'80 450SL, How do I get more power?

This is where the performance minded SL(C) owner can have piece of mind that there are others out there who would like to put more Pep into their "Pony", and do it on a reasonable budget too. We would like to promote ownership, restoration and modification of these cars. Yes, we said modification! As nice as these cars are, there is always room for improvement to be made. And we are not talking leather seat covers, fuzzy dice and cup holders either.

 

Consider initiating deep breathing with a  K&N air filter, and put some fire in your foot with Bosch Platinum Super-4 spark plugs, replace the viscofan which sucks off 8% of the engine power with a Kenlowe 16' (you will need to modify the thermostat to prevent overheating in city traffic Overheating and Thermostat Modification), set timing to 5º BTDC, replace standard coil Bosch (blue label) No. 0 221 122 01 and the switching unit TSZ-4 (which requires ballast series resistors) with coil Bosch (green label) No. 0 221 118 329, DB part No. 000 158 45 03 and switching unit TSZ-8 for high performance and high ignition capacity. (The coils are not interchangeable without the switching units).
Install Direct-Hit capacitors (see http://www.directhits.com ). These simple mods would make the engine more responsive and possibly add 20BHP of "giddy-up" to the old lump.

Here is a full shop step by step manual on a 450slc converted to MegaSquirt EFI

 

Did you also know that your 8-blade aluminum fan consumes about 3-5hp (due to rotating inertia and air pumping) at cruising speed (about 3100RPM)? That is power that doesn't get back to your wheels! Make the modifications suggested above or consider using a 16" electric fan, and operate it using a thermostat and a relay. The engine will run less loud and salvage a couple of horses in the process.

 

You should know that in the CIS injection system the largest and most obvious air flow restriction is the air flow meter. But did you also know that the throttle body can be opened up from a stock 65mm to 70mm. This is a 16.5% increase in flow area! i.e. an approximate 16% increase in flow! This flow translates to about 8-10% in power increase in the upper RPM ranges. Have a reputable speed shop do the work for you. You'll have to match the lower manifold throttle mounting for the same size (with a Dremel tool). Another thing is the bar across the air flow sensor plate. It is only there to prevent damage if the engine back fires and some of the combustion gases make it back into the intake manifold (as opposed to after fire) to prevent blowing the sensor plate up and out, and it serves no other purpose. I have never heard of anyone experiencing this incident. So removing this bar may get you a little cheap power as well. Little things DO add up.

 

In the mean time, a bit of info. on calculating 0-60 times for a given vehicle with manual transmission, and it is accurate to within 5% of actual times. Time = (2xW/Tq)^.6 where W=weight of vehicle, Tq is the actual maximum engine torque. This works great!

Mercedes 107 Engine Dress-up

 

Exhaust modifications: If you're thinking of "upgrading" or replacing your exhaust and keeping it smog legal, you can do it with some minor modifications! Two critical components are the catalytic converter and the muffler. There is a SMOG legal aftermarket 2"-in/2"-out converter. The muffler is something more complicated... You'll need a 2 in-2 out muffler of similar volume (cubic inch). The pipe will have to be 2" i.d. Now, this increase will not noticeably decrease the low end torque but will open up the top end horsepower. A muffler shop can do the modifications. for about $200 plus parts. Make sure they install a cross-over pipe of the same size (2") where the current one is.

Note: if the muffler is longer than the stock one, you'll have to place the new muffler right after the cat. under the car instead of the original location. I'd have no problem with this, as this would leave a clean look under the trunk.

 

Did you know that the early SL's were equipped with a heavier rear sway bar? Then they reduced the size to induce more understeer, which is considered a safety feature for the benefit of the average driver. This is at the cost of a flatter handling, more neutral cornering SL. We think they should have stuck with the initial setup, especially for such a heavy car as the SL's are.

 

Brakes: You can increase the response and improve brake feel by installing kevlar or teflon brake lines. You will actually improve the stopping distances! You can find them for about $75 per set.

 

Wheel and tire modifications. - The stock 205/70-14 wheels are nice but are less then "performance" oriented. Find the later model 16" rims and install a set of 225/50-R16 tires. This is not unheard of as AMG installed a similar setup on their cars. You'll loose some of the cushy ride, but will gain better handling! You can resize your wheel and tire setup here...Wheel / Tire Resizing

You can also try a 225/55-16 setup. This will be closer to the original size so your speedo (in your dash, not in your pants) will be more properly sized, and accurate. These "higher" profile tires are also a little less expensive. Personally, I'd go with the Firestone FireHawk SZ50 EP. Very grippy and ultra quiet, but don't expect more than 40,000 miles from them. More Here Performance Tires and Wheels

 

Now, we know that some of these ideas are radical by Mercedes standards (at least for these cars) but we think that they are worth checking into. Even with these cars as nice as they are there is still room for improvement in many areas. And if you think what was addressed above was radical, well than click on the two links below for engine upgrades,,, Now those are Radical!!!

Pumping Up The MB-SL With More Metal

Installing a Bigger Mercedes Motor

Installing an American V8

 

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