Diesel Question (1 Viewer)

[BajaTank]

Greetins, I would like your advice on the following please:
I have an Fj40 1978 with a NISSAN LD28 straight 6, 2.8L diesel engine, This engine was installed in New Zealand, I guess that type of engine is very common over there and Europe..... Not much here in the states (1981 to 1983 Nissan Maxima had them here in the United States). Finding parts are a pain but I am stuck with it, and although it has not given me much problems; it feels like it has to many RPM going at 55-60mph.
My question is, should install a turbo? (research told me a turbo from a Mercedes 300 diesel will work fine).
Or should I install a 5 speed tranny on?
I am not looking for a speed bullet just a little better than 55 to 60 mph with out hearing the engine at to much rpm.
Thanks in advance.

 

[Michael B]

3:70 gears would be an easier and cheaper way to get your RPM's down. A turbo would not affect your RPM range.

 

[BajaTank]

3:70 gears would be an easier and cheaper way to get your RPM's down. A turbo would not affect your RPM range.

Thanks, I never thought about that.....But I am running 33's, will 3:70 run fine with 33's?
What does the turbo do then?

 

[brian]

What does the turbo do then?

Witchcraft.

 

[Michael B]

33's and 3:70's are a great combo with a 4 speed. Turbos are power adds and will give better fuel economy.

 

[Jetlander]

Witchcraft.

 

[handcannon]

http://www.grimmjeeper.com/gears.html

Use this gear ratio calculator to see how the tire size and 3.70 gears will affect the rpm's of the diesel motor. I don't know about the Nissan diesel, but the best operating/MPG RPM for my GM 6.5 diesel is around 2K RPM. With a bit of searching on the internet you should find something that will give you an idea for the torque curve for that LD28.

A gear ratio of 3.70 and a 5 speed transmission may be what you need to get your RPM's in the range you need.

Don

ps- curiosity got the best of me and I went to grimmjeeper and plugged in these numbers:
H42 four speed trans, 1 to 1 TC high gear, 4.11 ratio (stock) 33" tires = 60 MPH at 2500 RPM, 2929 RPM at 70 MPH (your current setup)
H42 four speed trans, 1 to 1 TC high gear, 3.70 ratio, 33" tires = 66 MPH at 2500 RPM, 2637 RPM at 70 MPH
H55 five speed OD trans, 1 to 1 TC high gear, 3.70 ratio, 33" tires = 78 MPH at 2500 RPM, 2242 RPM at 70 MPH

 

[handcannon]

This site might help you find the best operating RPM, and other info, for that LD28. It is a very slow moving site compared to Mud, but had lots of info for my Nissan SD22 diesel motor.

http://nissandiesel.dyndns.org/

Don

 

[BajaTank]

Thanks for all the useful answers!, yeah even the Witchcraft one.

 

[SuperBuickGuy]

I knew nothing about these motors until a friend bought a Suburban with the motor in it. They're a really good choice for a diesel. What was said above is right - you need to reduce rpm through gearing or increased tire size. With a diesel, they have torque so increasing tire size actually helps them. For example, another suburban friend put a cummins diesel in his, and reduced the gear ratio (to 3.54). The diesel makes that possible, on top of that, add a turbo and you keep your top end.

the tl;dr - put a lift and bigger tires then a turbo....