I hope this is in the right section to post this.

I am planning on building an OM606.962 with an OM603 IP (goal of 200 HP). I've done a little bit of researching and it seems like some people are seeing an engine RPM of 2,600 to 2,800 at 70 MPH (113 KPH).

I plan to use the OM606.962 in a Jeep Wrangler, and I am having a tough time figuring out what gear ratio would be best for the axles.

This is the current plan:
Engine: OM606.962
Transmission: TH700R4
Tires: 305/70R17 (34.1"/86.6 cm tall when mounted)

When in 4th gear (overdrive) with the 700R4 transmission, these are the calculated RPM numbers I get for different axle gear ratios:

4.56 = 2,202 RPM @ 70MPH
4.88 = 2,356 RPM @ 70MPH
5.13 = 2,477 RPM @ 70MPH
5.38 = 2,598 RPM @ 70MPH

Normally, I would go with either 4.56 or 4.88 gears, but I am not too familiar with how this engine would run in that RPM range at that speed.

Does this engine like the higher revs of around 2,600 to 2,800 RPM at 70 MPH, or is 2,300 RPM at 70 MPH good to use with this engine?

If I have to go for higher RPMs, then I will look into a different transmission instead of gearing it so low.

Thoughts?


*as a side note, I want to use a non-computer controlled automatic transmission for this particular build.

2300 RPM is fine, so much smoother than 2800. The fuel mileage is much better around 2300 than 2800, too. After a 5-speed swap my car turns about 2000 RPM at 65 and it does alright, not much extra power, but it gets great fuel mileage. 4.88's would probably be a good choice for your application because you plan to run bigger tires, and you probably won't spend hours at a time on the highway.

Keep in mind this motor will lug under about 1500 RPM (in higher gears, in 1st or 2nd I can't really get mine to lug at all).

__________________
dieseleverything

'95 E300D 279k 717.411 5-speed swap 40 MPG
'78 240D Turbo 144k
'83 240D 201k

4.88 is kind of what I was leaning towards. Good to hear that the motor doesn't lug around that much at 2,300 RPM.

And the Jeep I plan on building will be for overland type of use, so it will be a highway driver to get to the destination. It could potentially see many highway miles, and I may tow a small little military type trailer behind it for additional storage. I know for sure that there will be multiple times per year where I will be driving 6 hours on the highway. Might be once or twice a year where I'm at 12-16 hours of seat time on the highway.