Cummins 4BT performance update...

[Heinz_67]

This post serves two purposes; to post an update on my rig and brag a little.

I've finally got the engine dialed in exactly where I want it. I waited to make any performance modifications until the engine was properly broke in and I felt sure the rings were well seated.

Dyno numbers really don't do justice so I thought I would share it's performance by comparing it to something many of us are familiar with.
One of buddies came over Friday in his Bronco. It's a very nice '77 with a 351 EFI engine and a built C4 auto. It has 33" tires and 4.56 gears. After driving both Broncos, we concluded that the 4BT holds it's own with the 351. It accelerated as quickly as the 351 and is AWESOME on the highway. For those who familiar with Boulder, CO, I can pull the hill on HWY 58 near Coors in 5th gear at 65 mph without having to downshift. This is something I could NOT do with my 5.0! Got Boost? (That would be a cool screen name)

I have to admit, I was very impressed. I apologize for gloating here, but since I get so many emails about the conversion asking about accleration and highway speeds I thought I would share this little update with the group.

;D

Jim

 

[COBlu77]

I'm the one who he compared engine set-ups to. Saying I was impressed is putting it mildly. His Cummins put my 351 w/EFI to shame. Not even close. The torque and acceleration was amazing. In 5th gear going about 35 mph it would still pull like crazy without lugging the engine.

This comparison ride made me a believer. I was always impressed with James' fabrication skills and by all the research he did to dial in the turbo and fuel, but remained a skeptic about a Cummins in a Bronco. I thought it would be like a tractor, good torque but slow. I don't know what his 0-60 times are, but it got up to 60 a lot faster than my Bronco and was very civil with the NV4500 5sp. It was faster than my chipped Power Stroke.

If you have the insatiable need for more power, this is the set-up, but get ready to replace any weak link in your drive train.

 

[Heinz_67]

Yeah, there is that!

The next day one of my Jeeper buddies came over and we went cruisin in the Bronco. He was commenting on the turbo whine and my ego could not resist. It all started with me saying... "Watch this". We were in second gear when I floored it. We sank back in the seats as the tach shot towards the 3200 rpm redline. I clutched and threw it in third. That's when we heard the sound of tires barking... and metal clanking.

Axle wrap sucks!

So, now I'm in the process of making a traction bar not unlike Sam's Offroad design and purchasing a new rear drive shaft and SEVERAL spare u-joints.

Nothing more humbling than being towed home by a CJ-5. He is never going to let me live that one down!

Jim

 

[Project_bronco]

<Crying because he can't wait to do the conversion!!!

 

[Madgyver]

This will have to be the next swap on my list..... It may just cut in line.....

 

[orange69]

I can believe it. I went wheeling w/ a guy who put one in '79 bronco. He says he has the power of big block. While we were leaving, I stomped it pretty good (I have a 351W w/ 35's & 4:10's) and he was right on my butt. I am definitely keeping my eyes open for one. Plus the gas mileage is awesome. One more thing I didn't think of is that a diesel will not flood out when climbing hills or going down.

Nicely done by the way!

 

[73stallion]

i wish i had the money to do the conversion. i'm sick of 302's!

 

[kb6677]

This post serves two purposes; to post an update on my rig and brag a little.

I've finally got the engine dialed in exactly where I want it. I waited to make any performance modifications until the engine was properly broke in and I felt sure the rings were well seated.

Dyno numbers really don't do justice so I thought I would share it's performance by comparing it to something many of us are familiar with.
One of buddies came over Friday in his Bronco. It's a very nice '77 with a 351 EFI engine and a built C4 auto. It has 33" tires and 4.56 gears. After driving both Broncos, we concluded that the 4BT holds it's own with the 351. It accelerated as quickly as the 351 and is AWESOME on the highway. For those who familiar with Boulder, CO, I can pull the hill on HWY 58 near Coors in 5th gear at 65 mph without having to downshift. This is something I could NOT do with my 5.0! Got Boost? (That would be a cool screen name)

I have to admit, I was very impressed. I apologize for gloating here, but since I get so many emails about the conversion asking about accleration and highway speeds I thought I would share this little update with the group.

;D

Jim

Jim,
Sounds great. Would you mind giving some tuning/mod tips for the motor to achieve the above performance level? Is there a particular year that is better than others to begin with-for ex. the '94-96 roller windsors are great. I have a buddy local who is in the process of shopping for an engine to begin his own conversion.
TIA

 

[73stallion]

Got Boost? (That would be a cool screen name)

Jim

why not make it your personal text under your user name?:
<---

 

[colobronco]

Well Jim, i should have my transmission very soon. I got the rear doors off the donor van, and thats it. lol. can't wait to get mine up and running around with you.

Brian

 

[6677ebman]

Well, I'm even sicker, now, that I didn't attend a local auction a few weeks ago that included an '80's Frito Lay truck w/ a Cummins 4BT, a friend that went thought it brought about $6-700. I believe that's the way to go, no doubt!!

 

[broncomanbrad]

Hey James I just got a new job and have been kinda busy (and so I haven't called %) ). When should I call you tonight? Or if not tonight.......... when?

 

[Heinz_67]

Hey James I just got a new job and have been kinda busy (and so I haven't called %) ). When should I call you tonight? Or if not tonight.......... when?

Anytime...

Congrats on the new job!

 

[Heinz_67]

why not make it your personal text under your user name?:
<---

I think I'll just have to do that. Corny I know, but I like it!

 

[rutwad]

What about the extra weight? Does it make the front end sag?

 

[Heinz_67]

What about the extra weight? Does it make the front end sag?

Chuck hooked me up with his 4.5" springs and I have exactly 4.5" of lift out of them. That is also with a plate style front bumper and a winch.

The 4BT is less than 200 pounds heavier than a fully dressed 5.0

A 351 with dual batteries is actually heavier on the front axle than my setup.

Jim

 

[Pa PITT]

congrats.on getting the jobs done
...i;m wanting one bad but funs are short ...so a couple of questions does your run so good because it a 4 bt or is it because ofyour up grades ....
I deal with 6 bt at dodge and i have seem seveal trucks come in that ''sure do scream'' It's mostly the upgrades ...you can really change the 6bt but is yours due to change or just becauswe it the 4 bt ....
I'm sure wanting one of these but problems ''arose''...

 

[BroncKelly]

Awesome.




BroncKelly

 

[Heinz_67]

congrats.on getting the jobs done
...i;m wanting one bad but funs are short ...so a couple of questions does your run so good because it a 4 bt or is it because ofyour up grades ....
I deal with 6 bt at dodge and i have seem seveal trucks come in that ''sure do scream'' It's mostly the upgrades ...you can really change the 6bt but is yours due to change or just becauswe it the 4 bt ....
I'm sure wanting one of these but problems ''arose''...

My engine is physically bone stock with the exception of a Spearco intercooler.

I swapped out the 16cm H1C Holset turbo for a 9cm H1C Holset turbo (both are OEM turbos). They are NOT hybrids.

I turned the main fuel adjustment up (very slightly - 1 1/2 turns) and turned the low boost fuel adjustment up 2 clicks.

Thats it!

It took a lot of trial and error to get to this point, but I'm now satisfied and intend to make no additional adjustments. A lot has to do with gearing and vehicle weight as well.

Jim

 

[Heinz_67]

Awesome.




BroncKelly

Thanks. What blue is your Bronco painted? I love it.