. This is taking into account a VE loss of 4% for every increase of 5 PSI produced by the supercharger which is an estimate based on information received from the following chart.

I am sure several people are going to disagree with this so lets see if this needs to be corrected.

Patm-Atmospheric Pressure
Vblower-Volume of Blower
VEblower-Volumetric Efficiency of Blower
Vengine-Volume of Engine
VEengine-Volumetric Efficiency of Engine

This is using the following formula to calculate boost
Pboost=(Patm*((Vblower*VEblower)/(Vengine*VEengine)))-Patm
VEblower=1-(((Patm*((Vblower*1)/(Vengine*VEengine)))-Patm)/5*0.04)

 

[toofast4u]

Originally posted by lethal
Brian-

Thought you were going with the KB blower? Trying to stay warrenty friendly? =)

John

My car is completely stock and staying that way until after the warrenty is over.:thumbsup:

I am just theorizing what I will be doing after the warrenty which currently might include either the KB or pulley the eaton. Unless of course Works comes out with something better.

 

[HotRodHarry]

I guess I was right in going with Jim D'Amore and his awesome crew at www.teamjdm.com. Because their interchangeable pulley system they made up for me using the interchangeable JDM Lightning Pullies and stock pulley cage customized and the 6 lb pulley netted me a true 6 lbs. Thanks JDM!

Harry
www.HotRodHarrys.com
2003 Cobra (20 lbs of boost and nitrous)

 

[Silver 03 Cobra]

Tofast4u, are these pitch diameters on your table? Do you know the diameter of the stock lower pulley?

You'll have less slippage staying with the stock upper and going with a larger lower on anyone's system.

 

[toofast4u]

Originally posted by HotRodHarry
I guess I was right in going with Jim D'Amore and his awesome crew at www.teamjdm.com. Because their interchangeable pulley system they made up for me using the interchangeable JDM Lightning Pullies and stock pulley cage customized and the 6 lb pulley netted me a true 6 lbs. Thanks JDM!

Harry
www.HotRodHarrys.com
2003 Cobra (20 lbs of boost and nitrous)

Hey Harry do you know what the diameter of your lower is? Also what diameter is your upper? Since you are definitely on the higher end of the scale I might be able to bring these numbers more in-line on efficiency if I had some high end data.

 

[toofast4u]

Originally posted by Silver03Snake
Tofast4u, are these pitch diameters on your table? Do you know the diameter of the stock lower pulley?

You'll have less slippage staying with the stock upper and going with a larger lower on anyone's system.

They are the numbers that were quoted to me and I believe they are pitch diameter, otherwise they really are useless. The stock lower is 7.35 I believe.

You'll definitely have less slippage with a larger lower, but the question is will you make as much power. The ultimate answer if cost is not an issue is going with the largest lower you can buy and an upper that complements to make your desired boost. Then you need to determine when is power loss due to parasitical mechanical and thermal forces and wear and tear on the system to high to substantiate more boost.

Personally if investing 400 for a lower, 60 for alternator pulley, 100 for an upper, 150 for an idler kit, and 150 for a puller which is going to be $860+S/H is going to be required to make 480+rwhp basically maxed out. Then I would be more inclined to spend the 3600 for the Kenne Bell try and sell the damn chip the send with it to recap some money and get 580+ rwhp efficiently with room to grow and say screw it.

 

[Silver 03 Cobra]

I saw it as I was reading your info tofast. Thanks for the info. I have one more question. What is V1 and V2? Would these be the pulley diameters?

 

[toofast4u]

Originally posted by Silver03Snake
I saw it as I was reading your info tofast. Thanks for the info. I have one more question. What is V1 and V2? Would these be the pulley diameters?

I fixed it.
V1 was Vblower
V2 was Vengine

 

[HotRodHarry]

Originally posted by toofast4u
Hey Harry do you know what the diameter of your lower is? Also what diameter is your upper? Since you are definitely on the higher end of the scale I might be able to bring these numbers more in-line on efficiency if I had some high end data.

Either when I get home from work today I will measure the lower(or maybe Jeromy,Anthony or Justin will be online and can measure the JDM 6 lb interchangeable lower)...the upper I have on is a 2.80 JDM.

Harry

 

[BOOOOST]

Originally posted by Silver03Snake
Sure that wan't a salesperson that didn't know what he was talking about? You don't measure the O.D. of the pulley. It is the pitch diameter that determines the size of the pulley. That diameter is near the middle of the groove below the surface of the pulley.

You always measure from the top of the grooves on the pulleys for comparison's sake, as the top of the belt rides upon the outer surface, which is what nearly all manufacturers use for the official measurements in determining actual accessory rpms.

Regardless, take a JLP "rated" 6# lower on a Lightning, and it will measure 9.0 inches at the top of the grooves, as does Sal's at Power Surge Performances. You take the old style "rated" 6# lower on the Metco and it will measure 8.625". The new Metco "rated" 6# lower is now 9.02" (the owner of the company measured it right on the phone for me and explained to me that they resized the pulleys about 1 month ago). Their new 8 # ring is 9.2somethinganother (I forget exactly what he said).

ALA G8R is right about the 3.0" upper gives the same blower rpm as a 9.0" lower would, and I brought this up back about a month ago here:

http://www.svtperformance.com/forums/showthread.php?s=&threadid=35045&highlight=pulley

What I said was:

A 9.0" lower on the Cobra adds 6#'s of boost, supposedly. The RPMS from a 9.0" lower is about the same as putting on just a 3.0" upper on our Cobras.

 

[toofast4u]

I was thinking about it and as long as both the upper and lower pulley are measured at the same location it shouldn't matter if it is measured at the peak or valley it will still be the same ratio.

 

[BOOOOST]

Originally posted by toofast4u
I was thinking about it and as long as both the upper and lower pulley are measured at the same location it shouldn't matter if it is measured at the peak or valley it will still be the same ratio.

BINGO! ;-)

I'm glad you said it that way. I did above but your statement makes it easier for everyone to understand.