Diesel Conversion Cummins 4BT (1 Viewer)
- Thread starter FS85
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I don't own one but have driven a 40 series with a 4BT. That engine is pretty loud.
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Dirty Koala
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The 4BT doesn't have a harmonic balancer like the 6BT does, I beleive you can put a 6BT HB on which will help with vibration.
For mouse, you will want some additional sound deadening material to keep the interior quiet. not much you can do other than a decent muffler to quit the engine down...are you running straight pipes.
For mouse, you will want some additional sound deadening material to keep the interior quiet. not much you can do other than a decent muffler to quit the engine down...are you running straight pipes.
Dirty Koala
SILVER Star
FWIW, I am in North NJ and have done a 6BT swap into my 97.
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I am not very familiar with these type of set ups bought it because I am a fan of the FJ80 and a big fan of diesels, so I thought this would be a good marriage. Having some doubts right now ....
Dirty Koala
SILVER Star
No I am not a mechanic, but I did do my own conversion.
Is that a big fuse block sitting up on top of the radiator? There are all sorts of crazy things going on under your hood...what's the extra windshield washer bottle on the firewall for? And what is the unit bolted to the driver's firewall next to the brake booster for.. looks like it has coolant running through it...fuel preheater?
Is that a big fuse block sitting up on top of the radiator? There are all sorts of crazy things going on under your hood...what's the extra windshield washer bottle on the firewall for? And what is the unit bolted to the driver's firewall next to the brake booster for.. looks like it has coolant running through it...fuel preheater?
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I am not sure on any of these things, I bought the vehicle from Alabama and had it shipped to NJ sight un seen, pretty crazy.. now I have it and need to figure out all these questions. Maybe one day we can meet up for a beer and you can check it out and let me know. Do you know of a good mechanic for these motors and the FJ80 ? Thanks Fernando.
if your use to modern diesel the 4bt ain't it. what kind of engine mounts does it have? you can go fluid (lots of work) but it still vibrates and idle noise will never go away. I put a Vibration Damper on mine not sure if it did anything or not. i did it all at once with the conversion with fluid mounts.
i'm rebuilding my engine right now and seriously considered redoing my swap to 6bt as they are some much smoother and idle tone is very different. the 4bt flat crank has inherent noise and vibration. but at speed the 4bt and 6bt are the same. you can't lug the engine down as low as the 6bt you really start to notice to 4cyl impulse like most.
higher idle can help with idle vibration but most people with the 700R4 i understand put pretty low stall where it pulls to hard with i higher idle. i've cept with a higher stall and don;t notice any issues with that.
i'm rebuilding my engine right now and seriously considered redoing my swap to 6bt as they are some much smoother and idle tone is very different. the 4bt flat crank has inherent noise and vibration. but at speed the 4bt and 6bt are the same. you can't lug the engine down as low as the 6bt you really start to notice to 4cyl impulse like most.
higher idle can help with idle vibration but most people with the 700R4 i understand put pretty low stall where it pulls to hard with i higher idle. i've cept with a higher stall and don;t notice any issues with that.
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CJ I am not sure on the engine mount, I do not think they are fluid, not impressed with the 4bt fuel consumption, I have fueled once when I hit it last week and the odometer read 250 miles on 19 gallons. Not very impressive, but I do not know if the speedo calibration on the odometer is calibrated but it seems right based on where I went with it. I did do the speedo check with a phone app and they were both very similar. If I do consider doing the 6bt how much of a pain and cost from 4bt to 6bt? Thanks.
Sell it. Walk away. Just being honest.
Good luck.
Good luck.
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- #14
Thanks CJ....
Trans would be questionable going 6bt which basically means your starting over some of the parts might cross over to 4l80 but then OD isn't as low and you'll need gears or part time case with OD Gears. I went 3.55 gears and get 15-20 mpg. Where the original gears I was 15-15. But depends on how you drive. Yes I ment 15-15 because I was over revin on the hwy to go with the flow at 75-80mph I think I got 16 around town occasionally and dropped mpg on the highway.
What rpm are you running around town and highway? Is the trans hydraulic or electronic? Not sure if you have shift control.or tuning ability
I have a used spare damper with tach pickup from a 92 dodge if your interested.
What rpm are you running around town and highway? Is the trans hydraulic or electronic? Not sure if you have shift control.or tuning ability
I have a used spare damper with tach pickup from a 92 dodge if your interested.
So really two ways to look at this.
One of the best attributes of an 80 series is its marriage of capability and comfort. There are many vehicles more comfortable and some more capable but the 80 hits the sweet spot merging the two.
As soon as you bolt something to the 80 you start leaning either to the more capable side or the more comfortable side.
So you have now taken a comfortable 80 and downgraded the comfort aspect, have you gained as much in capability? Really only you can answer that. The 1FZ is a pretty capable engine in my opinion the 4bt only betters it in it's simplicity and perhaps ultimate longevity.
If you are really turned off by the loss of comfort you're going to be very busy, pulling the interior, adding the right sound deadening materials. Wouldn't hurt to also do the engine bay side of the firewall and hood as well. Definitely get a harmonic balancer, and liquid filled engine mounts like CJmoon suggests. Heavier walled exhaust tubing and mufflers would also help with the resonance.
But after all of that, it's still going to be noisy and vibrate. Hence Beno's suggestion to walk, the 4bt is a great engine but is it great for an 80? Only you knowing where in the comfort/capability spectrum you want your land cruiser to be can you be the final judge if it is right for you. I know some guys love trucks that almost blow your ear drums out and rattle and blow huge clouds of black smoke, and I know guys who drive new LX570's and say they are too noisy. Lol
Take some video from inside the truck at idle and running down the road at say 40-60-75mph so maybe others can compare it to their setup.
Good luck!
One of the best attributes of an 80 series is its marriage of capability and comfort. There are many vehicles more comfortable and some more capable but the 80 hits the sweet spot merging the two.
As soon as you bolt something to the 80 you start leaning either to the more capable side or the more comfortable side.
So you have now taken a comfortable 80 and downgraded the comfort aspect, have you gained as much in capability? Really only you can answer that. The 1FZ is a pretty capable engine in my opinion the 4bt only betters it in it's simplicity and perhaps ultimate longevity.
If you are really turned off by the loss of comfort you're going to be very busy, pulling the interior, adding the right sound deadening materials. Wouldn't hurt to also do the engine bay side of the firewall and hood as well. Definitely get a harmonic balancer, and liquid filled engine mounts like CJmoon suggests. Heavier walled exhaust tubing and mufflers would also help with the resonance.
But after all of that, it's still going to be noisy and vibrate. Hence Beno's suggestion to walk, the 4bt is a great engine but is it great for an 80? Only you knowing where in the comfort/capability spectrum you want your land cruiser to be can you be the final judge if it is right for you. I know some guys love trucks that almost blow your ear drums out and rattle and blow huge clouds of black smoke, and I know guys who drive new LX570's and say they are too noisy. Lol
Take some video from inside the truck at idle and running down the road at say 40-60-75mph so maybe others can compare it to their setup.
Good luck!
Ah, so that's what happened to the 4BT 80 series down in Birmingham....
You could have asked us about it, many MUD members have looked it over.
You could have asked us about it, many MUD members have looked it over.
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- #18
Scott, very well said. As my first FJ80 this was probably an over kill. This rig is definitely set up to go out and play pretty hard. I was not sure what I was getting myself into, now that it is here I have to enjoy it. I am not going to go spending crazy money in trying to make it something it is not, a quiet vehicle. I will probably just make it more of a capable Overland land vehicle. I have already ordered the snorkel, aux lights and looking for a very good roof rack. Thanks for the words of wisdom.
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MCT.... this is the vehicle that was in Birmingham. I bought from Mike sight un-seen, pretty crazy. I was not in this forum before the purchase but now I am, game changer. What were folks in this forum saying about this vehicle ? Curious to hear some feedback. There weren't too many bidding on it. Only one person was trying to outbid me but he eventually stopped. Thanks
I think Scott is right The 4Bt is a downgrade in comfort for the 80, If your not happy with the noise now you won't ever be. Beno has it right walk a way lick you wounds and move on.
