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Discussion Starter · #1 ·
Hey guys!
Did some towing today, felt like my 4bt was doing pretty good for what it's worth.
Hx30 over hx35, 90hp nozzles, ve pump modded, colt cam, ect. Nv4500 manual Trans.
Truck is probably just over 6k lbs
Trailer is 2200 lbs, explorer was 4500 and travel trailer was 1500ish.
Pulling the explorer was a bit slow getting going for sure but got the job done.
Heaviest was 7k towing. So 4bt pulling 13k
What do u guys think?
20210501_142322.jpg
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Hey guys!
Did some towing today, felt like my 4bt was doing pretty good for what it's worth.
Hx30 over hx35, 90hp nozzles, ve pump modded, colt cam, ect. Nv4500 manual Trans.
Truck is probably just over 6k lbs
Trailer is 2200 lbs, explorer was 4500 and travel trailer was 1500ish.
Pulling the explorer was a bit slow getting going for sure but got the job done.
Heaviest was 7k towing. So 4bt pulling 13k
What do u guys think? View attachment 130904 View attachment 130905
Looks good, How tall are your tires and what gear ratio are you running? Truck I am building is being built just for towing.
 

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Discussion Starter · #3 ·
35s and 3.73. It does about 1800 at 60 mph. Any taller and it wouldn't be so good at lift off with a trailer.
 

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I have found that up to ~13K CGVW the 4BT is just fine north of that it has to really work, but to be honest my 53 year old 3/4 ton is not happy and does not need to be pulling any more that that on a regular basis. My heaviest trip was 16K from Bakersfield, CA. to Prescott, AZ. and that was with the he221 and a 200hp tune with that combination the grades required dropping out of OD but doing [email protected] 2,000rpm up a 6% grade is totally acceptable with a load like that.
 
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Discussion Starter · #5 ·
I have found that up to ~13K CGVW the 4BT is just fine north of that it has to really work, but to be honest my 53 year old 3/4 ton is not happy and does not need to be pulling any more that that on a regular basis. My heaviest trip was 16K from Bakersfield, CA. to Prescott, AZ. and that was with the he221 and a 200hp tune with that combination the grades required dropping out of OD but doing [email protected] 2,000rpm up a 6% grade is totally acceptable with a load like that.
It sure does feel like it's working hard lol. With auto I'm sure it's a bit better lifting off. I do like my manuals but I can see where the auto would be better. Once it's up to speed it's much better tho.
If I had my big set of compounds I'm sure it just would not have worked!

What auto are u running?
 

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It sure does feel like it's working hard lol. With auto I'm sure it's a bit better lifting off. I do like my manuals but I can see where the auto would be better. Once it's up to speed it's much better tho.
If I had my big set of compounds I'm sure it just would not have worked!

What auto are u running?
Now I have this...1968 F-250 4x4 crew cab 131" wheelbase 3.55 Dana 44HD/Dana60..4BT.. Wh1c/42mmHx30-6-W ,VE pump advanced,5x.012"SAC injectors, F-800 inter cooler plumbing, close ratio ZF5,NP-203/205 and at 13k CGVW it will keep up with flow up a 6% grade in OD as long as I can keep in it if not I'm pretty well stuck in direct till the summit.
I'm plenty happy with it where it is and after 10 years of flogging the Cummins it still amazes me how it will just "Cowboy Up" no matter what I ask it to do, now if all the other systems attached to it were up to the same duty level...........
 

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Discussion Starter · #7 ·
Now I have this...1968 F-250 4x4 crew cab 131" wheelbase 3.55 Dana 44HD/Dana60..4BT.. Wh1c/42mmHx30-6-W ,VE pump advanced,5x.012"SAC injectors, F-800 inter cooler plumbing, close ratio ZF5,NP-203/205 and at 13k CGVW it will keep up with flow up a 6% grade in OD as long as I can keep in it if not I'm pretty well stuck in direct till the summit.
I'm plenty happy with it where it is and after 10 years of flogging the Cummins it still amazes me how it will just "Cowboy Up" no matter what I ask it to do, now if all the other systems attached to it were up to the same duty level...........
Can't beat that combo! For some reason I thought u had an automatic...not sure why.
I haven't towed up any mountain passes yet, we will see on the future!
 

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Discussion Starter · #9 ·
I plan on running 35s and 456 with an allison 6 speed double overdrive. 2020 in 5th, 1765 in 6th, at 65.
Just finish a custom gooseneck trailer to pull.
A 6 speed auto would be real nice. Quite a pricey unit if u add the Trans, adapter, TC, controller ect
 

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A 6 speed auto would be real nice. Quite a pricey unit if u add the Trans, adapter, TC, controller ect
The engine I have is a 2005 3.9 ISB that came with an 5 speed allison. All the 2000 to 2005 T1000 allisons 5 speeds were actually 6 speeds. Change the valve body and reprogram the computer and you have a 6 speed, still not cheap. But the double overdrive will allow a lot more gear for pulling and acceleration. Do you have an idea of the power you are putting out?
 

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I think where I sit now my biggest shortcoming when towing is the close ratio ZF's 1st taking off on any sort of grade requires more clutch slipping than I like, I have needed to use the 203 underdrive to get it rolling and the change into direct being unsynchronized takes a bit of care..
When I was running the wide ratio ZF 1st was just perfect so I guess the "ideal" manual gearbox would be the ZF-6 as it looks like the close ratio 5 with a granny low added...$.02
 

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Discussion Starter · #12 ·
The engine I have is a 2005 3.9 ISB that came with an 5 speed allison. All the 2000 to 2005 T1000 allisons 5 speeds were actually 6 speeds. Change the valve body and reprogram the computer and you have a 6 speed, still not cheap. But the double overdrive will allow a lot more gear for pulling and acceleration. Do you have an idea of the power you are putting out?
Ah that's probably the cheapest and easiest way to do it. Yeah no allison parts are cheap for sure. But good quality stuff.
No dyno pulls yet on this tune, but my engine has done 2 dyno pulls with various fuel and turbo combos. My guess with where I'm at is 250 whp and 550 tq. Big fat torque curve too. Hx30 over hx35. But the short comings is gearing for sure. 4.10s would be great down low but leave me screaming up top.
Lift off is the hardest part with a manual
 

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Discussion Starter · #13 ·
I think where I sit now my biggest shortcoming when towing is the close ratio ZF's 1st taking off on any sort of grade requires more clutch slipping than I like, I have needed to use the 203 underdrive to get it rolling and the change into direct being unsynchronized takes a bit of care..
When I was running the wide ratio ZF 1st was just perfect so I guess the "ideal" manual gearbox would be the ZF-6 as it looks like the close ratio 5 with a granny low added...$.02
Yeah lift off is the not so fun part with all that weight. I never had to lift off up any real hills but u have to give throttle in 1st gear so it doesn't lug out. Zf6 is a nice box, but the big block bell housing is huge!! I would have gone with it but I had my 4bt in a ranger before and there is no way it would have fit
 

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Ah that's probably the cheapest and easiest way to do it. Yeah no allison parts are cheap for sure. But good quality stuff.
No dyno pulls yet on this tune, but my engine has done 2 dyno pulls with various fuel and turbo combos. My guess with where I'm at is 250 whp and 550 tq. Big fat torque curve too. Hx30 over hx35. But the short comings is gearing for sure. 4.10s would be great down low but leave me screaming up top.
Lift off is the hardest part with a manual
That power sounds good, an OD trans would let you pick the ideal gear. There almost a must with these diesels.
 

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I think where I sit now my biggest shortcoming when towing is the close ratio ZF's 1st taking off on any sort of grade requires more clutch slipping than I like, I have needed to use the 203 underdrive to get it rolling and the change into direct being unsynchronized takes a bit of care..
When I was running the wide ratio ZF 1st was just perfect so I guess the "ideal" manual gearbox would be the ZF-6 as it looks like the close ratio 5 with a granny low added...$.02
I had that ZF-6 in a truck, it was a smooth shifting trans.
 

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I had that ZF-6 in a truck, it was a smooth shifting trans.
When it was time to go larger that 11" on the clutch disk I would have opted for the ZF-6 over the 5 but having the 203 underdrive mated to the divorced 205 I did not have the room between the trans and underdrive my intermediate shaft is only 11.375" long as things are...
 

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Discussion Starter · #17 ·
That power sounds good, an OD trans would let you pick the ideal gear. There almost a must with these diesels.
I've got an nv4500, .78 overdrive, but yes. More overdrive would alow deeper axle gears. It's totally fine lifting off with 4k lbs, just 7k and up is where it's harder
 

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I've got an nv4500, .78 overdrive, but yes. More overdrive would alow deeper axle gears. It's totally fine lifting off with 4k lbs, just 7k and up is where it's harder
I didn't know it had an OD. I had a ford with FZ6 and a dodge with NV5600 but anything I built is an automatic. You just can't beat a torque converter.
 

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When it was time to go larger that 11" on the clutch disk I would have opted for the ZF-6 over the 5 but having the 203 underdrive mated to the divorced 205 I did not have the room between the trans and underdrive my intermediate shaft is only 11.375" long as things are...
Twin transfer cases, is that for rock crawling?
 

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Discussion Starter · #20 ·
I didn't know it had an OD. I had a ford with FZ6 and a dodge with NV5600 but anything I built is an automatic. You just can't beat a torque converter.
I've been a die hard manual Trans person for years, but I'm coming around to auto transmission seeing as they have been getting better, more gears ect.
With a diesel with a narrow rpm band they are great, fast shifting and towing its much nicer, especially on lift off.
Still can't beat the reliability of a good old manual Trans tho....
 
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