Moparts

to low gear set or not to low gear set?

Posted By: dmking

to low gear set or not to low gear set? - 02/15/12 03:01 AM

so what have you guys found on making the switch to a low gear set.

i have a 3170lb duster with 30x10.5 slicks with 4.30 gearset.
at numidia 1.51 60ft 10.35 to 10.45
at maplegrove and cecil md 1.46 to 1.48 60ft 10.20s mayve quicker LOL but busted the engine on the susposed pass faster than a 10.20.

what do you guys think? i bet i gain at numidia with the 1000ft elevation change from the lower tracks but what about the 500ft and 200ft tracks?
think it will hit the tires too hard and make me spin easyer?

i found a used set localy for 400 bucks
Posted By: Sport440

Re: to low gear set or not to low gear set? - 02/15/12 03:31 AM

What engine are you running. For your et you 60,s should be closer to 1.40 If your running a BB I would skip the low gear set. I might even skip it with a SB. Maybe a new vert is what you need or some further tuning.
Posted By: dmking

Re: to low gear set or not to low gear set? - 02/15/12 03:35 AM

what is a vert?
it is a 440 old indy heads. so i have been told the 60ft should be better. it could be the pig rich launch afr i see when the converter hits killing the 60ft. it pulls out around 5400 to 5600
Posted By: justinp61

Re: to low gear set or not to low gear set? - 02/15/12 03:38 AM

My pump gas 408 street/strip Dart weighs 3260# with me in it and goes 1.38-1.42 with 4.10 gears on drag radials. It's ran a best 6.57 in the 1/8.
Posted By: dOc !

Re: to low gear set or not to low gear set? - 02/15/12 03:43 AM

Quote:



think it will hit the tires too hard and make me spin easyer?





If your hook is on-the-edge ...it WILL DO just that.
Posted By: dmking

Re: to low gear set or not to low gear set? - 02/15/12 04:04 AM

here is a shot of the launch rpm with afr

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Posted By: jamesc

Re: to low gear set or not to low gear set? - 02/15/12 04:10 AM

Quote:

what is a vert?



converter, if i was looking to spend $400 on the race car it wouldn't be for a low gear set. i assume it's a BB and you already have a 2.45 first gear. i'm no expert but do the math. say the engine has 600 lb ft of torque. i believe typical converter ratios to be around 2:1 to 2.5:1. so now you have 1500 lb ft coming out of the converter at the hit. then run that through a 2.45:1 ratio, you now have 3675 lb ft of torque. now put that in a 4.3 final drive ratio and you have 15,803 lb ft of torque at the rear axles. now obviously these numbers aren't exact and there are losses but i don't think a lower gear set would be the best way to spend $400 on your car though more information would be helpful.
Posted By: tubtar

Re: to low gear set or not to low gear set? - 02/15/12 04:59 AM

I opted for the low 1st gear in my 904 because I have a 3.91 cog in back and I thought it might help it get moving , but whether it works or not is yet to be determined.
It sounds good on paper........whether that translates to asphalt is going to be interesting to find out.
Posted By: moparacer

Re: to low gear set or not to low gear set? - 02/15/12 05:14 AM

If you don't mind pulling the trans again to put the 2.45 back in after your 60 fts. get inconsistent by all means put the low first in!

273s 318s and 340s or a street car with 3.55 or higher gears maybe a low first, but any bigger cid or rear gears its a waste.
Posted By: Cab_Burge

Re: to low gear set or not to low gear set? - 02/15/12 05:49 AM

I run the mopar brand helical 2.77 low gear set in my Duster, 3450 lbs with a 518 C.I. pump gas motor with Indy SR heads, Dana 60 with 4.10 gears, M/T 10.5x31x15W slicks on ten inch rims, 1/4 Max ladder bars with double adjustable coil overs. It has ran a best of 1.43 60 ft at 9.993 at 134.5 with the air cleaner and full three inch exhaust system on to the rear bumper. Motor makes 725 HP at 6000 RPM and 710 Ft. Lbs at 4900 RPM on a DTS engine dyno, no problem in hooking the car anywhere with decent tires, low gear sets rock
Posted By: MoparBilly

Re: to low gear set or not to low gear set? - 02/15/12 02:53 PM

Dennis,

I agree with jamesc that the low gearset wouldn't be the best place to put 400 at this point, but more info is needed to decide where to put it.

Is 10.5 as wide a tire as the car can handle?
"Old Indy's" Are they -1s or SRs??
What broke on the motor?
What cam is in it?

If it's a 440 with -1 heads, the combination of converter and camshaft are key. Typically less duration will allow for more torque in the usuable launch rpm.

Attached picture 7072320-2974597120055648122zTUgsG_ph.jpg
Posted By: Valiant_Showoff

Re: to low gear set or not to low gear set? - 02/15/12 07:08 PM

Quote:

I opted for the low 1st gear in my 904 because I have a 3.91 cog in back and I thought it might help it get moving , but whether it works or not is yet to be determined.
It sounds good on paper........whether that translates to asphalt is going to be interesting to find out.



That's exactly my situation too. 360 powered street car with 3.91 gears on 28" tires with a 8" ATI converter. My typical 60' times are around 1.61 to 1.63 while running in the 11.70's in crappy Ohio air.

Attached picture 7072670-magnolialaunch.JPG
Posted By: 10.90 Racer

Re: to low gear set or not to low gear set? - 02/15/12 07:11 PM

Quote:

Dennis,

I agree with jamesc that the low gearset wouldn't be the best place to put 400 at this point, but more info is needed to decide where to put it.

Is 10.5 as wide a tire as the car can handle?
"Old Indy's" Are they -1s or SRs??
What broke on the motor?
What cam is in it?

If it's a 440 with -1 heads, the combination of converter and camshaft are key. Typically less duration will allow for more torque in the usuable launch rpm.



Posted By: dmking

Re: to low gear set or not to low gear set? - 02/15/12 11:31 PM

specs are old indy torquers from later 90s 270cc 335cfm 49.5cc
cam is predator 263 265 @ 050 630ish lift solid. i have 1.6 ratio rockers.
13.5 compression


1050 dominator m1 intake timing all in at idle @34deg

first pass was a 1.55 stumble cause i put a white cam in the back of carb ran a 10.27 @131.74
second pass i came out with about 3000rpm to get past the weaker pump shot and it left good considering how i left but only ran a 10.24@130 draging oil from half track till i stoped.
ended splitting the block up through the mains on the drivers side halfway to the heads.

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