4SFEDZ

iTrader: (6)

i put this here cause i know turbo car converters are a lot diff so i thought i might get some good info here!

ok, how do i decide where my converter needs to be? does it need to be close to my peak hp, tq, or in between both? ill post up my dyno which has the graph at the end, and a vid at the track. right now this is a 3k stall, it goes to 3k, but if i sit on it a little while the rpm will start rising, is this bad? i think the converter is too tight what do yall think?

dyno
http://www.youtube.com/watch?v=Zuzst...layer_embedded

track (this was stayin on the converter till bout 3400 and 2psi or so)
http://www.youtube.com/watch?v=348XtCFoWCo

black98ws6ta

iTrader: (77)

Does the car have a transbrake? If so....it should make boost fairly quickly. The tune can also be adjusted to help with the spool time, if it has not been played with already. If it takes too long to spool then the temp's will kill the transmission.

My car would not do anything on the foot brake but would go to the moon on the transbrake if my 2 step didnt stop it.

4SFEDZ

iTrader: (6)

how long do you usually stay on the 2-step? how long is to long? what size stall do you have and what rpm do you usually stall it to?

98Z28CobraKiller

iTrader: (17)

This is not an easy question and there is no right answer. Looking at your dyno sheet, I would run about a 4K-4.5K RPM stall. This will give you plenty of headroom on the 2 step in order to control launch RPM.

Here's the thing with a turbo and the 2 step. Your converter stall speed changes depending on boost. So as you start to stall it up, it will come up lazy and as the boost starts to come up, it will get up higher on the converter. The 2 step is what you use in order to set the launch point.

As far as how long to stay up on the 2 step, that depends on how long it takes to build the desired boost. Obviously you dont want to stay on it forever. You should be able to get off it within a few seconds. Here's my car getting up on the 2 step to 4K RPM with the stock LQ9 longblock. Once I am staged and you hear the motor reving, my foot is to the floor. You can hear how it takes me a couple seconds to get up on the 2 step and then a couple more to get to the desired 7-8 psi of boost.

The main thing that you want to make sure of is that you have a 900-1200 RPM shift extension between gears and that you dont exceed about 12% slip when going threw the traps.

http://www.youtube.com/watch?v=lskvR-0n06E

'Trust'

iTrader: (24)

^ you and I sir would be a good run.

black98ws6ta

iTrader: (77)

Does your car have transbrake?

Alot of the questions you are asking depend on the set-up and useage of the car. Ideally you want to spend as little time as possible staging the car, the lower the temps the better. Stall speed changes with power/boost level, and rpm will depend on the car/chassis/track/suspension/turbo.

4SFEDZ

iTrader: (6)

yes it has a t-brake, but i think the 3k is too low for my setup!

black98ws6ta

iTrader: (77)

The tighter the converter the better if u can spool it. If u have optimized the tune and it does not make a good launch psi within 5 seconds or so then it will need to be loosened.

sr71

iTrader: (17)

you need for the converter to be tight so that you don't blow through it when the boost comes up. my vette wouldn't go 2000 on the footbrake, but would easily go 5000 on the trans brake/2-step. if you want to launch at 4000, lock the transbrake and see how long it takes the engine to get to 4000. if the converter will stretch out far enough in 2-3 seconds you should be good. then you will just need a 2-step to hold it there.

also, when you start stretching converters out on the brake, you'd better have a darn good converter and a good trans cooler.

4SFEDZ

iTrader: (6)

i have a two step but havent used it yet, and i have a good cooler. but my question is how long it too long, whats max? 5 sec? i kinda makes me nervous staying on it too long.

black98ws6ta

iTrader: (77)

I would not try it much longer then that, unless you have a ton of time between to let it cool down.

98Z28CobraKiller

iTrader: (17)

Heat is definetly the enemy for the trans and the turbo.

98Z28CobraKiller

iTrader: (17)

I hurt the motor on that pass. Ran good to the 1/8 (6.32 @ 109.5 MPH). You can hear me let out before the light comes on. I put a rod out the side on the next pass......just to make sure. Now I am hunting for a new block that will get forged internals, nice cam and AFR225s which better run a 9.0 or better.

sr71

iTrader: (17)

I wouldn't stay full throttle on the brake for over 5 seconds but, you might be surprised how quickly it spins up when you load that turbo up hard against the brake.

set the 2-step at 4k and see how long it takes to bump it.