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How much torque?

10K views 13 replies 9 participants last post by  Machman 
#1 ·
I have a 3000 - 3500 lb vehicle. I was wondering how large of an engine do I need? How much torque do I need to look at?
 
#2 · (Edited)
well my dodge at 7380 lbs has 436 hp / 897 ft/lbs at the rear wheels and that seems to be satisfactory for me especially when towing. i liked it at 507/1060 on my old truck and ive been higher but for balance and scoot movement it seems like with the numbers rounded up a little 1 ft/lbs or torque to every 9 lbs of steel or 1 hp to every 17 lbs of steel keeps my butt o meter happy

but thats all factored around a rig that tows heavy. my cherokee chief i have the numbers a little lower


Stock Ford F350 215/440 (7000lbs) from 1997 and a dodge 2003 (7300 lbs) 305/555 truck had torque to weight ratios of 15.9lbs to every ft/lbs torque and 13.15 lbs to 1 ft/lbs torue respectively and around 13 lbs is where things started to feel pretty effortless in stock form with these heavy beasts.



3500lbs / 13 = 270 ft/lbs should scoot pretty well and would be well within the stock settings of a cpl 857. id turn it up jsut a hair decrease the size of the exhaust housing to improve spool up and call it a done deal you'd easily have 130-140 hp/ 290-300 ft/lbs scoot well and have good economy due to the relatively mild combination


my chief at 5100 lbs @ 430 ft/lbs will be at a 11.85

bread trucks at 9000 lbs roughly with a partial load and a cpl 857 4bta were sporting 120 hp+/- & 260 ft/lbs +/- were at a gastly 33.70 lbs per 1 ft/lbs of torque and they still maintained speed and booked right along. theres just my way of deriving a statistic to choose hp/torque number relative to a combination and estimated weight. I also factor in the hp and then after determining the hp/tq that i feel is relative to my objective i choose the gearing to get it all to perform at the speed i want also

there are a million other therories that work its all dependant on where you want to go, how fast you want it to move and what you are comparing it to. go out and drive a few diesel turbo charged rigs and figure out their hp/torque to weight ratio and that can get you started in a possible direction but then you need to determine what your final objective is. Track time, brute torque for trailering brute power for showing off...... its all relative in the end to what youa re trying to achieve
 
#3 ·
That's really an open ended type of question. Depends on your goals. Fuel economy or a something used to haul a load of tools around town.
 
#11 ·
machman[B said:
edit...
If your concern is accelerating a weight (or, taking a more holistic view, overcoming inertia of a given mass,
cut......cut....cut...

,But the Cummins is going to be a bit nicer to drive (if you ask me..)
Well said.
my $.02
 
#14 · (Edited)
Sorry, I was in verbose mode..

charles charles charles

..snip due to image limits in one post..

personally i liked the idea of the 4bt because no matter where I am, i am not that far away from someone that carry's parts. 4/6bts and cummins in general are everywhere. i can go to autozone and get a water pump. can you do that if you have a b3.3?

i drive about 30k miles a year, so that's important to me.

edit: for those that weren't here, this is charles: http://www.4btswaps.com/forum/member.php?u=238 looks like he last visited 12/10/08, but he hasn't posted since 9/27/07
Agreed on the parts availability being a prime consideration.

The thing about Charles was that, he was technically correct. But something got lost in his delivery. (Or others' interpretation.. Your pick.) I must have revised and pondered my take on it for an hour before hitting the Submit Reply button for fear of stirring that pot again. And even then it's still not quite what I was hoping to deliver.

nah

Decca Gills per Hecta Dram.:rasta:

At least they aren't measuring fuel economy in Rods per Hogshead. :rolleyes: :lol:
Just had to go there, eh? :grinpimp:
 
#12 · (Edited)
charles charles charles

he back yet?? bounce

just kidding :)

personally i liked the idea of the 4bt because no matter where I am, i am not that far away from someone that carry's parts. 4/6bts and cummins in general are everywhere. i can go to autozone and get a water pump. can you do that if you have a b3.3?

i drive about 30k miles a year, so that's important to me.

edit: for those that weren't here, this is charles: http://www.4btswaps.com/forum/member.php?u=238 looks like he last visited 12/10/08, but he hasn't posted since 9/27/07
 
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