Ideal operating RPM

[Sports140]

Hey!

Wondering about RPMs on Transits. Is there a consensus or definite answer on what the ideal operating range is, minimum and maximum? Optimal cruise RPM? Would it be different on downhill vs flat vs uphill? Does it differ between engine models? Can it change with engine age (miles driven)?

I'm thinking in terms of best practice for being kind to the engine and helping the van last. (Assuming it makes a difference there, and not only on mpg, cause it does right?)

Remember reading on here someone recommending to not take them above 2500 if you could help it, seemingly for long term reliability issues. I'm also raised on general advice that 1500 is close to lower comfortable operating boundary for diesel engines. Personally I just listen to the engine hum and try to cruise around where it sounds smoother but unconstrained, maybe 1800-2100 range, but that's not really based on any knowledge

My transit (2.2 140ps) seems a bit eager to tell me to change gears, giving the nod (up arrow) at about 1750, which usually would make new cruising rpm around 1400-1500, and my gut says that's on the edge low, but I'm an absolute beginner

Curious to hear someone chime in on this

Cheers, McGilvray

[dumper]

rpm is basically governed by the axle gearing so if you’re driving at the speed limit on what ever road you are on so unless you drive in a lower gear that’s all you can do control the revs.
My mk6 135ps jumbo had a 3.7 axel and at 55 mph the revs around 1800 to 2000 and was about right and at 60 mph on motorways in 6 th I never had to change gear all then I got the mk8 129 ps 460 x minibus it had a 3.1 axle at 50 mph 1600 revs so most of the time never used 6th until on duel carriageway or motorway and then it was charging gear all the time in the end I changed the crownwheel and pinion to a 3.7 made it a much better drive and didn’t affect the mpg.
The revs quoted are approximate as can not remember exact revs not sure what my latest van revs are with it being a automatic,
Me personally the gearing on moden diesels vehicles is to high that’s why dpfs are clogging up and the egr doesn’t help.

[metalworker0]

As dumper said .. DPF, EGR on a modern diesel, clogging, blocking , so you have to not baby it. not drive lots of short journeys without a large non stop large journey every couple of hundred miles to undo the short journeys

which sort of defeats the object of an EGR and DPF = garbage climate change nonsense.

best change oil every 6000 or every year what ever comes first, be prepared like someone trained in the military (know it like your rifle) to be able to service the EGR whenever needed ... you'll work that out , how often etc over time.

after long journey in the summer ... dont turn the engine off without a min or so idling ... or oil will "cook" into carbon in the turbo.

change gearbox oil every 60,000, change diff oil at the same time if RWD.
change power steering fluid at 100,000
and if you wanted to really nanny it you could take the drive shafts apart and change the grease if fwd every 60,000.

brake fluid every 3 years or 40,000
coolant system flush and new antifreeze every 4 years.


all the best.mark

[Sports140]

Thanks for the thoughtful replies!

Dumper: Right, so unless you reconfigure you axle ratio (kudos to you for doing that btw! Pretty kool mpg unaffected too, goes against the teachings, doesn't it?) you're dealing with applying the "speed meets gear makes rpm" vs the terrain you drive.
In my neck of the woods things get pretty windy, so a stretch of stable speed limit road can have a natural 15mph forced variation even when driving with zero traffic, which gets to my original question; what RPM ranges you try to stay within, where the sweet zone is, and what could change it. I'm interested in where people draw these boundaries, and I don't know the correct "textbook" answer either, so curious on that too

I guess the 3.1 ratio leaving you 1600 on 50 gets problematic because you have such a low distance to your "lower bound", making you gear up and down a lot as the road and traffic unfolds, rather than a theoretical constant cruise at 1600 being problematic? Or no? Does good cruise RPM lay some hundreds above that for you?

When gearing upwards in uphill, I'd usually add maybe 100-200 rpm before the switch to make up for the "headwind" draft vs where I usually would gear. Vice versa is the "tailwind" of downhill. Anyway, I wanna hear about RPM numbers and where people place their operating range, or "soft limits"
Also wondering what damage prolonged high RPMs can do, say 3k or 3.5k, and if that would be worse when under load, or if revving in free?

Sorry for being a bit newbie and needing to clarify, but; the higher gearing means a lower ratio, and the resulting faster engine doesn't leave enough time for the combustion to completely burn out in the chamber, guffing soot?
I'm no fan of egr either. Why can't we just make some deposit filter you change at oil change intervals and leave the combustion air alone?

Mark: Lot's of great tips here! Never heard about the "idle down" in big heat before, might even have been what's done my turbo seals in on my Vivaro. Speaking of, I'm used to going annual rather than on distance with oil change with less sensitive vans, and learned just recently how it matters on a Transit when I changed after about 22k miles (bought it just serviced march last year) and largely resolved a startup issue! To my knowledge neither gearbox oil or psf has been changed through lifetime (about 165k now) so better get to it On driveshaft I got a ripped one right side front. Got the boot and grease ready, just hope I'm not too late! Plan is to get my van into Olympic shape

A little nod to "garbage climate change nonsense"; the current oceanic heating, including very deep down, is something like 90% unaccounted for / unexplainable with the current human induced "green house" warming model, yet I've yet to see a headline about having to fully reexamine the models and presumptions that are being shook apart. I guess we'll live to sea

Anyway, where do you like to "fence" your RPMs, and do you have a cruise "sweet spot"?

Cheers, McGilvray

[metalworker0]

Sweet spot .. there have been engines all petrol in the past that ive owed that made a distinctive satisfying hum when they where in their sweet spot.

A sweet spot, i think is to be learned by you over 1000's of miles of driving, people here have all sorts of transits, different weights, lengths, different amounts carried in them , campers with different frontal areas .. a camper may not benefit from a change of gearing if its shaped like a brick with a 8 foot high roof.

If you had a real time mpg display .. then driving with that showing the most mpg all the time and learning from it would be a start .. but because of the DPF .. may not be to the benefit of that.

Diesel engines were initially designed to run at fixed Rpm's as stationery engines,running in their sweet spot, , then someone had the idea of fitting them in cars and vans.
a sweet spot is whatever you perceive that is .. most economical running conditions or least amount of stress on engine .

all the best.mark

[dumper]

You usually find that vehicles have a sweet spot that they are happy to run at if you don’t look at the speedo for a while it will tend to return to the speed it’s happy with most of the time I drive to the speed limit and don’t want to be charging gear all the time .
Back when I started driving transit mk 1&2 at work they didn’t have the power of modem vans so you was always driving them hard up and down the gears no rev counter to worry about.
The main reason I changed the axle was i Marshall on car rallies with a lot of off-road use on tight uphill hairpins I had to slip the clutch to get round them

[knobby1]

Your 2011 Euro-4 FWD only has 2 axle ratios available for each of the 5 or 6 speed gearboxes...cannot be changed unless you change the entire gearbox.

Sweet spot RPM for the 2.2 & 2.4 is ~1800-2200 rpm...this is in the meat of the torque curve.

You do not have a DPF. Your gearchange arrow shouldn't come on until much higher in the rpm range, approaching 4000 rpm.

Lord Knobrot (Smithy)

[DanMK7uk]

I keep mine below 2k revs until up to temperature and dont often go much past that day to day maybe 2.5 if steep hill to get it going.

Once a week or 2 a run out at 3.5k for about a mile to give it a clear out.