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Thread: 4bt

  1. #1
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    4bt

    Has anyone used this engine in a swap and what kinda mpg's should one expect from it?
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  2. #2
    turbo addict moparzrule's Avatar
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    Re: 4bt

    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.

  3. #3
    turbo addict TopDollar69's Avatar
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    Re: 4bt

    They must be decent, FedEx used to use them in their delivery trucks.
    84 Laser XE TII A555 89 Caravan SE TIV A568

  4. #4
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    Re: 4bt

    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

  5. #5
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    Re: 4bt

    http://www.4btswaps.com

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

    Martin R
    89 horizon
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  6. #6
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    Re: 4bt

    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.
    [FONT="Arial Black"][/FONT] ____________________________________________ 92 Voyager LE 3.3/A604 luxury liner 185k [COLOR="Red"]"They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety." Ben Franklin[/COLOR] [COLOR="White"]"It's not tyranny we desire; it's a just, limited, federal government." Alexander Hamilton[/COLOR] [COLOR="Blue"]Support our economy-BUY AMERICA: [url]http://nortonsusa.com/[/url][/COLOR]

  7. #7
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    Re: 4bt

    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/showth...hlight=mileage

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

    Martin
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  8. #8
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    Re: 4bt

    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.
    [FONT="Arial Black"][/FONT] ____________________________________________ 92 Voyager LE 3.3/A604 luxury liner 185k [COLOR="Red"]"They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety." Ben Franklin[/COLOR] [COLOR="White"]"It's not tyranny we desire; it's a just, limited, federal government." Alexander Hamilton[/COLOR] [COLOR="Blue"]Support our economy-BUY AMERICA: [url]http://nortonsusa.com/[/url][/COLOR]

  9. #9
    turbo addict moparzrule's Avatar
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    Re: 4bt

    Quote Originally Posted by Turbulence View Post
    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/showth...hlight=mileage

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

    Martin
    89 Horizon
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    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.

  10. #10
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    Re: 4bt

    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.
    [FONT="Arial Black"][/FONT] ____________________________________________ 92 Voyager LE 3.3/A604 luxury liner 185k [COLOR="Red"]"They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety." Ben Franklin[/COLOR] [COLOR="White"]"It's not tyranny we desire; it's a just, limited, federal government." Alexander Hamilton[/COLOR] [COLOR="Blue"]Support our economy-BUY AMERICA: [url]http://nortonsusa.com/[/url][/COLOR]

  11. #11
    turbo addict moparzrule's Avatar
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    Re: 4bt

    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.

  12. #12
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    Re: 4bt

    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.
    [FONT="Arial Black"][/FONT] ____________________________________________ 92 Voyager LE 3.3/A604 luxury liner 185k [COLOR="Red"]"They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety." Ben Franklin[/COLOR] [COLOR="White"]"It's not tyranny we desire; it's a just, limited, federal government." Alexander Hamilton[/COLOR] [COLOR="Blue"]Support our economy-BUY AMERICA: [url]http://nortonsusa.com/[/url][/COLOR]

  13. #13
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    Re: 4bt

    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!

  14. #14
    turbo addict moparzrule's Avatar
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    Re: 4bt

    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.

  15. #15
    The moderately moderate moderator Turbo Mopar Staff
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    Re: 4bt

    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.
    Bryan
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  16. #16

    Re: 4bt

    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

  17. #17
    turbo addict moparzrule's Avatar
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    Re: 4bt

    +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.

  18. #18
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    Re: 4bt

    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.
    [FONT="Arial Black"][/FONT] ____________________________________________ 92 Voyager LE 3.3/A604 luxury liner 185k [COLOR="Red"]"They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety." Ben Franklin[/COLOR] [COLOR="White"]"It's not tyranny we desire; it's a just, limited, federal government." Alexander Hamilton[/COLOR] [COLOR="Blue"]Support our economy-BUY AMERICA: [url]http://nortonsusa.com/[/url][/COLOR]

  19. #19

    Re: 4bt

    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

  20. #20

    Re: 4bt

    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

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