Mercedes performance tips?

[PeterSLC]

I have a '73 450SLc, which runs well but I would like to improve the performance. I've installed a K&N air filter and an electric radiator fan. I think I need more info on the Electronic fuel injection system though. That seems to be a limiting factor for performance. There is very little info availible on this system.

Haven't been able to find any info on other performance modifications. for instance, what tuning tricks did AMG do to those 450SLC's they raced? I've done a lot of web surfing with no luck. BMW's, AUDI's and VW's all have engine tuners selling parts to upgrade the cars. Anything like that for Benz?

[jfsehl]

"Performance Products" sells a book on all aspects of Bosch fuel injection. It may prove helpful to you. It did prove valuable to me. Good Luck in your walk toward better performance.

[RickM]

Does the '73 have Mechanical Fuel Injection or CIS? In either case you'll have a hard time finding ways to tweek more power out of them. The exhaust may be your best bet to start.

Or fitting a set of webers.

[PeterSLC]

The '73's used Bosch's "Electronic fuel injection" as opposed to the later CIS mechanical fuel injection system. I gather both have their issues though there is much more information availible on the later CIS system.

You're right about the Webers. I used to have a Citroen SM with a 2.7 litre V6 and triple double barrel Webers that delivered 190 hp and with the air cleaner off, sounded like a formula one car. However, I would need an intake manifold designed for the Webers and while such things can be found for Alfas, Jaguars and so on, there doesn't appear to be anyone offering those sorts of toys for Mercedes.

I had thought of shaving .01" off the bottom of the cam lobes and adding .01" shims to the valves for a backyard tuner's hot rod treatment since no one even offers performance cams that I'm aware of.

[RickM]

It seems you might have to resort to your own ingeniuity as I doubt there was much of a performance market for the typical SLC owner in the day...or afterwards for that matter.

Best of luck!

[PeterSLC]

It just seems odd. I know these cars were rallied successfully and there are plenty of 450 SL's around.

[dpatterson]

Peter,

If you find anything out about exhaust headers/extractors I'd love to know about it. I've been looking also (mainly because one of my 350SLs is in need of a complete exhaust replacement so I thought I may as well do it right).

Theres plenty of info on the D-jetronic system on the net but all about repairs and testing, nothing about upgrading performance. I did read a post somewhere about changing the injectors to a higher delivery rate but as Rick suggests I think you will have more joy with the exhaust.

I'm going to investigate custom made headers as there is no sign of anything available off the shelf in Australia thus far!! More expenditure I need to explain to my wife .....

Daryl

[RickM]

Over on the Porsche 911 Technical board is a gentleman from Germany who is quite knowlegable and owns (or runs) a salvage business....let me shoot an Email over to him and see what he says.

He has been great in supplying 3.6 engines as upgrades to early 911 owners.

[Robert Mowbray]

Don't forget, Guys, that these cars weigh nearly 2 tons, and were not made to be quick off the line, but to run the Autobahns at 120mph all day long. As RickM states, that may be why performance tuning is hard to come by. Best of luck.

[kip Foss]

As an American raised on early Chevy and Ford hotrods I would like my 450slc to at least squeel the tires a bit, but I've got $100 (or $200 as the last ticket cost me) that says that I can get a speeding ticket just as fast as the fastest hotrod.

Even if the tires don't squeel I do like the feel of the smooth acceleration from 0 to 120 mph. The police aren't crezy for it, but I like it. Or I used to like it until the police got interested.

[Robert Mowbray]

I know what you mean. But there is only so much you can do with a 2 ton car. I've heard these referred to as Panzerwagens...armoured cars!!!

[LOWMILE]

If you have Druck injection on your SLC you can remove the bakelite cover on backside of MAP sensor that is put on at the factory with a pocket torch. Once the bakelite (plastic used in old day's) is removed you will see an allen screw this allen is set at the factory and many mechanic's will tell you DONT DO THIS. This vacuum setting is done at the factory when the car is new and should not be changed... however this set's vacuum and more hg's of vacuum = more fuel and air sucked into the engine. This can only be done on the early Druck injection engine's If you want to experiment check your value's first if your are pulling 22hg's of vacuum dial it up to say 30 or so. These car's are all about vacuum. So fix all vacuum leaks FIRST and if you still do not see the desired result add more vacuum. I have not tried this on my car yet. I am looking for a vacuum gauge that I can permenant mount on the engine before I even think about this modification. I use the value of 22hg's of vacuum because if my memory serve's me right that is what my car pull's and my car smoke's the tire from a stop, when the moon is aligned just right in combo with cool clean air and new spark plugs, downhill help's.
Seriously my german buddy did his Druck injection on his SLC and he can fry the tire's off the rim's!

[Gregy]

Where is the MAP sensor located, or what does it look like?
I want to try this!!

[LOWMILE]

Just like many mechanics have told me I will tell you...unless you have a gas analyzer or a friend that has one. I would not recommend this mod. Some stuffy shirt old German mechanic's will tell you DO NOT ATTEMPT this. I think that if you get thing's a little on the lean side of thing's you can fry a perfectly good engine. You have to read into it a little I think there are some post's on this site, my speed demon German pal tell's me that you get some dentist pick's and a pocket (cigar or crack lighter) mini-torch and heat up the old Bakelite (see picture) once hot you can dental pick the old plastic like substance off of the magical allen screw inside. Then while using your vacuum gauge as close to the intake manifold as possible set your vacuum for desired result's. Check the intake vacuum pressure first if it is 22 23 24 hg's or such you may be chasing your tail, if the value is already good you will kick yourself for wasting your cigar lighter. My speed demon pal say's he has his set at 30hg's if my memory serve's me right! I will add an underhood gauge before attempting mine then I could alway's dial it down a bit if needed.
If you have deep pocket's or cast iron nut's go for it. I am a little bit scared of it all until I can find an O2 Gas Analyzer.
Good Luck Ernie

[LOWMILE]

Here it is on your firewall. Does your's look like this?