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1/10ths difference on ratios? #2754034 03/21/20 02:56 AM 03/21/20 02:56 AM
Joined: Jan 2003 Posts: 3,943 Melbourne.....Oz-land Moparmal OP master
Moparmal OP master Joined: Jan 2003 Posts: 3,943 Melbourne.....Oz-land	mid-low 11 sec car - 3700lbs - 4000 converter Swapping back from 4.10 to 3.91.....assuming all things are equal, how much will my ET suffer?

Re: 1/10ths difference on ratios? [Re: Moparmal] #2754037 03/21/20 04:22 AM 03/21/20 04:22 AM
Joined: Mar 2009 Posts: 2,457 Sydney,Australia tex013 top fuel
tex013 top fuel Joined: Mar 2009 Posts: 2,457 Sydney,Australia	Mal , At 3690lbs my plymouth ran 11.30 with 3.91 . Went 4.1 ran 11.18 😁 Tex New best ET 10.259@129.65 . New best MPH 130.32 Finally fitted a solid cam, stepped it up a bit more 3690lbs through the mufflers New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm Power by Tex's Automotive

Re: 1/10ths difference on ratios? [Re: tex013] #2754150 03/21/20 12:17 PM 03/21/20 12:17 PM
Joined: Dec 2006 Posts: 2,102 Byron, NY W.I.N. Racing top fuel
W.I.N. Racing top fuel Joined: Dec 2006 Posts: 2,102 Byron, NY	you may not loose at all. Way too much missing information to know your outcome. Last edited by W.I.N. racing; 03/21/20 12:18 PM. '01 P1500, Blown/Inj BAE,/Veney ,Bruno/CS2,Dana 60 '01 Dodge 3500 S Cummins Auto, Fresh air kit, 4" Exhaust, '05 Dodge Magnum R/T - Too Much to list '60 Willys CJ5 '01 International LPX - Project,DT466, Allison '64 Plymouth Valiant, Inj 528 Hemi, 2spd

Re: 1/10ths difference on ratios? [Re: Moparmal] #2754157 03/21/20 12:26 PM 03/21/20 12:26 PM
Joined: Aug 2003 Posts: 43,097 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,097 Bend,OR USA	My old pump gas Duster ran within 1/10 second using ratio from 3.55, 3.73,3.91, 4.10 and finally 4.30. Traction and fuel supply will determine how much your car and motor like or don't like that ratio change. Your deal is 4.7 % ratio change so it may not change your results at the track at all What RPM are you shifting at now? BB or SB motor? Last edited by Cab_Burge; 03/21/20 12:28 PM. Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: 1/10ths difference on ratios? [Re: Moparmal] #2754202 03/21/20 02:36 PM 03/21/20 02:36 PM
Joined: Dec 2005 Posts: 11,497 Fulton County, PA C CMcAllister Mr. Helpful
CMcAllister Mr. Helpful C Joined: Dec 2005 Posts: 11,497 Fulton County, PA	What you would accomplish is slow the engine down a few hundred RPM at the top end and take away a half point of SLR, assuming a 3 speed automatic. That might help reduce wheel spin on a marginal track. If the results don't match the theory, change the theory.

Re: 1/10ths difference on ratios? [Re: CMcAllister] #2754278 03/21/20 05:53 PM 03/21/20 05:53 PM
Joined: Jan 2003 Posts: 3,943 Melbourne.....Oz-land Moparmal OP master
Moparmal OP master Joined: Jan 2003 Posts: 3,943 Melbourne.....Oz-land	Motor is a 6.1 Gen3 Hemi. Ive raced the motor before in an A nidy,but not in the current 67 B Body. Traction gasnt been a major ussue Fuel supply never a problem. 60 ft doesnt change much when launching from idle and launching at 2500. Never foot braked it higher than that.. Sounds like Tex’s 1/10th might be a fair indication....

Re: 1/10ths difference on ratios? [Re: Moparmal] #2754289 03/21/20 06:35 PM 03/21/20 06:35 PM
Joined: Mar 2009 Posts: 2,457 Sydney,Australia tex013 top fuel
tex013 top fuel Joined: Mar 2009 Posts: 2,457 Sydney,Australia	Mal Isnt Heathcote faster in one lane than the other ? Have you run Calder or Portland ? Tex PS . Biggest change/improvement at that level was getting quality converter . Went from 4200-5000 very noticable Last edited by tex013; 03/21/20 06:38 PM. New best ET 10.259@129.65 . New best MPH 130.32 Finally fitted a solid cam, stepped it up a bit more 3690lbs through the mufflers New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm Power by Tex's Automotive

Re: 1/10ths difference on ratios? [Re: tex013] #2754309 03/21/20 08:02 PM 03/21/20 08:02 PM
Joined: Jan 2003 Posts: 8,018 Tulsa OK Bad340fish master
Bad340fish master Joined: Jan 2003 Posts: 8,018 Tulsa OK	With a 4000 converter you probably won't notice a thing. 68 Barracuda Formula S 340

Re: 1/10ths difference on ratios? [Re: Moparmal] #2754387 03/22/20 12:58 AM 03/22/20 12:58 AM
Joined: Aug 2003 Posts: 43,097 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,097 Bend,OR USA	All my drag cars with decent converters like to be foot stall as high as possible to get the best reaction and 60 ft. times Test it to see if your deal likes that or not Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: 1/10ths difference on ratios? [Re: Cab_Burge] #2754432 03/22/20 09:17 AM 03/22/20 09:17 AM
Joined: Nov 2003 Posts: 1,834 NW Indiana F fbs63 top fuel
fbs63 top fuel F Joined: Nov 2003 Posts: 1,834 NW Indiana	Originally Posted by Cab_Burge All my drag cars with decent converters like to be foot stall as high as possible to get the best reaction and 60 ft. times Test it to see if your deal likes that or not This. And gear change effects smaller cid engines more than larger. Plus the B body is probably weighs more than the A body.

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