1988 s1853 dt 360 hauler build and upgrades

[rwd4evr]

Yeah I'm leaning toward possiy a 6-7 but I may actually need that 1000 lbs ft at some point. A modified p pump and a decent turbo get you there in a hurry. I'm really wanting to get the rear regeared and get a feel for it as is then figure it out. One truck place I've been talking to said I really want to regear and put an overdrive trans plus turn up the pump(or replace) to be completely satisfied with my planned useage. I have found a couple Spicer's I'm looking into and the one is 660lb ft rated. I'd just hate to be limited. It sure would be nice to have a bus that does 0 60 under 14 seconds.

[Booyah45828]

See what your current power levels are. A lot of engines came in the 180 hp range. I think the dt360 came stock up to 210(pretty rare), going to 250 or so would make it a pretty good runner without sacrificing too much reliability.

You don't need 500hp and 1000+ ftlbs to make a bus a good runner.

Unless you're loaded to 40k lbs, then it's a different story.

Honestly, changing the gearing in a bus is a big step to drivability, most are gear bound to only go about 60 at rated rpm. Once a diesel engine gets near rated rpm, the power and torque fall off a cliff, which gives you the false impression that the bus is gutless. Adding more power to it won't change that, you'll still be gear bound. You have to put your cruise speed back into a decent rpm range. Do that and you'll be amazed at how much more driveable a bus is.

[rwd4evr]

Yeah that's what I'm hoping. It's 2700rpm at 55 mph and was dropping to 48 on big-ish hills down to like 23-2400 I believe. I'd like it to be more like 2300 at 65 I think. But it sure feels gutless below 2000 (maybe 1900) as well. So it only has a 4-500rpm powerband?

Edit. I'm still not sure 100% on power. It does have the goofy half radiator half "aftercooler" arrangement though. So is it a dta360 in fact?

[cadillackid]

the DTA360 has the split radiator..

[rwd4evr]

Been busy with other stuff and Pandemic and all. But I'm getting closer to finally getting all square on the bus and searching for a rear has come around. I found a
4.44 or a 4.10 for 550$ with exchange. I have to check my trans numbers to be sure but from what I can tell I've got a
Spicer 5 speed
Es42-5a/5d
Es52-5a/5d
Difference being 4th gear split 5a/5d and power level between Es42 and Es52

Rear gear /Final drive ratio /Rpm at 65mph Es42-5a 3rd 2.21 4th 1.42 5th 1.00
5.38 3rd 11.88 4th 7.64 5th 5.38 / 2726
4.44. 3rd 9.81 4th 6.30 5th 4.44 / 2250
4.10. 3rd. 9.06 4th 5.82 5th 4.10 / 2078

Es42-5d 3rd 2.21 4th 1.26 5th 1.00
5.38 3rd 11.88 4th 6.78 5th 5.38 / 2726
4.44 3rd 9.81 4th 5.59 5th 4.44 / 2250
4.10 3rd 9.06 4th 5.16 5th 4.10 / 2078

Es52-5a 3rd 2.23 4th 1.44 5th 1.00
5.38 3rd 11.99 4th 7.75 5th 5.38 /2726
4.44 3rd 9.90 4th 6.39. 5th 4.44 / 2250
4.10 3rd 9.13 4th 5.90 5th 4.10 /2078

Es52-5d 3rd 2.23 4th 1.29 5th 1.00
5.38 3rd 11.99 4th 6.94 5th 5.38 / 2726
4.44 3rd 9.90 4th 5.72 5th 4.44 /2250
4.10 3rd. 9.13. 4th 5.28 5th 4.10 / 2078

So I'm wondering if I'm getting greedy with the 4.10 and will it still accelerate at all plus will it still pull a hill in 4th or would I have to maybe drop to 3rd ? With the wide ratio box it would essentially be a .78 Od from my current gear. . I guess I need to look at trans and see what it is. The wide and close ratio makes more difference that the power rating and tiny ratio difference but I hope its the heavier duty one for sure. The 4.10 would be 2397rpm at 75mph which would be pretty nice on long drives. That 10mph over 10 hours cuts an 1:40 off. The 4.44 will have me at the end of comfortable at 2423 rpm at 70 but Making full power near 65 at 2250.

I need to get the pyro hooked up and turn the fuel screws too.

https://documentcloud.adobe.com/link...6-4c61d8e47e15

[Booyah45828]

Go with the 4.44.

I was always told for a good balanced truck you want your rpm at 60 to be halfway between peak torque and peak hp in direct gear.

For a dt360, I believe that is 2400rpm.

So when going 60, choose whatever rear axle ratio you have to to put the rpms around 2400. Since you're final gear is direct, I'd shoot for a little lower rpm then that, which will be the 4.44.

Just remember that your peak torque is at 1800, You don't want to cruise near that because if you slip below it, power falls off a cliff, and you'll have to downshift.

Plus, once you get a pyro, you'll likely be surprised at how hot it gets while running that low.

[rwd4evr]

Originally Posted by Booyah45828

Go with the 4.44.

I was always told for a good balanced truck you want your rpm at 60 to be halfway between peak torque and peak hp in direct gear.

For a dt360, I believe that is 2400rpm.

So when going 60, choose whatever rear axle ratio you have to to put the rpms around 2400. Since you're final gear is direct, I'd shoot for a little lower rpm then that, which will be the 4.44.

Just remember that your peak torque is at 1800, You don't want to cruise near that because if you slip below it, power falls off a cliff, and you'll have to downshift.




Plus, once you get a pyro, you'll likely be surprised at how hot it gets while running that low.

Not sure you put the right numbers in there somewhere.
If you're saying 60mph halfway between peak torq and peak hp and that Tq is 1800 and hp is 2400 that is 2100 rpm. You are saying gear it to 2400 at 60 in the same breath.

Edit; wait are you saying half way between is 2400? I thought I found something saying peak hp was 2250.

I did Id my pump. It's an A pump.
9.5mm element
I found this ID chart thing too.

[rwd4evr]

.

[cadillackid]

my stock DTA360 is worthless below about 2200 RPM.. granted maybe i need to turn up the smoke a little.. mine is geared for top speed of 68 at 2800 RPM.. it loves to cruise in that 2300-2400 RPM..

I used to think that aiming from that 50/50 split was right. and maybe it is when the average load factor is lower.. thus turning up the pump may allow you to cruise at lower RPM's. my issue may simply be the bus (even though shorty) is heavy and so on any incline it slows way down.

[rwd4evr]

Originally Posted by cadillackid

my stock DTA360 is worthless below about 2200 RPM.. granted maybe i need to turn up the smoke a little.. mine is geared for top speed of 68 at 2800 RPM.. it loves to cruise in that 2300-2400 RPM..

I used to think that aiming from that 50/50 split was right. and maybe it is when the average load factor is lower.. thus turning up the pump may allow you to cruise at lower RPM's. my issue may simply be the bus (even though shorty) is heavy and so on any incline it slows way down.

That's kinda what I felt too. When accelerating I was running it up to about 26-2700 so I didn't fall to far down in the rpm. I was gear bound at 55 at 2600 I think. I didn't want to hurt it so I was pretty tight on the 55 top but i did catch myself at a touch over 60 one time. Getting on the highway once I was in 4th and was just above the 1900 or so "downshift" recommendation on the paper printout stuck on the wall. I figured I'd be good and left it. That was a long stroll up to highway speed. What do you weigh?

[cadillackid]

ive never weighed that bus.. its gross is 27,500 (seems high for a 7 window shortie) but I need to hitthe cats one of these days.. the bus is basically stock.. still has seats.. I prob added a couple hundred pounds with the A/C and electricals..



I have 4 gears.. an MT643 auto.. my redline is 2800 RPM.. 4.78 gears and 11R22.5 tires..



main reason I havent spun the screws on the pump yet is I wont do it before I install a Pyro.. a must if you turn it up.. esp if you run lower RPMs and crowd it at all.. thats where you spike your EGT in a hurry.. mounting a pyro sensor on a 360 between manifold and turbo isnt too hard.. definitely need to use the shop vac method and maybe even have the engine idling while drilling the hole to ensure shavings get blown out vs into the turbo..



the A-pump stock isnt great for a ton of HP.. but heck if you can turn a stock 160 or 175 motor up to even 220 HP you have gained 25% or more..



its also worth making sure theres no exhaust manifold gasket Leaks.. the bolts love to backl out on the exhaust manifold on these things and cause an exhaust leak which greatly affects boost.. ive seen it more than once on the rear exhaust bolts.. a buddy of mine had a bolt completely gone.. said he thought his engine was a little louder than nornal.. something to think about anyway..

[Booyah45828]

Originally Posted by rwd4evr

Not sure you put the right numbers in there somewhere.
If you're saying 60mph halfway between peak torq and peak hp and that Tq is 1800 and hp is 2400 that is 2100 rpm. You are saying gear it to 2400 at 60 in the same breath.

Edit; wait are you saying half way between is 2400? I thought I found something saying peak hp was 2250.

I did Id my pump. It's an A pump.
9.5mm element
I found this ID chart thing too.

Halfway is 2400

Peak torque - 1800 rpm
Peak hp - 3000 rpm

3000-1800=1200 1200/2=600

1800 rpm + 600 rpm = 2400 rpm

Truthfully, something in the 4.78 range would be more desirable. But if the choice is 4.44 or 4.10, I'd go with the 4.44

All the info I can find shows a dt360 with a rated rpm of 3000. If your engine has a sticker on the valve cover showing something different, go by that.

Edit - I was wrong. Rated rpm for the 190hp dta360 is 2700 rpm.

So 2700-1800=900 900/2=450 1800+450=2250

Go with the 4.44 rear gear.

3000 is likely the fuel cut rpm.