CLK C209 320CDi OM642 Performance

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New Member
Aug 24, 2023
Clk 320 CDI
Hey everyone,
Hope you are well, I have a CLK CDi 320 that I am hoping to modify and gain some performance, looking online is seems that everyone has a turbo upgrade, injectors, cams and tunes for the OM642 but none that specifically pertain to the CLK is that just due to have cramed the engine is and they cant gaurentee the fit or it ks because there actually is a difference?

Whats a realistic horsepower goal (reading it seems like 300 is tops before opening the block) and whats needed before having to take apart the engine and reinforce some internals?

Has the 6 speed manual, whats the limit on the trans and or diff (if there is one, think when i was reading its around 600nm-ish unless I misread)

Tune-wise, would the tune need to be custom, plug and play or a downloadable tune, ecu wise stock? Piggy back or full new unit? (From everything ive read i believe there is a piggy back)

Sorry for all the questions just want to confirm lots before I start.

Is this the best diesel to start with? Or should I be looking at a different engine (factory engine, dont want to mess with engine swaps unless i can retain all oem functions and fit said engine without alot of hassle/custom work.)

Thank you all
I can't answer any of that although I did have a CLK, just amazed that you have one with a manual gearbox!
Sell it and buy a CLK500 for peanuts and get the performance you crave without the disgusting fumes and canal boat engine ambience. My old clk500 did 30 mpg on 70/75 mph cruise. But was a great overtaking machine on a fun A road and sounded wonderful at full bore.
Blimey....and I thought I was "to the point". Have you been in a modernish derv?.....most can't tell my daily (Alfa 159) is a derv once warm!.....and it produces more torque and at much lower revs than the 3.2 V6 version.
Is it RHD, I've never seen a manual 320!

The V6 OM642 is slightly different far as I know, especially the injectors.

You could start with a simple remap or go deeper with a 2872 hybrid turbo/larger intercooler and remap to suit. You will probably need to look at a new clutch and exhaust modifications to get the most from this.

I would ask myself what power am I looking for and what am I prepared to spend on the car? The best starting point would be a E320, the OM648 is easier to find parts/tuners.
The stock clutch won't handle 600nm for sure. Its limit is about 500nm and you can't deliver it at low revs (under 2000rpm) because you will get some vibrations.

The gearbox isn't made to run so high values low rpm torque. Some use the gearbox 716.6 on om606 tuning application but in this case the torque is deliver at high rev, then it's really different than very low rpm torque for the gearbox.

Here the transmission is the first limiting point for your project. You must install new clutch, it exists the 320cdi W204 or 250cdi W204 260mm clutch available reinforced by Sachs with heavy duty friction material. It would be good for 600nm or a little bit more...
The best clutch setup would be dual disk clutch, but you need disks with low hub profile, because normal disks can't be add to be mounted on the gearbox shaft, this one would be too short to mount 2 original disks. And you must think about a new flywheel too... Tenaci are making dual clutch setup but it's expensive.
Note : every Mercedes gearbox have the same hub profile, so you can put the 260mm clutch disk on the stock gearbox for example (but you would need new flywheel)

Then, the last and best manual gearbox Mercedes made is the 711.670 NSG510, it has been made especially for OM642 but widely used on om651 250cdi application.
On W211 chassis you need to adapt gearbox linkage lenght and have an on demand driveshaft, because (I didn't find ?) nothing adaptable. I guess it's the same way for C209 chassis.

Just for the transmission, be ready to spend a lot of money.

Then about om642 tuning, first generation with 18/1 compression ratio are good for 300-320hp. Go higher than that and you can risk to have the piston head cracking because of the increase of cylinder pressure.

The exhaust temp will be a serious problem, the airflow setup isn't made for power but for low rpm torque.

Going on hybrid turbo is a possibility but you should know that even a 2365 would spool late, approximately at 2000-2200 rpm and the reactivity for daily use would suffer. Keep in mind that the rev limit is 4200rpm.
The best thing to do is to adapt 2260vklr of the LS version on this engine, oem pressure is 2700mb absolut equal to 1,7 bar boost pressure. But it's not that easy.q

Injection system is fine for 320hp and 700nm torque. If you get the rail pressure sensor from the LS version, you can run 1800 bar as stock or more (they are rated to 2000 bar but there is always 200 bar security margin). Please understand that increasing injection pressure would increase cylinder pressure too.

Good Luck !

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