So starting from a blank slate, Aqualu build ground up, advice from builders sought.

What driveline behind the 4BT?

  • SM420 & Ranger OD

    Votes: 2 11.8%
  • NV4500

    Votes: 12 70.6%
  • Other

    Votes: 3 17.6%

  • Total voters

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Aug 17, 2006
I'm in the process of gathering the stones to submit an order for an Aqualu FJ45 exactly as pictured below, getting every part they make for it frame up, with a 6" cab stretch and 6" shorter long box. I have a 1980 FJ40 350/SM420 I've hit the end of the road with, it's now parked in my barn and has been for some time, and will be cannibalizing to get it back on road in a new more interesting form.

I have a NOS 4BT 105hp crate motor on deposit slated to go into her, but I'm not set in stone on that, have another truck it can go into. I'm at peace with the 4BT and its shakes and noise, and tow boats a good deal so narrowed down to either the 4bt or a fresher V8 than my 350. Attracted to the simplicity of the 4BT and used to noise and shakes fly helis for a the day job that were made in the late 60's that make the 4BT seem reasonable.

What I'd like to pander here for are opinions on my driveline from those who've built trucks, I'm not a builder, to date just a modder and usually take the path of least resistance. In this case that appears to be mating the SM420 I already have and a Ranger OD to the 4BT, and just changing driveshaft lengths for the new frame/chassis. This little truck will tow irresponsibly heavy boats, very slowly, and will be asked to launch 8000lbs at boat ramps regularly, crawling gears are welcome like the SM420's 1st.

Years ago I nearly bought a Ranger OD and never went through with it, tolerating the 350 kindly reducing my fuel load by way of the SM420s 4th gear on the highway instead. I think I'd really appreciate a NV4500 setup too though, as I do highway a lot, live up in BC and work at a different end of the province, 1,100 miles away, than where I live.

So right now I have a 350 I want to be rid of, an SM420, and stock cruiser transfer case. I'm most inclined to go NV4500 behind the 4BT right now, with the Ranger OD and my SM420 a close second. I suspect I may not be too bothered by the gear whine with that 4BT jack hammering the frame rails up front. But a smooth shifting 5 speed sounds pretty good and won't get in the way of the kid's legs in the middle of the bench seat I plan as much as two sticks.

If you were doing what I'm doing, what am I choosing that's stupid and what would you do instead? Would like to hear from guys who've built trucks in depth, I'm not one yet.

FJ45 Chassis Complete.jpeg
I wouldn't recommend a 4bt if you're going to be doing a lot of highway miles. They're loud and shake no matter how you try and tame it.
Fair points and I'm actually sure you guys are right, but I need it to be a tow tractor and like the ability to turn up the P7100 for vastly more power. Driven a lot of farm equipment and had a 12V cummins, used to wearing ear plugs while driving, sure the 4BT will surprise me still. There just aren't many good options that fit, that can make 250hp and 450b-ft if the desire arises, without electronics. I've already spent 12 years with a warmed up 350 V8 and it's not what I'm after, prefer diesels, and expired jet fuel is free at work.

Pierps, thought hard about the 2.8, but it doesn't have the power if I want the wick turned up down the road for pulling the ocean boat. The 4BT is cheaper and has a lot more power on tap if desired, with minimal effort to extract it. But it's rough and miserable. But it's also tough as a beat mule and does what I'm after.
I also vote for the R2.8 with the NV4500. Keep in mind, the numbers you see on the spec sheet have been tweeked to make it 50 State legal. I am sure it would produce much more power with a little tuning.
Another diesel option is the Mercedes om606. It is a 3.0 i6 that's about 170 hp 240ftlbs stock but is easily warmed up with a custom ip. The guys over in Europe are doing some really crazy things with them like 1000+hp drift cars and such. Personally I have a merc with a 606 in it and it's nice smooth and quite but still has that nice diesel sound to it.
I also vote for the R2.8 with the NV4500. Keep in mind, the numbers you see on the spec sheet have been tweeked to make it 50 State legal. I am sure it would produce much more power with a little tuning.
Not really familiar with running jet fuel but I'm guessing the 2.8s electronics might not like it so that's another thing to consider.
Jet fuel/diesel same thing. From my understanding, jet fuel is just a better grade.

It’s actually a cut of kerosene with additives, runs well in a diesel but has substantially less lubricity. We add two stroke oil to it, the inline pumps don’t seem to mind it but the VE pumps need more lubrication and fail early on it (based on one case of a coworkers 24V Cummins). I do suspect the R2.8 is going to be more particular about it’s fuel, also like that the 4BT is electronics free and can be submerged up to the intake manifold.
Find an HDT? Smoother. Similar power to 4bt but more refined. 1 wire. Tune with a 10mm and a screw driver. Decent fuel economy.

Would be costly is the trouble.
Find an HDT? Smoother. Similar power to 4bt but more refined. 1 wire. Tune with a 10mm and a screw driver. Decent fuel economy.

Would be costly is the trouble.

1HDT would be stellar, likely even the best option, as you mention cost though... a clapped out 200k 1HDT will cost more than my new in crate 4BT and won't be able to out pull it. I can tolerate a lot of rattle, noise, and vibration for a new motor with cash for a Vegas wedding still in my pocket.

Whole goal here is a brand new truck, everything going into her will be factory new or rebuilt, and a 1HDT while I'd be all over it at equal pricing to the 4BT I struggle with to put a 200k mile salvage motor into my brand new chassis and pay handsomely to do so. I didn't bring up budgets so you're point is good, unlimited budget a rebuilt 1HDT would be the cats' caboose.
I wouldn’t discount the 2.8. Ford recently replaced the 3.9 Cummins with the ISF 2.8 in the F-4000 (I.e Super Duty dually sold elsewhere). It’s gross weight rating is 6,800 Kg and towing is 10,400 kg if I’m reading the Portuguese correctly.

It however has a 5.38 rear gear and a 6.13:1 first gear (only offered with manual trans). It’s top speed is also only 117 km/h. Going slow is the only way to make up for as you say “irresponsibility heavy” loads.

I’ve driven both the 2.8 and 3.9 in 60 series and the 2.8 has a way more useable powerband, and is vastly more refined.

For moving heavy boats around a yard I’d look to gearing way before I wanted to add power.

The NV4500 gear splits aren’t great for a small diesel either - especially one with as narrow of a powerband as the 3.9.
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Kleatus appreciate the been there done that, it’s what I’m here for. Good to know on the 2.8, I’m crusty and really like mechanical diesels hence my 4BT pushing.

The 2.8 when I first learned about it had me fired up, the weight and packaging of it are great. Again though on price it’s a good $4000 over what the 4BT new in crate cost, even though it’s a fantastic value for what it is. And admittedly it doesn’t have as high of power ceiling, or the low torque, of the 4BT. The factory spec’d 140hp 4BT is putting out just shy of 400lb-ft at 1400-1500rpm, really nice tugging an four ton boat up a rough ramp. Agreed gears can make up for it look at bulldozers. I’m thinking I’d like to save the money and have the power capability, and that I may regret it. But it’s a regret I can afford.
I would stretch the wheelbase to 112ish inches. I would stretch the cab 12 to 15" instead of 6 because I like cab room and 45 cabs are tight and 6" just makes it livable not comfortable. I would have the firewall recession extended a few more inches. Then I would drop a 6bt in it. If your pulling a lot then you want the tow rig to have a long wheelbase and to have some weight, the 6bt would give you the weight and would be smoother. It would also give you plenty of power. The 4bt can be made to rattle less, if you use it I would take those steps. But personally I would just go all in and go 6bt. You could put the intercooler under the floor to give more engine bay clearance. For a Trans I would use a nv4500 or nv5600. I would put a 14bolt axle in the back, and fj60 axle up front or Dana 60 or ford 9" with Dana 60 ends. I would keep diff gearing around 3.70 for good highway cruising and use Trans and tcase low gearing if you need to pull up a boat ramp.
In your currency $15K with a package discount and doors not pictured, and no sweat.

This, my friend, I'll be watching very intently! Note, I'd swap out the aluminum hood for a standard metal one.
As White Stripe said, stretching the cab 12" would be better (and available from Aqualu). I've ridden in a standard cab 45, and it is definitely tight. 6 inches would be nice, but 12 would be ideal. The other thing I would look into is getting OEM fenders. To me, the Aqualu fenders have never looked right. They are better than they used to be, but they still are just a little off. If you can find a good set of OEM fenders, I think it would look a lot better.

There's obviously a lot of 4BT haters here on Mud. That's fine. Everyone's entitled to their opinion. However, look on the Hardcore forum at Boots4's build "Family Haulin'". It's currently on the front page in the Hardcore section - Family haulin'. He has a twin turbo 4BT set up in his 60 and has lots of good, practical knowledge in his thread. I've ridden in it, and it has gobs of power, it's not near as "rattly" as one would expect, and with the sound deadening he's used, it isn't all that loud. Last I heard, he was still getting around 20 mpg as well. Mike is an engineer by trade and a consummate tinkerer. If you want some good reading, crack open your favorite beverage or 3 and sit back and read all 124 pages.

Good luck with your build! I'll be watching!

Thanks I’ll look that up, up in bush camp with long evenings this time of year sixty degrees north. I’ve run a 6BT 12V a good deal, actually learned to drive on one, and Cummins rattle is pretty darn familiar. I’d like to avoid electronics and keep it simple, and torquey. Price is right too, willing to risk a regret at the price of the 4BT.

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