Hi,

This is my first post. Around May, I purchased my first Diesel. It's a 89 Dodge raider that has a 4d55 / 5spd in it. Around June, it blew a head gasket and I ended up puting a 4D56 head on. I've been driving it for a while now and I have a few questions for those with more info than I:

1. What should my RPM's look like? Currently, at ~50mph the motor is running at 3k. Is that high? I'm assuming redline is at 4K. I took it on I-5 a couple of time and it seemed like I had to floor it to stay up with traffic. Could lower gears have been installed?

2. What should my engine temps be? I have a temp guage installed and its reading between 195-210 at normal operating temperatures. One thing I did notice is that the oil cooler is attached directly to the radiator (after market), can this affect running temps?

3. Will I be able to run 33" tires without a lift? I'm wondering if larger tires will help "gear it up".

Thanks again for any insight. I plan to keep this thing forever After new tires, my plan is to install an intercooler that I found on the UK ebay. I found an extra hood that I'm gonna try to install my own hood scoop on.

No one has responded yet, how odd. Did you buy the red Raider that was in the Seattle area?

The Monteros and Raiders of that era had 4.625 gears most commonly. If you want to add larger tires to compensate for the low gears, the Raider will wear 33" tires with no lift. The only mods will be trimming the front bumper ends and pushing the sheetmetal lip of the front inner wheelwell forward slightly. Alternately, you could find appropriate third member and front axle chunk from a Mighty Max with 4.22 or 3.909 gears and remain with the stock tire size. A few pics of my Raider with 33" tires here: rxinhed on Cardomain

The operating temperature of the diesel is going to be similar to the gas engine. My 87 Raider always was cold-hearted until I changed out the OE thermostat (stuck open) for a new 180 degree F unit. Always verify that the radiator is serviced. The OE unit is heavy brass and can handle multiple rod outs.

Hope some of this helps, as I have no direct with the deisel, only the other things.

Cheers,
Russell

I am in the process of modifying a Gen 1 SWB Montero with a 4d56 turbo intercooler setup. I swapped in 3.54 gears which should put be around 2k RPM
at 65mph�this makes for very easy freeway driving, much improved MPG and puts in my the sweet spot of the torque curve. I currently have Scorpion 235-75R15 tires for general road use. I'll post full results once I have everything dialed in.

Thanks for the responses! I will look at rodding/ flushing the radiator. I have a new thermostat I can install as well.

Right now I have 31" tires on it, looks like I'll have to make a choice between bigger tires or taller gears. I think I can get a hold of some taller gears, my buddy has a few mighty max.

I bought a dark blue one in the Lacey area.

Nice Ronin, do you have any idea what you're going to do about a hood scoop? Or are you going with a front mount intercooler?

I am going with a front mount intercooler 23x11x3 2.5". I removed the AC system as there is no need where I live and it freed up the room and some weight.

I found this specialized K&N Air Filter kit for the 4d56 DELICA and I am going to try it in the Montero.
Mitsubishi 4d56 Delica Air Intake

Here is info for the RPM's at which speed, gearing, tire size. Excel or OpenOffice:

Gear Ratio / RPM / Speed calculator

That is a killer spread sheet thank you for posting!

So, after playing with that spreadsheet for a while and plugging in 31 inch tires and 4.625 gears, I should still have lower than 3k rpm at 50 mph. Does this mean it could have lower gears in it?

I think I'm gonna end up going with 33 inch tires and a small lift.

Guess I'm not sure what you are asking...