My caddy TD (1.6 with Garrett turbo) shows to be putting out 3-4 psi of boost while cruising at 60-65 mph.
From what I've read, this is normal since diesels take as much air as possible while running...the intake is not limited by a throttle body, etc.
I have two other turbo vehicles (1.8T Audi and a 5-cyl turbo quattro) and it seems those engines are actually not "in the boost" when cruising at the same speeds. The gauges read close to zero boost and that only changes if I'm accelerating to pass, etc.
Would it follow that the turbo's on diesels see more boost action / more frequently than on a gas engine? Does that mean that a turbo would possibly get more wear on a TD than a similar sized turbo on a gas engine? I just took a 200 mile trip and it occurred to me that the turbo was in the boost between 3-10 psi the entire time.
Not sure if that's even a factor since there are likely differences in EGT's and boost levels between applications, etc. I know these engines and turbo's are durable units and that they're "meant" to do this... I guess my question is more about the nature of TD's than anything else...
Thoughts?
The biggest enemy of a turbo is heat as it causes the oil co coke on the bearings. Diesels have lower EGT's on average which drastically improves the life of the turbo. My Jetta has ~220k on the turbo and it feels perfect. Virtually the same turbo came on gas Volvos and I've heard of them lasting 100-160k.
as long as the turbo is being cooled/lubricated by good clean oil... it shouldn't fail. just look at gas turbine engines
The Garrett on my 1.6L has 492000km on it
no shaft play
spools up to 10 psi at 3000rpm
3-4psi when crusing at 115 km/h
Last for ever if well taking care of
Veeman, my turbo Talon (gasser) does the same thing - no boost at all under steady-state cruise. OTOH, most turbodiesels use some boost all the time to assure cleaner exhaust and lower EGTs. It's normal. Just change the oil and filter often and the turbo should outlast the car...
