Too much power??

[Speedracer800]

So looking for opinions. Going to be building a new 351w for my baby. It's a freshly restored, totally used on the street Bronco. Mild lift, front and rear sway bars and very good Street manners.

Thinking about going a little nuts with a stroker kit, cnc ported aluminum heads, etc. Probably winding up around 450-500hp with torque numbers a bit higher than that.

Got some buddies that think it's just too much power for the drive train I have. Stock rebuilt Ford 3-speed, stock 9" with 4.56 gears. What do you guys think? Am I going way over board? I could save a couple grand and delete the stroker and use a ported cast iron head and would still have a very healthy 300hp.

Thanks for any feedback. Anyone out there running with some big power?? The fact that I'm even second guessing myself here is making me reflect on my old age because the me from 20 years ago would be putting a blower on the top.. Just incase. LOL.

 

[thorgan]

When I first put together my 427 Windsor my '69 only had a 3.5" Wild Horses lift, Dana 44 front, 9" rear, lockers at both ends, uncut fenders, NP435 with the stock Dana 20, power steering, 4.11 gears, no sway bars and 33x9.50 BFG's on stock steel wheels. I friggin LOVED it...and still do.

Was sitting at an intersection waiting to turn left across 2 lanes of oncoming cars when I suddenly got some smack talk from a passenger in the back seat about missing a few holes in traffic. So I romped on it! We got a lot of torque roll and, once across the intersection, I lifted a little and we all felt a little bump with a slight chirp as the left front wheel set back on the ground! I have 3 witnesses.

My only concern would be the 3 speed. Don't know how strong those are. I had 31 spline axles in the my 9" and never had a problem.

Go big and never look back!

 

[NYLES]

JW runs a 393.........

 

[JWMcCrary]

JW runs a 393.........

I did that before ever taking mine offroad. If I had it to do over again it would still have the stock 302. Absolutely nothing wrong with the 393, it's just a lot of money for something that doesn't add much to rock crawling, at least from my experience.

 

[Apogee]

It's all really about how you drive and whether you ever actually hook up and put the power to the ground. High-torque stroker motors are great for snapping axle shafts off-road...bump the throttle while you're wedged in a hole somewhere and somethings gotta give. That said, so long as you're okay upgrading the parts that can pass muster, I say go for it.

I had a friend in high school who had a Scout with a Chevy drivetrain, built small block 400, TH400 and full time NP203 transfer case. He was showing off one day doing 4-wheel burnouts through an intersection until both driveshafts simultaneously exited the vehicle...once the rear let go, it was just too much for the front to handle, so it bailed as well. You do what you gotta do.

 

[Speedracer800]

I never take this thing off road so I'm not worried about that. I'm not gonna be abusing the hell out of it but I'll definitely be getting on the throttle and dropping the clutch from time to time. The 3 speed is my concern too as I've never even put the truck in 4wd yet. Should my 74 have come stock with 31 spline axles?

 

[ep67bro]

Nope stock bronco axles were 28 spline. With that much power you will have axle hop, snap axle shafts and blow out u joints if everything is stock. I would say upgraded axle shafts and a anti warp bar would be a must with the numbers you are talking about.
And as for the 3 speed well that's a big ? I don't know anyone that has ran a motor with close to that much power behind a stock 3 speed.

 

[Apogee]

I've romped on my 3-speed behind a 351W for many years and it's never complained, it's still the same'ol loose pile it's always been. I do like how quick it shifts with the floor shifter, makes it really fun to drive on the road.

I've always been more concerned with the D20 output shaft than the 3-speed, but have no quantitative information supporting which might be the weaker link.

Right now, I think most people would agree that the weakest link would be the 28-spline axles. Get some 31-spline axles (35-spline might be better suited) and something to control wrap as noted above and see what goes boom.

 

[DJs74]

For what it's worth, I recently had a discussion with Phil (aka Viperwolf) regarding horsepower with a C4 instead of a 3 speed (I know probably apples and oranges but anyway...) and he advised that a well built, fresh C4 could take 400 HP, above that would require upgrades to clutches, shafts, bands, etc.
So, if a correlation can be made between the 3 speed and C4... I'd say transmission and axle upgrades would be advisable with the suggested HP referenced. One thing is for sure though, it'll let you know quick fast and in a hurry what the weak link is if any and then youll know.

Good luck

DJs74

 

[Whoaa]

A healthy engine is nice, but only one aspect of a well-rounded machine. I think you'll be disappointed w/ the stock 3 speed when you upgrade the engine...and then when you break it, you'll for sure be ready for a 5 speed transmission upgrade.

In real world numbers, the stock engines made in the neighborhood of 200/210 hp and about the same torque and we're pretty peppy.
A stout engine making an honest 300 hp, and around 260-270 ft. lbs of torque will make these old Bronco's dam snappy!

With a few variables, the complete transmission upgrade will cost around $3k, and for about $5k you can have a darn nice 300hp motor. Or choose to spend about $8-14k on a stroker motor, and then more, more, more...

 

[nvrstuk]

I'm running a very healthy 418 stroker and have had multifple drivetrain combinations...
things that will break first in 2 WD

- 28 spline axles...I used to eat these every couple months with my HP289
-rear pinions on the 9" because of axle wrap
-D20 output shafts

maybe the 3 speed when you literally dump the clutch with both rear wheels locked..they can take a LOT of abuse!

GO with the stroker...you'll love it..we only live once and you'll always wish you built it.

I drive mine on the street all the time and hopefully will be in Moab again in a couple weeks... IF you ever do snow or sand you'll never go back...

 

[Speedracer800]

Thanks for all the feedback. I've been kicking around the Nv3550 for sometime too and it's definitely on the list. What's been keeping me in the 3 speed is I kinda like the feel of the old school trans. Plus it's nice to just put it in second gear and go most of the time around town. That second gear has a nice range with my tire/gear combo. I just don't want to lose the "feel" of my bad boy by going to a modern transmission. I get very hot and cold about the trans. But I'm certain about wanting more power. I wouldn't have a problem throwing in some 35spline axles and maybe even the 1350 series yolk and u joints as well. The thing is this truck is a 3000 mile per year toy and NEVER gets pounded off road. I can feel the eye rolling that's going on by the purists out there but my off road days are behind me and this thing sees more car shows and trips with my girlfriend and our dog to the ice cream place then anything else.. But just the same I won't build a freakin poser.

Does anyone offer a slick (bolt on) anti wrap up kit for the rear end? Thanks again for the help.

 

[TheGanzman]

FWIW, I think you'd be "unhappy" w/the NV3550 in that application. It's big, it's cumbersome, and it ain't exactly a powershifter's dream. If you decide to upgrade from the stock 3 speed, I'd look at a Ford Top Loader 4 speed - BULLETPROOF, compact, and you have a wide choice of gearing options, including a 4th gear Overdrive...

If you're set on a 5 speed, look at a New-In-The-Box AX-15. I know I'm gonna get some heat about this suggestion from the "haters" that THINK they know it all about that transmission, but the latest ones can handle 400HP & 400 ft/lbs. of torque...

On edit: Wild Horses offers an "anti-wrap" panhard bar - the bracket for one end gets welded to the top of your 9", and the other end gets welded to a frame crossmember. I've got one sitting in the garage waiting for me to get off my dead azz and glue it up...

 

[Speedracer800]

Actually a top loader was my first choice but I wanted the over drive that the 5 speed offers. Had no idea that the top loader could be set up like that.. I'd definitely do that over the nv3550. I've gotta look into that for sure.. Way less money too. Thanks for the tip!

I need a bolt on anti wrap up kit because my frame and rear end housing is all done and powder coated. I guess if I had to weld on the rear end and refinish it, that wouldn't be a big deal but definitely not the frame. I'll have to look around and see about the different options out there. Thanks again.

 

[Bickster]

I built a warmed up 351w (ported iron heads, performer intake, RV cam, and WH headers) in mine. 1.5" BL to clear it and a ZF 5-speed. If you "need" more power than that I question your sanity. Mine has a 5.5 CAGE suspension so it is not as road worthy as yours. It can scare the pee out of me pretty quick. That said... If I could put a 393 or 409 of 427 in it my inner 12 year old would jump on it.

It is plenty with 4:11 gears and 35" tires.

 

[Whoaa]

Does anyone offer a slick (bolt on) anti wrap up kit for the rear end? Thanks again for the help.

^...yes! One good option is to cut-off the stock perch's, weld some larger leaf spring pads to the rear housing, use some high quality springs & U bolts, and then the WH anti-wrap bar

 

[Speedracer800]

Is that a bolt on cross member then? No welding to the frame?

 

[Whoaa]

Weld to frame

 

[sykanr0ng]

The NV3550 is only rated for 300 ft/lbs.

You are even more likely to break it with your planned engine than the stock 3 speed.

 

[lonesouth]

Ask Bax about the lifespan of transmissions behind big number engines.

I would think you'd want an NV4500 if you want it to live, but then it is not going to shift very quickly. If it were me, I'd run the stock trans as long as it lives, pick up another to toss in if the first one dies, and figure out the next trans at that time.