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Discussion Starter · #1 ·
Does anyone know what the actual power consumption is for the TH350,TH400,TH700R4 and the Torqueflite 727?
if my memory serves me correctly the 700 consumed the least amount of power followed by the 350,727 and the power hungry 400 but i cant remember actual figures.
Anyone ?

CJJ
 
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Discussion Starter · #2 ·
I don't know the actual #'s either, but it would make sense for the 700 to lead the pack you listed thanks to it's lockup convertor. The power "consumption" will actually change dramatically depending on how loose(or tight) a convertor you choose to run. The looser the convertor (higher stall) the more slippage at low rpm, therefore more apparent power consumption. The "lost"power is basically just being wasted heating (overheating most likely) trans fluid.

"My other car is a BULLDOZER"
 

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Just something to think about, but I've seen at least a few people on the Chevy board talkin' about the TH700R4 constantly needing rebuilds or something like that... Might also check over there and ask for opinions on what tranny they may recommend... Also, the guys over there may know the power consumption numbers are too... Hope that helps...

Tim
"The_Sandman_454"

/wwwthreads_images/icons/cool.gif '79 Suburban 4x4 454, 6" lift, 35x12.5s & '85 GMC S15 4x4
 

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/wwwthreads_images/icons/tongue.gif You also need to keep in mind that thr factory didn't put torque converter lockup in transmissions as a special favor to you.....it was to get by with LESS torque converter and get the fuel mileage up a little. By locking up, the torque converter is outa the loop, and doesn't get hot, EXCEPT if you are on a hard pull, and then there is little or no reserve. They can cook easy on a long hard pull where the lockup is de-activated./wwwthreads_images/icons/crazy.gif We have a TH400 in the SNOJEEP, and overall I am glad that we do. It isn't going to break just when we need it in the coming "times" in the Clintonoid US of A. We are trying to build a Jeep that will keep going no matter what, and has all dirt-common parts like a GM HEI and a Delco alternator.....well, you get the idea./wwwthreads_images/icons/crazy.gif

CJDave
 

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TF727s where available with lock up converters too, but Im guessing its still not as effecient as a Th700R4

You can get a switch-pitch converter for a Th400 which allos you to select lo or High stall on the move, pretty slick!!

I know Th350s are availble with a lock up too,

Im not really sure if all lock up trannys are pretty much equal or not, I guess it would depend on the power required to drive the pump in teh tranny, and the frictional loss thru the planetaries..

Id guess ( from turning one by hand) several HP in high gear with the converter locked up...



ozarkjeep
1977 CJ5 looking for T18a and hardtop!
 

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Forget the power loss , thats nickle and dime(we're not running quater mile times) The thing to think about is "how wil it hold up & $ to fix when it breaks".
I don't like the 700r4 ,unless I'm selling them....big money.
Without $$$$$$$$ in rebuild AND mods they don't last. BTW they get about $1500 to $1800 in my area for a standard 2wd rebuild/wwwthreads_images/icons/frown.gif
A monkey/wwwthreads_images/icons/tongue.gif(like me) can rebuild a 350/400 for a $100 kit.
I'll Stick w/ what I can afford & I can fix.(my cj7's got a crappy t5/wwwthreads_images/icons/frown.gif thats going to puke one day)

85'CJ7 258 4" runnin33's
 

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You seem to be forgeting that power loss (horsepower) through a torque converter, is gained in the torque multiplication. (torque) On the street, is is a disadvantage, but on the trails, it is an advantage! Think of it as lowering your rear end ratio, you cannot multiply horsepower, but you can multiply torque.

 
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Discussion Starter · #8 ·
I am with Dirt Dog. The 700 in stock form is weak and like he says expensive to boot. The only real advantage of the 700 is the overdrive. My brother had a S-10 Blazer. I want to say it was an '87 but am not sure. But it had a freshly rebuilt 700 and it blew up in under 20,000 miles (yes he had the reciets to prove it) The guys at the tranny shop said "those trannies are made out of plastic" and advised us to get a later model unit that was a little better but not much.

Scott C

 

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I beleive it was 1988 when the good TH700R4s came out, they can be built into a really strong tranny..

Overdrive is ONE of the benefits, a frist gear that is lower than most other auto trannys is another

ozarkjeep
1977 CJ5 looking for a Hard top near NW Arkansas!
 

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/wwwthreads_images/icons/tongue.gif We are running a TH400 behind the 304 in our CJ7 with Quadra-Sno drive. Because we aren't using the planetary Low-Range unit on the transfer case, we must depend on the torque converter to do all the work when the Jeep must pull through hard stuff at slow speed. In those instances, a TH400 is really the box to have. The low range planetary is nice to have, but there is so much slack in the drive train as it is that we hate to add more./wwwthreads_images/icons/crazy.gif

CJDave
 
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Discussion Starter · #11 ·
OH BOY! Thanks for all the input but I dont need help in selecting the tranny,just wanted to find out the Internal(forget the converter) HP loses of the tranys.
FYI.
I am currently running a CJ-8/modified 401/TH400/Dana 300,and am currently building a CJ-8/Highly modified 401/727/AtlasII


CJJ
 

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I think what you're asking is the hp drain to run the trans .........which I believe is around 5-10 hp in crescent pump and related resistance.

GeeAea

 

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a friend that races sez the th400 eats up 30-40 hp...thats why most folks build th350's for racing.. i think they are just cheap...hard to say for sure.. but the th400 is the only tranny i couldn't break in my cj....

 

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Look at the SAE net hp for a stick vs. auto for the respective trans engine combos.......it's nowhere near 30-40hp.....but in a race situation ........with a jumbo converter......maybe .......the smaller the converter the more hp is transmitted.

GeeAea

 
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