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What RPM to shift TH400

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Old 10-03-2010, 03:49 PM
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Default What RPM to shift TH400

I pulled her to 7500 on the dyno yesterday. I haven't finished hooking up the spray yet, so just a low compression NA motor for now. I've got 26" tires and 3.46 gears. Shifting at 7000 and it drops to 5300. Based on my dyno pull, where should I try shifting next time I go to the track?

Old 10-03-2010, 04:36 PM
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6700-6800
Old 10-03-2010, 06:51 PM
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The 1-2 shift you wont to shift a little early say 6700 6600 around there that is what ive been told by reputable racers.the 2-3 shift you wont to be right on on your shift so set the the tach at 6800 should be good to go.
Old 10-03-2010, 07:03 PM
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i'd go around 7200 if the bottom end can take it. it'll keep you in the curve a little better.
Old 10-03-2010, 07:11 PM
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Originally Posted by brandoz28
i'd go around 7200 if the bottom end can take it. it'll keep you in the curve a little better.
I built it to handle it. My rev limiter is set to 7700.
Old 10-03-2010, 07:28 PM
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id shift it at 7000 your just wasting the motor spining that thing to 7500
Old 10-06-2010, 08:11 AM
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Too much rpm drop. Appears engine doesn't have enuf steam at that hi rpm shift point..
Why worry about the shift points when you are going to change the entire dyno map w/ the spray??
Old 10-06-2010, 08:27 AM
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Experiment between 6500 and 7000. Anything past 7000 and you're just wasting your time. You want to shift at or near peak power, not after it.
Old 10-06-2010, 08:30 AM
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Originally Posted by Old Geezer
Too much rpm drop. Appears engine doesn't have enuf steam at that hi rpm shift point..
Why worry about the shift points when you are going to change the entire dyno map w/ the spray??
+1

Loosen that converter up. I was shifting at 6700-7200 and my old Neal Chance converter would fall back to 5300 and it felt DEAD on the track. It would only flash to 4700 though too.

I called BTE and got one for my setup and it flashes around 5400 and falls back to 6000. BIG DIFFERENCE

My 60fts went from 1.58's to 1.48s and my 300fts went from 4.57's to 4.40's.

So from 7.15-7.20's in the heat to low 6.90's in the heat.
Old 10-06-2010, 09:23 AM
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I wouldn't loosen up the converter until you see how it acts on the jug. I would shift at 6800-7000, just play with it some.
Old 10-06-2010, 12:31 PM
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If you plan on spraying it the converter is going to work awesome. Thats about what mine falls to on motor. If you are keeping to motor, loosen it up for sure.

Looking at the curve I think it might have a higher average powerband if you shift in the 7000-7200 range but that is just eyeballing it. Hard to tell. You are going to have to experiment.
Old 10-06-2010, 05:24 PM
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I'm hoping to finish the nitrous this month. In the meantime I will play around with the shift points when I go to the track next.
Old 10-06-2010, 06:36 PM
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Those cubes, that cam, that compression, that converter, and that gear... there's no way that combo is going to run well NA. How much do you plan on spraying this setup?

Shift it at 7100-7200 as it sits.
Old 10-07-2010, 02:15 AM
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Originally Posted by Wicked94Z
Those cubes, that cam, that compression, that converter, and that gear... there's no way that combo is going to run well NA. How much do you plan on spraying this setup?

Shift it at 7100-7200 as it sits.
I was surprised it went 12.8 at 108 on street tires with a 1.82 60ft and 4400ft DA. 4150 lb raceweight with me in it. Planning on a 250 shot. Going to start at 150 and work my way up. Hopefully in the next couple months I will have enough overtime to go FI.



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