Re: Increasing the cars reaction time
[Re: Going Commando]
#1233028
05/14/12 12:29 AM
05/14/12 12:29 AM
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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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Quote:
Would it be reasonable to assume that switching to a 28 inch tall slick from a 29.5 would increase my cars reaction time, less roll out, quicker start? Any help on this subject would be great. My car is low 12 second sreet car with a 4.10 gear.
To me your saying it backwards... (increasing would
mean slower) but yes the smaller tire will have less
time in the lights... pump up the tire pressure so
the tire sits higher will also fine tune it
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Re: Increasing the cars reaction time
[Re: Going Commando]
#1233030
05/14/12 04:16 AM
05/14/12 04:16 AM
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Joined: Jan 2003
Posts: 2,923
A shed in England
Tig
master
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master
Joined: Jan 2003
Posts: 2,923
A shed in England
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Could try deep staging 
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Increasing the cars reaction time
[Re: camastomcat]
#1233032
05/14/12 08:29 AM
05/14/12 08:29 AM
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Joined: May 2007
Posts: 1,443
Maryland
Dads426
pro stock
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pro stock
Joined: May 2007
Posts: 1,443
Maryland
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We run both 0.5 & 0.4 trees, so with the 0.5 tree we run a 29.5" front tire and launch at idle & higher; 0.4 tree a 28" tire and vary the starting line rpm from between 2500-3500. We fine tune the reaction time with the starting line rpm; the higher the stall speed the quicker the launch, hence lower reaction times. Change the car, not the driver. Leave at the same point on the tree.
2012 422 Allstars NSS Champion
2013 422 Allstars NSS Champion
2014 422 Allstars NSS Champion
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Re: Increasing the cars reaction time
[Re: Dragula]
#1233034
05/14/12 01:32 PM
05/14/12 01:32 PM
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Joined: Sep 2003
Posts: 2,008
Sweet Home Alabama
MRMOPAR622
top fuel
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top fuel
Joined: Sep 2003
Posts: 2,008
Sweet Home Alabama
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 Lets just say we are going to have to agree to dis-agree on this. I have a few friends one runs a track and has 6 race cars,that I sometimes drive for.If there is a Big Bracket Race they are going to be there and most times with more cars than they can drive. The reason they ask me to drive(I get part of what I win)is I can adapt to the cars which some-times are borrowed.If you can Win Bracket Racing you can win Index,Grudge Racing(most my work is on Grudge racers cars).If the car will 60' and run the same ET everytime,then all you have to do is make the adjustment to yourself not the car to win. I always shallow stage,why because that is the only way to stage the same way each time.I'm sure this post involves Foot-Braking. When Foot-Braking on the 1st hit I will leave when I see green,if that's to slow I will then leave when the last amber bulb goes out(not on).If that's to quick I will then watch the top bulb and count numbers 1,2,3 till I find the right number to leave off of for a good light.  I hope this Helps and Good Luck! 
"To Be The Man'You Have Got To Beat The Man"
"T/D and Pro-Bracket Racer"
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Re: Increasing the cars reaction time
[Re: Going Commando]
#1233035
05/14/12 04:52 PM
05/14/12 04:52 PM
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Joined: Jan 2003
Posts: 864
St Paul MN
73swinger
super stock
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super stock
Joined: Jan 2003
Posts: 864
St Paul MN
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Brian
If you have, or are borrowing the 28" tires, give it a try, the theory is good.
Another thing to consider is stiffer sidewall slicks, Radial Slick, or ET radial street tires.
I set my tires to 26# cold, and I think mine reacts to quick (lots of red lights to show), and I have no room for taller tire in front. I just changed my launch focus to bottom yellow only, I'll let you know how that works after a few more races, I was liking the results of it Saturday.
Good Luck
Chris Schwartz
73 Swinger 340 12.451 @ 108.78
73 Gold Duster, needs a plan.
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Re: Increasing the cars reaction time
[Re: Going Commando]
#1233037
05/16/12 01:38 AM
05/16/12 01:38 AM
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Joined: Jan 2005
Posts: 3,699
Newport, Mi
Evil Spirit
master
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master
Joined: Jan 2005
Posts: 3,699
Newport, Mi
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Quote:
Would it be reasonable to assume that switching to a 28 inch tall slick from a 29.5 would increase my cars reaction time, less roll out, quicker start? Any help on this subject would be great. My car is low 12 second sreet car with a 4.10 gear.
Unless you have a front wheel drive car (which would be an important piece of info in this case) most of the answers are about the wrong end of the car. On a rear wheel drive car tire diameter or pressure does nothing to affect roll out. It will change your initial launch which may show up as better reaction and 60' times. Now I'm guessing you are in the 1.80 area for 60' times, which is a tough 60' to tree for good reaction times off the botttom bulb - you really have to be on your game to consistantly hit good bulbs. You can't get consistant R/T's until you can get consistant 60's - pure and simple.
Now back to your post - the shorter slicks may help you 60' a little better, giving the car more effective "gear", which will also show up as a slightly better R/T. Once the 60's even out, then you can try staging a little deeper, more air pressure, or taller tires to adjust the rollout to help the reaction times, which unfortunately will come at the expense of slightly slower E/T's.
Hope this sheds a little more light on the subject.
Free advice and worth every penny...
Factory trained Slinky rewinder.........
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