4bt

[WickedShelby88]

Has anyone used this engine in a swap and what kinda mpg's should one expect from it?

[moparzrule]

What are you looking to swap one into?

I've done some research. Most of the 4bt swaps are into jeeps actually. Those guys get like 35-40 MPG I've heard.

[TopDollar69]

They must be decent, FedEx used to use them in their delivery trucks.

[ottawa rogue]

but they vibrate like a MoFo. if you look in some of the older Frito-Lay vans and bread vans, you can probably find one hooked up to a Muncie 4 speed like in a 1 ton chevy. the ones i used to have to work on had bellhousings that bolted on to the trans, it would make adapting another tranny easier anyway

[Turbulence]

http://www.4btswaps.com

is a good source of info. Bell housings for Ford/GM/Mopar transmissions are available

Martin R
89 horizon
90 sundance

[WickedShelby88]

Thats exactly what I'm thinking of doing is like a Jeep Cherokee Classic or a wrangler. I think the classic would be more doable as the wife would support that venture. I believe the 4.0 straight 6 and 4BT have similar dimensions. There are tons of parts for these engines too from what I've read.
As far as vibrations that won't be my main concern. If the guys are getting 35-40 mpg thats going to make it worth it by itself not to mention if I can make it run off of veggie oil as well.

[Turbulence]

From what I have read on 4btswaps, mileage typically ranges from low to high 20s depending on gearing/tire combinations and the total weight of the vehicle. A few claim mileage into the 30's.

http://www.4btswaps.com/forum/showthread.php?t=3265&highlight=mileage

There are a few Cummins 3.3 swaps on that site too. They tend to do a bit better.

Martin
89 Horizon
90 sundance

[WickedShelby88]

I'll have to read up on it. It seems with my plans I would be able to get into the 30's which would already be an improvement over gas. The only way I can justify it though is to be able to run part time on veggie oil.

[moparzrule]

From what I have read on 4btswaps, mileage typically ranges from low to high 20s depending on gearing/tire combinations and the total weight of the vehicle. A few claim mileage into the 30's.

http://www.4btswaps.com/forum/showthread.php?t=3265&highlight=mileage

There are a few Cummins 3.3 swaps on that site too. They tend to do a bit better.

Martin
89 Horizon
90 sundance


Man all those guys have like 35''+ tires and big trucks, the one jeep I saw had 37'' tires and like 4:10+ gearing. Thats not a good example of fuel mileage from the 3.9 4bt engine. In a dakota, 35 MPG would be a breeze if you have an overdrive trans and the right gearing. The truck itself weighs atleast 2000 pounds less than most of those guys, plus you won't have 35+ inch tires on there.
Seems a lot of those guys are using a 700R4, probably the easiest setup.

[WickedShelby88]

I hate the 700R4 because they fail time and time again. I wish I had a dollar for every one of those I swapped when I was turning wrenches. I'm not so sure its all the trans, but I think it has a lot to do with it. Yeah I guess some serious fuel mileage would be possible for what I'm looking into. At the most radical end I was thinking a wrangler with 33's, but also a mostly stock looking Jeep cherokee seems to be the most appealing for hauling the little dude around and towing a small trailer or dolly with FWD car at most.

[moparzrule]

Once they are rebuilt to better specs they hold up well with a tranny cooler.
An external trans cooler is a lifesave to the 700R4 I've found anyway. Our one work van is a 95' G20 with a 350 and the 700R4. It has a factory external tranny cooler, has 275K miles on the original trans! And this van usually has weight in it most of the time, and has had over a ton in it a few times.

[WickedShelby88]

Yeah there are definitely exceptions depending on how they are cared for as well. One of my friends had one in a camaro. It was the original trans and still going after 225k. It outlasted the engine actually. I would definitely want it built for some heavy duty though given the torque of the 4BT is still something to be reckoned with compared to what was normally paired with the 700R4 although they seem to live behind the 6.5 diesel.

[JimmieD]

If at all possible I'd strongly suggest an NV4500 5 spd trans, preferably the Dodge version. Gives you a granny low, 3 intermediate gears and a .77 o'drive. You do need to make sure the NV4500 has the 5th gear nut fix done. It's plenty of tranny for a 6BT, even more than that needs, and is bulletproof behind 4BT's.

The biggest difference in mileage on the 4BTswaps site is gearing, tires, 4WD or 2WD and the way the owner drives it. I swapped a 4BT & NV 4500 with Dana 60HD rear [Dana 70 full floating axle housing with D60 R&P] with 4.1 gears into my 5,500 lbs '67 Dodge D100 Town Wagon.

The power level is equivalent to a strong 360 4bbl performance build, far better torque from off-idle all the way through rpm range. With 31.5" tires I cruise easily at 75+ mph and on the highway see 32+ mpg. The other day I screwed up coming out of a parking lot, didn't see a car closing fast. Nailed it in 2nd and power shifted 3rd and amazed to get a loud 3rd gear chirp in a 3 ton truck!

4BT is quite heavy @ 750 lbs dry, NV 4500 is about 200 lbs, plus aluminum adapter plate-bell, 50 lbs of flywheel. I had to upgrade front springs a total of 500 lbs rating, from 1250 per side to 1,500 per side, when swapping from 360. I suggest heavier spings than that if you run a big winch, or else airbags.

That swap is maybe the smartest thing I've ever done on a vehicle and the truck's an absolute joy to drive, cheap too!

[moparzrule]

First off, what did you do to the engine to get the equivalent power of a performance 360? A mild 360 will yield you 250-300 HP and 300-350 ftlbs with an RV torque cam. A stock 4BT puts out 105 HP and I don't believe it's even 300 ftlbs. The older 4BT's have a similar VE pump like on the first gen ram's, not a whole lot you can do with that besides turn the pump up which may yield you 30 HP maybe. Maybe Lucas injectors for the 6BT would fit, you'd have 2 spares. Thats like another 40 HP. You're not even at 200 HP yet.
Perhaps swap something like a HY35 turbo on there to get some better response too.
If you are lucky enough to find a newer 4BT (more $ also) you can get one with the inline P pump and mod it just like the 6BT grinding down the torque plate for decent gains (60HP, 100 ft/lbs). Not sure if the governor spring kit would work with this though, the weights are probably different since it's a 4 cylinder.
Furthermore, I'd like to know where you are buying your 4BT's and NV4500 tranny's from that you can get it cheap. A complete 4bt runs about $2-3000, and about $1500 for a 4500 trans in good shape. Not exactly pocket change here.

Don't get me wrong here though, I think it's worth the money. Just not what I would call cheap. I've thought about a 4BT swap in my dakota plenty of times, but a 4500 won't fit too well and I hate auto's.

[black86glhs]

The later 4L60's have the improvements that the 700's didn't. It is just like the Dodge truck trans, put a oil cooler on it and you will be fine.
Why not put a nvg3500 from a dakota or s-10 behind it. Cheaper than the nvg4500 and can still handle a good amount of torque.

[fastasleep]

I have some experience with the 4BT's and 6BT's. I can tell you that gearing is essential in displaying the wide torque range of the 4BT. I can also tell you that a 4BT will not rev as well as a 6BT; it seems the 6BT's are more condusive to revving.
Yes, the early 4BT's came with the rotary-style pumps (at least the ones we have been getting out of these uniform trucks). HP numbers vary; I have mostly only bought the 105 hp models (I can't remember the CPL), but I have seen ones that are 120 hp with a different CPL.
A Bosch P7100 pump, injectors and an HX35 can get you to about 270 hp. If you wanted to make more power than that I would use a 6BT.
I have seen 28 mpg in a half-ton with a New Venture 4500, but have never seen better than that myself. I don't really care for the NV's as I like my automatics (4L80E), but if it is fuel economy you are after it is a wise decision. They are far lighter than most auto's and they don't rob as much power (obviously).
How about using a E4OD from a Powerstroke donor? There are many applications for the BT's, you just have to find the right plate to match them together.
Also, don't be afraid of using a high rear gear. The half-ton that I mentioned had a 3.25:1 rear gear.
BTW, I have a spare complete 4BT and a Grand Wagoneer if you are so inclined. I also do veg. oil conversions, too.

-Les

[moparzrule]

+1 on the high gearing.

I got a question for you though, the newer 4BTA's (the 120 HP ones) already have the P pump, sooo how would just injectors and the turbo swap more than double the HP output? I mean you can get 150 HP injectors for the 6BT, but thats very extreme and will blow the black smoke like crazy PLUS thats 2 more cylinders going to make that 150 HP increase. 150 injectors to a 6BT would obviously only be 100 HP injectors to a 4BT.
So I'm guessing you are modding the torque plate with the P pump? Grinding it flat like I mentioned earlier? That should give like 60-80 HP right there.

The turbo swap won't really increase HP any, the 4BT has an oversize exhaust side already, it will just lower EGT's because it's flowing more air. I said the HY35 earlier to help with the low end boost response, IMO the HY would be better on a 4BT than the HX.

[WickedShelby88]

I pondered the 6BT in the first place when I had my ram charger, but it was going to be just too darn much weight. I'd be happy right now with a veggie oil kit, 33's, 4:10's and 25-up mpg. I think thats pretty doable especially if I used a dak R/T clone and ran a diesel in it.. Can you imagine the looks I'd get with that sucker.

[fastasleep]

The Bosch pump I was referring to was the one (ones) we have ordered from Ken Diaz in the past. Yes, they are "turned up". Moparzrule, you are probably right about using the HY instead of the HX, but the HX's are what we have used due to the availability (we have been robbing them off of 6BT's).
The later year 4BT's (some of them anyway) do come with the linear pump. That same pump can deliver damned near twice as much fuel when modified correctly than in the stock 120 hp form. Injectors are a must to realize the increase in fuel from the pump itself. The ideal turbo is still up in the air. It seems to me you want the turbo that is going to supply just enough air to clean up the fuel. If you are seeing a ton of black smoke out the stacks, that means you are wasting energy. In my experience, the HX's are not the perfect turbo for the 4BT's as they take too long to clean up the air/fuel charge. This is another reason we have used such a high gear and an automatic; we had to stay in the boost to keep the cylinders filled with air.
Like I said, I am not the source for these engines but I have tinkered a little bit. Have you considered the Isuzu diesels for your swap? They are alike in power to the 3.9 Cummins and are (from what I have been told) considerably lighter. Just a thought.

-Les

[fastasleep]

WickedShelby88, a guy down here by me put a 6BT in a Dakota a few years ago. His name is Jeff Garmon and he owns a shop right down the road in McDonough. He wrecked it a couple of years ago right by his shop and has not since rebuilt it. He has, however, built some f'n sik half- and 3/4 tons. HE is the source on the 6bt's as far as they go. He has always done quality work and he doesn't half-step. Even his shop is spotless; exactly what you want to see when have to go to a shop to get something done.

-Les

[moparzrule]

^Exactly. The HY has a much smaller turbine, but only a 2mm smaller compressor. This is ideal for the 4BT.
I've seen 6BT's put out over 300RWHP with the HY, granted EGT's were on the higher side, if the turbine can support that much on a 6 cylinder it can support even more on a 4 and yet spool up very quickly too. I'm sure the HX35 isn't bad, it's definitely better than the stock non-wastegated HX30 which comes with some huge turbine on it and a tiny compressor.

[bfarroo]

The Bosch pump I was referring to was the one (ones) we have ordered from Ken Diaz in the past. Yes, they are "turned up". Moparzrule, you are probably right about using the HY instead of the HX, but the HX's are what we have used due to the availability (we have been robbing them off of 6BT's).
The later year 4BT's (some of them anyway) do come with the linear pump. That same pump can deliver damned near twice as much fuel when modified correctly than in the stock 120 hp form. Injectors are a must to realize the increase in fuel from the pump itself. The ideal turbo is still up in the air. It seems to me you want the turbo that is going to supply just enough air to clean up the fuel. If you are seeing a ton of black smoke out the stacks, that means you are wasting energy. In my experience, the HX's are not the perfect turbo for the 4BT's as they take too long to clean up the air/fuel charge. This is another reason we have used such a high gear and an automatic; we had to stay in the boost to keep the cylinders filled with air.
Like I said, I am not the source for these engines but I have tinkered a little bit. Have you considered the Isuzu diesels for your swap? They are alike in power to the 3.9 Cummins and are (from what I have been told) considerably lighter. Just a thought.

-Les

I'm looking at a Isuzu Diesel from a NPR for a possible swap into my dakota. I don't know much about the motor but I know I can get a heck of a deal on it. It has a auto trans currently which I would consider keeping just because it's already there. Pretty much the entire truck is there ready to be parted out. I just need to make a trip over there and decide if I want it or not. I was looking into the 4bt's but at 750# it's quite the beast for a regular cab 2wd truck. The Isuzu motor looks much lighter and easier to fit in the engine bay. I'll have to get the info on it one of these days.

[fastasleep]

To my knowledge, the aftermarket support for the Isuzus is far less than that for the Cummins BTs, but that should not detour you from buying that set-up. Isuzus are a fine diesel; moderate power, dependable and long-lasting. If you don't mind doing a little more foot work for your parts, I would highly recommend the Isuzus.
Also, look at Nissan units (UD). They are expensive, but worth it IMO. And keep in mind, too, that the MB diesels available in the Sprinters are starting to pop up here and there in salvage yards, too.

-Les

[bfarroo]

From what I've been finding there isn't to bad of support and I wouldn't be looking to crank the crap out of it. Just looking for something to pull my car on a tow dolly and get half way decent mileage. I was looking at a Fiat diesel but there isn't anything out there for those.

[WickedShelby88]

Les where is this guys shop at? Sounds like he might have some good tips on what and what not to do.

[fastasleep]

Garmon Performance Diesel in McDonough, GA. You can probably use the yellow pages online. I'll look here in just a minute. He is in an industrial park right across from Summit racing, which is about 15 minutes from my house.

-Les

[JimmieD]

I didn't get back to see other responses! To answer a few questions: the horsepower rating isn't the name of the game in diesels and many make a mistake there. Diesel engines first provide torque, and in a 4BT an amazing amount. Yes, hosepower will go along with, but not in the same relationship as in a gasser. This torque is produced nearly at idle or only shortly after. Example: In my 5,700 lbs truck with 31.5" tires I simply let out the clutch in 2nd gear to start from a full stop! After it's moving I can roll on the throttle. Can't do that in a gasser.

Previously I had a '79 360-3 with performance cam, Edlelbrock 2176 intake/1406 carb, Mallory race fuel pump, filter & regulator, MDS 6AL, Accel Super Coil & Accel 9mm stainless solid-core wires, Crane recurved distributor, heads milled, competition valve job, 1 5/8" Hedman Hedders into 2 1/2" exhaust with crossover and Walker '66 Dodge Hemi mufflers, NP435 trans with 8 3/4" '489 rearend. My 4BT hoses that combo even in its near stock form!

Most 4BT's come with a Bosch VE rotary pump. That pump is good for gobs of torque and horsepower if you've a mind to turn it up. A friend drag races one and pretty amazing the power he gets out of it. There are several simple pump adjustments for much more horsepower such that you can quickly need a whole lot more turbo, even compound turbos, to keep up with the fuel from a VE pump. Afterall, the VE manages more than enough fuel to make big horsepower in a 6BT with 2 more cylinders and 2 more Liters! In many cases an intercooler such as found on 4BTA engines or aftermarket is demanded to manage EGT [Exhaust Gas Temperature] in an engine with a tweaked pump.

On my truck I have stock injectors and a stock H1C turbo with compressor side I changed to HTT Stage II [no longer available] that converts it to a 56cm HY35, using stock 4BT 16cm exhaust exducer. I installed the 3,200 rpm governor spring. I've never adjusted the pump up because the engine with just that has such a great power range with super mileage. I see over 25 lbs of boost and EGT's as high as 1,200 so it's getting fuel and making good power, no smoke. As mentioned, 3rd gear chirps in a nearly 6,000 lbs truck says a lot!

There's little difference in the revving characteristics between a 4BT and a 6BT as they are identical engines except for number of cylinders. The 6BT has more inertial mass to get in motion so it's a wee bit slower if anyone could tell. The P100 pump will handle more fuel but unless you're racing or else want to drive your truck hard and at the limits of durability continuously it just isn't needed. Who can afford to stand on the throttle every trip nowadays?

Most are happy with stock 4BT injectors but all injectors used on 6BT's fit 4BT's. Mine happens to have a 7mm injector head but the 9mm heads have adapters for 7mm anyway. Lucas POD smoke-bomb injectors fit fine but are not the best choice at all. Probably 190 injectors for 6BT are good if you really want power, but you can go way up from there to custom extrude honed.

The Cummins 4BT & 6BT are quite possibly the single most reliable engine series ever produced by any manufacturer in the history of automotive transportation. The are commonly called 'The Million Mile Motor' because of so many that drive right on through that before a major rebuild!

In my opinion NONE of the GM auto trans are up to the task of handling a strong stock 4BT and certainly not a tweaked one. Many guys insist on using them and find out the hard way. The large majority of bread vans for sale have blown GM trannies, mine went through three built TH475's in 86,000 miles! If an auto is desired the A-618 or 47RH Mopar box is far better, specifically built for the 6BT.

My 4BT trucks loaded with over a ton of tools & steel, pulling another truck loaded with same, so about 13,000 lbs pulled like it was running empty. No problem towing 20,000 lbs combined with the 5,700 lbs 4BT truck.

[moparzrule]

I did state the torque, it's like 300 ft/lbs or so. Still not that impressive. Like I said a mild built 360 V8 can put out 400 ftlbs with little effort. So the 4BT turned up some will probably put out about 400 ft/lbs, but only have maybe 150 HP whereas a 360 would have over 300 HP on a mild build.

I don't know of ANY high HP 6BT's running a rotary pump. Perhaps you can point me to a few, but the guys running big HP are running the P pump. I've never seen a rotary put down over 250 HP, my 94' which has the smaller 175 P pump put down 325 RWHP with $600 in mods. $250 for 370 injectors, $250 for a 4'' exhaust system, $100 governor spring kit, and the free torque plate grinding mod. Even if you want to include the $200 for guages, you can't top that with the 1st gen rotary pump engines. And again, I have the small 175 pump. The 215 pump (96-98 5spd) puts down 350 RWHP with just the torque plate mod alone, with the 370 injectors it puts down 400. But of course you need a better clutch and a larger turbo to support all that fuel.

[JimmieD]

One place to check on some high horsepower 6BT's with VE pump is at:
http://www.1stgen.org/ also at http://www.dieseltruckresource.com/

You'll have to thumb through archived posts there of course. I don't say that a VE can equal a P pumped engine, not at all, but that it can put out some very impressive horsepower. Again I'm also saying that a diesel's power curve is entirely different from a gasser.

A diesel is at very high torque numbers right off idle and the max horsepower is showing at maybe 2,200 rpms! Typical gasser is slowly climbing in torque & horsepower until 5,200 to 8,000 rpm's, in which time the diesel has already shifted maybe 2 more gears.

I'm still at a loss to explain, only that there's far more useable torque and horsepower throughout the diesel engine's comparatively narrow operating range. I drove my truck for 10 years with that 350+ hp 360 described and instantly felt more raw power from the diesel even before I learned how to drive it and before it was dialed in. After the minimal upgrades I did, almost nothing, it is even better. I doubt I'll ever turn up the screws on the pump, fine like it is, but if I did there's far more power available right there. I'd need an intercooler for that.

One very obvious difference was that with the Cummins 4BT I could take a particular hill without stepping down on the throttle any more, but with the 360 it always took another 20%-25% pedal to make the hill when I came to it.

To me, personally, there is simply no comparison based on factory horsepower/torque ratings, plus Cummins is well known to be very conservative there. While it's very hard to explain unless one sits behind the wheel and drives it, the difference in power curves is why ALL serious transport trucks run diesel, plus the phenomenal mileage to boot. It's a whole different kind of power. Baffles me....

[moparzrule]

That would be why diesel's typically have high gearing compared to gas engines.

I'm well aware of the power, like I said I use to own a 94' ram 2500 cummins 5 speed truck. When I got my truck it was BONE stock, 175 HP and 420 ftlbs rated. Thats about what a very turned up 4BT would be putting out. I was not impressed, to say the least. My previous truck was a 77' power wagon with a very mild 360 in it (build for torque more than HP, but had about 300 HP and 400 ftlbs), it would have ran circles around it and laughed all the way.
I was also not impressed with the stock pulling power of the ram. Yeah it would tow a lot of weight, but take forever doing it with your foot flat to the floor all the way. You need HP, not just torque. After I turned the truck up and had over 300 HP, well now we're talking. When I sold my ram it was easily as fast as my old power wagon and also could have hauled 3 times as much weight faster than power wagon.

Now on the fuel mileage thing, of course thats the largest plus on the 4bt's side. No argument there.
I have contemplated putting a 4BT in my dakota, but I hate auto's and an NV4500 won't fit very well without some major hacking to the floor pans.

[JimmieD]

Some other notes: I was very fortunate on my swap, some of which is described at the 4BTSwap forums. I got the donor Frito-Lay van for $1,300, and the NV4500 delivered for $800, both rare events. It was a blessing as many now pay $3,000+ for a donor truck, or $2,000-$2,500 for engine alone, plus $1,200 or more plus shipping for an NV4500.

Cummins adapter plate, flywheel & clutch was roughly around $400+, already had a Dana 60HD sitting around, and a friend gave me a D200 front axle. I added new front Eaton Detroit Spring packs for $300, upgraded 1,000 lbs to get me to 1 ton, and beefed up my rear springs with leaves from the other D200. Got a custom built drive line
from Tom Wood's Custom Driveshaft, excellent quality and FAST SERVICE, for around $150, added Spicer 4160 u-joints and 6BT output shaft balancer/slip-yoke. Used the 32 gallon aluminum fuel tank from donor van, plus its fuel lines and electric fan.

Sold donor van for $1,500 less engine [!], got another few hundred for other leftovers, sold my 360 and NP435 and miscellaneous, ended up with about $1,000 total in the swap!

Vibration is an issue but so is the noise and smell, all part of the grand diesel experience hah!

Many of the guys on the 4BT Swap forum are running 2WD like mine, with smallish tires. I ran 29.5" up until my recent change to 31.5's. Either way an excellent daily driver, nothing but smiles on my face every time I fire it up.... :)

[JimmieD]

Few other thoughts: 4BT weighs about 800 lbs with fluids, NV4500 about 200 lbs, flywheel/clutch, Cummins adapter plate, 6BT bellhousing about 80+ lbs. so that's over 1,000 not counting extras like mounts etc.

4BT is pretty tall, about 36", many guys have to run a bulge or scoop in the hood.

Proper motor mounts are critical to a happy driving experience.

The single most important consideration with this swap is the RIGHT GEARS!