launching with Stall

[bwlizard]

Just got my 727 with 2800 stall speed converter installed. How do you guys launch with a stall speed ? Do you just floor it or do you rev just below the stall and then floor it? Or do you brake torque ? Just trying to learn

[1972roadrunner]

with my new cam, its a little sluggish on the bottom end so i hold the brake, and give her some juice till it almost breaks the tires loose, then when the light turns, the flag drops, or the third honk is sounded, i put her to the floor as i let up off the brake seems to work pretty well for me...

BTW: i have a 3800 stall so i can get my r's up higher for better launch... this is what i do...play around with it...as long as your kickdown linkage (or cable) is setup right, there shouldn't be a problem.

[451Mopar]

If you have the traction, usually the car will launch harger the higher the rpm you launch at. I only leave at 1,200-1,500 RPM because if I launch at a higher RPM the tires just spin.

[1972roadrunner]

thats true, but with giant 50's, or even some 60's you don't have to worry about that

like i said, go out and play with it, get a feel for it, and you'll figure out whats best for YOUR car...

have fun!

[cuda66273]

I use a Crane dial type studder box (Rev Limiter) and have the power side hooked to a toggle switch with the release wired to the brake light switch.

When the first yellow comes on I mash the gas hard to the floor, when I release the brake it shuts down the studder box and launches the car.

I dial the box between 3500 and 3800, in our case the 3800 works as long as the track is good, if it's a little slick we'll dial it down around the 3500 mark to take some of the shock out of the tires.

You just need to remember to turn the switch off before you apply the brakes or you'll get wild backfiring when you hit the brakes at the stripe.

Our Dynamic convertor flashes right at 4200 and for best results Dynamic reccommends you launch at 5-800 below the stall.

Warning:
This may not be suitable for those of weak heart or borderline transmissions. NO warrantee expressed or implied, bucket and broom for clean up is optional.

[The Dartman]

I have a TCI 4500 stall converter that stalls at about 4200.

I used to bring up the car against the converter and then mash it to the floor, but that can be inconsistant. I adjusted my back brakes all the way out (really tight) so I can hold the car in the beam with the gas to the floor (or nearly). This made me a much more consistant bracket racer and better on the tree. Some combos simply make too much torque to allow you to do this, but if you can set the car up to launch this way you can be much more consistant.

Sometimes the best ET's come from slingshoting your converter - that is, bring the revs up fast against the brake and dumping the brake like a clutch (not hard up against the converter). Lower stall speed (3000) cars can crank off some of thier best ET's this way, but it is absolutely not consistant for bracket racing. Higher stall cars hit the stall speed and just hang there this way, building heat and hurting expensive parts over time.

You can also get more consistancy be running a rev limiter like Cuda. One slant I saw on his idea is to run an actual switch mounted on your brake pedal. This has several advantages: We all know the brake switch is a pretty crappy plastic switch to begin with, and relying upon it to race can be a big gamble (ever price a fast transbrake switch? ouch). An aftermarket switch will be faster, more durable, and since it would be mounted on your brake pedal itself it would release a millisecond sooner. Also since it is mounted on your brake pedal, through the traps you can step on the brake pedal avoiding the switch (no backfire). I plan on running a setup like this when I get a MSD two step.

One other notable thing - it is also next to impossible to use a line lock to launch with. Line locks are illegal to run on back tires, and most fast cars simply overpower the back tires and start spinning at the launch.

The Dartman

[cuda66273]

I know what your talking about in regards to the dependability of the brake light switch and it was a concern when we hooked it up that way.

I had a very expensive trans brake button mounted on the steering wheel, but just couldn't get the hang of it....too old and set in my ways I guess.

Anyhow after several passes and alot of frustration one of the other Mopar guy's showed us how he had his set up and we thought we'd give it a try. It took a total of 5 passes in a couple of test and tune sessions before I got the confidence to use it in eliminations.

Our 60' times in the first 3 passes in eliminations were 1.723/1.723/1.724 and the car ran 12.363/12.364/12.368 reaction times improved from a sporatic average in the 540's to solid low .530's unfortunately the stupid good for nuthin' usless old fart of a driver red lit on the 3rd pass and we went home early....

Next time out the car continued the same consistancy, but we had made some changes in the weight distribution and she ran a...your testing my memory here but I believe 1.709/1.706 and a 1.71 flat at 12.270/12.278 and another 12.270 reaction times improved .508/.522/.532 ...then that same useless driver broke out by .0015 in the first round.....and we went home early.....again....

We've had a couple of weeks off due to special events and a leaking freeze plug so we'll be back at it again this Sunday.

....so...the point here is, yes there are better switches out there and I have one just sitting on my steering wheel, but a good driver should be able to adapt to the reaction time of almost any switch the same as he would the vehicle or driver reation times....sometimes we don't need to get the most expensive part to be consistant...and consistancy IS the name of the game and seat time is how you practice.

One more thing...on remembering to turning the switch off....I mostly forget(Old timers Desease)...until I hit the brake pedal...POW...a subtle reminder

I signed up for a memory improvement class one time...but forgot what night class was

[The Dartman]

Talk about forget!!

I usually forgot to turn my Alternator back on after a pass, so I would be charging my battery with a crash cart in the staging lanes just to make the show....

Many racing weekends have been nearly ruined when I get into the vicious cycle of dead battery/hot car/dead battery/hot car etc., so the alternator switch was only complicating matters. That SOB is in the trash and will stay there forever... or until I need another 5 hundreths or so....

PS - My best 60 foot of 1.67 came on a 13.02 pass on slicks back when my converter was fairly new. I cut a .501 light on this pass against a friend of my brothers in the second round of elims. I think with a newer, tighter converter I should be able to get 12.60's or so since my 60 foots with the same combo in a lighter car are around 1.85 - 1.90 or so.

[bwlizard]

Thanks for the excellent ideas.

[cuda66273]

Dartman

Awesome ET's with that 318!!!

You might give some thought to a Dynamic convertor if your gonna make a change....cut .2 of my ET and .08 off my 60'.

The brake switch release system took a solid .05-6 off my 60' and made them unbelievably consistant.

Don

[racebeeper68]

Heh Cuda66 you been looking at my car? LOL, I have the same setup wired to my brake switch. Never has gave me a problem, as long as I remember to turn the toggle off after I,m in third.

[cuda66273]

LOL...that's funny....Nice looking Runner!

I won a round a couple of weeks ago....I hitn the brake right at the stripe and it backfired hard...scared the other guy so bad he lifted .....LOL

He was crying afterwards saying that he thought I blew up and he lifted....I had him covered by about 2/10ths anyhow.....scared me worse...LOL

[racebeeper68]

Sometimes after my burnout I'll flick on the switch and with foot on brake clear out the throttle in neutral, Maybe it makes the guy start thinking something,s wrong with my car?
Also I wired up my w/w switch to the brake lights to try and fool someone chasing me But I hav'ent actually tried this one yet in comp.

[Billydelrio]

Those brake switch controlled rev limiters are fine, but in the "foot brake" class that I run, they are against the rules. My approach is to stage with the needle at 2000 rpm and then stomp it when the last yellow comes on. With a real loose converter, it does not take much brake pressure to hold the car, so I just rest my foot on the pedal. The car wastes a little time lifting before it goes, but it is consistant for me. Remember, I run a small 273, so you guys with the big engines (318 and up!!) have a low rpm torque advantage over me and probably run quicker than my 1.802 60' times.

Billy

[racebeeper68]

I feel that a 2 or 3 step is bending the rules but I checked at the tracks that I race at and they consider it legal and about 40% of the cars use 'em so? Usually keeps me pretty consistent and I don' t look at the tach at all.