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Posted by Paul ( in NY) [12.64.180.84] on Monday, October 19, 2009 at 10:14:33 :
In Reply to: 4bt in WM300 posted by Winslow Bent [69.144.101.124] on Monday, October 19, 2009 at 02:15:48 :
The trucks in the picture and a Power Giant W300 in build all are powered with Cummins B3.9 engines. They are capable of any legal road speed, as well as off road...Safely !
What you are asking is very doable. However, depending on your application, I have issues with the NP-420.
Cummins B3.9 engines are governed at 2500 RPM's. With that in mind, we have to decide what is the application for the truck. If your building a strictly offroad truck with speeds to 45/50 mph, then the NP-420/NP-200 with 4.89 ring and pinions will work well. If you want a truck that can run with traffic, with that combination, you will run out of available RPM's. You dont want to run at 2500 R's, against the governor, the sweet spot for fuel use and good running is 1800 to 1900 R's. My trucks all run in the 30 MPG range, with great power. My trucks all run
4BTA's. Thats the B3.9 engine with turbo and aftercooler. All my transmissions are NV-4500's, driving into 4.89 ring and pinion differentials, turning 36" 900x16 STA Super Lug Tires. Three of my trucks are running married NP-205 T Cases, 1 runs a divorced NP-200 T case.
As Kagi mentioned the NP-200 T Case will be fine, in fact my Bumblebee is running a NP-200 T case into a centered rear differential. The Np-200 T case is very strong, and if you run a centered rear differential driving off the center output of the NP-200, noise will be reduced and it will run cooler. I have no heat issues whatsoever with my NP-200. If you want to be able to run with traffic, I suggest either a GM 1993/1994 short tail shaft NV-4500 5 speed od or a Ford ZF-S542 5 speed od, either one in the 2 wheel drive version so you can use your divorced NP-200 T Case. Either of these transmissions can be mated to the B3.9, using the proper GM/Ford/Cummins flywheel housing adapter. The advantage with the GM 1993-1994 NV-4500 is the very low first gear. There are also disadvantages that we can discuss.
You will hear and read about some people changing the governor spring in the Bosch Injection pump to a Aftermarket 3200 RPM spring. I dont advocate this ! If Cummins felt
they could have LONG TERM longevity and no issues, they would have cranked the RPM's up right from the beginning. Trust Cummins engineering and design and you will have a great engine with absolute dependability.
The actual engine swap is quite straight forward. However, nothing is available off shelf for this conversion. You will have to fabricate everything, engine mounts, transmission mounts, throttle assemblies etc, etc. Prior to starting my Power Giant W300, I used to suggest a budget of $8500.00. Prices have sky rocketed and I now suggest a budget of $10,000. Keep in mind, you will have to beef up the front suspension, convert to 4 wheel disk brakes for safe stopping power at the higher speeds you will drive, power steering ( the B3.9 is heavy and makes steering even harder), pyro and boost gauges, some new wiring etc, etc.
If you have a source for parts or already have a B3.9, the price will drop. If you are unable to do your own fabrication, the price of the conversion will climb quickly above the $10K budget. I share these prices so you dont get trapped in a money pit and not be able to complete the job.
Due to popularity of the B3.9 engine, prices have gone from somewhat reasonable to absurd. A good running B3.9 in a truck you can drive and check out will command top dollar. Use maximum caution buying a B3.9 on a pallet that you have not heard start/run, and checked out. You could pay top dollar, then find you need a $800 + Injector pump rebuild or find the engine worn out needing a complete rebuild. Your sunk before your start. Used B5.9 engines are now cheaper than the 4 cyl B3.9, but dont be tempted to use the B5.9. Its much larger, very heavy, you will have to cut fire wall to fit her in. Its just not needed or in 'my' opinion wanted. the B3.9 is all the power you want.
This will get you going. I also suggest you go to the top of the forum, click on Phils Archives. Then do a search on Cummins. You will find more than you can read in one evening. I have only scratched the surface ! If you become serious and committed on doing this conversion, I will help you from start to roll out ! We will start with a LONG phone call. I will lay out everything so you know exactly what your getting into, what to buy, what not to buy, what will play nice together, what will not play together. I can level the bumps and provide you with probably every part number you will need. I am sure we will do a lot more than one LONG phone call LOL.
I also suggest you look at my Image Event Albums which cover the Cummins swaps in all my trucks. Look especially at; M37 Project, Bumblebee Power Wagon, 1943 Dodge Carryall, Power Giant W300. The link is;
http://imageevent.com/moosecreekmaple
The journey is expensive and not without challenges. Once complete, you will be happy and never look back.
Paul
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