What gear ratio with blown Hemi, 727, 30 inch tire?
#1235438
05/18/12 02:02 PM
05/18/12 02:02 PM
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Joined: May 2008
Posts: 902
Mopar Lane,Mississippi
67HEMI
OP
super stock
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OP
super stock
Joined: May 2008
Posts: 902
Mopar Lane,Mississippi
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If I ever get all my parts it is "supposed" to make around 1100 horsepower in the Coronet with about 3650 pounds and 30 inch drag radials. It has a Dana and will be street driven 75% of the time and WFO the other 25%. Would a 3.55 put too much load on the driveline or would a 3.73 work better? It has a 4.10 in it now, I am leaning toward the 3.55.
'33 Plymouth 5 Window Coupe Blown Aluminum HEMI w/bolt ons (under construction)
'69 Chrysler 300 Convertible 375 HP 440
'71 Plymouth Duster 360 W/EFI (Wife's Ride)
'12 Ram MegaCab Dually 6.7 Cummins
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Re: What gear ratio with blown Hemi, 727, 30 inch tire?
[Re: HEMIFRED]
#1235441
05/18/12 05:10 PM
05/18/12 05:10 PM
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Joined: Jan 2003
Posts: 525
Shannonville, Ont
Blown 68 R/T
mopar
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mopar
Joined: Jan 2003
Posts: 525
Shannonville, Ont
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I run 4.10 with 31x16.5 Hoosier QTP's. IMO the 3.55's will be too low.  What size conv are you using?
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Re: What gear ratio with blown Hemi, 727, 30 inch tire?
[Re: 67HEMI]
#1235442
05/18/12 08:56 PM
05/18/12 08:56 PM
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Joined: Jan 2003
Posts: 10,006
Frostbitefalls MN (Rocky&Bullw...
gregsdart
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,006
Frostbitefalls MN (Rocky&Bullw...
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With the 3.55 and guessing about 900 ft lbs torque, the 3.55 with a 30 inch tire will have a ton of launch torque. Starting line ratio is 2.45 x 3.55 =8.70. Torque times 2 (converter multiplication) times SLR is 15660 ft lbs at the axle, and less at the tire ,12528. Take away 10 percent for driveline loss, you still have 11275 lbs of thrust. Divide by the car weight, the thrust in Gs comes out to 3.09. I doubt you will be able to dead hook the car with a 3.55 gear. Maybe a 2.76, but Danas don't come with those  . So the 3.55 is your best bet for now. Tub it, put a 15 x 33 x 15 slick on it and some wheeliebars and ride the back tires to the 60 foot mark!
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: What gear ratio with blown Hemi, 727, 30 inch tire?
[Re: gregsdart]
#1235443
05/19/12 10:32 AM
05/19/12 10:32 AM
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Joined: Dec 2007
Posts: 12,587
Great Neck,LI,new york
hemi-itis
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 12,587
Great Neck,LI,new york
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I run a similar combo and use the 4:10's.My street tire is 16.5 x 31.
HEMI-ITIS has no cure.
My condition is fully BLOWN!!
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Re: What gear ratio with blown Hemi, 727, 30 inch tire?
[Re: 67HEMI]
#1235444
05/20/12 09:35 PM
05/20/12 09:35 PM
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Joined: May 2011
Posts: 4,489
northern,Ohio,USA
Clanton
master
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master
Joined: May 2011
Posts: 4,489
northern,Ohio,USA
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Quote:
If I ever get all my parts it is "supposed" to make around 1100 horsepower in the Coronet with about 3650 pounds and 30 inch drag radials. It has a Dana and will be street driven 75% of the time and WFO the other 25%. Would a 3.55 put too much load on the driveline or would a 3.73 work better? It has a 4.10 in it now, I am leaning toward the 3.55.
i am putting in my 3.73 back ing that i started with 12yrs ago but my vert was made for it.at 136 mph i trap at 6500 rpm with 4.10 and 28 tire.[slick,3900#w/driver]
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Re: What gear ratio with blown Hemi, 727, 30 inch tire?
[Re: gregsdart]
#1235447
05/21/12 05:55 PM
05/21/12 05:55 PM
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Joined: May 2008
Posts: 902
Mopar Lane,Mississippi
67HEMI
OP
super stock
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OP
super stock
Joined: May 2008
Posts: 902
Mopar Lane,Mississippi
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Quote:
With the 3.55 and guessing about 900 ft lbs torque, the 3.55 with a 30 inch tire will have a ton of launch torque. Starting line ratio is 2.45 x 3.55 =8.70. Torque times 2 (converter multiplication) times SLR is 15660 ft lbs at the axle, and less at the tire ,12528. Take away 10 percent for driveline loss, you still have 11275 lbs of thrust. Divide by the car weight, the thrust in Gs comes out to 3.09. I doubt you will be able to dead hook the car with a 3.55 gear. Maybe a 2.76, but Danas don't come with those . So the 3.55 is your best bet for now. Tub it, put a 15 x 33 x 15 slick on it and some wheeliebars and ride the back tires to the 60 foot mark!
Thanks for the calculations,tubbing has crossed my mind after this past weekend. I saw 2) 55 chevies with 20inch wheels 15" wide on the rear and both cars were about 6 inches off of the ground. 
'33 Plymouth 5 Window Coupe Blown Aluminum HEMI w/bolt ons (under construction)
'69 Chrysler 300 Convertible 375 HP 440
'71 Plymouth Duster 360 W/EFI (Wife's Ride)
'12 Ram MegaCab Dually 6.7 Cummins
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Re: What gear ratio with blown Hemi, 727, 30 inch tire?
[Re: 67HEMI]
#1235449
05/21/12 05:57 PM
05/21/12 05:57 PM
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Joined: Aug 2003
Posts: 43,195
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,195
Bend,OR USA
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I treid 4.30 to 3.73 in my street car, 700 + HP N/A, no differences in at the track performance other than it seem to be in high gear a lot longer with the 3.73.That was with the 8 3/4 that i bent the snout out of three years ago now  (It has dana 60 truck housing with 4.10 in it now ) That was with the M/T ET Street Radials 315x60x15 tires at 128.6 MPH with all four sets of gears   I would put the 3.55 in it, more pinion tooth contact to the ring gear teeth 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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