Increasing the cars reaction time

Increasing the cars reaction time - 05/14/12 04:17 AM

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.

Posted By: MR_P_BODY

Re: Increasing the cars reaction time - 05/14/12 04:29 AM

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

Posted By: Going Commando

Re: Increasing the cars reaction time - 05/14/12 05:20 AM

Yes, your right, I want to decrease reaction time of the car by getting out of the beams sooner.

Posted By: Tig

Re: Increasing the cars reaction time - 05/14/12 08:16 AM

Could try deep staging

Posted By: camastomcat

Re: Increasing the cars reaction time - 05/14/12 11:39 AM

Run a shorter front tire.

Posted By: Dads426

Re: Increasing the cars reaction time - 05/14/12 12:29 PM

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.

Posted By: Dragula

Re: Increasing the cars reaction time - 05/14/12 01:29 PM

Quote:

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.

X2 That's how we do it....

If its real close, we will adjust the air pressure in the front tires up or down. Lower scrubs a little off, higher reacts quicker.

Posted By: MRMOPAR622

Re: Increasing the cars reaction time - 05/14/12 05:32 PM

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!

Posted By: 73swinger

Re: Increasing the cars reaction time - 05/14/12 08:52 PM

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

Posted By: Going Commando

Re: Increasing the cars reaction time - 05/15/12 06:24 PM

Thanks for all the feedback guys, much appreciated. I'm in need of new slicks but I think I'll try a shorter front tire. I don't need much, just .050 to .070 quicker on the r/t.

Posted By: Evil Spirit

Re: Increasing the cars reaction time - 05/16/12 05:38 AM

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.