Lowest upper with a 6 lb lower

[JPKII]

Originally posted by sambandit
You know what, I, of all people, am beginning to realize the diminishing returns of spinning the blower too fast. You can see my combo in my sig, but I am seriously considering a 4 lb lower instead. I'm gonna experiment like a mofo at the track this spring and find out just what the limit is. The Apten mod and an aftermarket HE have raised the bar a little though. JPKII, what are those rpms numbers at 6000 rpms? That is where I shift anyway. I personally wouldn't go smaller than a 2.93 upper to to try to battle belt slip a little better.

6000 Crank RPM

2.8/6Lbs = 19500 RPM

2.92/6Lbs = 18635 RPM

 

[jhwalker]

Originally posted by JPKII
6000 Crank RPM

2.8/6Lbs = 19500 RPM

2.92/6Lbs = 18635 RPM

I have never really understood why the lower creates such torque compared to the upper. Your stock upper with your lower is making effectively the same torque as my 2.80 upper and stock lower, whereas we have a 50 diff in rwhp. Is there a hardcore techie post on the physics of the upper vs the lower? And if the answer is butt simple, somebody feel free to just state it.
:rockon: :smmon:
James

 

[sambandit]

Originally posted by JPKII
6000 Crank RPM

2.8/6Lbs = 19500 RPM

2.92/6Lbs = 18635 RPM

So, technically with my combo, since I shift at 6000 rpms, I'm not really overspinning the blower any more than a 2.8 car is at 6500 rpms. Just dosen't make sense why my car kinda takes a dump at 5500 rpms. I'll post my graph.

 

[sambandit]

See how it peaks at 5500 or so?? I still love the torque but why can't I squeeze power up to 6000 rpms? 18000 rpms isn't really high, although it's up there.

 

[HIGH ROLLER]

Can someone tell me what my blower will be spinning with these pulley combos at 6000rpms.Thanks!

1. 2.80 upper with a 2 pound lower

2. 2.93 upper with a 4 pound lower

3. 3.10 upper with a 6 pound lower

 

[HIGH ROLLER]

Anyone know??

 

[JPKII]

Originally posted by HIGH ROLLER
Can someone tell me what my blower will be spinning with these pulley combos at 6000rpms.Thanks!

1. 2.80 upper with a 2 pound lower

2. 2.93 upper with a 4 pound lower

3. 3.10 upper with a 6 pound lower

I'll post it tomorrow...

 

[jhwalker]

sambandit,
My web access SUCKS!!!! tonight, but I wanted to say your numbers, and that falloff, are interesting. I still wonder about the heat, and I hope my dynos later this week will shed light. I have all this mojo cooling shit that is intended to let me overspin the HEaton -- so we will see and I will post. I finally have a decent camera (damn it, that money could have gone into mods.)

James

 

[ak_cobra]

Originally posted by jhwalker
I have never really understood why the lower creates such torque compared to the upper. Your stock upper with your lower is making effectively the same torque as my 2.80 upper and stock lower, whereas we have a 50 diff in rwhp. Is there a hardcore techie post on the physics of the upper vs the lower? And if the answer is butt simple, somebody feel free to just state it.
:rockon: :smmon:
James

i am wondering this as well.

 

[JPKII]

Originally posted by HIGH ROLLER
Can someone tell me what my blower will be spinning with these pulley combos at 6000rpms.Thanks!

1. 2.80 upper with a 2 pound lower

2. 2.93 upper with a 4 pound lower

3. 3.10 upper with a 6 pound lower

I don't have a diameter for a 2 pound lower, sorry

2.93/4lbs = 17611 RPM
3.10/6lbs = 17612 RPM

All at 6000 RPM

 

[Cobra10thaniv]

Re: Re: 8lb lower what are you spinning the eaton off hand

Originally posted by JPKII
With just an 8 lbs lower (and stock 3.65 upper) I am spinning 17007 RPM @ 6500 crank RPM.

Is that with the newer larger revised lowers or the smaller older lower 8lb?

 

[JPKII]

Re: Re: Re: 8lb lower what are you spinning the eaton off hand

Originally posted by Cobra10thaniv
Is that with the newer larger revised lowers or the smaller older lower 8lb?

My 8lbs lower is 9.550" in diameter. I am not sure of what the old/new measurments are.

 

[Cobra10thaniv]

Maybe somone on the board knows when metco changes there sizes? I think I read posting that it was around july.

They were having problems attaining the boost levels and up sized every dia.

 

[Derek@Amazon]

best combo ive seen so far on our dyno is a 6 lower and a 3.1 upper. makes good power and good torque

 

[Cobra10thaniv]

JPKII i dont meant to spend your whole day calc speeds but what is stock at 6500rpm

I had gone to the eaton site and see they only recomend up to 12,000 rpm on the M112

http://automotive.eaton.com/product/engine_controls/M112.html