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TH400 robbing hp?

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Old 02-26-2009, 02:50 AM
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Question TH400 robbing hp?

ive heard th400s rob alot of hp on the dyno BUT its opposite at the track? about how much hp is loss with a 400? thanks.
Old 02-26-2009, 03:03 AM
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what do you want high dyno numbers or lower E.T.s?
Old 02-26-2009, 06:52 AM
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automatics and dyno's are never a good match-i think the converter stall is more of a problem than trans
what other trans are you trying to compare the 400 with-if its a lockup trans, then the lockup trans will show less loss, but do you race with the converter locked up?
if you dyno in lockup mode, make some big HP claims, then run it unlocked, the HP is not going to match the MPH
i have no idea what i just said, lol-i have run quicker times than some cars claiming over 100 RWHP than me, so whats dyno #'s mean anyway
if your using a 400 for strength, and dont care about o/d, i wouldnt worry to much about any small hp diff-a broken trans doesnt get you far
the converter has to match your engine/drivetrain setup, thats where you put the power to the road
Old 02-26-2009, 08:46 AM
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On a 383 that was making 500 thru a 6 speed, it dynoed 430..... so yea, it lost some power, it had a 4kish stall
Old 02-26-2009, 08:56 AM
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The slip from the stall throws the numbers off. The 400 was rumored to lose 42HP on its own, the 350 28HP and the PG 18HP. This goes back to the 70's info. It would be nice to guage them all and know for sure. Maybe a "Clutch Turbo vs Stick", direct drive on the dyno. No High Stall Converter.
Old 02-26-2009, 09:17 AM
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That would be a sweet review. I would even provide a Direct Drive converter if any shop wants to do the labor and dyno tests. Of course you still need some transmissions.

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Old 02-26-2009, 09:20 AM
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All I know it that when it comes to and auto, DYNO # mean nothing and are only usefull for tuning.
But at the track well there the lower # auto is generally the winner. When it comes to Autos use the dyno for tuning and the track to say whos faster.
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Old 02-26-2009, 09:25 AM
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i made 500 rwhp with my M6 ...i just did a TH400 swap with a 9in converter w/5200 stall and put down 461 so i know the thing will rip but like said autos are not dyno kings

Last edited by ndfrsd6; 02-26-2009 at 09:34 AM.
Old 02-26-2009, 09:33 AM
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^^^and that was through an unlocked converter ...
Old 02-26-2009, 10:23 AM
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thanks for the info and the relief guys, i recently picked up a complete th400 setup and will be using it on a 347 nitrous combo. id like to get it tuned N/A first and make a few N/A passes before introducing my newbe self to a progressive 200shot...

now the combo came with a fuddle 3600 and wonder if itll be sufficient enough with my cam: 249/254? i was thinking of keeping the fuddle for the n20 setup and getting a 5k stall for the N/A fun? also is a proper stall necessary for a dyno tune?

but yes ET is more important to me than dyno numbers.
Old 02-26-2009, 12:51 PM
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With my old 6 speed in the GTO I would trap 115. With the new TH400 I'm trapping 1 sec faster on ET and 114.3mph on street tires. I would say I didn't loose much. But I haven't been to the dyno, nor do I really care to go. My old numbers through the six speed are in my sig. I had Greg at FTI build my converter for 4000rpm stall at it's NA power and then when I hit it with 200-250 it will stall between 700-1000rpm higher.



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