[mcbear]

Turbocharging
The most tried and true method of gaining horsepower from the M103/104 motor is by adding a twinturbo system from either one of the two aftermarket suppliers [neither of which are supplying units any longer] or a “roll your own” approach. Several examples of completed systems are written up on the forum and owners are requested to write up a “white paper” to document the process. 300+BHP can be a realistic goal from this application.

Supercharging
Supercharging the M103 and M119 series have both been talked about and there are currently folks poking around at doing something but so far I have not seen a operational system. Hopefully I can update this paragraph soon.

Transplant
The two major transplant options appear to be either dropping in a General Motors Small Block [350ci] or installing a Nissan or Toyota 3L powerplant that is designed around twin turbos.

The GM option is usually the easiest to buy as there are so many variants and suppliers available by mailorder and breaker yard. Aftermarket industries are built around this motor so there is no shortage of parts available to make the car go up in horsepower. 350BHP is a starting point with a myriad of options to take a LSx motor to over 700BHP. The motors can be bought for as little at $300 and up to $7500 and the rest is manhours required to fabricate the fitments. NOT for the faint of heart

The Japanese option is a bit less brute force and more elegant but has the same potential. Again, motors are available [along with 5 speed manual trannies] with stock turbo packages that can start with 300BHP and go to 1000BHP [I don’t think I would try that one]. The motors can be bought for $2500 and the rest is manhours required to fabricate the fitments. NOT for the faint of heart.



Breath In, Breath Out Grasshopper
The quickest way to a bit more power [although not the 100-300BHP gains other options give is simply to increase the airflow in [a cold air induction system] and increase the airflow out [a more freeflow exhaust, new high performance Catalytic Converter and ditch the Resonator. It can be worth about 10%.

Trade UP
The last option, if you love the W124 body but hate the slow M103 is to find a good 400E [275BHP] or really go all out and get a 500E and your base HP is now at 320. For the money you spend on buying a transplant motor and fabricating all the fitments, UNLESS you are planning to go toward 500HP, your best bet is just find a 400E. You will same time, money and enjoy the engineering that Mercedes put into the very nice M119 motor.