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TH700R4 Horsepower Rating

Bross82

Bross82

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About how much horsepower do you think an old TH700R4 will take in an 85 Blazer? This I believe is the origional tranny, which the origional owner I bought it from 3-4 years ago said had it rebuilt. not sure when. The truck had about 120,000 when I bought it and 150,000 now. I had been planning on a while eventually adding a 454. But, if I want a new engine realistically soon (plus the 305 in it might be done), I have been looking at a new crate 350. I dont want to compromise too much on the power and wonder if its even worth it considering it I guess.
I was looking at one that did about 355hp and 405 torque.
what do you think of this?
http://www.gmpartsdepot.com/store/product2.aspx?SID=2&Product_ID=456
I'm already guessing that no, it won't be able to handle it. but i want to be able to drive it again soon...and not get a crappy engine to replace the old one with.

Thanks,
Matt
 
I have a '90 K5 and I'm about to rebuild my engine too. I would also be interested in knowing how much power a 700R4 can handle. I was going to try to hit at least 400 h.p. with my new engine.
 
Are you planning on keeping your tbi or switching to some other kind of injection system? That is a lot of horsepower for a tbi, what kind of work do you plan on doing?
 
as far as the engine and the tpi goes...isnt the engine linked to above just for a regular carb. engine? i just have a regular 305 with a carb...i believe tpi started a year or two after 85. i plan on staying with just a carb for now, and doing light to medium general wheelin... rocks, mud (anything in general).
so you think that is too much for a carb setup?

thanks
 
i don't know the max..but those are one of the stronger tranny's out there...it sat behind the corvette motor for years...i've also seen build up programs where built 700r-4s were mated to high horse 1/4 mile outlaws...reguardless, you will have to go through and upgrade or alteast overhaul what you currently have...the more hp, the faster warn parts will decide they've had enough!!!!!!!!!!!!
 
i think i pretty much expect that no matter what i get. thats been the case with everything else... upgrade one thing, something else goes...was just hopin some of the main stuff lasted a bit longer until i could get what i really wanted.
btw, i thought the th400 was supposed to be better and stronger, just not have the overdrive capability of the 700r4?
thanks
 
yes the th400 is stronger, the 700-r4 is about the same as a th350 strenght wise, it just had a OD, the 4l80e, and the 4l85e are as strong or stronger that a th-400 and they both have OD, but are alot more expinsive, and comp. crontrolled
 
When I asked about the tbi, I had replied to the other guy. TPI never came in a truck and tbi started in 87.

About the ZZ4, I think that it would be a great motor, to use. Although you could build one yourself and get more horsepower, be stronger and for cheaper, but that is not for everyone.

I have an 89 with a 700 and a strong running 350 with a few bolt-on mods with 180,000 miles and as far as I know it is the original transmission it and is fine still, pulling 39.5s on 4.56 gears, I have a big cooler and I am about to put a shift improver kit in it. I also have a nitrous system that is about halfway hooked up and when I finish getting it hooked up and I gonna spray a 100 shot on it, don't know if the tranny will hold up or not, but it has been fine so far. I was thinking about the 400 route too, but if you talking to many people you will see that many people have even blew up 400s, so I think that if the 700 goes out I will put in a 465 manual tranny. So much less to worry about.
 
How much power will a stock '85 high mileage 700r4 take you ask? Nothing more than a high mileage matching 350 will put to it. IF the transmission is somewhat fresh and was somewhat updated than you are in luck. You can pop in a shift kit and be able to support 300HP for quite a while. You might as well plan on building a th700R4 shortly after the motor because it won't last behind 355/405 for long. When I built my 406sbc I started saving for a built tranny right away because I figured it wouldn't last for long. I went about 3 months and could smell tranny after a long drive when I shut it off and jumped out. When the shop went through it a few weeks later they said the 3/4 clutches were burnt and it didn't have much life left.

To support 355HP you will need to be running at least the later 10 vein pump and the aftermarket 13 vein is supposed to be better. Extra clutches in the packs, bigger aftermarket sun gear, aftermarket blueprinted converter with a billet steel center hub(stock is cast) and late model rear planetaries and sprags. A corvette servo and/or shift kit should be also used to make sure the shifts stay tight. I have been running this setup behind my 325/400 406sbc for a couple years now without an issue and has endured lots of mud and drag racing since being installed.
 
Check out the transmissions that 700r4.com has to offer. Look like good deals. Especially the stage 3.
 
what do you think of this transmission to go with the motor then??

http://www.bowtieoverdrives.com/catalog/catalog_inc/viewitem.php?ITEMID=9

this transmission is probably $400-500 cheaper than the link in the post above, but not sure about the shipping cost here.

compared to what is installed in the one in the link above this post? is there any real reason for the price difference, is it any better?

thanks
 
say i was to run the Level 2 700R4 tranny from bowtie overdrives, what kind of convertor do you guys recommend? 6.2 turbo deisel, and a heavy right foot. 33 - 35 inch tires.
 
I can say I know from a fact that a level 3 BTO will work beautifuly with over 350/hp an more then 400 lbs tq

These 700R4 have really proven them self to me even when I did sled pulls and shifted it many times with the weight on me I couldent have asked for anything better
 
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