6.3 into 1973 450Sl

[SteveStromberg]

I was offered a 1973 450Sl with a blown motor for a song .Its a little rough but it all there and no rust. I was thinking about do a hotrod out of it. The fellow at the shop across the way has a 6.3 motor that has low miles and has been sitting in the corner of his shop for the last 20 years.I can get it from him fairly cheap. Now has anyone ever do this? I have done engine swaps before so I know it's not bolt in but will it fit and will the 450 SL Trans mate to the 6.3? Thanks in advance for any input. Steve

[suginami]

The 1999 November / December issue of the Star Magazine has an article about a 1973 107 chassis 350 SL that had a 6.3 liter conversion.

The article is three pages long, and the number of modifications was enormous.

The 6.3 liter engine is too tall to fit. They had to cut out the top of the front cross-member then made plates and gussets and welded them into place, lowering the engine about 4 inches.

The 3.5 liter transmission could not be used, so they had to use the 6.3 transmission, which was much larger, with its linkage and a modulator sticking out of the right side. Like the 500E of 20 years later, they had to widen the transmission tunnel. The shift linkage also had to be modified to work with the 6.3 transmission.

They had to fabricate a complete stainless steel exhaust system, from headers to muffler. The cooling system had to be altered to accomodate the different hose fittings.

Once the engine and transmission was installed, they found they still had to modify the hood. With those big plenums sticking up, they had to cut a hole in the hood, and ended up fabricating a new hood out of fiberglass with a huge bulge in it.

The rear suspension was changed to an adjustable-camber type, and a 2.65:1 rear axle from a 450 SEL 6.9 was installed.

The radiator was replaced by one from a 560 SEL.

A modified 450 SEL 6.9 distributor eliminated the contact points.

The York a/c compressor was replaced with a Sankyo SD 508.

The oil filter housing was removed, and new oil-fittings were attached to the block, allowing dual spin-on Mercedes Benz oil filters to be installed on the left inner firewall.

Despite all these changes, the only non-Mercedes parts are the a/c compressor, the tube on the air cleaner housing, the exhaust system, and the custom oil filter housing, which had to be machined.

They apparently spent over $30,000 on the conversion. And that is $30,000 1973 dollars. An enormous sum.

[kip Foss]

Steve,
When I first got my 450slc I was looking for one with a blown engine so that I could install a SBC 350 or a 5 lt. Ford. I didn't find one before I found my present car with a good engine so I put the project on hold. My idea was to make the swap, one, to get more hp., two, to have an engine whose parts I could afford, three, to have an engine for which you could get speed parts, and four, to have an engine that I could work on w/o a tool box full of special tools.

I spoke with a local MB mechanic who, was appauled, and rightly so, by the idea of a swap. He said that the current 450 will easily take the car to 130 mph, which is more than enough to get all the free speeding tickets that I could possibly use. Secondly, with moderate maintenance the engine should go well over 250K miles w/o major reapirs. He knows of a 450 that has 400K on it or so he says. I know of a Dodge Diesel with 1.4 million on it but that doesn't mean that my Diesel will do that.

A 6.3 in an sl would be interesting but deadly, not only to yourself but to your wallet. I unserstand that 6.3 parts are especially costly, but as the mechanic says you may be able to get 250k out of the engine w/o a hickup.

If you look on www.collectorcartraderonline.com there is a 1980 slc in Cali. thah has had a small fire under the hood available for $1,900. It has been there for many months which means that you could get it for $1,500 or less. Might be a good project car. There are about 100 slcs on that site in good condition for around $4,000 that might require less fixing up and therefore less money that your 1973. and, after all an slc is so much better looking than an sl.

Good luck. Keep us posted on your progress.

[SteveStromberg]

Thanks, Ifound this photo on the net. I belive it is the 73 you were speaking of. Kip I have a 1986 560 Sl now.

[4NDELIT]

Originally posted by kip Foss
He said that the current 450 will easily take the car to 130 mph, which is more than enough to get all the free speeding tickets that I could possibly use.

he's definatley right on that one, I have a '78 450SL, and it's seen 135 (gear limited). The speeding tickets are right too, I've had two in 12 months (and took traffic school both times!), one for 64 in a 35 and one for 80 on the freeway (kinda lame... all san diegans do 80). the 450 is quite a powerfull motor, especially on the highway when it's in it's power band.

[gerryvz]

Well, I don't know about doing a R107 SL, but at least it was designed for a V-8 engine. This conversion has been done in the past with these cars, at least with a 6.9 engine which is of similar size. I believe the owner of the MB dealership in Sacramento CA did this many years ago.

Over at M-100.org, we have a guy in Florida, Derek Jettmar, who stuffed a 6.3 motor into a R113 280SL. You can see the project at:

http://www.ritzsite.net/280SL63/01_SL63.htm

Cheers,
Gerry

[cbdo]

Unbelievable!
I can't imagine trying to keep it straight in the rain....

[suginami]

Originally posted by SteveStromberg
Thanks, Ifound this photo on the net. I belive it is the 73 you were speaking of. Kip I have a 1986 560 Sl now.

Yep, that is the car that is featured in the article.

[SteveStromberg]

That link was great he did just what I was thinking of doing.I saw a bltp on a car done by Gullwing Eng. anyone know about that car? I was thinking of using a Six speed vette gearbox. Is there a flywheel that would bolt to the 6.3. Steve

Here's the hood bulge they needed to cover the 6.3:


Sorta 747-ish, eh?

I corresponded with the builder of that one before deciding to do the 5.6 swap.

[kip Foss]

When I lived in Dubai in the '80's I had a Euro 280slc. On the way out to the port to ship it to the States I put the pedal down and watched the needle climb. It got up to about 235 km/hr when the overrev safety cut out the engine. I had a feeling that it would have kept climbing and finally lifted off.

[gerryvz]

Franz at Big Toys in Australia, has just created an adapter that allows one to connect a GM 700R4 four-speed automatic transmission to a 6.3 (MB M100.981) motor.

He is also working on similar adapters for the 6.9 (M100.985) and M116/M117 (380, 420, 560, etc.) motors.

You can see all of this at:

http://www.big-toys.net/cgi-bin/detail.cgi?0&49

Cheers,
Gerry

[SteveStromberg]

The 5 speed caught my eye. That Hood blister is not happening. Steve

[kip Foss]

I don't see the reasoning behind stuffing a 6.3 or a 6.9 down the throat of a sl/slc aside from the 'Hillary factor', i.e., do it because its there. If one wanted more hp, ergo, more performance, would it now be a much better use of time and money to install something like a 5 lt. Ford? One can easily get 300-500 hp out of these engineswith not all that much effort and cost? To spend 30K in 1973 style dollars to get an extra 50 hp seems like trying to buy bragging rights rather than trying to make a useful car. Granted, the installation is a work of beauty, but, God, what a waste of resources.

Have you considered a 5.6 transplant into the SL? Compared to a 6.3, it'd be downright cheap and easy (compared to putting another 4.5 in the 450SL, though, it's not THAT cheap and easy!).

See http://www.carcentric.com/MB2MBswap.htm for more info.

M D "Doc" Nugent
Creator of 914 Lite 2.5 (now parted out)