Quote:
Originally Posted by 08crd
It could be an issue if you towed, as the gearing on the Merc gearbox, lends itself to towing.
However if you aren't towing, the taller gearing should help the diesels fuel economy, by lowering the revs.
This is mainly due, to the Merc gearbox being designed ,for high output petrol engines.
The diesel produces heaps of grunt around 1800RPM, whereas the gearbox/tyre combination, has the Jeep running at about 2200RPM.
Like I said, great for towing, but doesn't help unloaded cruising economy.IMO
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On my recent road trip to the NT with my van in tow I found that the sweet spot where the engine temp & transmission temp stayed coolest with 265/70/17 tyres was 110kph in 5th & RPM at 2200. Dropping back to 100kph saw my transmission wanting to jump between 4th & 5th. Temps raised from 85 to over 100 (engine temp spiked as well) & it made no difference if I locked the trans in 4th, the temps still went up.
So 2200rpm is the preferred rev range for this engine/transmission combo.