Does a TDI use the turbo at all at a cruise at say 70 on the motorway?
I guess some are 'always on' but I know my 110bhp has solenoids etc controlling the turbo, which itself has variable vanes.
I have it at the back of my mind that maintaining a 70mph cruise would need no more than about 40bhp.
Would 'reverting' back to N/A save any fuel?
Just out of interest really! Only person I know of with a similar setup is Mad Max!
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Average car is around 27BHP when cruising at steady 70. Certainly all the diesels I've had are barely on boost at this stage.
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Variable according to conditions of course. Up hill fully loaded and into a head wind can require rather a lot of HP.
Its all about throttle postion really, if you are feathering it to keep it on the move its requiring very little HP.
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TourVanMan TM < Ex RF >
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Does this mean that after a c70 mph cruise there's no need to idle the engine for a minute or so to cool the turbo down and prolong bearing life? (I do this to play safe...)
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I thought that a turbo engine was least efficient when not on boost because you have the restriction on the turbo on the induction and exhaust systems but no boost. Isn't a engine at it's most efficient at max torque in terms of fuel consumed and power generated?
Steve.
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For Sale - Xantia HDi Exclusive.
XM 2.1 VSX.
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I thought that a turbo engine was least efficient when not on boost because you have the restriction on the turbo on the induction and exhaust systems but no boost. Isn't a engine at it's most efficient at max torque in terms of fuel consumed and power generated?
Is there a restriction on exhaust/induction with a Variable vane turbo ?
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I guess that would depend on how long it look you to achieve 70, how long you'd been cruising and how long it took you to slow down (as you'd be using engine breaking to do this).
I'd keep idling the engine for a minute or so (as I do).
Interested to hear any views to the contrary though.
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>>Does a TDI use the turbo at all at a cruise at say 70 on the motorway?
Why not temporarily rig up a simple boost gauge, and see for yourself? It needn't cost much, or need any holes drilling - I think you will be able to tee into a small bore rubber pipe rather than having to drill into the manifold.
I suspect that during 70mph cruise conditions, you will barely be producing any boost even though the engine might be in the rev range where it could produce boost if acceleration were demanded.
Number_Cruncher
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Why not temporarily rig up a simple boost gauge and see for yourself?
Sounds like a plan, don't have one and I'm a bit skint at the moment but is something to think about I guess!
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I'm about to go out with VAG COM connected in my TDI, so will report back with some graphs!
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www.flickr.com/photos/13666355@N00/sets/7215760017.../
there's a couple of graphs...atmospheric pressure is around 1040mb I think.
Remember though, even though boost is low, turbo can be spinning quickly anyway due to closed vanes.
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BTW - You can click on the graphs and click sizes and view them at the larger original size.
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