Topic: M117 performance modifications, 78 450se

[ClassicCarRepair]

Hello all,

I am new to this site.  I've read many posts from different topics, but I have a few questions that I haven't found answers.

I recently purchased a 78 450se euro spec for $200 USD.  The car was last running in 1994.  The engine is original m117 as built.  My plans for the car was to remove the power plant and trans to use for another project, because the car is in poor shape from sitting in the Texas sun. 

I have had the time to research the various methods to upgrade or "hot rod" these engines, for several years. My business mechanically restores classic Mercedes, and has for the past 7 years, to varying degrees. 

I am interested in hearing your experiences with these engines pertaining to performance modifications.  Here's where I am today:

Caribou performance, talked to them concerning a fuel injection system upgrade (replacement) for the V8.  Talked to old school (80 year old mechs) Benz mechanics for upgrade of the original K-Jetronic fuel system, and talked to some old school, and new, power adder experts.  All of these people have dyno experience, many still do it today.  I am no newbie to mechanical and automotive engineering, but am now out on my own as a specialty Vehicle builder at 52 years old. 

I am asking for real world applications on this engine from some seasoned mechanics and technicians.  I have been unable to find any performance publications here in Texas, related to this engine (performance upgrade tech articles, books, etc.) that are very useful.  However, I have been very successful with Jaguar 5.3l V12 engines, as they have been successful in the classic boat racing applications.

Understand, that I want to produce a very inexpensive minor power increase in the M117.  I am at the conclusion now, that a short tube, carburetor type designed intake manifold with TBI for use with a turbo boost of 10 psi could achieve the same numbers as the 6.9 liter, or better with stock mechanical internals, as built.  My experience with V8 engines is where I get this data.  I'm not wanting to build a race car powerplant, but some extra power when you want to step on the gas.

If anyone here has experience with this M117 in that respect, I would appreciate your input.

Thank You,

Brandon Sheehan
Lubbock, Texas

[daantjie]

Welcome 
Not sure how many folks on the forum have deep knowledge on heavy or even light mods to be honest.
One area that is known to be a candidate for improvement is the exhaust manifold.   They are quite restrictive so a good set of headers could unlock some hp with tuning as well of the rest of the exhaust. If you don't need to pass smog then you can rip all that smog crap out for starters 

[ClassicCarRepair]

Ok, thanks for your response.

[ptashek]

Wasn't replacing the pistons and heads with high-comp euro versions one of the quicker ways to get extra grunt from the US-market M117?

The euro M117 is not far off the US M100 performance wise, while the US M117 is closer to the euro M110, no?

Haven't the guys from Dkubus in Australia tuned the M117 in their R107 for racing, with the electronically controlled WUR, custom manifolds and cams as well? All available from their shop I believe.

Just repeating what I've read/seen over the years. I've absolutely zero engine building knowledge...

[thegreg92]

I currently have the engine out of my 450SEL 4.5 k-jet for a reseal job that quick evolved into a (relative) performance build. It’s all experimental but my plans are as follows:

Euro d-jet pistons
02/03 cams for a 500SL
Throttle valve from a 560SL
New timing chain, guides and sprockets
New fuel injectors and various other parts

Hopefully all this makes a decent power bump 

[ClassicCarRepair]

I currently have the engine out of my 450SEL 4.5 k-jet for a reseal job that quick evolved into a (relative) performance build. It’s all experimental but my plans are as follows:

Euro d-jet pistons
02/03 cams for a 500SL
Throttle valve from a 560SL
New timing chain, guides and sprockets
New fuel injectors and various other parts

Hopefully all this makes a decent power bump 

I'm a purist for old performance mods, but damn, I've spent over 2 grand this past year on 2 SL's, that barely made a difference in performance, except to make them just barely meet as built performance.  I really want to explore some newer tech to make power from some power adders, like a supercharger, etc.  I've learned that the long block setup as built, is pretty reliable, if you don't push it too much. 

Considering the performance coming from the newer cars today, like 350 hp coming from a V6 for the everyday car, that was unheard of just several years ago.  I'm leaning to the easiest way to gain power without altering the long block. 

The reason I'm even interested, is a short story;  As a 13 year old kid, a German mechanic and tuner, came to my father's shop with a 6.9l shoved into a 110 chassis.  He took us for a ride a 220 sedan.  It had a 4 speed on the floor.  My father built race cars.  But, I was amazed sitting in the back seat, my head and back planted against the back seat for at least 6 or 7 seconds!  I couldn't move.  I was hooked.  So, here we are today, 40 years later...

And, I can tell you, besides the acceleration, it was the wooden dash and gauge pack that still, today I can see when I close my eyes.  Timeless.