I’ve had my 3.6 for sometime now and to date gives great open road performance. I’m a bit of a nerd when it comes mechanical knowledge but I’m learning fast and trust my questions are ok with you guys even though they’re just bread a butter.

Being a manual 5 speed, ( I love driving a manual my other cars including a Motorhome are automatic)
you get to know what revs are needed. My question is more of a query, do I have anything to worry about the engine doing kangaroo jumping if in say 4 th gear at 50km an hour, it is just too slow to drive in the built up areas that the authorities demand a maximum of 50 kph or in uk similar would be 30mph. I find I need to stay in 3rd gear to stop the low rev jumping if I remain in 4th. I presume it’s just a manual gear attitude and a big 6 engine needs the higher revs.

mike

 

You’re lugging it and so stay in a lower gear. Kangaroo jumping is not a thing. Lurching is.

 

Excuse me! Explain your in Ept comment. You’re USA mate I’m a Kiwi, Think.

 

Engine power is measured in two ways Torque and BHP. Lack of Torque is what you are dealing with.
In a petrol engine, torque (ie turning power) is revs-dependent. By remaining in 4th at such a low speed you are reducing the revs (and so the torque) to a level that will not pull the car smoothly. So the engine is turning unevenly, stressing the crankshaft and the drivetrain, and screaming at you to select a lower gear! Lower gear = higher revs = more torque = smooth running.
My old Ferguson tractor will pull a house over at 1,000 rpm, and start quite happily on top gear, because the engine is designed for high torque at low revs. Try starting your car in 5th and it will stall.
By contrast, a Formula 1 car produces huge BHP, (maybe three times as much as a Mack truck semi) but very little torque, same with a racing motorcycle. However the Mack truck produces VAST amounts of Torque, so can pull anything at very low revs. Engines are built with their uses in mind, in a car there has to be a balance between (a) pulling power to get it off the line and able to carry passengers and loads (b) BHP which means acceptable high-speed performance, and (c) useful Torque across a decently wide rev-range so you are not continuously having to change gear.
The real reason modern cars have 8 speed autoboxes is because their engines (whether diesel or petrol) are optimised to give the best fuel economy/torque/power compromise, and this entails a VERY small useable rev band; hence their need for loads of gears to keep the thing at the optimised revs.

 

I've kind of figured over the years with typical 'car' gearbox ratio's, certainly the more modern ones the optimum gear is typically the speed limit (MPH) divided by 10 - so 20 = 2nd, 30 = 3rd, 40 = 4th and so on until you've no gears left - not saying this is a hard and fast rule but it is how I educated the wife.

The wifes car has a gear recommendation and I totally disagree with the shift points it recommends as it really labours the car (for fuel economy I would guess - screw the repair bills). In stop start traffic select a real low gear - just enough to stay with the flow but not enough so that you're stopping all the time - this avoids wear and tear on the clutch and associated items and also the drivers knee etc - dont' be so eager to close the gap and be constantly shifting and stopping. It takes more energy to get something moving than it does to keep it in motion - something you learn fast if you drive larger vehicles.

I've had similar issues on older autos where they are too eager to increase - or not eager enough - modern auto's with manual features are so much more civiliised.

 

They be up there and have some very odd sayings, as do we I suppose on the other foot.

Kiwi/Aussie for "lurching", = Kangaroo Hopping.

 

Im In England, Germany and USA. You’re excused. Still, stop driving the car in 4th gear while driving that slow. Its called Luggin an engine all over the world.