4bt or 6bt into a K5 blazer

[DougKrebs]

I drove and wheeled (off-roading) my K5 all through college to the point where every body panel is dented from many off road trips. In college I always dreamed of graduating and buying a 96-98 12 valve and pulling a gooseneck with the K5 and a rock buggy. Well reality hits when you want to buy land and build a house.



Right now I'm driving a 96 Ford 150 with the inline six (300CI) and it's nice and it tows decent, but I liked my blazers ability to handle muddy roads, ranch roads, etc... better.



So 2 weeks ago I get a good deal on a new blazer body and found out it had been a diesel. So I get to thinking about how a diesel blazer would be nice to have. Good MPG, power, and off road ability. I first thought of the GM diesels that were orginally in it, but I know these diesels are gutless. So I've decided on a cummins.



I know plenty of mechnical knowledge from offroading to make it work, but I lack diesel knowledge. So I'm starting to look at the 4bt and the 6bt options. I really don't care about fitting them in, if it's a problem I can cut out the fire wall and move it back. I plan on doing a custom dash anyways.



So would the 6bt be a better option for the obvious power gains? I'd probably leave the 6bt stock as I'm not looking for huge power. Whats the difference in economy? I've heard it's pretty negligible.



What are sources for these engines? Obviously the 6bt could come from dodges. Where else can they be found? Whats the best year to use? I know 4bt can come from bread trucks and are usually coupled with an SM465.



I'll probably use an NV4500 and a 205, but I've also thought about using a SM465 with a gear vendor overdrive and NP205.



So what is ya'lls advice? Any help would be appreciated!



Thanks - Doug Krebs

 

[Cooker]

I'm sure you are aware that you would need to swap front axles if you went with the 6BT. I would plan on swapping the rear as well.



The 4BT was in a ton of "bread" vans. The Frito-Lay trucks around here are running 4BT's. I would imagine you could find one pretty reasonable.



If you are looking for a fun, economical, trail rig I would opt for the 4BT. Maybe I am a little partial though because I have always wanted to put one it a CJ

 

[DougKrebs]

Originally posted by Cooker

I'm sure you are aware that you would need to swap front axles if you went with the 6BT. I would plan on swapping the rear as well.



The 4BT was in a ton of "bread" vans. The Frito-Lay trucks around here are running 4BT's. I would imagine you could find one pretty reasonable.



If you are looking for a fun, economical, trail rig I would opt for the 4BT. Maybe I am a little partial though because I have always wanted to put one it a CJ

Rear is a 14 bolt already, front is a 8 lug 10 bolt. Are you saying that i would need to swap the front axle because it couldn't handle the weight? Or it couldn't handle the power and i would break shafts?



This really wouldn't a truck to purposely go off-road in. It would be an all around truck. Daily driver, mild tow rig, and driving ranch roads. I'm building a full tube buggy for offroad, so I'd never be hard on this truck offroad.



If I do this, the blazer would need to be my full time daily driver as I would sell the F150.

 

[Cooker]

Originally posted by DougKrebs

Rear is a 14 bolt already, front is a 8 lug 10 bolt. Are you saying that i would need to swap the front axle because it couldn't handle the weight? Or it couldn't handle the power and i would break shafts?

I have never been a fan of the 10 bolts. There is no question in my mind that it could not handle the weight of the front of the truck with a 6BT in it. I also don't think it could handle the torque of a properly tuned 6BT.



I don't think you will have any serious issues with the 14 bolt in the rear.

 

[SRadke]

Figure on a thousand pounds for a 6bt. Just the engine.



-Scott

 

[DougKrebs]

Originally posted by Cooker

I have never been a fan of the 10 bolts. There is no question in my mind that it could not handle the weight of the front of the truck with a 6BT in it. I also don't think it could handle the torque of a properly tuned 6BT.



I don't think you will have any serious issues with the 14 bolt in the rear.

God I hope I wouldn't have any issues with the 14 bolt, there's not too much stronger. I guess a Dana 80.



What do you think would not hold up on the 10 bolt? The ball joints? I doubt the wheel bearings are going to notice a 1000 extra pounds. If we are figuring that the 6bt block weighs 1000 pounds and a 350 weighs 400, that's really only a difference of 600 pounds.



I really don't think the 10 bolt will be an issue with handling the weight. Now breaking shafts and U-joints is a different story.



Lets get onto things I don't know about, like intercoolers. I know what one does but don't know much about what I would need. I guess the best thing to do would try to find a wrecked truck and take everything out of it. What do these engines use? Air to air, or air to water?



What about brakes? Am I going to have to switch to hydroboost?



Thanks for the help so far!!

 

[SRadke]

Dodge uses an air to air intercooler that sits right in front of the radiator. To salvage one from a pickup would be the easiest. The older model engines (everything before 97) used a regular old vacuum booster for brakes. A conversion should be no issue as far as that is concerned.



-Scott

 

[DougKrebs]

Originally posted by SRadke

Dodge uses an air to air intercooler that sits right in front of the radiator. To salvage one from a pickup would be the easiest. The older model engines (everything before 97) used a regular old vacuum booster for brakes. A conversion should be no issue as far as that is concerned.



-Scott

Thanks for the info!



How big of a radiator is needed? I have the stock diesel one for the 6. 2 that came with the blazer, it's a 4 core and is pretty big. Do you think it would be adequate?



I'm going to have to start checking out junkyards. Only problem with that is I've been going to junkyards for years to get 4x4 parts and have never really seen a cummins in a junk yard. What do insurance companies do with wrecked trucks? If I could buy a whole wrecked truck that was smashed from the side or rolled that would be optimal.

 

[britannic]

The 4 core will work fine, fyi, there are guys on www.thedieselpage.com using 300HP 6. 5LTDs with that radiator for heavy towing.

 

[DKarvwnaris]

I had a 79 blazer with a 6bt in it back 1994. The 10 bolt front end in it held up fine. I had 285/ 75 r16 tires. (I didn't drive irt like an idiot either though). transmission was a Getrag out of a 91 dodge along with the dodge transfer case. Rear was a 14 bolt full floater

with 3. 41 gears. My main problem with the truck was the steering box section of the frame breaking out. I ended up building a crossmember to tie the frames together along with the steering box. I had a 6bt and opted to not install an innercooler. The engine fit fine and since I had a Dodge donor truck, the exhaust even fit in between the frame rails with the dodge transfer case.

My front end was all fiberglass prerunner parts with a tubular steel coresupport. The weight difference between the big block 454 and the cummins conversion ended up being 175 lbs heavier as I put the fiberglass parts on the same time as the cummins. The engine fit with the cummins fan using the stock coresupport so you should not have a problem. My biggest problem was the copper radiator coming apart all the time. I ended up going to a 94 dodge aluminum one with the plastic tanks, it is still in the truck after it has changed hands to to its new owner and several desert seasons of severe abuse. He has upgraded the front axle to a dana 60 but then too, he is a little abusive to his rigs jumping them in the sand etc.

A 4bt will go in on the stock GM mounts. If you get one out of a GM p-30 bread truck with the 465 transmission, it will be almost a bolt in conversion. I have installed several of these in 1/2 ton 2wd gm pickups, mileage was in the upper 20's. Power is more than any small block I have seen, so if you're towing with a small block, you'll have no problem with a 4bt, you can always outfit it with an inner cooler and get the pump adjusted up a little. Weak point will be the clutch when you start getting the motor turned up. They are cheap enough though, that it is a consumable part you can swallow, unlike the dodge cluthes, but they hold up uncomparably. I have seen 465's with cracked input shafts using the 6bt's, keep that in mind before you crank the motor up too much, even stock they'll do a job on them.

 

[GOLIATHGMC]

6BT sources

Doug -

I am currently gearing up to put a B5. 9 into my '85 GMC Crewcab, and like you I have been on the hunt for a good source for a donor engine. I have found a Freightliner FL70 in a local medium/heavy duty truck wrecking yard that has one. A bit of research showed that FL's could be ordered with several different engines, one being the B5. 9 Cummins. I am also hearing that they have slightly beefier bottom ends, but basically they seem the same.

George

 

[DougKrebs]

Re: 6BT sources

Originally posted by GOLIATHGMC

Doug -

I am currently gearing up to put a B5. 9 into my '85 GMC Crewcab, and like you I have been on the hunt for a good source for a donor engine. I have found a Freightliner FL70 in a local medium/heavy duty truck wrecking yard that has one. A bit of research showed that FL's could be ordered with several different engines, one being the B5. 9 Cummins. I am also hearing that they have slightly beefier bottom ends, but basically they seem the same.

George

DKarvwnaris - Thanks for the Info



Goliath - In a few years after I get married, buy a house, etc... I'm planning on doing a 8. 3 cummins swap into a older chevy crew cab with a fuller 9 speed transmission, 2. 5 ton t case, maybe rockwells, don't know. Thats a couple years down the line though...



How much are they charging you for the 5. 9? Where are you getting your NV5600 from?

 

[DKarvwnaris]

Give my buddy Kenny a call for the 4500 and 5600 kits, he is getting them direct from NV from what I understand. I am not sure what his costs is on the 5600 as I haven't ponied up for one yet. MY 4500 was $2100 last year though. I think they went up $100 or so now. 406 727 8915 autoworld.

He has numberous 5. 9 engines out of dodges, If I remember right he had an entire driveline coming in this month.



I doubt there is a differnce in the bottom end of the cummins motors installed in the Freightliner's. The 5. 9 blocks are the same in all applications I have seen them in so far. Usually the difference is the fuel systems. Farm engines have the variable speed pumps verses the automotive 5. 9's with the throttle controlled pumps. All the recon engines I have seen have been the same part # regardless of what they were going in if you ordered a long block. This is in regards to the 12 valves as I will put off as long as I can owning a 24 valve or newer.

 

[GOLIATHGMC]

5 and 6 Speeds...

Doug...

Go out and get yourself a current 4Wheel & Off road Mag - in the back you will find a Vendor ad that says "HEAVY DUTY DRIVETRAIN COMPONENTS". The company is called Gear Tech Heavy Duty, and the person I spoke to was Wayne. I dont remember the exact numbers (it was several months ago), but it was around $2500. That would get me an NV4500 DHD with a custom adapter to mate it directly to my NP205. They are located in Richland, MS - (601) 898 - 4552.

Your plan for the 8. 3/Fuller/Rockwell truck sings me a tune!

And once more, back to the "Beefier" FL70 B5. 9... ... PM F8LDOSE about the differences - he has hands on experience with one of these, and says most parts carry the same part #'s as the Dodge versions, but they have larger fastners for the mains, and visually they appear heavier duty (larger). You can also check out his response to my original post in this forum titled "5. 9 from a Freightliner".

Just so you know, I am not that far ahead of you - I am in my house less than a year

George

 

[DKarvwnaris]

Goliath,



The only "adapter" needed to put a 205 behind a 4500 is the coupler sleeve that connects the output shaft of the transmission to the input shaft of the 205. I don't remember these being a very big cost last I checked. The actual bolt pattern of the housings are identical. I had to adjust my transfer case shifter in my 93 a few years back when I pulled the getrag for a 4500, but that was about it.

Shipping might be an issue getting the stuff to your area but I know Kenny can get the stuff cheaper than that.

 

[DougKrebs]

Adapters are not a problem for me. I've got a friend who's a machinist. The problem is I'm cheap!!!