Om617 turbo
This was my grandmothers car since new(previously they had a grey market euro 280) and is now mom's but she hardly drives it as I've not installed a sanden compressor yet.
I am two months into daily driving this 78 300D with an k26 swapped onto it. I blocked off the egr ports and softened the wastegate and am running 9/10 psi boost when flat out. I went 2.5 staright pipe past the down pipe. Boost is 7/8 when running 65/70mph with the 3.42 gear and egt's on flat ground are 290-350C until a hill or pass.
The engine runs under 200F unless climbing a rather large hill when the egt's stay at 450C for some time, and this is with the Ada backed out 1.5 turns.
I'm running an external trans cooler line in front of the drivers side tire to help prolong its life and then a 4speed manual is in order.
I am needing to do the oil filter housing gasket and an10 oil cooler lines. I intend to screw in the full load screw one turn to get max egt's up and performance more on par with a factory turbo car.
My old 300sd was a rocket with the Alda unscrewed but this MY78 with 79hp originally is moderately faster and more efficient now, maybe 90 or so hp but still far off the 120hp mark.
If the old motor(with 298k) lets loose I will get a turbo motor in its place. As it is I have turbo injectors and a turbo pump(whose setting would give far more fuel than mine even with the full load screwed in one turn) i would like to install at some point.

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Nice.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

More pics?

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Poor car....I am sudden mindfunkled by all that

A reason I don't read this area....

Diesel Performance Tuning - PeachParts Mercedes ShopForum

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Pics

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Mais

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Local biodiesel place
I'm keen on switching the rear gear to a commonly available 3.07(same gear my 190D 2.5t has(I feel like it is revved out at 85mph)) since going over 70mph in the 78 makes the engine scream and run hot. It is probably at or above 4k/4200rpm(as I recall my 83 w126 was at 34/3500 at 75/80mph)

But I won't swap the ratio until the power output is significantly increased. As it is, it is noticeably more quick and efficient and sings a sweet song, but I fear it would be a dog with a 3.07 and only the Ada backed out.
I am hoping the car will run below 200F if the water pump is slowed down

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One more

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Really? Where does thou get their info from??

A properly tuned and maintained w123...in stock form can be amazing....



This is stock including air filter w123....

Instead of adding more junk onto the motor....why don't you work on reducing weight....

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I would just remove the ADA competently, if you have a turbo on there it serves no purpose any longer and should be fine. I agree that swapping the rear end would be a good call. I found the rear end in my 79 300D to be a little low for highway cruising as it was quite loud and wound out after about 100km\h. If you do swap in the 3.07 make sure you swap the speedo as well as it is geared to the rear end ratio.

All of this being said, swapping in a om617 turbo engine may give you better return for money and time spent. Just a thought.

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2004 F150 4.6L -My Daily
2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold

Second swapping the diff to 307.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.