Cummins 4BT performance update...

[Scotty]

Success, Congratulations!

I seem to recall a tremendous debate over the benefits of your swap, Jim...

Wait, isn't it time for 68ford to chime in? :-X

Nevermind, let's not start that crap again!

 

[BroncKelly]

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

The truck had a Toyota 05' Pacific Blue Metallic paint. That was my previous Bronco, the one i have now is red. I was VERY happy about the way that blue turned out. Thanks....


BroncKelly

 

[bigpappa]

Now that you have it all finished and the way you want it. If you had it to do all over again would you? If so would you do anything differently? What did you finally end up with as far as gearing from the engine back? What RPM are you running at hwy speeds say 65 - 75? With the torque of the engine you do not need as low of a crawl ratio right? So if I were running a 70-80:1 with a cummins would that be safe to say it is in the ball park performance wise as a 351W with a 100:1 or there about?

I know it is a bunch of questions and some assumptions on my part. (and yes I know what it means to ASS U ME) ;D I am still debating on which way to go though. %)

Thanks,
Kris

 

[Heinz_67]

Now that you have it all finished and the way you want it. If you had it to do all over again would you? If so would you do anything differently? What did you finally end up with as far as gearing from the engine back? What RPM are you running at hwy speeds say 65 - 75? With the torque of the engine you do not need as low of a crawl ratio right? So if I were running a 70-80:1 with a cummins would that be safe to say it is in the ball park performance wise as a 351W with a 100:1 or there about?

I know it is a bunch of questions and some assumptions on my part. (and yes I know what it means to ASS U ME) ;D I am still debating on which way to go though. %)

Thanks,
Kris

Your question is really a double edged sword for me. I have never been more happy with my Bronco than how it is right now. However, it is the thrill of the build that keeps me in this hobby; not necessarily the wheeling part of it. I enjoy sifting through new problems and venturing into the "project". The Cummins experiment was awesome and if I were to build another multi-purpose Bronco, I would build it to the exact specs I have now with one exception; I would have gone with full width axles.

My rpm's are right at 2,000 at 70 mph. I'm running 4:10 gears with 35x12.5x15 BFG M/T's on 15x8" Mickey Thompson Classic II's.

I'm not sure, but it sounds like your crawl ratio question boils down to, "Was the Atlas worth the expense?" Yes, it was. I just came to realize that this last week. I do prefer really low crawl speeds because they give me control and time to pick the right line. Since my offroad driving skills suck, I need all the help I can get! Also, there is less need to use the clutch. I don't use mine at all when in low range. It is next to impossible to stall the 4BT so I just use the brake and throttle to contol my speed. The clutch is only for stopping and starting. In addition to the crawl ratio, there is the fact that the rear output shaft on the D20 is subject to failure. I'm not saying it is destined to fail so all you guys that are running one with no problems don't jump me for that comment. But, I have twisted a rear output shaft; with a 5.0. The 4BT would be merciless on that weak link if you ever bind up your drivetrain on the trail. For that reason alone, the Atlas was worth the investment.

The power of the 4BT really does not factor in much with crawl ratio believe it or not. Yes, it is true that I generate around 450# of torque at only 1300 rpm, but that is in high range with the engine under a load and generating boost. When the Bronco is in low range, the gearing decreases the load and the torque only get's to about 250-300 pounds at 1300 rpm (according to Rocky Mountain Cummins). I'm not sure what the 351 specs are, but under the same low speed/ low range conditions I bet they are pretty similar.

Now it's time for another project. I'm picking up a sweet ass 1981 Mercedes 380SEL with a cracked head for $500. I've been wanting to squeeze a 351 EFI into something for a while now. I may just have to go molest this thing. I think a 350 horse 4-door 380SEL with a Borla exhaust note would be sweet.

I'm just twisted that way. Ask me about our 1967 VW bus/truck with a Toronado 455ci FWD drivetrain mounted mid-ship in it. That one sure turned heads. ;D

Jim

 

[bigpappa]

Your question is really a double edged sword for me. I have never been more happy with my Bronco than how it is right now. However, it is the thrill of the build that keeps me in this hobby; not necessarily the wheeling part of it. I enjoy sifting through new problems and venturing into the "project". The Cummins experiment was awesome and if I were to build another multi-purpose Bronco, I would build it to the exact specs I have now with one exception; I would have gone with full width axles.

My rpm's are right at 2,000 at 70 mph. I'm running 4:10 gears with 35x12.5x15 BFG M/T's on 15x8" Mickey Thompson Classic II's.

I'm not sure, but it sounds like your crawl ratio question boils down to, "Was the Atlas worth the expense?" Yes, it was. I just came to realize that this last week. I do prefer really low crawl speeds because they give me control and time to pick the right line. Since my offroad driving skills suck, I need all the help I can get! Also, there is less need to use the clutch. I don't use mine at all when in low range. It is next to impossible to stall the 4BT so I just use the brake and throttle to contol my speed. The clutch is only for stopping and starting. In addition to the crawl ratio, there is the fact that the rear output shaft on the D20 is subject to failure. I'm not saying it is destined to fail so all you guys that are running one with no problems don't jump me for that comment. But, I have twisted a rear output shaft; with a 5.0. The 4BT would be merciless on that weak link if you ever bind up your drivetrain on the trail. For that reason alone, the Atlas was worth the investment.

The power of the 4BT really does not factor in much with crawl ratio believe it or not. Yes, it is true that I generate around 450# of torque at only 1300 rpm, but that is in high range with the engine under a load and generating boost. When the Bronco is in low range, the gearing decreases the load and the torque only get's to about 250-300 pounds at 1300 rpm (according to Rocky Mountain Cummins). I'm not sure what the 351 specs are, but under the same low speed/ low range conditions I bet they are pretty similar.

Now it's time for another project. I'm picking up a sweet ass 1981 Mercedes 380SEL with a cracked head for $500. I've been wanting to squeeze a 351 EFI into something for a while now. I may just have to go molest this thing. I think a 350 horse 4-door 380SEL with a Borla exhaust note would be sweet.

I'm just twisted that way. Ask me about our 1967 VW bus/truck with a Toronado 455ci FWD drivetrain mounted mid-ship in it. That one sure turned heads. ;D

Jim

Cool this answers my questions. My question about the crawl ratio was focused more on me figuring out my axle gearing. I am planning on running a 203/205 doubler and I was looking to see if I run 3.50s would the torque make up the difference. I had not thought about it not making the torque at crawl speeds.

Thanks,
Kris

 

[broncokak]

The more I hear about this swap the more I'm interested in doing it. Please keep the info flowing.

Thanks,
Ken

 

[Mtn Gote]

Cummins 4bt

I hope I am not being a pest, but my buddies and I went to naches a week ago and we ran into a '66 bronco with the 4bt in it and i really liked it. But I was just wondering what all did you have to do to have the motor in the bronco. And did you have to put a hood scoop init to fit? I am just another bronco enthusiest trying to make their ordinary bronco into something worthy on the trail and road.

 

[Heinz_67]

Mtn Gote,

Was the Bronco a member of CB? I sorta feel like the lone ranger on here sometimes. I know there are several projects in the works, but I'd love to talk shop with another running Bronco!

No hood scoop here (although I think they look cool as you know what). I did have to do a 2" body lift for the NV4500 and the Atlas. With that done, the engine cleared with no problem. Why do you ask? Did the one you saw have the intake tube crossing over the head and sticking out of the hood?

I have given serious thought to grafting a huge (3-4') shaker cowl induction onto my hood and mounting the intercooler above the engine sitting in the scoop. However my wife has used the homemade term ghetto-neck (ghetto and red-neck combined) to describe how she thinks it would look.

You don't have to go diesel to have a good trail rig. I can't tell you how many times I've said, "I wish I still had my old '66 with the 6 banger and 3 on the tree!" With the right gearing, that was an awesome (and reliable) setup.

Jim

 

[supercoupe5]

i have been considering this swap for quite a long time now. i have tracked down 2 engines but have yet to go get either one. now with the mods you have done to yours for the performance end of it (and it sounds like they worked quite well). have you checked to see if the mods have affected the mileage of the bronco at all. i found in some reading of conversions that it is possible to get 25-30 miles to the gallon with the 4bt. not that mpg is a big deal but when i get my kids i drive 350 miles round trip 2 times every other weekend and my 96 eddie bauer only gets around 17 mpg. that is around $150-$200 a weekend for fuel depending where we go and what we do when they are here. dave

 

[mlogan24]

Jim,

I'm curious to learn more about the intercooler. I was looking at Summit's site and the custom Spearco's are $770 (the retail pricing on their website seems to be in that range)! I was wondering if you could give a little insight on if you bought new or found a used one that worked. If you have any dimensions or pics of how you currently have it mounted that would be cool to.

I'm considering the 4BT swap (and trying to figure what kind of a budget I'll need), and know its a pricey proposition-but $770 for an aluminum radiator?! If that's what I have to buy, then that's that, but I can't help but think there's a more economic solution out there.

 

[Mtn Gote]

4bt

The reason i asked if you had to put a hood scoop on it is because this guy had one on there and i dont want to put a 4" scoop on my Bronco, maybe a 2" scoop but nothing big. The Bronco over at Naches was a yellow '66 i believe, and it had a partial exo cage, and it did have a snorkel on it but i do not remember where it came out of. it had 35" bfg i think and duffs 3.5" lift and a 2" coil spacer and a 1" block. The reason I want to put the Cummins 4BT motor in is because the uncomprimised power of a Diesel and the great fuel mileage. The 351 Windsor that is in my Bronco is fuel hungry if you know what I mean. I don't want to have to fuel up as much with the 351 since gas is at a low of 3.09 a gallon. Do you know how much your 4BT's MPG, The Naches Bronco got 35 MPG trail and street.

 

[Heinz_67]

I'm slightly less than 30 mpg on average.

 

[Madgyver]

What's the best donors that have this motor?

 

[relm4x4]

Hey Jim, I've been following your project for a while now and it sounds like it has worked out awsome. I was just checking your website for updates and it didn't seem to be working, is it still up and running or does my computer just hate me again ? I wish there were more 4BT's up here in Canada, just doesn't seem to be as common.

 

[hucklburry rev2]

I hope my good friend forgives me, I did not ask before posting:

When I saw this project I thought of one guy who knows 4Bts like the back of his hand and has something like 8 Eb's in his family. That guy had an interesting story that I am sure he is too nice to discuss with most here.

I would be impressed if people did what they said. Its really easy. Say your gonna do something and do it. My friend does, no doubt. Thats part of how you all are reading about this, as help was dispensed and things were sold but not really paid for. He has done it before and am sure he will do it again. thats just how he is.

So like I said, a friend did not approve of me doing this, I just think if you get parts from someone for working on your EB you should pay for them or live up to the deal you struck.

--Jim

 

[Heinz_67]

Excuse me.... Exactly who and what are you talking about?

Me?

I've got no ghosts! Speak your mind.

Jim

I hope my good friend forgives me, I did not ask before posting:

When I saw this project I thought of one guy who knows 4Bts like the back of his hand and has something like 8 Eb's in his family. That guy had an interesting story that I am sure he is too nice to discuss with most here.

I would be impressed if people did what they said. Its really easy. Say your gonna do something and do it. My friend does, no doubt. Thats part of how you all are reading about this, as help was dispensed and things were sold but not really paid for. He has done it before and am sure he will do it again. thats just how he is.

So like I said, a friend did not approve of me doing this, I just think if you get parts from someone for working on your EB you should pay for them or live up to the deal you struck.

--Jim

 

[mlogan24]

I hope my good friend forgives me, I did not ask before posting:

When I saw this project I thought of one guy who knows 4Bts like the back of his hand and has something like 8 Eb's in his family. That guy had an interesting story that I am sure he is too nice to discuss with most here.

I would be impressed if people did what they said. Its really easy. Say your gonna do something and do it. My friend does, no doubt. Thats part of how you all are reading about this, as help was dispensed and things were sold but not really paid for. He has done it before and am sure he will do it again. thats just how he is.

So like I said, a friend did not approve of me doing this, I just think if you get parts from someone for working on your EB you should pay for them or live up to the deal you struck.

--Jim

Ahhhh, the vague anonymity of the internet . . .

 

[Heinz_67]

I just reported his post to Jon. You don't come on here and make blind accusations while hiding behind anonymity. Numerous friends from this board have emailed and called me asking what the hell this guy is talking about. They, as I, felt this post sounded as if it were directed to me. I have responded in this thread and also sent him a PM with no response.

You're in St. Louis and I'm in Denver. I seriously doubt you are talking about me, but you need to clarify.

James Miley

 

[bigpappa]

I have not ever met Heinz in person but he has answered every question I have asked him about his project, sometimes many questions in a row all without any frustration. I don’t know about you but to me that is something that I consider a trait of an upstanding person. I do not see how you can come on here making vague accusations to someone who is just showing progress on their rigs and helping others who is thinking of doing the same type of projects.

If you have something to say get your facts straight and be a man and say you mind and give more than just random thoughts that are not aimed at anyone and quoting your friend.


Kris %)

 

[bigmuddy]

cummins 4BT update

I know huckleberry as I used to be from St.louis MO. He is a stand up guy and will probably post later? Heinz I will PM you.

Ben