OM617 Performance, C111

[wolf_walker]

Manufactured in 1978, 5-cylinder inline OM 617 A, placed before rear axle, longitudinally, standing, four-stroke diesel with pre-chamber injection, mechanically operated Bosch injection pump, turbocharger and intercooler, bore x stroke 90,9 x 92,4 mm, 2999ccm = ca. 183,2 cu in, compression 1:17,5, maximum power output 230 PS (NOT 320 PS!) = 169 kw at 4.200-4.600 revs, maximum torque 403 Nm at 3.700 revs, engine block made from grey cast iron, cylinder head made out of light alloy, detachable, 2 valves per cylinder, one overhead camshaft, driven by duplex-chain, firing order 1-2-4-5-3, one glowplug per cylinder, electrical Bosch starter, vented disc brakes front and rear, rear-wheel drive, double plate dry clutch, ZF 5-speed manual transmission with integrated axle drive, central floor shift, recirculating ball steering, length 5380 mm, width 1715 mm, height 1045 mm, car weight 1400 kg, engine weight 244 kg, one seat place, fuel tank 140 litres, top speed 325 km/h = 202 mph, ((other sources report a top speed of 327,3 kmh = 203,4 mph)), drag coefficient 0,183, another DC source says 0,195, diesel consumption was ca. 16 litres/100km = ca. 17.6 mpg UK = ca. 14.7 mpg US

I had been wondering what specificaly was done to it, and I ran across this. Looks like basicaly an intercooler, aluminum head(heat disapation?), lower compression(for) more boost. Interisting..

[engatwork]

I'd be interested in one of those 5 speed manual gearboxes.

The C111 sits in the MB Museum in Stuttgart. As I recall, the car behind it is a land speed record looking car with hand formed aluminum skin. It set the worlds speed record on public roads in the late thirties. I expect that the C111 could have gone about as fast.

It's an amazing thing to see. If you're ever in Germany, do your best to get a chance to see this small but extremely significant museum. Also, you won't want to miss the long line of one off Executive cars that are parked in front of the museum.

Have a great day,

How hard would it be to make an aluminium head for the 617? I'm no metal worker, but wouldent you just take the cast for the iron head, rework some structure points to make it stronger, and pour in the aluminium?

[wolf_walker]

Originally posted by 82-300td
How hard would it be to make an aluminium head for the 617? I'm no metal worker, but wouldent you just take the cast for the iron head, rework some structure points to make it stronger, and pour in the aluminium?

I have been a little bit of a metal worker(though not on that scale), and I'd hazard to guess that it's a lot more involved than that. The expansion rate of aluminum, it's relative strength per thickness, the list goes on. I'd imagine it's significantly different.


But I bet plasma coated steel parts, cryo treating, and damn careful assembly could get you close...

It'd cost a bomb, but I swear you could get a heck of a lot more power from the 617, and I bet with a good degree of reliablility too. So what if you cut it's life span in half, then it will only last 250K miles?

[Rick Miley]

It took a company with the expertise and deep pockets of Mercedes-Benz several years to get it right. Witness the OM603. Odds are you would not succeed on the first try.

?My wish list..... Are you listening Banks Engineering?

I'm sure that you'd want a balanced and blueprinted bottom end.

An intercooler and increased boost potential.

Possibly tougher pistons to deal with greater heat and combustion forces.

I understand that diesel cams have almost zero valve overlap, perhaps greater lift?

I forgot who, but one member on an old thread suggested that porting and polishing doesn't offer the same advantages in a diesel than in a gas engine.

Would one of those crank case vacuum pumps that they use on drag engines help with blowby?

Are there larger than stock injectors available

[wolf_walker]

I think the stock bottem end parts are fine. I like the heat disapation of plasma coating and the endurance of cryo treating.
Absolutly you'd want it balanced and blueprinted, but the thing is it already IS from the factory(another reason they seem to last forever). I think a very, very careful rebuild to tight specs with hand gauged parts, cryo treat the riciprocating assembly, plasma coat the pistons(and what ever that low friction coating on the skirts is). Maybe beam the rods like we do with V8's. I wonder if ARP makes any rod or main bolts, or head studs.

Porting and poloshing has got to help some. Any reduction in the friction of the air comeing or going is good.

A newer turbo that spools faster/higher, intercooler, someone who actually knows how the injection pump works internally so that they can tune it to flow more fuel, ditto the injectors.

I doubt the cam can be changed much, there was great discusion about this with the VW diesels some time ago. But I'm not as familier with the 617, so maybe..

Head gasket, and a way to lower compresion noticably. I wonder if a fresh motor will start with 16:1 in the cold with just glowplugs?

[Jim Anderson]

I seem to remember someone running a computer model to see how much you could theoretically boost a diesel. They got up to 100 pounds and ran out of computer.

[The Warden]

There's a guy with a twin-turbo'ed Cummins that can get up to 100 psi of boost.

For a 617 (or just about any IDI engine), the big limiting factor for boost is the compression ratio. More than 15 or so lbs of boost will just put too much strain on the head gasket and on the head bolts.

So, the solution? Lower the compression ratio I don't think that putting a thicker head gasket would be that great of an idea, simply 'cause it probably wouldn't have the needed strength to hold the added boost. So, the best way would probably be to slightly shorten the connecting rods. There's a guy who's gotten a 6.9l IH IDI diesel (like the one in my truck) down to about 17:1 compression, and unless it's a really cold day, he sayd it'll still start on the glow plugs without needing ether.

So, get the compression ratio down, and put head studs and a heavy-duty head gasket in, and the sky should be the limit as far as boost goes. Then all you have to do is make sure that the intake and exhaust have as few restrictions as possible and add enough fuel to make use of the extra air (through bigger injectors, ALDA adjustment, etc).

Lastly, make sure you have an EGT gauge

Yes, I've got ideas for when I have $$...

[wolf_walker]

Warden, clean out your PM box..

[The Warden]

Just did