What RPM to launch at with 3400 converter??
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TECH Junkie
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From: East Brady, Pa
What RPM to launch at with 3400 converter?? Looking for a little input as I'm new to the auto/turbo game. Car is a 408 wiht 91mm turbo, 4l80e and yank PY3400 converter. Car makes 650 to the wheels at 8lbs of boost on a mustang dyno. Power seems a hair low but I know the turbo is really inefficient at that low boost level. Took it to the track with the 2 step set at 3000 it launches like a dog. Just as it starts to pick up it loses momentum. 1.68 was the best 60' on a 10.85@129 pass. I know I need to leave on more boost but I'm not sure if it's a good idea to set the 2 step that close to the stall speed. A couple other ideas I have is to wrap the hot side and to stay on the 2 step/transbrake longer. Right now I'm not setting on the 2 step/tbrake very long at all. I tried to attach the video but it appears to be too big of a file.
I always leave at about 200 below the converters flash point. I like to hit it hard if the track will take it. I have a 4k stall and leave at 3800-3900 . It also takes me about 5 seconds to build to 13psi. And it took a lot of tuning work to get it there as it was only making 3 psi at first and wouldn't go any higher. Spark cut and fueling really helps if you are capable.
Ok what gearing in rear end? and how tall of tire? Whats this car weigh with you in the seat? Load helps yet with a heavier car, it need some help getting spooled up, yet should come alive quickly if the setup is good for your combination... hence gearing and weight...
Are you using race fuel or pump gas with meth? whats the goal with this setup and hoping you have E85 or Some high Octane fuel... hope you get this beast Rolling some MPH soon
Are you using race fuel or pump gas with meth? whats the goal with this setup and hoping you have E85 or Some high Octane fuel... hope you get this beast Rolling some MPH soon
How much power does this engine make NA? It may need more stall to make this a sweeter launcher, if the engine is a bit down on power it will add to the Boost Lag, hence running more compression for a responsive engine...
what are you using for tuning?
what are you using for tuning?
just keep going up with the 2 step until it leaves the way you like it. that converter is a 3400 but if you set the 2 step at 4000 it will get there once boost starts slipping the converter harder.
I have buddys that just let the turbo spool against the converter and use the 2 step to limit the boost leaving at like 12 psi. one guy has a 3600 stall and sets his 2 step at 4400 getting 12 psi boost launch. takes him almost 6 seconds to get there on the brake.
I have buddys that just let the turbo spool against the converter and use the 2 step to limit the boost leaving at like 12 psi. one guy has a 3600 stall and sets his 2 step at 4400 getting 12 psi boost launch. takes him almost 6 seconds to get there on the brake.
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Pretty much how I tuned my launch. I went up until the track couldn't hold it anymore and backed it down 100 RPM. My PY3400 started to hit pretty hard with the 2 step at 3200.
I recently bought a PTC Torque converter. Dusty knew I had a transbrake and a 2 step. He said to "set the 2 step at 3,000 and start tuning from there". I've tried 3,000 and 3,500. With the 3000 setting it would build 2 psi but real quick on the brake. I reset it to 3,500 and it builds closer to 4psi, again within 2 or 3 seconds. I left hard the first time I tried it at 3,500, getting a 1.5 sixty and 10.6 ET at just under 129mph using 17 PSI. I tried setting the 2 step at 4,000 but it just blew the 315 M/T drag radials off. It's set back to 3,500 right now.