I want a few more HP out of my 1977 450 SLC. It had 31,800 miles when I bought it in Omaha, drove it to Lost Wages at 80 to 85 MPH on what looked like good tires. Had 70% of tread left and no dry rot. I was shocked when I found out the tires were from 1994!!!!

I don't have to do any smog checks in this car, so I can change the exhaust a lot.

I was thinking about a 2.25 dual inlet dual outlet cat converter into a 2.25 dual inlet dual outlet Magnaflow muffler. Then 2.25 dual pipes to the rear of the car with chrome tips.

I hate the look of the muffler hanging down under the trunk.

I have seen 2 inch converter and muffler recommended, I just not sure that wouldn't be restrictive compared t the 2.25"

Any recommendations?

Also going to go with a dual snorkel air cleaner, half way thinking the air cleaner off my 2006 CLK might fit

Any recommendations to years of W126 air cleaners?

Any advice?

107 chassis cars with low miles like that are fairly rare. I personally wouldn't modify it unless the car is already messed up in some way. Keep it stock for Max value.

The largest restriction is apparently in k-jet intake manifolds. What year do you have?

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Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl,

See first post

There's a thread on benzworld where a 560sl owner, after disappointing engine and exhaust modifications took his car to carobu engineering in Southern California, and they did some real scientific work and engineering on it. They determined that d-jet intake runners were far better and they also increased the height of the plenum. There were other modifications, but they were near 400hp out of an engine that sounds like it was making no more than maybe ~250hp before they got their hands on it.

The pipes on r/c107 cars are apparently good enough for up to around 225hp before they become small for the HP the cars put out (perhaps a reason that the 240hp 5.0 cars all got tri-y headers/manifolds).

Your 1977 is probably putting out around 180hp, and I bet you could go to 225 before the exhaust even becomes a restriction, unless you have a clogged catalytic converter or something.

Louder exhaust certainly helps these cars sound more powerful. :-)

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Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl,

Benzworld sucks trying to log on. can you post a link to that thread.

I am an OLD hot rodder, built a lot of engines. Everything from Fords to a minicooper engine with ported heads and 11:1 pistons, installed in a Morris pickup.

Being an engineer I have seen a lot of dyno runs and smaller exhaust is a quick way to strangle torque and HP. A lot on my personal cars had tri-Y headers, better on the street than equal length tubes.

I figure my 450 SLC is worth about $25,000 right now and after the front sub frame and other parts are done it will be worth closer to $30,000. It really is nice.

But it will never be a 190 SL, and they made a whole lot of 450-560 SLs.

I sure would like to get a MB tri-Y exhaust, not sure if it will bolt onto my heads though.

Most of the modifications can be undone easily, like a dual snorkel air cleaner with fresh air pipes. And a larger exhaust won't be noticeable to 99% of people.

Thanks for the information!

Here. You can get some meat without even going to benzworld: http://www.carobu.com/other-finished-projects/2016/11/21/1986-mercedes-benz-560sl-engine-building-project

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Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl,

I have watched Wheeler Dealers and their Mercedes AMG tribute car and engine work.

Amazing that the bundle of snakes intake manifold is the real issue with greater HP.

Any recommendation with spark plugs? I am more used to the original Champion.

LS Swap

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With best regards

Al

Nah, I am more of a 351 Windsor fan. Back in 1970 I put Pontiac 389 valves into my 351 Ford engine in my 68 Cougar. Just over 400 HP at the flywheel.

That'll work too

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With best regards

Al

I am too old for engine swaps, just want another 20-30 HP on my Mercedes 450 engine.

Just put chrome 14 inch Bundt wheels on it, the old were actually perfect zero road rash but faded. The tires were 23 years old!!! I put on 215/65/14 H rated AA tires on, corrects the speedo to read super accurate.

Unfortunately, the cheapest easiest way to get 20-30hp is an engine swap. Pull the M117 that's in the US car out and drop a Euro 450SLC engine right in. It's good for 225hp which is probably 40hp over what you have now.

They are higher compression motors and the difference is in the pistons so you're not going to get there with your engine unless you pull it out and take it apart.

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With best regards

Al

Back in the early 70's German engineers used to laugh at American cylinder heads and combustion chambers. Far superior to most US engines.

A 275 cubic inch Mercedes engine should easily put out 225 to 250 HP if the intake and exhausts not strangled. No hot rodder ever said I think "I will put an 1.75 inch exhaust system on my 283 Chevy or Ford 289". Minimum would be 2 inch and 2.25 or 2.5 would be used if cat converters were required.

The stock intake can be opened up, I have never opened one up though. Supposedly the " throttle body can be opened up from a stock 65mm to 70mm. This is a 16.5% increase in flow area".

Anyone know who does this work?

Looking at spark plugs now, there are over twenty different plugs listed. I have seen the Bosch Platinum Super-4 spark plugs recommended.

Since this era there was no multi spark units, don't think the expensive "Iridium Power Performance Upgrade With World's Smallest Center Electrode" is needed.

What's recommended?

Bosch WR-9-DC+

Bosch Platinum Super-4 spark plugs 4478

BP6ES or NGK BPR5ES

Bosch Platinum WR9DP+
- Spark Plug; Standard Electrode