Re: better 60'- trans low gears
[Re: Monte_Smith]
#2245178
02/01/17 09:44 AM
02/01/17 09:44 AM
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Joined: Aug 2003
Posts: 4,989 new jersey usa
11secdart
master
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master
Joined: Aug 2003
Posts: 4,989
new jersey usa
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Yes more power and to be competitive in an 11.50 class you should in reality be capable of running 11.40s. My car 60fts in the the low 1.50s a few years ago we tried a low first gear set in my 904 and there was no improvement in 60ft or e.t. But that could just be my combination.
Last edited by 11secdart; 02/01/17 09:51 AM.
68 Dart 410 / 904 92 D150 original owner 21 Ram 1500 Quad Cab, Big Horn , Hemi ,4x4 23 Audi Q5 16 Honda HRV
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Re: better 60'- trans low gears
[Re: His and Her 69's]
#2245183
02/01/17 10:10 AM
02/01/17 10:10 AM
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Joined: Oct 2015
Posts: 570 UK
rb446
mopar
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mopar
Joined: Oct 2015
Posts: 570
UK
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Just crunched some numbers here and came up with>
@423hp/3700 60 Foot E.T. : 1.67 1/8 Mile E.T. : 7.57 1/8 Mile Trap Speed : 89.76 1/4 Mile E.T. : 12.00 1/4 Mile Trap Speed : 112
@493hp/3700= 60 Foot E.T. : 1.59 1/8 Mile E.T. : 7.20 1/8 Mile Trap Speed : 94.46 1/4 Mile E.T. : 11.40 1/4 Mile Trap Speed : 117
So around 70hp more is needed, depending on what you have now and how you run it...ported heads/cam/carb improvements would certainly help towards that and then perhaps a look at the l/spring & shock set up depending on results...my2c.
1969 'Cuda 446ci, best 9.96@133.9 in 1990 1971 340 'Cuda, best 11.01@122.8 in 1987
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Re: better 60'- trans low gears
[Re: His and Her 69's]
#2245185
02/01/17 10:12 AM
02/01/17 10:12 AM
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Joined: Jan 2003
Posts: 5,894 Florida
Locomotion
master
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master
Joined: Jan 2003
Posts: 5,894
Florida
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The cost of what a new low gear for a 727 goes for will be a good start towards a 904 with a low gear + longer driveshaft. (Selling the 727 related stuff will also help.) Back in the '70's, Chrysler did a lot of trans testing and the results showed that with all else being equal, a 904 was .15 faster than a 727 due to less rotating weight. Then you have the added benefit of the available 2.74 low gears from later 904s. The results will vary based on weight, rear gears and torque curves. I believe that a lighter car with a bigger engine/longer stroke will benefit less than a heavier car with a smaller engine/shorter stroke. A low gear in my 360 dart helped a bit, but it weighs well over 3,500 lbs.
(But if it's a big block, the 904 suggestion is not applicable.)
A online calculator could show how much more gear you can get by with - at least a step or two.
Also remember that the suspension and tires will also have to handle the extra torque multiplication from more gear and power. Were the tires hooking the same with the converter comparison?
Accelerator pump tuning can help with 60' as well, which "might" need adjusting with gear/converter changes.
Last edited by Locomotion; 02/01/17 10:15 AM.
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Re: better 60'- trans low gears
[Re: J_BODY]
#2245350
02/01/17 03:54 PM
02/01/17 03:54 PM
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Joined: Jan 2003
Posts: 5,894 Florida
Locomotion
master
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master
Joined: Jan 2003
Posts: 5,894
Florida
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Sure the 904 option is available for a big block.... just like my buddy's stocker wagon with a Pro Flight (not cheap... not even close to cheap). I didn't think that the engine might be a big block till after I posted. Then had to edit it just in case. But a cheaper alternative to a ProFlight (custom 904 guts in a 727 case for those who don't know) would be a JW Ultrabell to mate the 904 to the big block. The 904 would just need to be built well, not with all the custom & billet parts.
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Re: better 60'- trans low gears
[Re: Locomotion]
#2245588
02/01/17 10:47 PM
02/01/17 10:47 PM
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Joined: Jan 2004
Posts: 13,247 Mt. Vernon, Ohio
dartman366
I Live Here
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I Live Here
Joined: Jan 2004
Posts: 13,247
Mt. Vernon, Ohio
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Sure the 904 option is available for a big block.... just like my buddy's stocker wagon with a Pro Flight (not cheap... not even close to cheap). I didn't think that the engine might be a big block till after I posted. Then had to edit it just in case. But a cheaper alternative to a ProFlight (custom 904 guts in a 727 case for those who don't know) would be a JW Ultrabell to mate the 904 to the big block. The 904 would just need to be built well, not with all the custom & billet parts. I know that this is not apples to apples but I started out with a low gear set in my car origionally and it was suggested to me to put a stock gear set in, glad I did car picked up almost 2 tenths in my 60 foot, my combo just did not like the low gear.
Light travels faster than the speed of sound,,,this is why some people seem bright untill you hear them speak.
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Re: better 60'- trans low gears
[Re: His and Her 69's]
#2245636
02/01/17 11:50 PM
02/01/17 11:50 PM
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Joined: Jan 2008
Posts: 4,255 Canada
WO23Coronet
master
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master
Joined: Jan 2008
Posts: 4,255
Canada
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Wouldn't a really dialed in torque converter be the way to go? In a stockish low hp application I could see it making an improvement (the low gear set, reason it was originally made), but a dialed in high stall would make a low gear set have a negligible effect.
Last edited by WO23Coronet; 02/02/17 07:59 PM.
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Re: better 60'- trans low gears
[Re: His and Her 69's]
#2245699
02/02/17 01:23 AM
02/02/17 01:23 AM
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Joined: Jan 2003
Posts: 4,448 Phoenix, AZ
MoparBilly
master
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master
Joined: Jan 2003
Posts: 4,448
Phoenix, AZ
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The quickest way to turn a 12.00 street car into an 11.50 index racer is a small N20 plate system.
My Belvedere's best pass N/A is 12.43-109, runs 11.50-120 on the spray. We have two different promoters who do an 11.50 class, and it's been a blast.
Fin angle on a J converter wouldn't allow for any gains if you switched to a low gear set.
"Livin' in a powder keg and givin' off sparks"
4 Street cars, 5 Race engines
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Re: better 60'- trans low gears
[Re: MoparBilly]
#2245773
02/02/17 06:19 AM
02/02/17 06:19 AM
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Joined: Jul 2005
Posts: 1,559 Oh
His and Her 69's
OP
pro stock
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OP
pro stock
Joined: Jul 2005
Posts: 1,559
Oh
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Thanks for the info guys. The car is raced by the woman and no NOS for it as the parts are just not that good and I don't trust her. Lol The motor is a basic 440, trw piston 9-1 comp pump gas, 557 lift area solid flat tappet isky cam, (Don't have the card handy), 906 heads gasket matched and blended, stock valve sizes, torquer 2 intake, 950 holley. stock stroke crank etc. The fuel pump is a magna fuel 250 I believe, it worked good when we ran 10.80's. The engine was a throw together with what I had after we dropped a valve on the good motor. The motor made 500 hp at 5600 rpm and 496 trq on the engine dyno. Sounds like most cases the low gear set didn't show a big enough improvement for the cost and the work involved. It sounds like the best route for me is probably to install my set of ported heads. They flow 290 @ 600 so I am sure that is a huge improvement over mine now. I just got a pair of adjustable rear shocks also to try. So between the heads, shocks, and I can reinstall the domi if needed I should be Good. Traction didn't seem to be an issue and if it does I will get some slicks to use. How does this sound to you guys ??? I am thinking the heads alone should get me the 11.50's easy. Anymore suggestions would be considered. Thanks Guys for the Help and Info. David
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Re: better 60'- trans low gears
[Re: His and Her 69's]
#2245933
02/02/17 03:14 PM
02/02/17 03:14 PM
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Joined: Aug 2003
Posts: 43,252 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,252
Bend,OR USA
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I ran the old Mopar 2.77 helical cut gear set in my 727 in my B/SA one year and then sold that car after the last race. I had done the math on the starting line ratio in 1st gear(2.45x4.89=11.98 compared to 2.77x4.56=12.63) and swapped the rear gears out from 4.89 to 4.56 and put a different fresh motor in the car, it ran its fastest ever with those parts That was on new 9x30x15 bias ply slicks mounted on 10 inch wide rims, the car didn't have a traction problem before or after but it did run its best ET and MPH with that set up On your deal I would swap them in in a heartbeat
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: better 60'- trans low gears
[Re: His and Her 69's]
#2245978
02/02/17 04:43 PM
02/02/17 04:43 PM
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Joined: Oct 2015
Posts: 570 UK
rb446
mopar
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mopar
Joined: Oct 2015
Posts: 570
UK
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Thanks for the info guys. The car is raced by the woman and no NOS for it as the parts are just not that good and I don't trust her. Lol The motor is a basic 440, trw piston 9-1 comp pump gas, 557 lift area solid flat tappet isky cam, (Don't have the card handy), 906 heads gasket matched and blended, stock valve sizes, torquer 2 intake, 950 holley. stock stroke crank etc. The fuel pump is a magna fuel 250 I believe, it worked good when we ran 10.80's. The engine was a throw together with what I had after we dropped a valve on the good motor. The motor made 500 hp at 5600 rpm and 496 trq on the engine dyno. Sounds like most cases the low gear set didn't show a big enough improvement for the cost and the work involved. It sounds like the best route for me is probably to install my set of ported heads. They flow 290 @ 600 so I am sure that is a huge improvement over mine now. I just got a pair of adjustable rear shocks also to try. So between the heads, shocks, and I can reinstall the domi if needed I should be Good. Traction didn't seem to be an issue and if it does I will get some slicks to use. How does this sound to you guys ??? I am thinking the heads alone should get me the 11.50's easy. Anymore suggestions would be considered. Thanks Guys for the Help and Info. David I would go with that,.....my old Cuda ran 11.2 with a stock 440-6 motor with single plane intake/850DP and a big solid cam, fitted some BV 906's template ported to probably nowhere near the 290cfm that you have, it went 10.7 first run with no other changes. Probably could've tweaked that for a high 10.5 or 6's. According to the Wallace calc the heads were a 64hp increase.
Last edited by rb446; 02/02/17 04:57 PM.
1969 'Cuda 446ci, best 9.96@133.9 in 1990 1971 340 'Cuda, best 11.01@122.8 in 1987
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Re: better 60'- trans low gears
[Re: rb446]
#2246060
02/02/17 07:00 PM
02/02/17 07:00 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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A low first gear gives you a quicker reving engine in LOW gear.. so you make it quicker to the torque range of the engine... then you shift earlier and have to have TORQUE to pull longer in high gear.. it MAY not change the rpm of the run... a gear change changes the whole run which is a multiplier EDIT Bottom line is always... HP to weight ratio.. then make it efficient
Last edited by MR_P_BODY; 02/02/17 07:29 PM.
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