Calling all Diesel Broncos

[bigpappa]

I think I am going to drop a cummins in my bronco while I am doing my frame off. I am currently debating engine options. My question is is there room to shoe horn a 6bt in the engine bay? Just looking at the few pictures I can find it looks like it might fit but it would be tight. If I had to move part of the fire wall I would not have a huge problem with that seeing as I have got to do some panel replacement there any way.

What are the length differences in the 4bt and the 6bt? Both at the head and down at the crank. Does anyone have some video of their rigs running (Miley, swa0330)? I did a little photoshop on two of swa0330's pictures and it looks like it would be real tight both front and rear. This is just total guestamate at this point because I do not have real world measurements. That is why I am asking about it here. Below is the origonal pic and the photoshop versions.;D

 

[broncomanbrad]

With the 6BT you would also really want to consider the weight. The 4BT is around 700lbs and I'm sure the 6BT would be at least another 100lbs. Probably more. You would need to upgrade your suspension in the front heavily. You'd probably want to offset it in the back with something heavy. I kinda doubt you'll be able to fit it in without serious mods to the firewall. Always worth it to try though.

 

[bigpappa]

Yea from what I have read the 6 is about 900lbs. I am putting in a new suspension anyway with a full width d60 front and rear and extending the front forward a couple of inched and the rear back about 4 inches. Hopefully that would help with the weight a little bit. I do agree that it would be nice to have some counter weight. I still have not made up my mind yet I am just trying to figure out if the 6bt is feasable because it seams like they would be easier to get my hands on. I may end up going with the 4bt in the end.

 

[broncomanbrad]

Ya they are definitely easier to find than the 4Bt. You know...... if you REALLY cut up your firewall it might easily fit. Hmmmmmmmmm.........

 

[nutter3]

What a dream;D I would love to have the power and torque from my Dodge in my bronco. I have always just dreamed about a 4BT in there, now I'll have to up the ante and start dreaming of a 24V 500 HP, 1000 ft-lb coal breathing monster with a 6" stack coming out the bed of my little bronc!

 

[swa0330]

You pretty much better plan on resectioning your body if you want a 6BT in there. In addition, you are going to have to probably reinforce 1/2 the frame with C channel steel to accomodate the 1100lb (not 900lb) motor. Consider this, the 95 Dodge ram 6BT in stock form put out 160hp and 420 ft lbs. My
4BT puts out 105hp and 330 ft lbs in stock form. That is more than enough to move 38" Michelin ZXL's and a Keiser M715 with a 14bolt rear and 60 front. Just ask Lee Alessi on TDR. I have added the HY35 for more performance and intend to do moderate fueling changes to get about 175-200hp and 500ft lbs or so. I cannot imagine how unruly and powerful it is going to be at low end trail speeds where torque is at a peak.

I really hope you are a body expert, welding master and patient if you want that in there. There is only about 5 inches of clearance between the radiator and the all of the pulleys on the motor. One cylinder is almost 5 inches in length. My motor is also as far back as it can go for the most part. The pics don't show it, but going back isn't much of an option. I am not trying to sound like a smartass, but just be realistic and use a 4BT. Then you will have a lot more to discuss with others on the board who have done this.

 

[bigpappa]

You pretty much better plan on resectioning your body if you want a 6BT in there. In addition, you are going to have to probably reinforce 1/2 the frame with C channel steel to accomodate the 1100lb (not 900lb) motor. Consider this, the 95 Dodge ram 6BT in stock form put out 160hp and 420 ft lbs. My
4BT puts out 105hp and 330 ft lbs in stock form. That is more than enough to move 38" Michelin ZXL's and a Keiser M715 with a 14bolt rear and 60 front. Just ask Lee Alessi on TDR. I have added the HY35 for more performance and intend to do moderate fueling changes to get about 175-200hp and 500ft lbs or so. I cannot imagine how unruly and powerful it is going to be at low end trail speeds where torque is at a peak.

I really hope you are a body expert, welding master and patient if you want that in there. There is only about 5 inches of clearance between the radiator and the all of the pulleys on the motor. One cylinder is almost 5 inches in length. My motor is also as far back as it can go for the most part. The pics don't show it, but going back isn't much of an option. I am not trying to sound like a smartass, but just be realistic and use a 4BT. Then you will have a lot more to discuss with others on the board who have done this.

I know you are not trying to be a SA this is exactly why I was asking. And this is exactly the kind of ansswer I was looking for. It just looked from the pictures above that you had all kinds of room so if you did why not add some more muscle. ;D

Have you got yours out on the road yet? How does the power compair to a 302 or 351 at both trail and road speeds? Could you see it at 70-80 mph with a zf and 3.8? - 4.1? gears? I am looking to build it as a dual purpose machine that is road worthy and trail worthy. I figure I can gear the axels for the road and get the trail gears with a doubler. From what I have read you do not need real low gearing with it because of the torque. Do you have any video of it running. I have only seen 1 video of one running and it was crappy video and it was short so I could not get a feel for the sound of the engine. If you have video I would love to see it. Thanks for your input looks like I am on the hunt for a 4bt. ;D

 

[swa0330]

I am still working feverishly. I am dam close and expect that the next week is when I will fire the motor. The video you saw was for Miley's bronco. It really doesn't do it justice. Miley has an NV4500, Atlas 3.8, and (at the time) 4.88 gears. When he put the thing in 4 low, he couldn't stop it with his 4 wheel disc hydroboost and the thing woudn't stall. It was like the terminator or something. I am running the NP241 because I don't need that much gearing.

I looked into running a 6BT in a 78-79 bronco. After doing enough thinking, I have come up with the conclusion that the easier route would be to make matching body mounts and just throw the bronco body on the truck frame. You wouldn't need to do much except change the leaf spring hanger location and cut the excess frame. The major point is that if you look at a 3/4 ton truck frame these days, they are WAY more stout than the 78-79 frame (I am pretty sure they are c-Channel and not boxed like an EB). In addition, the front end is already 4 linked, which is better in my opinion. In my talks and observations with many people, the most difficult thing in a project when considering roadworthiness is getting the front end set up right in the caster, etc...

The clearance for a 6BT in a big bronco is pretty tight too though. I calculated, and I think that the bay still need to be 2 inches longer. That would work with an EB, because you could cut the inner core possibly. The big broncos just have a grill.

As far as the power, from the brief ride in Miley's rig (which he is still tuning and stuff) I felt it was far from gutless. I am not hoping to get anyone riled up, but with the direction fuel prices are headed I couldn't be happier to do the conversion at this point. I know someone will get out their math book and show me how the average fuel cost versus conversion cost don't pan out. However, when you are already planning a frame off, those mathematics go out the window.

All breadtrucks are starting to be auctioned on dovebid.com. Go there and you'll probably win a Frito truck at the auction. PM if you have specific questions.

 

[Heinz_67]

IMO, a 6BT in a Bronco would be a total waste. You would not be able to take advantage of the pulling power because of the short wheel base. I have a friend that put a 6BT in a K5 Blazer and he wishes he would have just gone with the 4BT because he is only getting around 20 mpg and I out run him in my Bronco. Granted, I've done some serious math and experimentation to find the optimal turbo and fuel curve on mine, but the fact is I out accelerate him and get 30 mpg while doing so.

As far as size goes, I never consider that a limitation. If you want it bad enough, I'm sure you can make it fit.

Jim

BTW - I just bought a Frito truck I was going to canibalize for a Grand Wagoneer project, but I've decided to go with an ISB engine instead. If anyone needs one, let me know. It's a low mileage strong running van with turbo and hydroboost.

 

[74BroncoCO]

Just listen when the bread truck comes by. I have heard Miley's and if you're a diesel nut, it will excite you. It is somewhat loud, but I wouldn't say any more than my 7.3L PSD. The 4BT is a great match for the bronco. I have not riden in any yet, but someday I will! Heck, I may put one in myself.

J.D.

 

[bigpappa]

I I out run him in my Bronco. Granted, I've done some serious math and experimentation to find the optimal turbo and fuel curve on mine, but the fact is I out accelerate him and get 30 mpg while doing so.

Jim

Do you have any video of your truck running? Or does anyone know of any video on the web? The only video of a 4bt in a bronco I have seen is one where a guy is climbing a hill in it and it is real grainy and is about 5 seconds long. I would really like to see something with a clear picture and good sound. ;D

 

[Heinz_67]

I'll try to post some vids on my site next week. I've got to borrow my buddys digital camcorder finish up my exams first though. I'm so sick of school! My first degree sucked, but this second one is killing me!

Jim

 

[bigpappa]

I'll try to post some vids on my site next week. I've got to borrow my buddys digital camcorder finish up my exams first though. I'm so sick of school! My first degree sucked, but this second one is killing me!

Jim

Awesome, Iam sure there are others that thank you as well.;D

Kris

 

[swa0330]

The one thing James and I talked about last night was that you cannot truly gauge the loudness of the bronco via a computer video. You can just slide the volume bar on your computer and that is how loud it is. It is just relative. I have just had some new developments in my schedule that will ensure that I will be starting mine by next weekend for sure.

 

[broncomanbrad]

The one thing James and I talked about last night was that you cannot truly gauge the loudness of the bronco via a computer video. You can just slide the volume bar on your computer and that is how loud it is. It is just relative. I have just had some new developments in my schedule that will ensure that I will be starting mine by next weekend for sure.

Would it give a better perspective if someone was beside the Bronco talking in a normal voice? Or it might have to be yelling. ;D

 

[broncoman1972]

Are any of you diesel guy's going to have your rigs in Knoxville in May?? I would like to check one out in person...

 

[bigpappa]

The one thing James and I talked about last night was that you cannot truly gauge the loudness of the bronco via a computer video. You can just slide the volume bar on your computer and that is how loud it is. It is just relative. I have just had some new developments in my schedule that will ensure that I will be starting mine by next weekend for sure.

I am not really worried about the loudness I just would like to hear the tone of the exhaust (I know this can change with the muffler) and how the whole setup sounds. What size exhaust tubing are you guys using, 3"? I know a lot of the guys running the bigger diesels are running 4" or so. With the diesel you do not have to worry about the back pressure right you just want it to breath the best it can.

Kris

 

[Heinz_67]

I'm running a 2.5" full mandrel bent exhaust with a free flow Magnaflow muffler and I can't hear the damned thing at all!!! I'm going to remove the magnaflow and just run straight pipe as soon as I can get my butt down to the speed shop and buy the materials.

Seriously, you can ask Scott. You CANNOT hear my exhaust note at all because of the turbo and the muffler. SUX!!

Jim

 

[broncomanbrad]

I'm running a 2.5" full mandrel bent exhaust with a free flow Magnaflow muffler and I can't hear the damned thing at all!!! I'm going to remove the magnaflow and just run straight pipe as soon as I can get my butt down to the speed shop and buy the materials.

Seriously, you can ask Scott. You CANNOT hear my exhaust note at all because of the turbo and the muffler. SUX!!

Jim

Well that's just not cool. I thought it was the law to have to have a loud diesel. Absolutely no muffled ones.

 

[74BroncoCO]

I can vouch for James' exhaust. The cackle of the motor is too loud to hear any of the exhaust note. But I would bet that once he removes that muffler, she'll sing real pretty.

J.D.