Yanmar 4JH2-DTE turbocharger question

[curlysue]

At what revs should the turbo kick in on this engine. We have this engine fitted in our boat and although she is not sluggish we have been told that the turbo is not working. The engine was only taken up to 2000 revs when this comment was made. They stated that there is an obvious change/noise in the engine when it kicks in which did not occur. The engine was not under load at the time of the test. We normally only take the engine to 2000 revs and occasionally 2200 as that seems to deliver all the power we need.

 

[Steve Clayton]

At what revs should the turbo kick in on this engine. We have this engine fitted in our boat and although she is not sluggish we have been told that the turbo is not working. The engine was only taken up to 2000 revs when this comment was made. They stated that there is an obvious change/noise in the engine when it kicks in which did not occur. The engine was not under load at the time of the test. We normally only take the engine to 2000 revs and occasionally 2200 as that seems to deliver all the power we need.

These engines (I've got one) need to be occasionally worked hard; say 4 to 5minutes in any continuous running hour and for a short period during the last 10 minutes before you switch off ; take it up to 4 to 4.2K revs - helps to reduce things like bore glazing.

I don't tend to notice when the turbo kicks in but it's probably between 2.4 to 2.6K revs

Engine oil should be bog standard mineral oil for diesels - none of this semi or full synthetic stuff

 

[Norman_E]

I have the 88bhp version, and full power is quoted at 3400 revs which is the maximum continuous speed, with a maximum of 3600 revs for short periods.

I do agree that the engine should be given a burst at full power every so often though I do not do so every hour. I find that 2500 is a good cruising speed. The engine has run for over 5500 hours and appears to be in very good shape. as for oil I believe that Shell Rimula R4 is currently being used (The engine was serviced for me over winter) and I do not know whether that is a semi synthetic or not as the Shell website makes it very hard to find the data. My understanding is that older diesels are best run on ordinary mineral oils whilst new to avoid bore glazing, but that later in life the use of semi synthetics does no harm. As for the speed that the turbo kicks in, my own experience of the engine is that there is no sudden surge of power and it is likely that the turbo begins to spin at quite low engine loads, and just gradually builds up speed. In any turbo engine the load as well as the revs influences turbo speed. An engine that is running under a heavy load at low revs needs heavier fuelling than it would at the same speed with no load, and is putting out more exhaust gas to drive the turbo.