4bt cummins swap
 

Hey all I know this is probably a quite popular topic but I'm looking to put a 4bt cummins in the 66 with an sm465 tranny maybe put in dana 40 4.10 geared rear end is there anything in particular I should consider? Cutting the firewall frame etc.

Re: 4bt cummins swap
 

If you get one with a Chevy adapter plate an flywheel, it will mate right to a tranny from behind an inline 6/sbc/bbc.

The firewall and frame are fine.

It would be pretty cool to see a 478 toro-flow under the hood. It should bolt right in too.

Re: 4bt cummins swap
 

Re: 4bt cummins swap
 

Anyone know the spec's on this engine (hp) max rpm, peak torque. Looks like it would get better fuel mileage with a OD transmission instead a stock 4 speed granny. how about a NV3500 or NV4500.....????they should handle the diesel torque......I always shoot for 65mph at 1800rpm on a diesel engine....someone get me the specs on the engine and I will work up the performance information. Kieth


I looked up the spec's and this little engine will perform rather well, it has the torque performance of a 327 4 barrel engine but is only rated at 2300rpm with peak torque at 1600 rpm. Looks like it needs a transmission with very close gear ratio spacing to keep from falling off its torque curve. Will review and look for a good transmission for this engine........Kieth

105hp@2300 peak torque 265ft/lbs@1600 rpm

Re: 4bt cummins swap
 

I know this is big an bulky an expensive....but a Richmond 6 speed will give you 5 direct gears and a 6th gear od. It is pretty close ratio. :chevy:

Re: 4bt cummins swap
 

Hi, I have a 90 1500 swb 4x4, 4bta with 4500 and 342 gears. To do this swap I would not use the 3500 trans, only the 4500 with around 3.42 gears and remember if you use the GM bread truck block to bellhousing adapter you will either have to cant the motor or the trans I think 7 degrees. We normally get 25 to 28 mpg, one time we got 34 in mass, checked the figures 3 times and came out the same. One time we pulled our smaller two axle fifthwheel camp trailer about 100 miles with no negative effects running 55 to 60 mah. Our truck has at least 400K on the 4bt and never been touched. Getting ready to put one in our blazer chalet.

Re: 4bt cummins swap
 

Hey Peanutbutter, I know who you are.
The Dodge diesel NV4500 or even the Getrag G360 would be a good option and wil bolt right up with the Dodge parts.
I run the original SM420 with a Ranger overdrive, have no problems with it and it gives me more gear options for my heavy truck when towing.
I average 24 mpg in combined driving in a 6300lb 3/4 ton 4x4 and have got as goood as 30 on a trip to Denver.

Re: 4bt cummins swap
 

I've got a 4bta in a 61 gmc 4x4. I used a late model frame, it makes getting parts easy. I love mine. Dieseldude helped me a lot on my build. Unless you go with a add on OD drop the 4 sp and look for a 5 or 6 speed.

Don't let the numbers fool you they have all kinds of power! Enough to rip gas componates apart

Re: 4bt cummins swap
 

Guys I'm intrigued by the 4bt swap. How does it stack up against a big block for power? Obviously it gets double the mileage. I had considered a 6bt but it looks like they're big and heavy and hard to make fit. Sorry if I'm thread jacking!

Re: 4bt cummins swap
 

I would say my 4bt (pump is turned up and different turbo) is somewhere in between a hot SBC and a mild BBC. There is a big difference tho, until you drive a diesel you cant really understand what I mean. Even tho my engine probably puts out 400-420 ft/lb, but at 1600-1800 rpm. The HP is very low, so it doesn't feel like driving a BBC until you hook a trailer to it.... IDK if Im making sense.

Re: 4bt cummins swap
 

^^2x what he said.

Re: 4bt cummins swap
 

My opinion is this isn't a popular topic, at least not here.

My 6BT with NV4500 in my dodge is the slowest thing i've ever owned/driven. Gets good mileage, about 18 mpg average. Pulls decent. My old 94 chevy with a 454 pulled way better but at the cost of 8 mpg... Parts are far more expensive, my (indestructible P pump) injection pump went out last year, costed me $2200 for a rebuild. You can build a nice small block for that much.

I dunno, I don't buy into the cummins hype even though I own one. A swap would be very expensive, around 6-8 thousand? You can buy a lot of gasoline for that, years and years and years of gasoline.

4BT's aren't balanced, so they'll rattle your teeth at idle. I've seen many a 4bt swap that ultimately ended in the owner selling the vehicle because of the harmonics and vibrations.

You want good mileage and torque, and affordability? Why not an older stovebolt 261 or so. It'll produce more power than a 4bt at less weight and costs and with fuel that costs 50 to 70 cents cheaper a gallon.

Just my opinion and experience on it.

Re: 4bt cummins swap
 

Jmack

I agree with a lot that you a have said except for

"You want good mileage and torque, and affordability? Why not an older stovebolt 261 or so. It'll produce more power than a 4bt at less weight and costs and with fuel that costs 50 to 70 cents cheaper a gallon."

I doubt that a 261 would pull anywhere near as well as my 4bt, nor get the mileage.

Re: 4bt cummins swap
 

No, you're right, it wouldn't get near as good as mileage as a 4bt. But when you factor in cost difference in fuel, it's not quite as good a deal you know? For the money and time spent that is.

I think a 261 or 292 will put out as much torque as an old 4bt, and a lot more hp. But then it has to do with where the two engines are making torque, how the truck is geared, transmission, etc.

My 6bt doesn't feel like it's really making any power till about 1700 rpm, then after 2300 rpm it's basically making a bunch of noise and not doing anything haha. So you've got such a small powerband. I know you can mess with the governer spring and all that fun stuff in the IP and "turn the fuel up", but I just haven't yet.

A good running stovebolt with a newer style HEI ignition and the such, coupled with a 5 or 6 speed, geared correctly should produce respectable power numbers, tow what you'd need within reason and probably get 20 mpg highway.

I'm not knocking the cummins option, just giving an alternate view.

Re: 4bt cummins swap
 

A stock 292 inline 6 makes 153 HP and 265 Pound feet of torque...these motors were lucky if they were getting 15 miles per gallon. I am not sure if your 4bt is turbo charged are not...I forgot. lol. Anyhow, If you turbo stock 292 to 8 pounds of boost your power will increase to around 300 hp and over 300 pound feet of torque...a 261 is not the best motor for 1...parts are scarce...2 trying to find performance parts are nearly impossible. If you were going to do a 6 cylinder a 250 or 292 would be your best bet. Note that many parts aren't interchangeable between the two...a 292 crank will fit a 250..or a 250 head on a 292. The 292 will get much better rpm rang then your cummins will...I can rev my 292 to 4,500 rpm between shifts...and the bottom end is stock...but my carb and manifolds and ignition aren't. The 292 peaks torque around 1,600-2,000 rpm...and hp around 4,000 according to factory. Now if you do a 6bt 5.9 turbo cummins you'll put us all to shame! LOL!

Re: 4bt cummins swap
 

Yeah that's all pretty much accurate. A 261 would produce about 150HP at 2,000 and 230 ft lb at about 4,000.

What transmission and rear end are you running in your truck TJ?

Re: 4bt cummins swap
 

You mean 150 HP at 4,000 rpm and 230 ft lbs 2,000. ;) I am running the stock transmission( 4 speed on the floor) and the stock C-10 axle. GM 12 bolt rear axle...gear ratio probably 3.90 or 4.11. The only reason I rev it to 4,000+ between shifts is the rpm travel between shifts...2nd to 3rd is almost a 2,000 rpm split..if I was to rev it to 4,000 in 2nd then shift to 3rd my rpms would start just around 2,000 rpm....3rd to 4th is worse, But hey...these weren't made for speed. lol...which I am going to change to a richmond 6 speed...5 direct gears and a 6th gear overdrive. Spendy, but worth it. :chevy:

Re: 4bt cummins swap
 

Yeah, my fault haha.

Re: 4bt cummins swap
 

4bt vibrations are over exagerated, I have 3 trucks with them and they vibrate no worse than a lot of the 6.2L trucks I have driven.
I also have 4.10 gears and the sm420 and I don't have to rev to 4000 rpm between shifts so there must be a large differance in toque down low between it and a 261.

Re: 4bt cummins swap
 

If the diesel thing bothers you, you can get good numbers out of the newer LS
style engines. They would give good mpg, and power...

I can't stand computer controlled engines tho... This was the biggest appeal to me... My 4bt is completely mechanical...

It doesn't require any electrical connections at all. Matter of fact, if you push it hard enough it will start and take off down the street.

Re: 4bt cummins swap
 

dieseldude - with the ranger overdrive how did your sticks work out? Is there room in front of the bench to put the SM420 stick still?

Re: 4bt cummins swap
 

The 420 stick moves back 7 1/2 inches and the ranger stick is to the left and in front of that. as is my transfer case stick.

Re: 4bt cummins swap
 

The 4BT.....

gobs of torque, fuel efficiency, and even a bit of noise on the side....

It won't go anywhere fast..... but it'll keep going and going.....

I know a few things about that motor.....and its big brother 6BT....

(my last project 1947 Ford 1.5 Ton on hydroboosted disc brake, 4 link air suspension)

https://scontent-b.xx.fbcdn.net/hpho...0_251059_n.jpg

https://scontent-a.xx.fbcdn.net/hpho...0_311539_n.jpg

https://fbcdn-sphotos-d-a.akamaihd.n...72205939_n.jpg

Re: 4bt cummins swap
 

That looks like a cool project!!

Re: 4bt cummins swap
 

I'll have to agree that the light duty Cummins diesel thing was also a little bit of a letdown to me when I really looked into it. Still cool, but not nearly as cool as it looked at a glance.

TJ; FWIW, your truck should have 3.73 gears. 3.90 was the earlier (pre '63) Eaton ratio. Could have 4.11's, but I doubt it.

I'll also add that IME/IMO 4,000RPM is a really excessive shift point for normal driving with the SM420/inline six. I have a weaker 250 in my one ton and normally shift @ something like 2,200-2,500RPM (most of the time). It's certainly not necessary.

FWIW, 292 GM spec is (net) 153HP @ 3,600RPM and 255ftlbs @ 2,400RPM in '65. (I'll post the dyno sheet as an attachment).

So, (in stock form) the 4BT and 292 will probably pull similarly up to 2,000RPM or so, but the 292 will have another 50HP available higher up. That ability to wind it up a little and get half again as much power is kind of nice... ;)

Re: 4bt cummins swap
 

One Awesome project :metal:

Re: 4bt cummins swap
 

A typical 292 gets 11 mpg loaded or not, wether its in a 1/2 ton pickup, or a single axle c60 dump truck.

Re: 4bt cummins swap
 

For under a grand it is easy to get a 4BT to 200 HP and well over 400 ft. lbs of torque. That is the advantage to the diesel.

I have a 4BT in my '90 F350 4X4. This winter when I have time I will hopefully get it over 300 HP and 700 ft. lbs of torque. Try that with a 292.

Re: 4bt cummins swap
 

Where on the planet earth do you buy a nice 4BT + mods for <$1,000??? I'm calling BS on that one.

My understanding from reading is that a <200HP 4BT in a working/towing truck (run hard) is generally considered to have compromised longevity.

As far as cheap power, do you really think a 4BT is going to make more HP per $ than a junkyard 5.3/6.0 LSx???

Again; I'm not knocking the diesel stuff, but it's not what some people make it out to be IMO.

Re: 4bt cummins swap
 

Not the whole engine. I have bought a little under $700 worth of performance parts and have 196 HP to the wheels. Yes the engines are spendy.

I didn't know that we were talking about LSx engines. Everything has been comparing 261's and 292's to 4BT's.

As far as longevity, I have seen commonrails (305 and 325 hp) over 500,000 miles. I would think that 200 HP on 4 cylinders would be similar to 300 HP on 6 cylinders.

Even if it only runs 300,000 miles, it will be a far cry better than the 7.3 that I took out - and still better than a stock 292.

Re: 4bt cummins swap
 

One other point is that the 4bt is a very simple engine to work on compared to the modern gas engines. I really enjoy mine, it's dependable, good on fuel, very powerful, and a conversation piece.

Re: 4bt cummins swap
 

I was just saying that because you said "This winter when I have time I will hopefully get it over 300 HP and 700 ft. lbs of torque. Try that with a 292.", and I was noting that both are really probably the wrong choice if you're going for cheap power.

My understanding is that when running one really hard consistently (heavy towing/boat application) that they don't really like to make a lot of power, which is understandable.

I would be surprised if you couldn't make a 292 go 300,000, though. I think I had two people recently tell me that they had cars with 283's that they had for over 300,000, and a local 305 V8 went almost 500,000 before the timing chain fell off (IIRC). I'm pretty sure one of my own 250 powered trucks has way more than 300,000 on it, too.

Not to say the diesel wouldn't be nicer at 300K (I'm sure it probably would be), but you also have to factor in that the rebuilds cost more, plus the other stuff like injectors, injector pumps, etc.

I still think it's neat, but I just don't think it's quite what many seem to make it out to be.

Re: 4bt cummins swap
 

Yeah, I think they are neat (like I said before); if I find a deal on a 4-53 Detroit I'll stick one of those in something. (Nothing says conversation piece like a two-stroke diesel! Unless you are too deaf to converse as a result of it... :lol:)

Re: 4bt cummins swap
 

I would agree with all of this.

The reason most people entertain the idea of a diesel swap is better fuel economy. Unfortunately diesel is like $.50 more a gallon. So when you factor that in plus the fact that you'll spend significantly more building them and fixing them. It almost ends up being a wash.

Re: 4bt cummins swap
 

I like this mentality, it helps keeps the cost of diesel and used parts down.:metal:
I have three Cummins 4bt conversions and a Dodge Cummins truck. I don't find them more expensive. And $.50 more a gallon for $4.00 fuel is only about a 14% increase for which I get 100% better fuel mileage.
Just my 14+ year real life experience not speculation.

Re: 4bt cummins swap
 

I will agree that if you are doing an engine swap for mileage only, it will take a LONG time to pay for itself.

That's why I have a Honda that gets 60 to 80 MPG.

I'm still not convinced that you can get 700 ft lbs of torque out of an LSx and still have it be driver friendly and be able to tow heavy.

The reason i went with a 4BT is that the 7.3 that I had was shot and I wanted more power and I like Cumminses and lots of headaches associated with swaps. I probably should have went with a 6BT but I was told by many people that "you couldn't get any power out of a four cylinder" - so I did.

Re: 4bt cummins swap
 

Well, to start off with, the 700ftlb number is kind of meaningless; it's the same deal as peak HP numbers. I can put more than 700ftlbs on that input shaft if you hand me a long wrench, but that doesn't mean I'm suitable as a truck engine. :lol:

HP is what actually does the work, and that is why when talking about the power output of the "real" diesel engines (as in big OTR/equipment stuff) HP is what is always used. Torque is only a measurement of force, which does nothing without speed; speed x force = HP.

Say you have 300HP with your diesel, and I have 400HP with a BBC; if I run @ the same RPM you are running at (and am making less torque there), I am as a result making less HP. However, if I kick down a gear and wind up it, I'll pass you like you're chained to a pole. Why? You have more peak torque, but don't have the extra speed to make more actual power. This is where everyone seems to get confused; HP at the speed you intend to operate the engine at is what actually pulls the truck down the road.

From everything I've read, a 4BT pumped up like that will kill itself in short order if you actually load it up and start up the side of a mountain WOT.

For example, take the 893CID 3406E Caterpillar; the versions that made 435HP or more had 2-piece pistons with steel domes to resist melting them (or whatever) under sustained heavy load. A 4BT is only 239CID, or roughly 1/4 of the size; hard for me to believe that adding 654CID only adds 135HP... :lol:

As far as hot-rod power like that, a V6 Camaro my father stuck a turbo setup on at the place he works at made 421HP @ the wheels (or about 500HP @ the crank); this engine had nothing done to it besides the turbo, and as a result ran like stock until you opened it up.

Re: 4bt cummins swap
 

BTW, I'll again add that I'm not saying the diesel thing sucks; I just think that it's a little over-glorified today.

The 292 in stock form is rated @ 153 net HP @ 3,600RPM; no problem holding it wide-open there until the sun burns out. It's a truck engine, and that's what GM designed it to do.

The 4BT normally makes something like 105HP @ 2,300RPM from what I'm reading; it's also a truck/tractor engine, and can also do that until the sun burns out.

292 wins hands-down here IMO, as it makes pretty much 50HP more than the 4BT does--a 50% increase in power!

A jacked-up 4BT will make more power than the 292, but it also might melt it's pistons out pulling a long hill running wide-open. Likewise, you could also put a turbo on the 292 (or otherwise hot-rod it) and push it until you start finding the weak links. Just my opinion, but those are my thoughts on the matter as of right now.

Re: 4bt cummins swap
 

Its more important to look at the torque vs. RPM curves here guys.

A 292 (even being a I-6'er) will still have to get some spin on it to do anything grunt worthy. (Actually turns out to be a 1100 RPM peak difference)

The 4BT you'll idle right out on anything.

292
115 hp at 3,400 rpm and 215 lb. ft. at 1,600 rpm

4BT
105 hp @ 2,300 rpm and 265 lb-ft @ 1,600 rpm

in some delivery applications.... 292's were removed and replaced with 4BT's.... (IE the stepvan most 4BT's are found in)

I have a hard time believing that even with the right gearing a 292 could push this (see below) down the road at 60 MPH. (This is what I found my 4BT in on my 1947 Ford diesel 1.5 ton project... and yes I drove it home.... the 4BT in my van replaced an existing 6.2L diesel and was mated to a TH 400)

https://fbcdn-sphotos-c-a.akamaihd.n..._3624856_n.jpg

If you've never owned/driven a diesel pickup.... your wasting your time trying to really describe... there two way different animals.

Take the big brother here guys... the 6BT 12 Valve... a 190HP, 440 ft-lb ft of torque engine.

Take a 6.0L LQ9 LS engine.... same torque, twice the HP.... it should be better right?

The 12V will pull the house down over the 6.0. At a slower speed yes... but at 30,000 lbs.... 12V 6BT diesel > 6.0L LS gasser




Differentiate what they really are guys...... 4BT: A puller meant for work.. and in stock form.... a MPG sipper if you have extremely favorable highway gearing. 292: An occasional puller capable of running out empty to highway speed without any issue or concern for gearing in most platforms.

The 4BT 'rarity' now leads to its increase demand in price. For the same amount of money... I went LS.... will get similar mileage, blow the doors off of the 4BT in a race, and be able to pull from a stop about the same. (yes... about the same... even though I have x2 the HP and torque.)

Now my 5.3L LS vs. a 292..... pulls harder from a stop, faster, better mpg etc.

If the 292 is in there and free... and your not looking for a project.. leave it.

If your pulling off idle more then cruising..... 4BT

If your looking for win/win/win in regards to $$$/mpg/tow ability - today - its the LS.

Tomorrow.... is a new day... a new fad.... different generations of motors becoming available in the junkyard and new technology every day... who knows.

one thing I know for sure... beer is good

Re: 4bt cummins swap
 

Read my post again (did you read it to begin with?).

The numbers you quote for the 292 are from the later smog era; '64-'66 made 255ftlbs of net torque and had the added power higher up that the 4BT just doesn't. Yes, the 292 makes its peak power a little higher up; that's where GM intended you to run it.

The 292 is/was a schoolbus/dump truck engine--you know that, right?

TURBO diesel. Want to race my 454 spark-knocker with your 6.2? :lol:

Again, no. Wind the 6.0 up to the moon where it makes its power, and it'll out-pull the diesel. You think the diesel is more powerful because WHERE YOU ARE RUNNING IT AT IT MAKES MORE HP. And what do you mean "At a slower speed yes..."? More power=faster on the planet I'm from.

The 292 was never intended as that; it is a HD truck engine, designed for HD truck use. The (stock) 4BT is also a truck engine, but just a lamer one that is missing the entire top end of its powerband. :lol:

Just think of it this way; the 292 can spin 1,300RPM faster than a 4BT, right? So, 3,600/2,300=1.56. I'm just going to use that extra gear on this hill, and you can use that badazz 4BT grunt in high gear. ;)

Now my 292 makes 400ftlbs @ less than 1,600RPM, and makes another 48HP @ 2,300RPM. 4BT isn't so bad anymore, is it? I can hold 3,600RPM as long as you can hold 2,300RPM. :)

Again, HP where you run it is what makes the truck go. :chevy: