bigdsz

iTrader: (1)

I dynoed 524/502 with a 408 and just went from a T56 to a T400, launched @ 2200RPM foot braked, with a 1.6+ 60ft, before I got got thrown out for no cage at 11.41. I'm gonna get a cage, however my question is at what RPM do I launch on the trans brake?

xpndbl3

iTrader: (23)

start low and keep raising it until the 60' drops off. Track conditions can change what rpm you can leave at as well.

Pro Stock John

iTrader: (34)

As high as it will go for NA, I would floor hold it to the floor on the brake regardless of what combo it is. You could get a 2 step to limit the launch rpm but trying to modulate your launch rpm with your foot looking at the tach is not the easiest way to do it.

JL ws-6

iTrader: (50)

Foot to the floor whatever it will go to on the converter and let go of the brake button

If the car spins, adjust the car. 2 step as John stated, is useful, but probably not needed unless you have a real race n/a converter in the car that goes to a good 5500 on the brake, in that case, you may be better off with a 2 step. Also get some more flash out of it..

440LSX

iTrader: (3)

I'm willing to bet that if you push it on the trans brake as high as the converter will go you will spin the tires. Use a 2 step I would start around 3500 and go from there.

bigdsz

iTrader: (1)

I think you guys are right about the 2 step, which one would you recommend? PSJ's comment about getting the correct launch RPM while looking at the tach, tree, etc is a PIA, plus the longer the trans brake is engaged temps are sky rocketing. FWIW I've got a Circle D 4,600/4,800 converter, Chris really puts out a quality product.

Packy

iTrader: (11)

I launch mine at around 4200-4500 rpms depending on the track and conditions usually. The higher the rpms the better the 60' time is usually. It depends on the track though if I spin badly then I adjust the rear shocks and tire pressure a bit.

Pro Stock John

iTrader: (34)

If I couldn't hook a car NA, I'd be looking into a 2 step. You can set up the 2 step for the desired rpm, and then be able to 100% floor the gas pedal.

440, are you using a 2 step. Congrats on the ET.

BAIN

iTrader: (5)

Peak TQ on a T-Rex is around 4800-4900 rpm (atleast mine is). Wouldn't you want to set the 2-step around 4500-4700 rpm to get the most out of it?

I had my converter restalled 3 times. Originally it went 4600 on the brake and the 60's sucked (1.6's). I had it restalled and it went to 5100 on the brake and pulled 1.5-1.49 60's, but was still too tight between gears (shift extension) This last time I think may be too loose. I logged it Sat. and it stalled to 3100 footbraking and 6300 on the TB. I don't know how this is going to work. I guess I will try it and see. I may have to get a 2-step.

440LSX

iTrader: (3)

Thanks John and yes there I use a 2step. Bain in theory your explanation sounds good but you may have some traction issues.

Pro Stock John

iTrader: (34)

What I would say to folks who reading the thread and doing research...

Guys with heavy or low powered setups won't really need to limit their launch rpm as long as they have sticky tires and suspension work. After all if you are making 350rwhp and are full weight, the car will probably work.

Now if you are making 800rwhp, that will be a different story. Or if you make 480rwhp and are 3000 raceweight, those combos will be trickier to hook.

A 2 step will allow you select your max rpm at launch. So if your converter is flashing to 6000 on the spray and you can't hook it, you can run a progressive controller and/or a 2 step. Maybe at 5200 launch rpm on the 2 step you can hook.

2 steps are great for manual transmission guys too because you can make your launch rpm more consistent and thus add or take out rpm as needed.

440LSX

iTrader: (3)

Well said John...

bigdsz

iTrader: (1)

Hey guys, once again what 2 step should I install? I'm really naive about these controllers and really need some input. Thanks again.

Pro Stock John

iTrader: (34)

I think LPE has one. I've only used the one in the BS3.

Wicked94Z

iTrader: (26)

Only 3 passes so far for me on the 'brake, best was a 1.45 at 3500, then 1.49 (worse track) at 3800 and 1.51 at 4000. No anti-roll bar yet, the car twists more the higher the launch it looks like on video. This is at 11 psi in the ET streets, tried ~12.5 and slowed to 1.61 at 4000 I'd put tubes, stiffwall slick, or radials on it. I'm slamming the sidewall on these with no tubes, but raising tire pressure didn't work for me.

Villain281H

iTrader: (5)

Every car and combination likes a different rpm on the brake. I started at 3800 rpm on my TH400 in the Nova and got a best of 1.526, but had to start backing down the rpm due to red lighting when I was running 5-tenths pro tree open comp and index stuff. I'm all the way down to 2700 rpm now and the car still went a new best of 1.503 60 foot in early November.

FWIW, the car will move quicker from the beams the higher you rpm in most cases, but launching off the converter (no 2-step) is hard on the converter and may lead to shorter life I've been told by quite a few companies and racers.

Derek

Wicked94Z

iTrader: (26)

I've heard both ways on launching off the converter vs 2 step. Some say it's bad, some say it's not. From the people I've talked to, the higher they go on the 2-step the higher the tendency to put it on the bumper. These are lower powered cars however.

JRracing

iTrader: (35)

I have a 5K stall 10" TCS converter and it likes to leave off the brake around 3500-4100 rpms and that is on the 2 step. In the later part of this year my car cut 1.36-1.39 60' at 2850 race weight. Making around 600 fwhp NA.