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Gear change/ 60' loss #1326969 10/27/12 03:11 PM 10/27/12 03:11 PM
Joined: Feb 2009 Posts: 1,532 off the grid 340B5 OP pro stock
340B5 OP pro stock Joined: Feb 2009 Posts: 1,532 off the grid	I need a gear change in my Duster and just 3 days ago had a new best of 1.49 60' and a 10.95 ET. Problem is that it hits the rev limit (7k) in 3rd around 1000' I wonder how much 60' I will give up going from 4.86 to 4.56 gears? This is a 3.58 stroke 374 inch engine. Any guesses or personal experiences? Yeah, it's got a smallblock.

Re: Gear change/ 60' loss [Re: 340B5] #1326970 10/27/12 03:14 PM 10/27/12 03:14 PM
Joined: Aug 2006 Posts: 1,613 Deerfield, Ohio 70dusterjohn top fuel
70dusterjohn top fuel Joined: Aug 2006 Posts: 1,613 Deerfield, Ohio	We lost none, at all... I really dont think that the 56 is going to be a big enough drop to make a difference, I think I gained maybe 200 or so rpm. So I still feel that you would hit the rev before the line. I ended up going to a 4.30 and the car picked up a little more on top end, and again lost nothing in the 60ft. Thats with a 30" tall tire..

Re: Gear change/ 60' loss [Re: 340B5] #1326971 10/27/12 03:21 PM 10/27/12 03:21 PM
Joined: Jan 2003 Posts: 1,142 Central New York slippery440 Crybaby440
slippery440 Crybaby440 Joined: Jan 2003 Posts: 1,142 Central New York	What size tire? Try a 2 inch taller tire and that would be close to the 4.56s. If the MODS did their job I would not be hitting the notify MOD button. LOL

Re: Gear change/ 60' loss [Re: 340B5] #1326972 10/27/12 03:24 PM 10/27/12 03:24 PM
Joined: May 2003 Posts: 13,189 aZLiViN J J_BODY I Live Here
J_BODY I Live Here J Joined: May 2003 Posts: 13,189 aZLiViN	is the combo done at 7K?

Re: Gear change/ 60' loss [Re: 70dusterjohn] #1326973 10/27/12 03:35 PM 10/27/12 03:35 PM
Joined: Feb 2009 Posts: 1,532 off the grid 340B5 OP pro stock
340B5 OP pro stock Joined: Feb 2009 Posts: 1,532 off the grid	Quote: We lost none, at all... I really dont think that the 56 is going to be a big enough drop to make a difference, I think I gained maybe 200 or so rpm. So I still feel that you would hit the rev before the line. I ended up going to a 4.30 and the car picked up a little more on top end, and again lost nothing in the 60ft. Thats with a 30" tall tire.. I would be happy if I didn't loose any, and yes I thought about still hitting the limiter, but it should be for less time anyway. Slippery: I already have the gears, so that fits the budget better. J body: The combo should be done before that. I have factory iron J heads(worked over some)I'm gonna guess 6700 or so, but I haven't felt it nose over before the limiter. I've only made 5 complete passes w/ the combo and I'm still getting re-acquainted with the car after a 2 yr hiatus. Yeah, it's got a smallblock.

Re: Gear change/ 60' loss [Re: 340B5] #1326974 10/27/12 04:43 PM 10/27/12 04:43 PM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	That gear change should drop you 500 rpm may cost you .01 in the 60 foot. I would just race the limiter to 7600 RPM is your friend! :-)

Re: Gear change/ 60' loss [Re: Dodgem] #1326975 10/27/12 04:54 PM 10/27/12 04:54 PM
Joined: Jan 2003 Posts: 6,266 Renton Washington T Triple Threat master
Triple Threat master T Joined: Jan 2003 Posts: 6,266 Renton Washington	If the converter is big enough, it shouldn't hurt too much, maybe .02 to 60 foot, but the car will run better down track... -Dustin 67 Dart, 9 second, 392" G3 Hemi 68 Barracuda 340 F/SA

Re: Gear change/ 60' loss [Re: Dodgem] #1326976 10/27/12 04:59 PM 10/27/12 04:59 PM
Joined: Jul 2012 Posts: 429 Washington skrews mopar
skrews mopar Joined: Jul 2012 Posts: 429 Washington	Few years back I tried 4.30, 4.56, 5.13. No notable difference, except that the 5.13 would turn the tire a little off the line sometimes making the car inconsistent. This was running in a 7.5 ET 1/8 mile car for what its worth. I've watched alot of guys try really deep gear hoping to shave of some ET and lower the 60 footers, only to find no gains at all.

Re: Gear change/ 60' loss [Re: Triple Threat] #1326977 10/27/12 05:01 PM 10/27/12 05:01 PM
Joined: Aug 2006 Posts: 1,613 Deerfield, Ohio 70dusterjohn top fuel
70dusterjohn top fuel Joined: Aug 2006 Posts: 1,613 Deerfield, Ohio	Like I said we did it with zero change. Didn't make a difference at all. If you have them and can do it, heck try it. What are you out? Then if need be you could go up 2 in the tire size(if you can) or go to a 30 for next year. Are you running an 8 3/4 ? Where you located. I have complete pigs in 489, 456, and 430.. Heck I got a 410 also....

Re: Gear change/ 60' loss [Re: 70dusterjohn] #1326978 10/27/12 05:16 PM 10/27/12 05:16 PM
Joined: Feb 2009 Posts: 1,532 off the grid 340B5 OP pro stock
340B5 OP pro stock Joined: Feb 2009 Posts: 1,532 off the grid	Thanks for the replies. It looks like I'll be good to go w/ the 4.56's. The trans has the 2.74 low anyway. Yeah, it's got a smallblock.

Re: Gear change/ 60' loss [Re: 340B5] #1326979 10/27/12 08:22 PM 10/27/12 08:22 PM
Joined: Jan 2003 Posts: 10,008 Frostbitefalls MN (Rocky&Bullw... gregsdart I Live Here
gregsdart I Live Here Joined: Jan 2003 Posts: 10,008 Frostbitefalls MN (Rocky&Bullw...	going from 4.86 to 4.56 is only a 6.2 percent drop in gear ratio, so it should see 400 rpm drop. I am betting it will run as good or better. With the 2.74 low you still have a 12.49 starting line ratio, and that is pretty high. 8..603 156 mph best, 2905 lbs 549, indy 572-13, alky

Re: Gear change/ 60' loss [Re: gregsdart] #1326980 10/27/12 08:40 PM 10/27/12 08:40 PM
Joined: Jan 2003 Posts: 25,933 United Socialist States of Ame... T tboomer Too Many Posts
tboomer Too Many Posts T Joined: Jan 2003 Posts: 25,933 United Socialist States of Ame...	Quote: going from 4.86 to 4.56 is only a 6.2 percent drop in gear ratio, so it should see 400 rpm drop. I am betting it will run as good or better. With the 2.74 low you still have a 12.49 starting line ratio, and that is pretty high. Greg...I find that interesting. If I crossed the line at 6400 instead of 6800,I would still be in my powerband. Might run a hair faster with 4.56 instead of 4.88s.. Need your rear end checked out? Contact Grizzly!!

Re: Gear change/ 60' loss [Re: tboomer] #1326981 10/27/12 09:23 PM 10/27/12 09:23 PM
Joined: Jan 2004 Posts: 903 Saskatchewan, Canada cudabin super stock
cudabin super stock Joined: Jan 2004 Posts: 903 Saskatchewan, Canada	One school of thought is that you should peak at the 1,000 foot mark which by then most of the acceleration has reduced your ET and you are already at a higher MPH for the last 320 feet... This assumes the engine can handle the rpm and is not nosing over... My motor made peak HP at 7,200 rpm and I cross the stripe at 8,000 - 8,100 rpm. I think it ET's decent... Best way to find out is to test it, so let us know how the 4.56's affected the ET and MPH once you cahnge. Cheers, Arnie 67 Cuda 8.48@ 158.7 mph 1.18 60' 2,600 DA(so far...) 70 Super Bee 440 Six Pack 4-speed. 13.2 @ 104 Stock exhaust/Street tires.

Re: Gear change/ 60' loss [Re: cudabin] #1326982 10/28/12 01:27 AM 10/28/12 01:27 AM
Joined: Sep 2010 Posts: 170 renton , washington P perfmachst member
perfmachst member P Joined: Sep 2010 Posts: 170 renton , washington	hi, changing gears does affect E.T. and 60' times. went from 5.13 & 29.5 tire to 5.57 & 30" tire, E.T. dropped .30 & gained 1 MPH. 60', dropped .13. car was faster period!!! also, rpm was 6400 after is 7000 rpm +. it doesn't lay down last 300 ft either.

Re: Gear change/ 60' loss [Re: perfmachst] #1326983 10/28/12 11:24 AM 10/28/12 11:24 AM
Joined: Feb 2009 Posts: 1,532 off the grid 340B5 OP pro stock
340B5 OP pro stock Joined: Feb 2009 Posts: 1,532 off the grid	I've tried to factor in everything. The tires will turn 7.6 times in 60', stall is increased ever so slightly w/ the 4.56's, etc. I think I'll check the logbook today and see what going from 4.56 to 4.86 did for the 345 in engine a few years back. Yeah, it's got a smallblock.

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