max hp ratings

[wideblock]

what do you guys think is the max hp you could put thru an 8.75 rear without turning it into a twisty straw? same goes for the np435???

[MountainMoparRobin]

Well I've seen 750 hp in a challenger on tv, the prostock cars are running somewhere 800-1000 hp, so somewhere around 1300 ponies.

[Hobcobble]

Think of all the ponies that went through those 340, 360, 383, 426MW &
440 engines to an 8.75 with a smaller pinion on the muscle cars.... not to
mention those who performed mods to get more HP. If you're running
a mild to wild Poly, the set up you have will work just fine.... although
ANYTHING can be overworked. Your A318/NP435/8.75 combination, with
new u-joints, carrier bearing, etc. should do you justice, provided all the
internals are in good working order. Like any piece of machinery though,
the harder it is pounded, the sooner you find out its shortcomings. As far
as an actual HP at which things will break.... too many variables to look
at if you ask me. As far as an educated guess.... at least 400HP??
John

[cowboy]

Trey, John is right & you also know that anything that will go wrong will , when it cones to all those ponies running loose :roll: I have seen some of the best people build car's /Trucks make a couple of run's & all seem's well then boom something come's loose , it's the law of nature , I'll say on the horse power between 400- 600 , as thats the best I've ever done & the 8.75 held it real good :roll:
8)

[MowagW200]

Hello

I think not the horse power is the point, but the torque. The force to the gear or the rear end is not the same if the engine puts 400 HP at 4000rpm :roll: or 400 HP at 6500 rpm :twisted: . So the stress is a lot bigger on a engine that puts 400 HP at 4000 rpm. So for my the question is what's the biggest torque.
Do you have an idea, how s about a NP420? Is it smaller than a NP435?
Thanks,

[MountainMoparRobin]

Well the 8 3/4 re-end is the rear end of choice all the way up to the Pro Stock division and they put out a lot of torque, for that is what wins the race! you would have to build a monster of a torquer to twist a 8 3/4 re-end, its the top re-end except for the ford 9". Seriously I'd be more worried about the carrier bearing, I haven't seen any serious horsepower put through one, thats where horse power would be lost, I don't know though I haven't owned anything with the carrier.

[wideblock]

you pointed out one fo my concerns robin. big torque up front, good grip out back....what are the chances of the shaft just ripping out of the center? that much torque on the drive shaft has got to play havoc with the carrier bearing. another concern i had, if the drive train, trans mainly, is designed around a stock red line of 4000rpm, whats gonna happen when you put 6500rpm thru it?

[MowagW200]

What happens in the gear box I don't know, when the red lined speed changes from 4000 to 6500. But for sure, I think the drive shaft could start with hard vibrations. Mainly in the top gear, because the drive shaft is at the fastest speed. I would check the balance of the drive shaft. I don't know, what happens with the 8 3/4-rear end. But as far as it's used in stock cars or tuned big sedans (as described earlier on), it should work with no problems.
At higher speeds not only wheels begins to rattle, drive shafts, too.
Kind regards

[MountainMoparRobin]

Trey
as mowag points out definetly, definetly have the drive shaft balanced!!! The stock drive shaft (one piece) that came on my truck from the factory is a overkill and can handle torque beyond what I'm building from the street, as mentioned earlier also all the Muscle cars came with the small yoke in the rear end and that would be considered the weak link, however you have seen what Brian Deeds runs 12's consistanly for you even put a picture of him doing a burn out on the calendar, while running his warm ups, I know he pushing a few more ponies than I and for the last 2 years he hasn't had not even a mention of problems, before camming my engine higher, I entertained any fords and chitty's that was brave (even spotted some) and the only problem I had was the traction for I couldn't nail it coming out of the hole, but now, with the tank moved to the rear and some improvements in the springs hopefully that will be taken care of, won't know until I get it here and take it out for one of the cruiz nights! but I don know that Brains tractionsetup has done justice to his truck!

[Hobcobble]

MOWAG,
You're correct on torque but HP is essential in its calculation.. meaning
they're both applicable.
In answer to your question regarding the NP420... it was the pre-cursor
to the NP435.... very similar ratios but only synchro-ed between 3rd & 4th.
Hope this helps.
John

[Hobcobble]

And.... the NP420 is comparable in weight.... a bit heavier if you factor
in the in-line e-brake.... which the majority of them had.
John