The official 6bt conversion thread

[averagef250]

You should drive a diesel pickup, preferably one with a mechanical 5.9 Cummins so you get a feel for how drastically different everything is from an old carb gas engine.

[1971ford]

A buddy of mine has a 6bt swapped into his chevy crewcab, maybe i'll see if i can test that beast out.
Drastically different as in RPM ranges, shift points, etc.?

[averagef250]

A buddy of mine has a 6bt swapped into his chevy crewcab, maybe i'll see if i can test that beast out.
Drastically different as in RPM ranges, shift points, etc.?

That would be a good start. Ideally get some seat time in a stock dodge diesel, possibly even towing with it so you understand what you're getting into. Compare how the dodge drives with a 5 speed and then go drive one with a 6 speed. Then have a good start to understanding what it is you want to put in your truck.

[gregamorton]

completely different!! I am a big fan of autos over 5 speeds. I would like the 5.9 with np435 and factory style clutch feel though. I just bought a 93 dodge one ton with the 5.9 and auto overdrive. I love the sound of a 12valve that is stock over the newer common rails. Good luck with what ever you decide to do with your ride!

[fireguywtc]

Ahh, i see...
So dodges from 92-98 ish or whatever that time frame is, came with one option for a manual transmission and that is the nv4500 5spd?

I just realized, that I'm going to be losing my granny gear. I loved the gear sooo much. Hopefully the 1st gear in the nv4500 is somewhat low, sounds like it is, just not as low as the granny in the np435.
You said the zf5 is like my np435 with a OD. Does the zf5 have a granny 1st like the np435?
Where do i find a zf5 that will bolt to the cummins or would i need to also find an adapter plate? What would i expect to pay for a zf5? If i could sell the nv4500 and find a zf5 for the same or lower price then why not?

Dustin is right, you need to drive one to see what it feels like. To me the first gear is an in between granny and second gear that is syncroed. But it works fine, but reverse is higher too and that is something I don't like. You have to float the clutch a bit if you want to back up slow. The Dodge reverse is too high imo. I am not up on what Dodges have what, but I know what you are looking for is pretty common. I don't know what they are valued at either. I am 99% certain a ZF5 would need to be adapated, but I think they are longer so they would also be more difficult to fit between the engine and transfer case. Also know that you are probably going to have to adapt a hydraulic clutch setup also.

[CrypticRacer13]

This one is for you Ryan just to put more in your head haha dont know anything about this, an dont know if its whats needed or wanted from a 4bt but its worth the pics
http://sfbay.craigslist.org/eby/pts/2595677817.html

[CrypticRacer13]

Also this one
http://sfbay.craigslist.org/eby/pts/2547922038.html

[averagef250]

Adding to above, If you don't intercool you can probably get away with running a bump radiator, but the ports are all wrong. The old ford copper/brass radiators are not compact at all. You really need a supercool to hope to keep a 5.9 cool towing in a hot climate and the supercool is just too darn thick. Well, the core itself isn't thick, but the tanks are and they keep it pushed towards the engine away from the core support making it very hard to fit in place.

I've done some of this stuff (31 diesel installs since '07) and have only done a handful of Cummins six installs into pre-79 Fords. They were a b*tch to say the least, the engine and the components to support the performance wants of the customer and a desire to keep the truck somewhat original appearing just don't play well together. Most hate cutting the engine crossmember and there's no way around it. There's not room for an adequate size radiator or intercooler in these trucks, not just because the engine bay is too short, but because the inner fenders set where they do.

If you want ease of install forget the intercooler or just live with a 91-93 dodge peanut intercooler being the biggest thing you fit behind the grill without major cutting. This is going to limit what the engine can do to less than most people want from a six Cummins and quite a bit less that a 4 cylinder diesel can do in the same real estate because there's loads of room for a proper radiator, fan and intercooler to support whatever power level you want.

The 4 cylinder diesel comments are not reality, the internet is not the best source for real world evaluations. "The 4BT"- I say "the 4BT" in quotes because I get a kick from people grouping all 4BT's together like all 6BT's are dodge engines. I've done lots of 4BT stuff, had 50+ engines that Cummins calls 4BT's go through the shop here and maybe a dozen of those were very similiar engines, all the others were variations built for thier ordered purpose. Depending on the parts they had in and on them they made different power, sounded differently, had different mileage and so on. I've had people trash on 4BT vibes and gutlessness only to be amazed they are actually riding in "Oh my god! This has a 4BT in it?". It's funny to me and it just takes a bit of tuning to get a lot out of these little guys.

Art is over dramatizing the downsides to 4 cyl diesels, but he is right about the power pulses, not how they destroy your vehicles drivetrain though. Depending on the engine, you will feel the individual power strokes for each cylinder below 1700 or so past a certain throttle position. I feel it's a non-issue. My wifes Expedition locks the converter in OD at 55 MPH and 1460 RPM. I regularly drive with switches overriding OD and Lockup and run it down to 35 MPH or so in OD with the converter locked and still accelerate. I remember a customers 1994 F-350 4x4 with a factory settings 105HP VE 4BT and M5R2 I did. It had 35's and 4.10 gears. I took him for the first ride in it, he was pretty impressed and we ended up going from a dead stop to 5th gear without touching the gas pedal. When you did use the skinny pedal it still had decent power and I ended up setting it to around 200HP later on for him. That F-350 is no slouch.

Isuzu has, oh, say 10 million or so NPR and NQR trucks on American roads today with hundreds of thousands of miles on each of them on average. They almost all have 4 cylinder diesels. You probably drive next to them everyday not realizing you're sitting at a light next to a 210HP 500 lb/ft 4 cyl diesel moving 20K pounds down the road without a sweat getting 15 MPG.

Just saying a deal on a four diesel might not be something to pass up when you consider what it is you want to do and the real estate your truck has to do it with.

[1971ford]

Thanks for the info.

So if 4.10's, 37',s and a nv4500 is a terrible combo, what diff gears would make this a decent combo? 4.56?
How would a 6bt, nv4500, 4.10 diff gears and 35's do?

So the downpipe from a dodge truck isn't even close?

Do you say high teens for mileage because of the 37's, 4.10's and nv4500 combo? would mileage be in the 20's if properly geared?

So is the top of the valve covers a good enough spot to measure angle? Not sure how exact it is to crank centerline, it must be close.

D24= bad idea, I figured you would say that, I do plan on swapping on a np205, is that better? I'd like to keep a divorced t-case.
So what if i re-ask the question... How do i hook up the shift linkage on the NP205 when running a nv4500?

Sounds like i'll have to live with the factory highboy radiator (I'll swap the lower port over to passenger side) and the smaller dodge intercooler.

So i'd have to add a return line to my mustang gas tank, where does the return line need to go? Can it go to the bottom of the tank near the sender? Sure would save some work if i could just flush the tank and TIG a return line to the bottom, but maybe it needs to go to the top of the tank..

Is there a pump somewhere on the frame of the dodge that i'd just have to swap over and wire up?

[1971ford]

Hmmm

Art fit a big powerstroke intercooler with some mods, and using stock highboy radiator . I believe this would be the route i'd go


And another 6bt cummins highboy with powerstroke intercooler and highboy radiator






I could always do this.

[averagef250]

I guess I'm just too picky, Sawzall away!

[fireguywtc]

I say skip the intercooler if you just want a mild diesel. But if you insist, you could also consider using a custom smaller intercooler in a more remote area like below the radiator support, or doing a custom air to water intercooler. They are smaller I believe.

[Ranchero50]

Hood latch is gonna be a bear with any intercooler. I'm working through that now...

Jamie

[1971ford]

I guess I'm just too picky, Sawzall away!

I don't see a problem, provided that you keep all cuts clean. Sawzall definitely wouldn't be my weapon of choice for anything! So you have to trim the grill down where you will never see it unless the hood is open, but i think more attention will be focused on the 6bt And last resort... grab another $40 grill.

I say skip the intercooler if you just want a mild diesel. But if you insist, you could also consider using a custom smaller intercooler in a more remote area like below the radiator support, or doing a custom air to water intercooler. They are smaller I believe.

But i know if i skip the intercooler i will be regretting it every day i drive the truck just wondering what little more power i could get out of it if i had of done the intercooler. I dont mind trimming the grill a little.

Hood latch is gonna be a bear with any intercooler. I'm working through that now...

Jamie

Yeah I noticed that, not too worried, nothing a little fab work and thinking cant fix.




Any input on my second series of questions?

[Ranchero50]

That little fab work is turning into a monster so don't belittle it too much or it'll eat you up... With the aluminum IC I used (similiar to the one on the Volvo) I had to torch out the bottom of the rad support where the corners will go so it would fit in the recess of the rad support. With it there I'm about 1/2" away from putting the grill flush with the fenders at the bottom so trim or bend to fit at the options now.

On the hood latch I've pretty much given up on the OEM setup because it will crash into the intercooler now. I'm probably going to fab in a '90's hood release on the rad support and modify the hood to suit.

Jamie