Let's discuss 500 ft-lbs of torque...

[243]

I am posting this in response to a member stating that a 401, after balancing will pull 500 ft-lbs at less than 3500 rpm. I am not using his example to dispute what he said, only to discuss 500 ft-lbs of torque.

I have only driven one vehicle with close to 500 ft-lbs of torque. My 99 Dodge diesel dynoed 282 hp and 492 ft-lbs to the ground and the truck weighed 6,680 lbs. The rest of the powertrain included a D60 front diff, a D80/D70 hybrid rear diff, NV4500 trans and a NV241HD xfer case. I towed Blue approximately 600 miles at between 60-80 mph with out a problem. I rarely drove 80 mph for any length of time, normally to pass other vehicles out in West Texas. GCVW was approximately 11,980 lbs.
In comparison, Ford advertises the Lighting as 4,670 lbs with 380 hp at 4,750 rpm and 450 lb-ft tq at 3,250 rpm. Very similar in weight to an FSJ and below the magical 500 ft-lb mark.

Is it safe to assume that a Jeep would have to have major upgrades in the drivetrain to handle an engine putting out 500 ft-lbs?

Is it a waste of money to build a high dollar, high torque motor if the rest of the drivetrain will remain close to stock?

What are 99.5% of IFSJ owners going to build their Jeeps for?

Will you need or want 500 ft-lbs?

If not, how much?

[ December 28, 2002, 11:22 AM: Message edited by: 243 ]

[FSJeeper]

Once you go diesel, you never go back. I recently towed a surplus 1980 AM715 military Jeep service truck and the drivetrain/axles out of CUCV trucks. I figure about 12,000 lbs worth. I have a 2001 Dodge HO Cummins with the 6 speed. The torque that engine cranks out makes towing a pleasure. That torque eats up hills and makes passing a breeze with that kind of load. Thats why you need 500 ft lbs.

In a FSJ you would have to literally modify everything to handle that kind of torque which is what I have done. If you want to play with big torque, you have to pay. Whether or not I actually will use the 500 + ft lbs my FSJ has is yet to be seen, but I figure I can crawl up anything at 1900 rpms all day long without even straining the engine. At the end of the day, gearing is the key to four wheeling and massive HP and torque numbers are more for fun than necessity.

[WillyPete]

bragging rights!

of course, until i can afford all those cool 1.5" axleshafts and beefy engines, i'm stuck using a near-stock 360 and drivetrain

i keep fantasizing about building a 454 for over 500 ft lbs and 350+ hp. that could just be a pipe dream tho

[243]

FSJeeper~

Are you a member of TDR?

[Stuka]

I dont see a FSJ *needing* 500ft pounds for anything. Our 77 ford F150 trailor special with a factory 460/C6/9in has had the engine modded a bit, to pump out 480ft pounds, and it screams up hills with a big load. Never had ANY trouble with power in it. But then its a full size truck that hauls and such.

For a wag/chero..they dont need this. A J20 on the other hand, I would love to build up a 401 to have 450+ ft pounds. Which wouldent be to tuff to do NA, but would be much easier if you slapped a SC on it. The AMX SS with a 390 had 445ft pounds of torque NA, with stock cam. They just upped the compression to 12.5:1, ported the heads, and put a cross ram intake on it (it had 385hp). That engine I feel would work well for a jeep, as it has stock cam, so its not gona have a lopy idle. Has more then enough torque and HP for most things a FSJ would ever do.

My jeep does ok at towing, except for the tranny. The gears are to spread apart to be great at towing. It does slow stuff fine, but going up some hillls here it doesnt like because i get stuck between gears 3rd is to low, 4th is to high. But is fine on the flats.

But a J20, yes that would be a great candidate for a tow rig. Put either a diesel or a nice 401, and it would do well.

[heydave]

What is an Olds 350 diesel rated at? I may be getting one of these cheap and it is already in a 78 J-ten.
Would this be alright with 3.73 gears for a daily driver. I don't tow so it would just have the weight of the truck to move.Any thoughts?

[FSJeeper]

Nope, not a member of TDR, guess I should be.

WillyPete, those 1.5" 32 spline shafts are a necessity with big torque. I have been warned by the guy that makes the doublers that with the torque my engine makes at low rpms, and the 110 to 1 crawl ratio I have, I am probably going to have breakage problems with my front Dana 60 unless I really be careful. I upgraded the entire with all brand new parts, detroit locker, 35 spline custom shafts, Forged steering jounts, etc, etc. About $1800 worth in parts. I am probably going to toast the lockouts for sure and have to go with drive plates instead.

I also had to go with a 32 spline transmission, 32 spline NP203 gear reduction box, and 32 spline all the way out NP205. These are hard to find and not cheap but with all that extra troque, I can't take a chance with anything less. The shafts will have 1410's on them also.

For the average guy all of this time and money to upgrade a FSJ to handle big torque and HP is a total waste of time. A stock FSJ is quite capable and most FSJeepers should focus on keeping their jeeps in perfect condition rather than build big HP and torque and exceeding its strength limits and creating breakage. Unless you totally upgrade the drivetrain and axles on a FSJ, the more HP and toprque you make the more undependable and less reliable you will be. It is simply not smart to go with big power unless you upgrade the drivetrain and axles to handle it.

My FSJ is definitely not practicle and will only be good as a toy rather than as transportation. Why am I building it this way? Cause I have been building these things for 25+ years and decided to build something fun with no limits or budget.

[Elliott]

My point about the torque.... if what I was told was accurate, and Stuka's points on the 390 may support that, was that a relatively mild build on a 401 can produce a lot of available torque.
Here's link you can scroll down to June '98 Hotrod and pick up a few things from a drag built 401 that steered the build of my 401: http://www.javelinamx.com/JavHome/articles/article2.htm
The oiling mods are highly recommended, cheap and fairly straight forward to install, I won't build a motor without them.

[243]

"For the average guy all of this time and money to upgrade a FSJ to handle big torque and HP is a total waste of time. A stock FSJ is quite capable and most FSJeepers should focus on keeping their jeeps in perfect condition rather than build big HP and torque and exceeding its strength limits and creating breakage. Unless you totally upgrade the drivetrain and axles on a FSJ, the more HP and toprque you make the more undependable and less reliable you will be. It is simply not smart to go with big power unless you upgrade the drivetrain and axles to handle it."

FSJeeper~

I could not have said it better!

Elliott~

Thanks for the link, I will read it shortly...btw, I hope you understand that I was not taking shots at you with this thread [img]smile.gif[/img]

[Stuka]

That site rocks. When I go to rebuild my 360, I am wondering if I should either find a 401 to replace it with. Or just build the 360 stronger. I only need 300hp and about 400ft pounds of torque, which I think is easily atainable, and still have it be reliable.

Just wondering if I should do it myself, or find a good AMC rebuilder here in california.

But its a long ways off...i hope [img]smile.gif[/img]

[gwdawg]

Originally posted by HeyDave:
What is an Olds 350 diesel rated at? I may be getting one of these cheap and it is already in a 78 J-ten.
Would this be alright with 3.73 gears for a daily driver. I don't tow so it would just have the weight of the truck to move.Any thoughts?

There was a discussion about the Olds diesel on the general board a couple of weeks ago. The general consensus is that the Olds diesel is a POC.

[Elliott]

243,
I didn't take it as a shot, thanks though. I realize that tons of torque ain't fo most jeeps, and boy did I enjoy reading about a guy in a basically stock 6cyl Renegade winning a trail run.
Problem I have is in leaving anything original and with the history of Jeeps being what it is they have to be about the most built rigs on the planet. The Cherokee I built the 401 for did everything but pull my 22' boat well, when the wife of the moment blew my 360 for not watching the temp gauge when I had a bad radiator... I was going to build another motor.
For the money... might as well be a 401. I didn't build it for torque, but that 401 seems to exude it soon as you start with a cam and balance. Remember that torque to the rear wheels is less then at the flywheel, maybe 100lbs.
FSJeeper... what I've been reading about doublers has me planning to downsize my ideas of building this shortbed. I'll probably stick with the jeep axles (with flattop knuckles) and run around 35-36 tires to keep from building an extreme drive line to handle the 38+ tires I was looking at. Save all that for a long bed truck, 1/2 of which is already waiting.
That torquey 401 in my Laredo only spun 31.5 yokohama mud diggers (awesome tire by the way) so it never hurt my driveline. I am sure I could have put it in a destructive situation, but I don't wheel hard as a lot of guys do around here.

[ December 28, 2002, 12:44 PM: Message edited by: Elliott ]

[Gwamp]

500lb of torque? Why not build it if you are going to beef up the drivetrain behind it. I know that the mildly built caddy mill that is going into my blue pig may be too much motor for the NP-205/D-60/14 bolt combo that going to go in there and I may have to put a set of Rockwells into it to handle the torque. The sad thing about the Rockwell bit is that you cen get a set for about $700 which is less than the cost of your average front D-60 unless you find a deal. Lockers for hte Rockwells are reasonable $400 or so I have seen them on the web selling for and you cen install them yourself with no problems.(I just re-read this and it sounds like I am trying to sell myself on a set no?) I will probably go with whatever I find first. the D-60 or the Rockwells. I could always stuff that 14 bolt under my Cherokee....

[Elliott]

Gwamp,
with the snarlin' thing your building you best go with Rockwells! Heck, keeps your center of gravity low right?

[Chero77]

It really comes down to what are you going to use your Jeep for? Before this discussion can be meaningful I think you have to narrow down the "use" category. Pick a category like daily driver, mud bogger, rockcrawler, etc. 500 ft-lbs in a daily driver is probably counter productive. In a purpose built mud bogger (if that's your thing) its probably useful.