Cummins Turbo Diesel in a 109 5-door

[gallf1]

Hi:
Just completed the installation of a Cummins 4bt Turbo Diesel in a 1971 SIIA 5-door. It has Salisburies front and rear, 1-Ton springs and a Ashcroft High Ratio T-Case and 36.3" diameter 9.00x16 tires on NATO rims. I cruise at 65mph tunring 1900 rpms.....

[leafsprung]

Looking good. What transmission? Find some comfy earplugs :D

[gallf1]

It has a Borg-Warner T-18 4 speed mated through an adpater plate to the Ashcroft High Ratio T-case. !st gear is a "granny gear" and with the Cummins torque at idle even, it will crawl over anything.

The diesel clatter is louder at idle and at road speeds, I can still hear the radio/cd player and hold a conversation.....:thumb-up:

[leafsprung]

I have a 88 with a similar setup (cummins, salsburies, HR t-case, NP435). Conversations are possible but its not really pleasant conversation like you would have in a typical car or even a gas powered rover. Distance driving is really taxing and the droning of the diesel really wears on you. Makes a good around town car though. Im sure the diesel is nicer than the Ford? that was in there before. There is a growing number of cummins rovers Im tempted to start a mailing list.

[msggunny]

Damn that things pretty.

[KingSlug]

I really need pics of the engine mounts and the exhaust routing. I have a 4BTA w/ inline pump/NP435/HR Xfercase, ready to go in my ambulance if I ever find the time.

Jared

[jimsshuman]

Damn that things pretty.


2nd that
mine's not going to be that pretty!

[gallf1]

Thx Guys...
The motor mounts are aftermarket polyurethane mounts as used on the Cummins 6bt...you can get them here:
http://www.autoworldmt.com/Page_11.html

They are not too rigid and not too soft...just right! They are a much, much improved version of the OEM mount with not only polyurethane instead of rubber, but much thicker steel plate. They were tested to destruction and the 5/8" mounting bolt will shear before the steel/poly pulls apart!

The bulkhead will need slight mods (depending on how you route your exhaust) for the turbo downpipe. I basically cut a 3" vertical piece out of the footwell area from the frame up to where the throttle cross shaft is and welded in a new 16 gauge piece, seam sealed it and then gave it two coats of POR-15 before a top coat and insulation. I have roughly 1" clearance all around the 3" turbo down pipe and it is wrapped in a fiberglass wrap for heat deflection. The bulkhead gets warm, but not so much that you cant keep your hand/finger on it for a long time or paint flakes off...

The only other important thing was that the original set-up of most 4bt's is to have the engine tilted off of the vertical for hood clearance, which I didnt like so I midified the mounts accordingly and I modified the T-case mountings to center the engine in the LR frame.

Felix

[BGGB]

That is my dream vehical, i've been looking at the 4bt for some time now...who set up the adaptors for you? cummins to t18 requires a adaptor correct. also if you don't mind where did you source the 4bt from, i see alot of peoplle pull them out of old step vans/frito lay trucks. Your truck looks great good job and have fun!

[gallf1]

I had a local machine shop make the 3/4" aluminum plate adpater (to adapt the T-18 to the Rover T-case) and to make a custom input shaft for the transmission....I took my time and measured it carefully with all the components out of the Rover and on a bench.
I joined the cummins 4bt forum and founda person in the Eastern part of the USA who had just removed one from a bread truck. You will also see them on Ebay....

[TeriAnn]

Hi:
Just completed the installation of a Cummins 4bt Turbo Diesel in a 1971 SIIA 5-door. It has Salisburies front and rear, 1-Ton springs and a Ashcroft High Ratio T-Case and 36.3" diameter 9.00x16 tires on NATO rims. I cruise at 65mph tunring 1900 rpms.....

Except for the engine we are running very similar drive trains (T-18 -> Series transfercase with Ashcroft high ratio kit -> Salisbury rear. Except I have Rover front assembly with 24 spline SeriesTrek axles & TruTrac diff).

What R&P gears are you using? I'm running 4.75:1 and with tiny 33.3" dia tyres am rev'ing 2650 RPM @ 65 MPH. I'm being too lazy at the moment to run the numbers but it seems 750 RPM is a lot to drop for an extra 3 inch dia on the tyres. Or maybe not.

Where did you find the 9.00X16's? What brand?

[gallf1]

Hi TeriAnn:
Originally I followed in your footsteps and installed a Ford 302 V-8 to the T-18 with the adapter plate, just like you did. The low end torque of a diesel and mileage plus engine longevity was lacking in that set-up, so I went with the Cummins 4bt, (plus I could never get the Holley carb to not sputter when it was really cold outside!!)

The diff's are 4.70:1 and the overall diameter of the tires are 36.3"...the gear/rpm calculator I used on-line gave me those numbers and it was confirmed when I had to calibrate the diesel tach with a laser RPM device.

The tires are "McCreary Super lug" 9.00 x 16LT Bias Ply. If you Google it you will see a lot of the M-37 Army aficionados use them. I found mine through STA (Specialty Tires of America) and when I bought them 3 years ago they were $125.00 each.
I think that they will rot off the rim before I wear them out...they are like load range E or something and the tread depth appears to be like 3/4"!!

I have aired them down to about 12psi and they still held on to the LR NATO style rims....(no tubes).
Felix

[TeriAnn]

Hi TeriAnn:
Originally I followed in your footsteps and installed a Ford 302 V-8 to the T-18 with the adapter plate, just like you did. The low end torque of a diesel and mileage plus engine longevity was lacking in that set-up, so I went with the Cummins 4bt, (plus I could never get the Holley carb to not sputter when it was really cold outside!!)


I was never fond of Holleys off road. I had a Carter AFB clone (500 cfm) set up for economy and got about 15 - 16 MPH highway out of the V8.

Recently I switched over to 1991 Mustang 5.0 EFI. Much better fuel mileage, more power and really smooth at low RPMs in low range first. With the carb I couldn't keep that 70:1 low range first running smoothly at low RPM. Though I will admit I had more than my share of teething problems, most due to buying out of spec used parts off eBay. I suspect eBay is what happens to the bad parts that the mechanic hands back to the customer.

The most insidious was me not knowing that the EFI computer keeps the engine in warm up mode until the water temperature in the engine reaches 185 degrees. I had a 180 degree thermostat and a good radiator. The engine never got to 185. In warm up mode,the computer leans out the engine to help it heat up the coolant. The radiator kept the engine temperature low but the exhaust temperatures sky rocketed. This resulted in melted clutch hydraulic hoses, melted subharness wiring, heat damaged carpet over the muffler and vapor lock from overheated fuel lines. It drove me crazy until someone mentioned that the computer stayed in warm up mode until the coolant reaches 185 degrees and that the stock thermostat for the EFI is 190 degrees. DUH!

As far as engine longevity I'm guessing somewhere between 150K and 200K miles between rebuilds with the EFI. My rebuilt long block came with a 30 month or 30,000 warranty and only cost me $1300 plus exchange. I figure is a lot cheaper than dealing with a 2.25L petrol engine rebuild and 150K miles is a reasonable length of time between rebuilds.

It has more torque at idle than a 2.25l engine has a peak and has met all my needs with a power reserve. So for now I'll stick with it. On the other hand if someone handed me the LR TDV6 with all the parts I'd sure consider the swap. For now I'd rather drive my truck than work on it.