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Max HP without breaking things?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BranndonC, Nov 19, 2002.

  1. BranndonC

    BranndonC 3/4 ton status

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    what is the max horsepower a 700R4 can handle safely? and what other componants will suffer from say 400+ horse power? or 450+ torque?
     
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

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    I've used a 700 HP 454 with a stock 700R4 and 10 bolts with 2.73 gears before while running 38" tires. /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif





































































































    Nah...I'm just yanking your chain!! /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/thumb.gif
     
  3. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Built with the right parts, the 700R4 will handle what you describe. But IMO that seems like the limit. I know the Raptor aka (Craptor) is said to handle like 600 ft/lbs but has a very shady way of doing business.

    I do run that kind of power and more , I'd go t-400 or 4L-80E if you can afford it. I personally run T-400's. Virtuallly bulletproof when built right.

    Just my .02,
    John /forums/images/graemlins/pimp1.gif
     
  4. BranndonC

    BranndonC 3/4 ton status

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    how much do you think a stock 700r4 can take?
     
  5. RedDwarf

    RedDwarf 1/2 ton status

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    Why don't you find out?

    Leave your 700 stock and keep adding K&N filters until it tears up.

    Be sure and let us know what the magic number is
     
  6. fortcollinsram

    fortcollinsram 1/2 ton status

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    it can barely handle a stock TBI 350 (210 HP) with a lift and 35's...id sasy with stock (say 3.73) gears, 31's, it may be capable of dealing with 300 hp..I have a friend who has a C5 with a ZZ4 crate and a stock 700 ant is is doing will, but that is with 3.73's and like a 40-series tire...

    Chris
     
  7. wrathORC

    wrathORC 1/2 ton status

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    I've read that a stock 700R4 can handle 425HP and 400ftlbs of torque but that was on a car. Tire size and mass are completely different. It was also for the 88-91 version of the transmission. The earlier ones, and especially the first version, were a lot more weak. I'd say no more than 350/350 for the first version (82-84 if I remember correctly).

    I have an 84 with 78,000 miles. I bought the truck with 64k on it. I've beat on it pretty good in the last year. I have ~230hp, 2.73s, and 33" rubber. All I've done is change the transmission filter. The previous owner abused it, it'd never been serviced and it had 3 pints too much fluid in it. Probably the only thing that saved it was the giant transmission cooler. It's been good to me so far.

    However, if I were pushing 400 horses I'd have another 700R4 waiting to go in. You can beef a 700 pretty easy. You can buy new planetary gearsets, kevlar frictions/bands, and a Corvette servo. Those three things are the weakest parts on the transmission. I've only seen/experienced 3/4 clutchpacks smoking and planetaries grenading. A good set of frictions can be found in a rebuild kit or bought separately. Front and rear planetaries will cost you ~$225. I'd avoid shift kits. The 700R4 appreciates soft, squishy shifts as opposed to bone-jarring TH400 shifts. The key is to be soft yet not slip excessively.


    Heat kills 700R4s. Usually what kills them is people running in overdrive and the torque converter locking and unlocking. They rely on the torque converter locking to keep heat at bay. Compound that with the fact that most of these people will let their transmission shift in and out of third gear constantly and the transmission really cries. If the torque converter unlocks or the transmission downshifts more than once every five miles it's time to put it in third gear.

    I'm planning on finding me a good used later model 700R4--probably from the late eighties. I've got several TH350s but those don't hack it. I'll stick some stuff in it so I don't have to worry about it breaking.
     
  8. BranndonC

    BranndonC 3/4 ton status

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    well i'm getting 4.56's and looking for maybe a 383 stroker next year and wanted to limit my Hp and torque. So i'll maybe get something like this.
     
  9. Pookster

    Pookster 1/2 ton status

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    So then is it safe to assume that as long as you dont drop out of overdrive at all, that your tranny is relatively safe?

    I have a stock 350, 3.73's and have tried 31's and 33",s and on the highway, it never comes out of overdrive. Well, except when I add a lot of gas to pass. /forums/images/graemlins/smile.gif
     
  10. zcarczar

    zcarczar 1/2 ton status

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    I would think it would be OK if it down shifts to passing gear when you give it some gas, but I think what kills any tranny is when you keep the tranny busy by shifting in and out of OD and the torque convertor keeps locking and unlocking.

    Brandon, Why not get this 383 you'll need the new intake but everything from your current engine will bolt on over, and just get a nice little chip for the computer and you will be good to go. /forums/images/graemlins/thumb.gif
     
  11. BranndonC

    BranndonC 3/4 ton status

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  12. morphed86k10

    morphed86k10 1/2 ton status

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    Unless you're getting a high stall converter and run only in sand or mud, I wouldn't want that 383 anyway.
     
  13. VisionxOrb

    VisionxOrb 1/2 ton status

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  14. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    As I recall, my Gm performance parts catalog... They had a "beefed" 700R4 for use in police cars. GM's max input torque rating was 380ft/lbs. I think you may be pushing your luck with much more than that in heavy truck.
    With that said, I have a friend that runs a 700R4 in a blazer with a ZZ4 crate motor. (355HP/405TQ) He went through 3 trannies until he built it right. He now has no problems with it. He even tows about 6000lbs with it occaisionally. And he is not an easy on the "go pedal" driver.

    Hope it helps,
    John
     
  15. 84k5

    84k5 1/2 ton status

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    How are you going to use one of those engines and pass CA emissions??? /forums/images/graemlins/confused.gif My 305 will die one day and it seems like they're aren't too many options in the motor swap department. Or are you going to just drive it offroad?
     
  16. wrathORC

    wrathORC 1/2 ton status

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    Yeap, she's about as safe as you can get.

    My truck will barely hold 60mph in overdrive with 2.73s and 31" rubber. With my 33s I don't even try overdrive.

    So, you like your 3.73s? I'm planning on either going with 3.73 or 4.11 axles. I'm going to go do some junkyard scrounging either tomorrow or Friday here in the U.P. and if I don't find anything then I'll be junkyard hunting when I'm downstate.
     
  17. Pookster

    Pookster 1/2 ton status

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    I like the 3.73's. with the 35's and 3.73, it gets a little bit slower, but overall, they are ok. I still dont have a problem with it dropping out of overdrive. If you find 4.11's I'd use those. I check my fluid often, and it doesnt seem the least bit burnt. Maybe the highway speeds keep the tranny cooler cool. /forums/images/graemlins/pimp1.gif
     
  18. wrathORC

    wrathORC 1/2 ton status

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    Is it as bad with 35s and 3.73s as it is with 33s and 2.73s? The biggest I'll ever go with this truck is 35s. I plan on going 4" upward and 35s will fit with some moderate trimming I'm told. 35s are as big as I want to go for a on-highway vehicle.

    If it wasn't for the fact that I run 235x75r15 snow tires in the winter I'd definitely find 4.56s since we can get away with it with our overdrive transmissions. However, my snow tires and 4.11s would be wound pretty tight and 4.56s would be excrutiating on the expressway.
     
  19. ratlover

    ratlover 1/2 ton status

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    Well I nuked my 700 with my pathetic 305 right after I put the 32's on it /forums/images/graemlins/crazy.gif I'm running 342 gears BTW and was cruising on the highway at 65 70 when I started smoking the 2-4 band. My truck was not hunting between gears(actually didnt down shift at all) and the converter was locked the entire time. This was because of a couple of things. First because of that squishy cady like shift. This kind of shift builds heat and wears out the clutches. This is bad for the tranny and starts the nuking process. Now we run into the problem of driving with a heavy load(or just moving my POS down the highway in my case) like towing in OD. The extra load is more than the bands can hold and the transmission it self starts sliping a bit, not much at firts but as you keep going it starts to nuke the band a bit more and build more heat so it slips more and it becomes a very vicious cycle. The only way you can remidy that is by applying more holding power to the band. This is done with the vette(or aftermaket) servo, better pump design(early models sucked) and you can rasie the line pressure a bit.

    A shift kit will cause less delay between shifts so your tranny slips the clutches less and that creates less heat(one of the biggest killers of trannys) and extends the life of the clutches. <font color="green"> [begin rant] </font color> There is a difference between a good shift kit and a junk one. The junk ones are more "cosmetic" I would say. People think that performance=banging the gears hard and tire chirping shifts even at low throttle with a worn out 305 turning it. People think this is how a "performance" trany should shift so some manufactures give the customer what they think they want. Ever notice what a B&amp;M stage 2 will do? They yank the fawking accumulators /forums/images/graemlins/crazy.gif Thats f-ing brilliant /forums/images/graemlins/rolleyes.gif But it makes it shift like how people "think" a tranny should shift......ahhhhh <font color="green"> [/end rant] </font color> A good shift kit will provide a shift you can feel(unlike the stupid caddy shift from the general) at low throttle applications but as you give it more throttle it will shift more firm. A good shift kit from the likes of transgo or other good co.s will vary the line pressure(how much pressure is applied to the bands and how firm it shifts and such) depending on the throttle position and load of the motor. There is a novel approch /forums/images/graemlins/eek.gif, make a transmission shift just firm enough to get the job done and limit heat build up and slipping of the clutches and not be hard on the other parts as well as your teeth.

    A transmission that is hunting for gears will build up more heat than one staying in a certian gear.

    Heat is one of the bigest killers of trannys. Put the biggest cooler you can on your rig. 350's and 400's cant really be over cooled, the OD's and newer tranys are a bit more particular. Depending on your climate and what you are running and all that jive depends on if you should run a big honking cooler by itself or with the stock through the radiator cooler.

    Edit: I nerver really answered you Q. I would say with 450 foot#'s she will go south in a hurry unless its in a nova or a go cart or otherwise light vehicle. One could be made to handle it but stock is just asking for trouble. Theres my .02$
     
  20. imiceman44

    imiceman44 1 ton status

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    35 on 3.73 is like 26 on 2.73, so if you consider the drag and weight of the 35 and add it, it would be like 2.73 and a 28 inch.
    /forums/images/graemlins/thumb.gif
     

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