1/4 mile launch techniques

[sailsmen]

With the cooler weather we will be making another run to the 1/4 mile track.

I am having traction problems now that it is 57* out.

Anyone have any suggestions on launch techniques to limit spin?

I am afraid if I don't stomp it that I will have a slow 60' time.

Is there a technique to roll on the throttle to get the car moving w/out losing more time than stomp/spin?

[Smokie]

sailsmen I had "minor" traction problem in Atlanta last week when I brake-stalled at 2000 rpm (my slowest ET) I had the best results at about 1200-1400 Rpm's, your car is faster than mine so it may not apply, try to do as many time runs as u can prior to the actual bracket racing, have you tried to lower air pressure in rear tires? At Atlanta a S/C MM. ran as high as 14.8 due to lack of traction until he managed to feather that start and ran 13 flat and still he really wasn't hooking up completely, practice as much as you can. Others who know more about this than I do I'm sure will offer better advise.;)

[sailsmen]

I ran with 28psi in the rears. I will try 25 or 26.

[BillyGman]

open to other opinions on this, but frankly I don't see why there would be any benefit in brake torqing a car w/a factory engine as far as better ET's are conerned. That technique is used by professional and amatuer drag racers who run radical cam shafts in their motors which cause the powerband to be moved up much higher in the RPM scale. Therefore their cars run real rough at idle, and don't have any power until they hit 4000RPM. With a car like that they have a need to rev the motor up while waiting for the light on the tree to turn. But for a car that has a factory stock camshaft in it, I don't think there's any real benefit to be had from brake torqing off the line. Constable ran consistent 14.0's at E-town a couple weeks ago by simply hitting the gas pedal when the tree turned. And I used the same techique when I was there too. I had some wheel spin too, which I equated to the 4.56 gears that I've installed in my car. I think that as long as I run the stock tires on the track, the best thing for me to do at the Launch is to take off using half pedal, and as soon as the car gets moving at about 20MPH than I can stomp it to the floor.

[Smokie]

BillyGman: It was my first time ever at a track so I had no idea what is best, obviously going to 2000 rpm and holding brake did me no benefit (slowest ET) however no matter what; you do have to hold the brake or the car keeps moving forward. I had a choice of holding brake with left foot or right foot. Left foot for brake seemed to me a better idea, right foot on accelarator, my car idles about 700 rpm so I added about 500 rpm's and got my best result of the day. I have a total of 5 runs under my belt (lifetime) so I am listening to all suggestions since I have no idea what best is, also I was told to turn off O/D although not sure why, my car never shifted into 4th gear inside the 1/4 mile. :cool:

[BillyGman]

I've had a number of Hi-perf cars in the past, and got into a number of street races. However I don't have any long history of drag racing on the track either. So that's why I've stated that I'm open to other opinions on this. My comments weren't neccessarily directed at you, because from what I'm hearing, the majority of guys on this board who take their Marauders to the track use the brake torqing method during their Launches, and I'm not so sure that it's a real advantage to do that. Especially since Constable has done very well w/out it. But that's merely an opinion based on an educated guess on my part since I'm really not speaking from experience concerning this specific topic. And sure you have to hold your foot on the brake to keep the car still,(atleast I do w/my Marauder) but that doesn't mean that you have to hit the gas while your other foot is still on the brake.

[Smokie]

Billy Looking at your mods I would have to agree with you, your car I'm sure launches like a scalded cat, mine not quite (stock gears) What do you think about O/D ? Makes a difference ?

[CRUZTAKER]

Originally posted by BillyGman
open to other opinions on this, but frankly I don't see why there would be any benefit in brake torqing a car w/a factory engine as far as better ET's are conerned.

I agree...I found no benefit to the brake torque unless your showing off for the kids at the corner filler up when they beg for a burnout.....

Not being much of a racer yet, I found my MM to like 25lb rear pressure, and a nice stomp of the pedal on the 3rd light. I lose a little traction for 5 feet or so, even with warm tires...but that is to be expected until I purchase a better tire setup for race days.

Barry

[BillyGman]

Smokie, I'm w/you on the O/D thing. many guys say that it should be left off during a race, but this is another thing that I don't see any reason for. At WOT I don't think that the car is going to hit O/D weather you have the button on or off anyway, but certainly not sooner than 100MPH. Right? And by then, you're already done w/the 1/4 mile anyway. So what's the difference? I left mine on when I was at E-town.

[TripleTransAm]

This OD-thing is something I wish I could ask Jerry (The Man) himself...

I could swear I'd run slower on the runs where I forgot to disable the OD.

On older hydraulically-brained transmissions, there is a very clear cause-and-effect, especially on the General Motors transmissions (which I'm more familar with). Leaving the car in '3' or 'D' (no overdrive) blocks off the hydraulic paths to the overdrive circuits, leaving more line pressure for the other gear ranges. Shifts are snappier and more positive. Also, there are some extra bands and clutches that are applied in these ranges, which can help in the power delivery.

But on our electronically-controlled transmissions, I'd imagine the 'od-off' button simply tells the PCM not to command a 3-4 upshift, ever. Nothing more (I think).

So what about those danged slower runs I ran with the OD-on?

[TripleTransAm]

My memory hasn't been as good as it usually is, with all the current stress in my life (good positive stress, nonetheless). But I think I got my best launches at 1200-1500.

One positive aspect is that the car is just about ready to lurch, at the green. Heck, I never thought I'd actually red-light in this car, but I did. Charles (MTL_CV) noted how my car shot out of the hole, that night we went racing.

I haven't really focused on the launch technique so much, but next time I hit the track I'm going to try bringing it up to 2000 or so, and ease into the gas rather than stomping on it. The increased torque multiplication at that RPM might make for a hard launch but I might have to wait a car length or two before matting the pedal.

[CRUZTAKER]

Those of us hitting over 96 mph on the 1/4 turn it off (OD) cause the cars speed climb's higher-faster with the OD gear off.

Those of you who had 5-speed manuals should remember that the tallest climbed the slowest, thats why we stayed in 3 or 4 till redline and ignored 5....atleast I did with my rotory.

[TripleTransAm]

I didn't seem to hit 4th gear on the 1/4 on the runs I forgot to lock-out the OD. But then again, those were the slower runs, whereas the quicker ones were with the OD locked out.

So it's a catch-22... I didn't make it into 4th gear (OD) with the OD not locked out, but the runs were 95 mph or slower. Yet I made it above 95-96 mph on the runs where I *did* lock-out the OD and therefore stayed in 3rd all the way. So what happened in the lower 3 gears with OD-locked-out that is different from when the OD is enabled?

(side note: we all agree that OD gear is simply 4th gear, right? With OD off, you get 1-2-3, with OD-on, you get 1-2-3-4)

[sailsmen]

Interesting responses, thanks.

I do note that my best run and that of others has been w/out power braking. I would like others to advise the launch tech for their best time. Others that do not have the high stall convertor.

I was totally shocked the way it spun when I power braked to 2,000 RPM.

[darebren]

I did not try with OD "on" or with TC "on". I don't think I hit 4th gear anyway, but sure felt like 3rd was running out of power, and had I done a couple more runs, I might have tried to let go of the gas pedal quickly and get back on it to force a shift into 4th sooner...probably would not have done any good though, might have just downshifted again at WOT anyway. I also did not try manually shifting it either from 1 to 2 and 2 to D.

There is not much time during staging to look down at your rpm's and try to get them up and not miss the 3rd yellow light to GOOOOO!... so for me was easiest to get idle just slightly up, but I was not sure where it was, never looked, just went be feel..

felt I had some decent times for a first timer.

also, ran tires at 28psi, should have gone lower like 20-25, cause I had wheel spin at launch, and again on the 1 to 2 shift-car got sideways slightly on the 1 to 2.

[2003Marauder]

A lot of regular racers have told me that you're more likely to red light if you "torque brake." That's not what they called it but I can't remember their jargon at the moment.--just finished a big lunch.

I've tried many a way on both my MM and Tbird. "Flashing the engine" has always yielded the best ET. Because of the low-end torque on the Tbird. I have started in 2nd gear when track conditions were bad. I get a better ET under slippery track conditions with start off in 2nd as the Tbird does not break loose.

F.Y.I. My Tbird computer was programmed about three years ago by some guy named Jerry out of somewhere MI. He did two things of note: 1) Taking OD off results in higher shift points. 2) removing the "octane plug" from under the hood advances my timing about 3 degrees when running on 104 octance--good for about 25 more HP. Normally, removing the octane plug retards timing if your having serious ping or using mexican gas.

Question: Does the MM have an "octane plug?"

[TripleTransAm]

Is your T-bird a Turbo?

[2003Marauder]

My '96 Tbird has the 'roots' Allen Engine Development Eaton M90.

www.allenengine.com

[TripleTransAm]

Oops, forgot about that... I couldn't for the life of me remember about the 3.8 SC in that generation. Also, if I didn't have my cranium firmly inserted in my anal region today, I would have read your sig and seen all the data right there in plain black and white for me to read. :up: Yes, it's been that kind of day, folks...

Anyway, the "octane plug" is probably some sort of boost limiter or timing limiter. Some turbo Volvos I worked on with my cousin in the late 80s had this boost limiting system... sometimes mechanics would remove them for "test driving" and have the time of their lives, unknown to the customer. Once, a tech forgot to put it back in... the customer came back complaining the car had become very unruly, too strong, LOL!

[Paul T. Casey]

I'm with Smokie on this, as my best time was on about 1000-1200 rpm launch. Some of the Impala guys there that day told me to run tire pressure down to 22 psi, couple even said 20. Also my drag racer buddy says a little tire spin don't hurt, especially with our cars, as we don't start making big power numbers until we get up around 3500 rpm. (Hence, that's why we were running the Impala's down at the end of the track.) Weather permitting, I'm going to try to practice some more launching techniques this Friday night on the 1/8 mile track here in Chattanooga. Maybe we can collectively find that sweet spot for some good 60' times!

[SergntMac]

Originally posted by TripleTransAm
This OD-thing is something I wish I could ask Jerry (The Man) himself...I could swear I'd run slower on the runs where I forgot to disable the OD. On our electronically-controlled transmissions, I'd imagine the 'od-off' button simply tells the PCM not to command a 3-4 upshift, ever. Nothing more (I think). So what about those danged slower runs I ran with the OD-on?

I've had my share of confusion on this, and I spent the better part of the '03 season working on it. Keeping in mind that the race is determined early on, watching your 60' time is critical. Anything above 2.0 needs to be lowered, you're just burning up at the line.

I've tried all of the RPM/brake torque/tire pressure and slicks/no slicks I could imagine, and ran out racing season disappointed. I'll be back there early in '04, and pick up where I left off.

The only launch I haven't tried yet, is NO brake torque, just drive her out with a paced 1-2-3 pedal to the floor on the last yellow. If I see green, I'm late. Anyone who can still try this this year, please let us know?

/Steve, I have asked Jerry..." no OD, turn it off." You are correct to cite the "electronic" nature of our trannys here, where once the correct RPM is achieved, the tranny will shift regardless of your intent. I've had a few launches where it upshifted into 2 before I passed the tree due to tire spin, and I had to pull up and hit it again. Ran a 16.x @ 111MPH, go figure.

Truth is, you DON'T know if you're spinning at the 2-3 shift or not, you surely won't hear it above the roar of the engine, and I am sure you are concentrating on other things right about then. Just a bit of slip, and you CAN send the shift signal for the trans to drop into OD, and it's unlikely you will recover from this in time to win the race, or, earn a decent ET. Why worry about it, shut the OD off and you won't have to wonder. BTW, Jerry can change this in his dyno tune, he can preset/reset shift points if you wish.

My best ET to date is on Pirelli tires @ 25 PSI, and my 60' is still 2.12. I have some work ahead of me in the launch and the tire/PSI areas, and I expect to improve my 12.81 soon.

[FordNut]

Another thought on launches: A 'stang buddy told me the best launches and ets they were getting was with traction control on, overdrive off, and torque-braking at 3000 rpm at the tree. Maybe some of you 300B owners can try this. It just might work.

Edited: Of course the rpm would have to be adjusted due to stall speed of the torque converter, but you get the idea.

[sailsmen]

Well my first run was power brake to 2,000 RPM. Spun like crazy all the way into second, started going sideways and had to let off.

Of course that ET was 16.50+.

After a can of tar remover and 4 detail rags I was only able to get the tire debris off the rear bumper and meg tips. The fender wells are so coated I an't even gonna try!;) ;) ;) ;)