Torque and HP in a CJ7 - JeepForum.com
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post #1 of 45 Old 09-23-2017, 01:12 PM Thread Starter
swatson454
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Torque and HP in a CJ7

How much honest, real world torque and horsepower can a CJ-7 take before it becomes just stupid?


Shawn


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post #2 of 45 Old 09-23-2017, 02:00 PM
skizriz
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Originally Posted by swatson454 View Post
How much honest, real world torque and horsepower can a CJ-7 take before it becomes just stupid?

Shawn
Way more than I got. Lol

The stock 360 in mine does everything I need. Crazy torque right off idle for rock crawling, and enough HP to use high range to get up that snot slick hill when only wheel speed will get the job done.

Did I mention that there's plenty to break axles if you aren't careful?
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post #3 of 45 Old 09-23-2017, 02:27 PM Thread Starter
swatson454
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That's why I'm leaning on you guys to tell me all the ***** that could break beforehand. I think a spring-over lift with 35s puts me in axle-wrap territory even before throwing big torque at it, yes?

The engine combo I'm contemplating should, assuming I pay close attention to detail, net 1.3 to 1.35 foot pounds per cubic inch for a total of ~475 pounds. Hp will likely be less for the simple fact that I don't want to spin it past 6,000 rpm.

Is that a really dumb idea in a CJ? Totally wasteful?


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post #4 of 45 Old 09-23-2017, 02:51 PM
skizriz
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Originally Posted by swatson454 View Post
That's why I'm leaning on you guys to tell me all the ***** that could break beforehand. I think a spring-over lift with 35s puts me in axle-wrap territory even before throwing big torque at it, yes?

The engine combo I'm contemplating should, assuming I pay close attention to detail, net 1.3 to 1.35 foot pounds per cubic inch for a total of ~475 pounds. Hp will likely be less for the simple fact that I don't want to spin it past 6,000 rpm.

Is that a really dumb idea in a CJ? Totally wasteful?

Shawn
My tired worn out 258 would trash leaf springs with no anti wrap bar. It's a must if running SOA. My front springs seem to hold up without anything though, no idea why though. Maybe just the weight transfer to the rear doesn't wrap the front as bad.

Totally wasteful?? Just depends on how much fun you want to have. Plenty of people would say mine is totally wasteful. It's perfect for what I want to do though.

I would definitely consider one ton axles for that much power though. I've snapped two Dana 44 shafts like they were Lazer cut, and tore teeth off of one ring gear.
Going to tons myself next year.
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post #5 of 45 Old 09-24-2017, 01:30 PM Thread Starter
swatson454
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Shoot, I was hoping there would be some guys with stout 401s that had some input.


Shawn

Edit: Damn, skiz, that didn't come out right. Thank you for your input!

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Last edited by swatson454; 09-24-2017 at 02:13 PM.
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post #6 of 45 Old 09-24-2017, 02:57 PM
TIPPEDITOVER
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Quote:
Originally Posted by swatson454 View Post
How much honest, real world torque and horsepower can a CJ-7 take before it becomes just stupid?


Shawn
I've been asking myself that question lately. I'm gonna be pumpin' 400hp / 400tq through my stretched frame once the LQ9 is going. My rear axle is up to it, I think. Front axle, no, not in 4wd (massage the throttle). Dakota rear leaf springs yes, with anti torque bar. They are quite robust.

I'm counting on a full roll cage tied to the frame providing the extra strength needed. Will it be controllable? I don't know, but I'm gonna have fun finding out.

Shaun

1978 CJ5 to CJ6 - Build in progress......


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post #7 of 45 Old 09-24-2017, 03:26 PM
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Originally Posted by skizriz View Post
My tired worn out 258 would trash leaf springs with no anti wrap bar. It's a must if running SOA. My front springs seem to hold up without anything though, no idea why though. Maybe just the weight transfer to the rear doesn't wrap the front as bad.

Totally wasteful?? Just depends on how much fun you want to have. Plenty of people would say mine is totally wasteful. It's perfect for what I want to do though.

I would definitely consider one ton axles for that much power though. I've snapped two Dana 44 shafts like they were Lazer cut, and tore teeth off of one ring gear.
Going to tons myself next year.
Would that have been a Chevy 44 front axle shaft with the strange necked down section close to the diff spline?
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post #8 of 45 Old 09-24-2017, 04:11 PM
skizriz
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Would that have been a Chevy 44 front axle shaft with the strange necked down section close to the diff spline?
Waggy 44. It was very close to the splines.
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post #9 of 45 Old 09-24-2017, 04:14 PM
skizriz
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Originally Posted by swatson454 View Post
Shoot, I was hoping there would be some guys with stout 401s that had some input.


Shawn

Edit: Damn, skiz, that didn't come out right. Thank you for your input!
No negativity read into it. It's all good.
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post #10 of 45 Old 09-24-2017, 04:51 PM
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Just a quick look on wiki and for perspective

Low pinion Dana 44 30 spline............3460 [ft/lbs]
High pinion Dana 44 30 spline...........4170 [ft/lbs]
Low pinion rear 8.9" Dana 44 32 spline..5340 [ft/lbs]
Several other sites say about the same.

@475 fl/lb from the engine
So I would take your lowest gear lets say a SM465 tranny, first gear 6.55:1 ratio and say you are running 4.88 gears with 35's you could generate 15055.044 ft/lb of torque to the rear wheels and with a rule of thumb 30% power loss to the drive train thats about 10K ft/lbs to the rear

Something like a turbo 400 with a 2.48 first gear puts you at 4024 ft/lb with the 30% rule, so to me its a matter of what transmission and gears you run along with the rear end as to how beefy you will need the rear end and what is holding it in place, I'm thinking four link to keep it in place.
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post #11 of 45 Old 09-24-2017, 08:59 PM
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Quote:
Originally Posted by Dryseals View Post
Just a quick look on wiki and for perspective

Low pinion Dana 44 30 spline............3460 [ft/lbs]
High pinion Dana 44 30 spline...........4170 [ft/lbs]
Low pinion rear 8.9" Dana 44 32 spline..5340 [ft/lbs]
Several other sites say about the same.

@475 fl/lb from the engine
So I would take your lowest gear lets say a SM465 tranny, first gear 6.55:1 ratio and say you are running 4.88 gears with 35's you could generate 15055.044 ft/lb of torque to the rear wheels and with a rule of thumb 30% power loss to the drive train thats about 10K ft/lbs to the rear

Something like a turbo 400 with a 2.48 first gear puts you at 4024 ft/lb with the 30% rule, so to me its a matter of what transmission and gears you run along with the rear end as to how beefy you will need the rear end and what is holding it in place, I'm thinking four link to keep it in place.
The low pinion D44 spec is as used as a front diff? I would guess the high pinion spec is for front diff application.
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post #12 of 45 Old 09-25-2017, 05:34 AM
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Depends on what you want to do.....
My CJ5 (and I feel better about publishing some fairly accurate numbers now that it's sold...LOL) in stock frame, leaf spring configuration, was making upwards of 1,000HP. We made a little over 670 on motor, then sprayed it with typically 250, but at times 300. The plate was maxed out at 300 on E85, so we had to run more fuel pressure on the nitrous than I liked at 300, so we typically kept it at 250.
Now, with that said.... I am starting the build of a CJ7 with the expectation of more power, so I may have a better answer on what a CJ7 can handle a little later on :-)
Again, it's all dependent on what you're doing. With a 33" paddle, no axle wrap/issues. With a 32" casing scoop, no axle wrap/issues.

'76 CJ5
434 pump gas SBC with an NX/HVH plate system
th350/Coan 5,000 converter/Dana 300 tcase
Dana 30 front with 4.56's/Dana 44 rear with 4.88's
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post #13 of 45 Old 09-25-2017, 06:53 AM Thread Starter
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Originally Posted by AFRd_CJ5 View Post
Depends on what you want to do.....
My CJ5 (and I feel better about publishing some fairly accurate numbers now that it's sold...LOL) in stock frame, leaf spring configuration, was making upwards of 1,000HP. We made a little over 670 on motor, then sprayed it with typically 250, but at times 300. The plate was maxed out at 300 on E85, so we had to run more fuel pressure on the nitrous than I liked at 300, so we typically kept it at 250.
Now, with that said.... I am starting the build of a CJ7 with the expectation of more power, so I may have a better answer on what a CJ7 can handle a little later on :-)
Again, it's all dependent on what you're doing. With a 33" paddle, no axle wrap/issues. With a 32" casing scoop, no axle wrap/issues.

Ahhh, that's right. You haven't been around much so I forgot about your nasty hotrod. And Fuzz had a 401 that ran 11.some odd in the quarter so I'm probably over-thinking the deal, as I often do, lol.

Is it even possible to mount a transfer case to a close-ratio 5-speed stick from a Camaro or "Vette?

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post #14 of 45 Old 09-25-2017, 07:38 AM
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Though the 60' times sucked because I was babying it, I didn't have any axle wrap issues at the track either. I tried some asphalt stuff. Went 1.7 60', which isn't good, as I can do that on the sand, but I was worried about breaking an axle at first.
I went 10.7x's letting off at the 1/8 mile. Well, letting off enough to disengage the nitrous, and do an "in and out" of throttle thing to slowly bring speed down.
No axle hop/etc. though. I've seen guys run 8's on leaf springs.

'76 CJ5
434 pump gas SBC with an NX/HVH plate system
th350/Coan 5,000 converter/Dana 300 tcase
Dana 30 front with 4.56's/Dana 44 rear with 4.88's
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post #15 of 45 Old 09-25-2017, 10:26 AM
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More that my 318 will make, but hopefully I push the stupid boundary when I build the 408 out of one of the extra 360's sitting on the floor.

I think though it also depends on how it builds that hp/tq. A rabid small block will be stupid, but a big block making the same power may be a docile easy to handle machine. Then when you get to the LQ9 that Tippeditover is building, that motor should be easily controllable and have a nice smooth torque curve.

Quote:
Originally Posted by swatson454 View Post
Is it even possible to mount a transfer case to a close-ratio 5-speed stick from a Camaro or "Vette?
As for a close ratio 5spd, you can build a Jeep T-5 into world class specs the same as Mustang guys and put plenty of power through it. Camaro 5sp would also be a T-5 then later as a T-56 as a 6 speed and 'Vette' transmissions were bolted to the rear axle so you would have to build a custom bell and adapter for the t-case..

http://www.5speeds.com/t5/jeep.html

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