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Discussion in 'Diesel Tech / 24 volts' started by MiniPigg, Feb 10, 2009.
Good match for powerband on a 4BT?
Maybe for the powerband, but not for the torque.
The Toyota V8 diesel puts out more torque(317ft/pounds) than a stock 4BT(265ft/pounds)and its using the H151
The H151 has also seen service behind the 1HD FTE and its predecessors and seems to be holding up quite well.
I dont think I am going to tune the 4BT up much past factory specs.... going for fuel economy over getting to the next stop light before the guy next to me.
So I am thinking of the 4BT with the H151 and its tcase in my 1994 FZJ80.
Seriously!?... Most 4BT's making their way to the public are 15+years old and closer to 290lb-ft. stock. With a fuel screw or plate pending on the type of pump you've got can get you an easy 500+lb-ft. of torque.--that's with 4 not 8cylinders like you mention at 317lb-ft.! Compare your new 8 cylinder to the new ISX-common rail(again still 4 cylinders!) you've got 160HP @ 460lb-ft. unmolested. No comparison!!!
So is the H151 a go mated to a 4BT?
No one mentioned turnng up fuel screws in the original post nor did they mention which Cummins from which year.
I got the torque info from Proffits
Cummins Diesel Conversions
The 290lbs/ft is still less than the 317lbs/ft the V8 puts out.
Seeing as though you want to turn this into a Toyota vs cummins engine debate,the torque figures I mentioned are for the aussie spec V8 which are lower than the European and the ME version and they are also for the single turbo version.
The twin turbo aussie version has 480lbs/ft and is probably a much nicer drive than a potato crisp truck engine.
The Middle Eastern version of the engine has even more power and they can be rechipped and have the fuel turned up
I dont know why the number of cylinders makes a difference. Torque is torque.
the only issue with the Toy trannys working with a low rpm engine like 4BT or 6BT it's the HW driving .. the .84 aprox 5ft speed don't help a lot ..
Maybe it can be compensated with bigger tires .. just to keep your rpm inder 2k and your engine ( and wallet ) happy ..
Tapage has the best argument against this. Besides the lack of adapter. The NV4500 has a nicer 5th gear, and trust me... you need every bit of it. I ran an NV4500/4BT and 35's on my 80, and that engine likes to be at about 1900 RPM, but freeway speed dictates more like 2100. The 3200rpm spring helps a _lot_ with drivability, but ideally... finding (very rare) 3.7's for the axles (europe? australia?) would be more ideal. BUT, the first gear on the H151 (have one in my converted HDJ80) will be hard to get the truck going with 35s. Overall... i'd recommend against it.
BUT... the NV4500 was very tough to fit in the 80. the shifter comes up very far forward from stock. the transfer case ends up so far forward, we had to cut the floorboard just in front of the passenger seat to clearance it.
The H150 4.54:1 IRRC could help for first .. actually an H55F with 4.84:1 can help much more but still the 5ft issue on HW driving ..
hmmm, considering the weight of the 80, and the cost of the swap... and the strength of the H150 and H55F vs. the amazing 4BT torque... I would not recommend either of those.
actually I don't think any of those trannys will be in problems with the 4BT ..
At least my H55F it's still holding nicely my setup .. much more that I can tell from my rear axles ..
How much longer is the NV4500 compared to either of the TLC 5speeds? I thought about that route but figured staying with a LC 5speed would be a better bolt in application and everything from the transmission back would be pretty much in the same locations.
Where exactly does the factory tcase fall into place after the NV4500?
I can make an adapter for the mating of the diesel and transmission when using the TLC 5speed. If the NV4500 is the best gearing choice then I can just go with the AA kit.
I also thought about staying with my factory automatic transmission but did not know if it would stand up to the Cummins.
I intend on staying with 33" tires but I am not opposed to going to 35" tires if that would accommodate the diesel conversion.
There is another option on the diesel... I do come across Isuzu 4BD1's that are about a third of the cost of a Cummins 4BT. Different bolt pattern and less money for the cost of a motor.
Well today I found a guy that has a 6BT Cummins engine and a damaged NV4500 that goes with the engine. I hope to buy these as soon as I secure a deal with the guy. I wanted to stay with a 4BT to save on weight. From what I read at Cummins the 4BT dry was 950lbs and the 6BT dry was around 1150lbs. Only about 200 lb difference. Also I thought the 4 cylinder might gave me better fuel economy and would have more then enough power for what I need.
What do you guys think so far?
But you are right, Toyota's engine certainly is smoother and more quiet!!! The ISX's are about half as loud as the old BT's and still loud!
I say put the 4500 behind the 4BT, same bellhousing, lighter...
RoscoFJ73 will blow his mind if you put a 6BT in there, fuel plate, 4K gov spring kit, starwheel cranked, BHAF and a stack....
Is the 4BT 750lbs or 950lbs? net weight?
This is why it matters.
In a big angry 4 cyl you've got two big bangs per revolution producing an average of 290 ft-lb of torque.
In a V8 you've got 8 smaller bangs per rev producing the same average torque.
It's the large torque impulses which wreck gearboxes, which is why 4 cyl's are better at wrecking gearboxes than 6's or 8's with similar torque figures.
IIRC my 2H was about 700 - 750 lbs range .. maybe the 4BT are in the 1K range ..
Before you pull the trigger on the 6BT, you might want to get you tape measure out. The 6BT is a long and tall engine. The 4BT is tall.
Just a thought.
Very helpful info and several mudders on there.
The Cummins ISX is a 15L Class 8 OTR engine, the 4.5L common rail 4 cylinder is still called a ISB. The 4 cylinder B's are a great engine but I have never understood their attraction for a light duty application as they are loud and vibrate terribly.
The only place I have seen even the new 4.5L OTR models offered in NA would be in Workhorse vocational vans, they are no longer offered as they have been replaced as an option by the Navistar VT-275 a while back
Cummins has a great website and still makes the mechanically injected B engine for off road applications:
Cummins Every Time - Brochures