Blueprinting and stroking a m103 300E... - Page 2 - PeachParts Mercedes-Benz Forum

300EVIL · #16 04-05-2002, 12:49 AM

I also heard 350 diesel crank and con rods from a C280 would give you a M103 stroked to 3.6... Fact or fiction?
Adam

chupr98 · #17 04-05-2002, 10:25 PM

Hi guys,

Does a GM 350 has different bearing arrangement compared to M103

I think AMG has a 3.2 stroker kit

#18 04-06-2002, 09:18 PM

Trying to fit a 350cu.inGM engine crank in a M103 engine is as easy as trying to replace your headlight wiper motor with a Boeing 747 engine.
The only communality between a 350 crankshaf and a 103 crankshaft is the name.
Forget it. It has never been done, will never be done, it can't be done
jackD

Ashman · #19 04-06-2002, 09:37 PM

you sure they mean a GM 350 Or a Mercedes 350 Diesel engine.

I thought they were talking about a mercedes diesel engine from a 350 diesel model...

Alon

300EVIL · #20 04-06-2002, 09:42 PM

Jackd and chupr98,
Yes, a GM crank would be pretty hard to adapt to any Mercedes engine. Thats not what we are talking about though. The crankshaft in question comes from a 350SD-SDL which recieved the 603.970 engine. The M603 diesil engine is an inline six with 3.5 liters of displacement. Theoretically, when combined with con rods of the C280 it is capable to achieve 3.6 liters of displacement in the M103 engine.
Hope this helps!
Adam

KNanthrup · #21 04-07-2002, 01:35 AM

Is it as easy as it sounds? do you just take the connecting rods from the C280 and the crank from the 350SD-SDL and bolt it all up, or is some hard work involved. Wouldn't the timing gear have to be replaced as well or is this not a problem. Has anyone in these forums tried it?

#22 04-07-2002, 11:15 AM

Mr Chupr98 was really talking about a 350GM engine, pls. re-read his post. If this is the case, better forget it.
If you are refering to a 350 Mercedes diesel crankshaft, my spec book give different crankshaft journal diameter and width. Installing 280C con rod on this crankshaft would require major machining surgery and pssibly engine block machining as well. I don,t have specs on the lenght of the 350 crank lenght so it might require stretching/cutting, which is generally not within a backyard mechanic capabilities.
Anything can be done (almost) but the results are sometime not worth the efforts (read $$$).
A transplant with a 5.0l from a 500E might be easier/cheaper to acheive.
JackD

300EVIL · #23 04-07-2002, 11:49 AM

I never said it was easy.
Well, the guy I recieved the info from may be completely rong or partially rong. It dosn't hurt to do the research.

Jackd,
Since you have these technical manuals on an assortment of Mercs, check and see if any other con rods will work or would be easier to adapt to the 350 crank. Inline 6 or inline 4, check it out!
Thanks!
Adam

300EVIL · #24 04-08-2002, 12:26 AM

Jackd,
BTW: Do you mean 280C or C280?? there is a big difference in engine config.

ItalianBenz · #25 04-08-2002, 01:23 AM

Bad info. If your interested. My friend has this kickass head for a 103 engine from the late 80's I belive its a brabus wiht big valves ported and polished heads,with a nice brabus racing cam and Valve cover. The thing just sites in his garage. I know he wants some serious money for it. Its brand new I think from what he told me never been ran. That would be a big improvement to this 103 engines. I had a 300 last yr before i got my 500. Let me know.

2phast · #26 07-15-2002, 09:21 AM

How about posting a price on the Brabus head?

Speedtek · #27 07-15-2002, 02:05 PM

The M103 AMG 3.6L is a stroker crankshaft which is a BRAND NEW crank that has been reground to 93mm instead of the normal 81mm. The bore of the engine is increased from 88.5mm to 90.5mm. You could buy a brand new unground crank from AMG but the price of the machine work would not make it worth it. AMG could still do the machining but the price is in the $6000 range. I have been using welded strokers for years in BMWs and VWs. The Mercedes would be the same. The material content of German crankshafts are really good with a high nickel content that usually makes them very hard. A welded stroker crankshaft for a 6 cylinder is about $1500.00 and a brand new USA made 4130 Chromemoly crankshaft is about $3500-$4000. 90% of the 4130 crankshafts that are sold are made in the USA! and used by major race teams and engine builders. They are exported and then sold back to users in the US who think they are buying a HIGH QUALITY foreign made crankshaft!

Of course in using a stroker crank you will need to use special pistons or shorter rods and those can also be made.

There are a lot of horror stories about welded strokers but that is usually done by a bad machine shop or someone who did not know what they were doing. A lot of engine tuners use welded strokers and charge the customers BIG $$$ for them. some of them are really hard to tell it has been welded. On the good crankshafts the welding is specially done. then the crank is xray-ed to look for air bubbles or cracks. then machined. sometimes sandblasted or shotpeened. and Nitride Hardened treated.

I have used stroker cranks in engines that rev to 10,000 rpm with no failures! In fact I have never had a failure in any crankshaft that was welded to my specifications. or done by a machine shop that specializes in this.

Also the longer the stroke the lower the peak torque RPM.

example: (not exact)
80mm stroke = 7500 rpm peak torque
88mm stroke = 6000 rpm peak torque
93mm stroke = 4500 rpm peak torque

Sorry for the long post but I just felt the need to educate people in this very misunderstood area of engine tuning. If you feel the need to redesign an engine let me know!

Badinfo · #28 07-15-2002, 06:59 PM

Thanks a bunch Speedtek, your post really did clear up a lot of confusion! It looks as if strokking the m103 engine just isn't worth it when you consider a turbo setup (thanks to you Speedtek) can be had for $1k, and the turbo will probably give you better hp results.

2phast · #29 07-15-2002, 09:45 PM

Ok, were making progress here. But I think the issue of whether or not the 350 diesel crank will work in the M103 motor is still in limbo.

Also, the M104 motor displaces 3.2l, would this crank work in the M103 block as a option.

I too am exploring stroking the M103 motor, but if a viable alternate can not be found, I will be sticking with the 3.0l displacement and using a highly modified head/cam/header package.

#30 07-15-2002, 10:43 PM

According to my references, a Mercedes 350 camshaft has different journal diameter, is longer, uses a different timing gear, the distributor set-up is different and lobe configuration is also different.
Converting this cam to a 103 engine would probably be more trouble (cost) than building a new cam shaft from a raw piece of steel.
And forget about the 350GM cam. It is a totally different beast.
The best and chapest way to improve performance on a 103 engine is bring it up to specs on eveything and to get rid of 1000 pounds off the car.
Good luck
JackD