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MG ZR ZS ZT Technical - ON/OFF Turbo

Is it possible to have an on/off facility on a turbo to keep fuel consumption down when high performance is not needed?
Tony

Yes, it's called the accelerator pedal ;-)
David S

David,
I would have thought you capable of a better answer.

We all know that it helps to go easy on the acc pedal,but on my existing diesel turbo,the turbo comes in at 2100 RPM whether I want it or not.
Also,On a DT the fuel effect will not be as serious as on a petrol engine.
(My special interest is regarding the 160 HP K series engine)
Tony

Some years ago, when the Intercooler split on my Montego Turbo (allowing all boost to escape), I ran around for a week or so off boost before I fixed it ..... no option! Did not notice any improvement in mpg during that time though......drove like a slightly under powered but very smooth 2 litre car ... which is what it was ... still pretty nippy though ... just big bang boost effect totally absent ... which is addictive .. the boost I mean.....lol. I still have this car ... drove it today .... still addicted ..lol

More seriously, bleed valves are used to increase boost so, why not adapt one to turn down the boost if/when needed.... something no doubt already exists ... search the web....

David's 'One liner' did have a winking smiley ... BTW, I prefer to call it the "Throttle" pedal .... but then, I'm old fashioned that way....;-)

JMcF
John McFeely

If you fit a boost gauge you will see that it's possible to drive with a light throttle and remain 90 percent off boost, especially if you use IAM-type techniques to read the road ahead and anticipate traffic flow. Whether you will see a worthwhile reduction in fuel consumption is a moot point.
David S

Yes, I see we are talking about pressure-charging the K Series VVC lump here?

It's called Head Gasket Failure - now that's a novel fuel-saving idea!
Eric

Having a turbine wheel in the induction airflow and in the exhaust flow is a restriction if it is not contributing to the power generating cabailities of the engine.

However, the main issue on fuel consumption is the engines actual compression ratio as this needs to be as high as possible within the operating parameters of the fuel used. As forced induction significantly raises the actual compression when in boost conditions this is why you have lower static compression ratios for forced induction.

Of course this is also the basic reasoning behind low pressure turbos where manufacturers are trying to balance the best of both worlds in keeping a reasonably high static compression ratio, but by doing so can't have too high a boost if they are still to be using normal road fuel.

The 1.8T engine is a low pressure turbo design which also sees far less difference between on and off boost and is characteristic of small displacement engines with forced induction used in larger cars to generate tax related low CO2 emissions.

Rog
Roger Parker

How about EKF, that'd be a really novel idea.

(Eric Keyboard Failure that is)

:(
Smiley

Smiley......you crack me up!
Eric

Roger,
You have overwhelmed me with technical facts!
Can you now try to answer the question in simpler terms please?
Tony

Tony, if you don't quite have the depth of technical knowledge to fully understand Rog's reply, then for your purposes the answer you are looking for is 'no'.
David S

This thread was discussed between 09/01/2004 and 18/01/2004

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