I want everyones opinion on the Cummins 4BT. Pros and Cons. Is it really everything its chalked up to be?
Is The 4BT All That? (1 Viewer)
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Depends on what you consider "everything it's chalked up to be?" and what it is going into.
It's loud and it shakes. Not refined like the 6BT.
Need a lift to get over front axle.
Parts are easy to get.
Easy to work on.
If you are a diesel guy most of the negatives probably won't bother you.
It's loud and it shakes. Not refined like the 6BT.
Need a lift to get over front axle.
Parts are easy to get.
Easy to work on.
If you are a diesel guy most of the negatives probably won't bother you.
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Really liked the 4bt in a giant brush chipper. It's straight-up industrial. Lots of power and the noise to back it up. I much prefer the Isuzu 4bd2tc. But I'm a Jap Diesel Nut and enjoy the finer things in life.. Lots of builds with the 4bd2tc too.
sailor
Jackass of all trades
Great motor. Coarse as a bastard. If you want an audio preview just chuck a handful of gravel in a mixmaster. That'll give you an idea of the NVH...
Like everyone said noisy and shaky,if you decide to install it in a vehicle need good isolators and dampeners to reduce NVH. Good engine and reliable i have worked on a few that's mounted on generator and other equipment and the only vehicles it was installed into are the bread vans or panel vans not really for passenger use unless you enjoy that shaking and noise i would rather listen to 24v 6BT.
A few years ago someone asked the same question and another member pointed out that just about everyone who does the 4BT (and maybe the 6BT, too) ends up selling their vehicle. A lot of people think they won't mind it, but when it's all said and done, they get tired of putting up with it. I've been inactive for a while and don't follow the classifieds like I used to, but at the time I would have certainly agreed with his observation.
I've got an old rv bread van it's great mileage can pull anything plus I have a three speed splitter behind an Alison but anything under 1500 rpm you'd better be in love with it its loud and shaky. Be careful with an adapter the torque will eat most trannies.
(IMO)
Pros
Relatively cheap and easy to obtain.
Easy and cheap parts, even aftermarket/performance.
Many adapters.
Proven strength and performance.
It's easy to have confidence the motor will hold up to what you throw at as it's all been done before.
Extensive info, virtually everything has been done and has been written about.
Cons
Unrefined, even for a big 4cyl diesel.
Relatively high BSFC for what it is.
Quite limited RPM range standard.
Pros
Relatively cheap and easy to obtain.
Easy and cheap parts, even aftermarket/performance.
Many adapters.
Proven strength and performance.
It's easy to have confidence the motor will hold up to what you throw at as it's all been done before.
Extensive info, virtually everything has been done and has been written about.
Cons
Unrefined, even for a big 4cyl diesel.
Relatively high BSFC for what it is.
Quite limited RPM range standard.
There are a few builds in the hardcore section with 4BTs. They all have some vids in the build thread. I've ridden in Boots' rig. It's noisy, but not horrible. He has done a fair amount of sound proofing to help things out. I guess it just depends on what kind of noise you are willing to live with.
Boots4 - Family haulin'
1974FJ - Diesel FJ40, 1974FJ
D'Animals - FJ 45 Extended Cab Custom Vehicle Build Finally Begins
Here is a vid from last summer on the Rubicon. Boot's rig is the white 60 and the red one is a turbo'd 3B for sound comparison.
Boots4 - Family haulin'
1974FJ - Diesel FJ40, 1974FJ
D'Animals - FJ 45 Extended Cab Custom Vehicle Build Finally Begins
Here is a vid from last summer on the Rubicon. Boot's rig is the white 60 and the red one is a turbo'd 3B for sound comparison.
And if you really want to get obnoxious, how about a good old Detroit 2 stroke diesel. I had "test driven" an fj45 decades ago that had one. Fun as hell, but also louder than hell.
maat
yeah nah maybe
There are a few builds in the hardcore section with 4BTs. They all have some vids in the build thread. I've ridden in Boots' rig. It's noisy, but not horrible. He has done a fair amount of sound proofing to help things out. I guess it just depends on what kind of noise you are willing to live with.
Boots4 - Family haulin'
1974FJ - Diesel FJ40, 1974FJ
D'Animals - FJ 45 Extended Cab Custom Vehicle Build Finally Begins
Here is a vid from last summer on the Rubicon. Boot's rig is the white 60 and the red one is a turbo'd 3B for sound comparison.
man, @boots4 's 60 made that look easy!
Ya the torque Just eats any bumps . Funny jeff you mention detroits I'm looking for a little Detroit for a project. Man I love the sound of those screaming motors. I'm thinking not so good for a 4x4 unless your into punishing the truck my jimmy sees a hill and it's starts screaming because it's a dog when it comes to torque.
sailor
Jackass of all trades
George- even a DD 353 weighs about 900 lbs.... I am looking for one of those but the turbo ones are rare. Pit y- I just sold a set of 71 series N90 injectors that would give your bus some more punch...
Here's my experience over the last 9 years running a 4bt in my rig. I've done a lot of tinkering/experimenting and mine's gotten a little louder with all the mods I've been doing. There are certainly other engines on the road that are louder than me but that's really the only rub I could give the 4bt. If you want quiet, this is not the motor for you. Spotting on the trail is best done with visual signals rather than voice commands. On the freeway the hum of my tires are louder than the noise of my engine.
I must be used to the vibs but it certainly doesn't rattle my teeth. At rpm it has a nice purr to it. It always puts my kids to sleep on any trips we take in it.
What has impressed me the most is how dang beefy the engine is. I have certainly abused mine and it keeps running. This darn little motor would literally pull it's guts out if you asked it to. Mine is pushing power well beyond stock but it has held up to quite a few mods I've done to it. There's definitely been learning lessons along the way but it's pretty easy to get and support more power than stock with these engines. I don't think I'll ever stop tinkering with it so I'll always have a slight level of dis-satisfaction with it but I'd be that way with whatever engine I run. @Kief brought it up recently that I've probably forgotten what it's like to drive a stock 4bt and he's probably right because getting on the freeway up to speed is now fun, not a challenge. My landcruiser is not slow.
Overall I've been pleased with how the 4bt has performed for me and has held up to what I've asked and forced it to do. It just keeps chugging along and I've been able to share some great experiences with friends and family because that engine got us there. I'm looking forward to more years to see what it can do.
I must be used to the vibs but it certainly doesn't rattle my teeth. At rpm it has a nice purr to it. It always puts my kids to sleep on any trips we take in it.
What has impressed me the most is how dang beefy the engine is. I have certainly abused mine and it keeps running. This darn little motor would literally pull it's guts out if you asked it to. Mine is pushing power well beyond stock but it has held up to quite a few mods I've done to it. There's definitely been learning lessons along the way but it's pretty easy to get and support more power than stock with these engines. I don't think I'll ever stop tinkering with it so I'll always have a slight level of dis-satisfaction with it but I'd be that way with whatever engine I run. @Kief brought it up recently that I've probably forgotten what it's like to drive a stock 4bt and he's probably right because getting on the freeway up to speed is now fun, not a challenge. My landcruiser is not slow.
Overall I've been pleased with how the 4bt has performed for me and has held up to what I've asked and forced it to do. It just keeps chugging along and I've been able to share some great experiences with friends and family because that engine got us there. I'm looking forward to more years to see what it can do.
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Anyone know the difference in weight between the 3B and the 4BT?
4bt weighs about the same as the 2F that was originally in the FJ60 so around 700lbs.
I hope to do some boost gauge videos in the near future to see how the turbos are working together. Hard to watch the gauges and be safe on the road without watching where I'm going so I'll have to grab an assistant.
As for cracks in the motor mounts I built or in the surrounding frame, I've seen none in my FJ60. If mounts are built and supported well you shouldn't have issues with any engine. Good isolation will help keep from transmitting harsh vibs to the frame which will reduce the chance of metal fatigue.
For mileage in my set up (lifted, mud tires) the potential is for low to mid 20s but my right foot isn't calibrated that well. I did see 22 mpg on a trip to Moab one time. I'm still not good at not enjoying the turbos so I see 18-19 mpg on average. At little less when towing and little more if I adjust my driving style.
I hope to do some boost gauge videos in the near future to see how the turbos are working together. Hard to watch the gauges and be safe on the road without watching where I'm going so I'll have to grab an assistant.
As for cracks in the motor mounts I built or in the surrounding frame, I've seen none in my FJ60. If mounts are built and supported well you shouldn't have issues with any engine. Good isolation will help keep from transmitting harsh vibs to the frame which will reduce the chance of metal fatigue.
For mileage in my set up (lifted, mud tires) the potential is for low to mid 20s but my right foot isn't calibrated that well. I did see 22 mpg on a trip to Moab one time. I'm still not good at not enjoying the turbos so I see 18-19 mpg on average. At little less when towing and little more if I adjust my driving style.
- Thread starter
- #19
Considering your lift and tire size that is surprisingly good mpg! Sorry for so many questions but does it cruise at 65-70mph well? whats the rpm range at those speeds? You said you've done a bunch of things to the 4bt, what are they and have they improved the engine overall or provided little to no improvements? I feel like an interrogator, but how much HP are you pushing? @boots
For all the nitty gritty and the ups and the downs the details are in my build up thread in my signature. Just a warning though it'll take some time to get through it.
I run about 19-2000rpm at 65-70mph and it cruises great. I've found that 4.10s with 37s with my automatic ratios are my best compromise for daily driver, towing, and wheeling.
With compound turbos running 50-55psi I'm pushing around 300hp and over 500ftlbs of torque. She scoots pretty good now.
I run about 19-2000rpm at 65-70mph and it cruises great. I've found that 4.10s with 37s with my automatic ratios are my best compromise for daily driver, towing, and wheeling.
With compound turbos running 50-55psi I'm pushing around 300hp and over 500ftlbs of torque. She scoots pretty good now.
