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I do not know whether this is the right place, but will ask.
When I bought the truck, from the service told me that i must drive at 2500-3000 rpm, for best performance and care to engine. However, I discovered that I could drive into town with 1000-1500 rpm at flat road or downhill (50 km/h; 5th gear). How bad could it be for the engine?
On the other hand, when driving at low rpm are all cooling systems work well or they are included only at high rpm?
I hope you understand my questions...
1000 to 1500rpm is OK on light to medium throttle, but if you have your foot flat to the floor then it's time to select a lower gear. I can't remember what engine you have but the diesels deliver maximum torque at about 2000rpm and peak power at about 3400rpm, so driving between those two will get the best out of the motor. Petrol engines work better at slightly higher revs.
Cooling systems will adjust to suit whatever you do.
On diesels the exhaust gas temperatures will usually be lower at 2500rpm on medium throttle than 1200rpm on full throttle. Turbos on standard engines with standard exhaust won't be at full boost below about 2000rpm.
Tony
as above, I'd also say just don't let the engine struggle at too low revs. Otherwise, low revs are good for engine wear and fuel economy. It's tricky with an auto as there's so much slop, like they go around slow corners in 3rd, but in a manual it's more straight forward.
Agree with YNOT, best engine revs for a majority of diesel engines is between about 1900 and maybe 3400.
In my experience, petrol engines operate at higher revs e.g. 2200 to 4000
As a "rule of thumb" where there is a tacho fitted, 40% of the "redline" is around the low of operating revs and about 80% of "redline" is the high end.
For example, if the red area on your tacho begins at 5000 RPM, then the low end would be around 2000RPM and the high end would be around 4000RPM.
But listen to your engine, if it really screams at 4000RPM then reduce your revs. Likewise, if it shudders at 1500RPM increase the revs.
Besides which, too low an engine speed will not "throw" enough oil around the gearbox and may cause wear problems.
So, as a general rule - in any gear but first gear, keep the engine revs above 1500RPM.
Labouring you engine no matter if its petrol or diesel WILL damage your engine
Thanks!
the engine is RD28TD.
Now I understand that I will save on fuel, but I'll go 10 or more times as expensive as a damage the engine or the gearbox.
I found on the net this too:
"the maximum torque in catalog given is the most effective and economical for the engine speed"
So i think i must stop drive the patrol whit low revs to save the engine.
Thanks again!
How I see it;
General daily drive -
2nd for take off. i.e. at lights.
3rd for corners.
4th for straight road.
-
5th highway
1st for heavy loads and uphill take off.
Daily drive can be minimised to two gear changes 3rd and 4th.
4 Low on beach
2nd for take off
3rd for bends
4th for straight - Max' speed 40k's
-
5th N/A
1st extreme boggy sand.
4 High
Unfamiliar gravel roads.
Maintain sufficient torque/revs at all gears