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MECHANICALS With a 30 year-old automobile, there will always be discussion here - maintenance, modifications and mechanicals.

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Old 9th February 2012, 07:58 AM
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Oversize Oversize is offline
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Default D-Jet to K-Jet and back

Can anyone explain why MB used D-Jet (which is very similar to today's MPFI systems), then went to K-Jet (which wastes fuel through continuous injection) and then went back to something similar to the old D-Jet??? It seems to me they tried something different, but found it wasn't any better and went back to something that everyone else was using. I ask myself the same question with the vacuum central locking vs electric... Then there's airbags, hydropneumatic and back to airbags... What gives?

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Old 10th February 2012, 02:45 AM
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Styria Styria is offline
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Default Re: D-Jet to K-Jet and back

Mark, I am just not so sure that I can answer your post correctly. Regarding injection, let's not forget that it was Bosch that designed the various systems and the manufacturers would use whatever Bosch would place at their disposal. Back in the '70s, emissions was a dirty word, and K-Jet was formulated and introduced as cutting on emissions. Engines were supposed to run much cleaner. So K-Jet and KE lasted until the early '90s.

Since then, of course, computer controlled injection has taken over, and engine management, injection and sensors have taken fuel injection to an entirely more advanced and efficient level.

Regarding suspension with its variation from air to hydraulics and back to air, it pays to remember that Mercedes, with its own and unique 6.9 system - oh, and we must include Citroen, were just about the only manufacturers to offer a hydraulic system. Air suspension is now offered only on high price vehicles such as Mercedes and Range Rover (any others ?), but let us not forget that the McLaren MP4C (?) offers a hydraulic system that is much reminiscent of the old 6.9 arrangement. There is a lengthy and thorough appraisal of the McLaren system somewhere on our website. Regards Styria

N.B. Okay, found it. Introduced by none other than Mark. Have a careful read of how the system works. Marvellous.

Last edited by Styria; 10th February 2012 at 02:50 AM.
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Old 10th February 2012, 10:28 AM
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WiSeGuYY WiSeGuYY is offline
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Default Re: D-Jet to K-Jet and back

INTERESETED??? MARK , in 1970 i was about to enter UNI to study MECHANICAL Engineering and my dad at that time managed to divert my passion to CIVIL ENGINEERING ( glad he did) still love cars but buildings are really have other feeling.
PLUS rthey don't move as fast TECHNOLOGY i mean.

few month ago i did visit the BMW dealer i had overheat lamp was on. they kept the car for 24 hours to check why the water was down , in the past you just open the hood and fill more water, now there are no place to fill the water LOL.


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Old 10th February 2012, 09:46 PM
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Default Re: D-Jet to K-Jet and back

Mark I believe the K jet upgrade was in response to the US emissions laws and the oil crisis in the early 70's.

Bear in mind that the US would be a very valuable market for any car maker and looking at how other manufacturers model lineup changed in 1973 thru 1978 Mercedes Benz solution was a clever one.

So while the others were downsizing their cars and engines to cope Mercedes sacrificed some power.

But for what its worth I too think that Mechanical fuel injection has no right to be in a car after 1970.
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Old 10th February 2012, 09:50 PM
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Default Re: D-Jet to K-Jet and back

BTW Vacuum Central locking was a safety feature incase your vehicle ended up in water without electrics.
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