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Discussion Starter · #1 ·
My car is coming back together after extensive downtime. I decided to be a bit different and put a cog drive F1C on the ol Cobra. Car sports a new valvetrain, front mount A-A, TH400 trans, and spooled 8.8" with 3.73's and 28" tire. For the life of me, I can't seem to narrow down the perfect cog pulley setup/ratio. I'm hoping to trap close to 150 which puts me at 7100 RPM assuming 6% slip thru the 400. I need to determine where in the powerband I should hit the blower redline of 74K RPM, and how much can the F1C be over-spun? I'd like to make 27-29 PSI and max out this blower.

I got the 70T crank and 38T blower initially, which is only 70626 RPM at 7100 @ 150, thats probably not gonna work, blower wouldnt hit redline until 158 MPH and I dont think the car is gonna go that fast.....

800 RWHP should be almost enough powa to run an 8 at my weight if the converter is correct

Any ideas or starting points?
 

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I wouldnt overspin a 74K blower but thats just me.

I run a 7.25/4" pulley and go through the lights at 153mph around 7220rpm which puts the blower around 71K. I have run a 3.9, 3.8, and 3.7 pulley and while the boost does go up so does the heat and the car really doesnt pick up a whole bunch going smaller than a 4 inch. I might do better with an A2W IC but the A2A I have is marginal at best with this blower.

Thats an F1A though which is smaller than the F1C, same 74K max impeller though. I would try what you have and see what happens rather then try to max it out right off the bat, you may be surprised what it does..
 

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Discussion Starter · #4 ·
I wouldnt overspin a 74K blower but thats just me.

I run a 7.25/4" pulley and go through the lights at 153mph around 7220rpm which puts the blower around 71K. I have run a 3.9, 3.8, and 3.7 pulley and while the boost does go up so does the heat and the car really doesnt pick up a whole bunch going smaller than a 4 inch. I might do better with an A2W IC but the A2A I have is marginal at best with this blower.

Thats an F1A though which is smaller than the F1C, same 74K max impeller though. I would try what you have and see what happens rather then try to max it out right off the bat, you may be surprised what it does..
What kinda boost does your combo make with the F1A?
 

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I've looked on several sites to find out how to calculate blower speed. Can't quite get it. I'd like a lesson please. School is in. I'm running an F-2.
 

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Thanks Brian, just what I was looking for. I love this site.
 

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What kinda boost does your combo make with the F1A?
Around 18psi @ 7200rpm when it ran the 8.90s with the 347 with a 7.25/4 pulley, naturally more CID = less boost on the gauge.

I was going to try a F1C but I dont think my 8 rib drive will handle it, neither will my 170.00 eBay intercooler ;)
 

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crank pulley dia (or # of teeth) X blower step up ratio X engine RPM
Blower pulley dia ( or # of teeth)


I've looked on several sites to find out how to calculate blower speed. Can't quite get it. I'd like a lesson please. School is in. I'm running an F-2.
 

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Discussion Starter · #10 ·
Around 18psi @ 7200rpm when it ran the 8.90s with the 347 with a 7.25/4 pulley, naturally more CID = less boost on the gauge.

I was going to try a F1C but I dont think my 8 rib drive will handle it, neither will my 170.00 eBay intercooler ;)
Thanks for all the great info. So going 152 at 7200 sounds like you run a 28" tire and 3.73's?

I'd like to keep the 3.73's so I have some room to grow ET wise, but I dont want it to be a slug outta the hole. I'm hoping Lenny's new converter (UCC) will be close. Its basically the same converter as Bart Toebner, NMRA Renegade, and should stall at 5600-5800, so I hope to make some decent boost on the T-brake.
 

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Thanks for all the great info. So going 152 at 7200 sounds like you run a 28" tire and 3.73's?

I'd like to keep the 3.73's so I have some room to grow ET wise, but I dont want it to be a slug outta the hole. I'm hoping Lenny's new converter (UCC) will be close. Its basically the same converter as Bart Toebner, NMRA Renegade, and should stall at 5600-5800, so I hope to make some decent boost on the T-brake.
Yea, 3.70 with 10.5x28S tires.

I have an ATI 8" 5500 converter in the car and I'm very happy with it. I leave at 3000 on the 2 step, thats only about 3-4psi but any more than that and I get into wheelstand issues. Most likely with less CID you wont have that problem. But 1.25-1.28 60's at 3000rpm on the two step is fine with me, easy on parts if anything.
 
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