trying to get the most efficiency out of my car... I've come up with some solutions and they are closely related to getting making the most out of the power that comes with the car... but I dunno. Wanna throw it around here and see what I can/can't do.

stiffen up the suspension and replacing motor mounts with something more solid - to put more power to the ground instead of squatting (wasting energy) or torquing the motor when moving from a stop.

lowering the car a little to help with aerodynamics going faster than 70-80mph

lighter wheels to decrease unsprung weight.
convert to floating rotors or 2 piece to decrease more unsprung weight.

rebuild the head with higher compression to use fuel more efficiently.

Is it possible to modify the stock fuel trims? (IE: ECU modification for a slightly more agressive fuel trim)

tires are a go/or no go because going thinner will gain better milage and allow for better rain handling, but god, it looks fugly! ... going wider will increase traction and manuverability on dry pavement - I guess this would be more performance sided.

increase the amount of voltage running through the spark plugs and get thicker plug cables to ensure a good isolated path to the cylinders

exhaust, remove a resonator or two, get some stright through mufflers that will stilll dampen the noise, but allow for better exhaust flow... convert to high flow catalytic converters and mandrel bend piping.

gasket match headers and down pipes for even better exhaust flow.

remove spare tire and replace with spare donut.
replace back seat with something lighter in terms of material so that it's still functional.

I'm not going so far as to remove the windows and replace with lexan, I'm not removing the A/C unit (even though It doesn't work still) because then I'd lose functionality from the vehicle.

any other possibilites? are my ideas even feasible on the m103 w124? let me see how the MB represents!

 

Stick with the 195 or 205 series tires, if this is your goal. Also, removing the spare is going to do so little in terms of weight loss for this car. These were not designed with weight as a concern, there are many many pounds of sound deadening material everywhere.... If you really wan't more efficiency, drop in a newer diesel motor The E320 CDI's can get nearly 40mpg, you will not get close to that with all the time and money you put into the m103, and that I6 diesel will be quicker.

 

Behind the battery, there is a black plastic cover. Take it out and try to find a little box that has a inscription that says "M.A.S" that is a device used to spark earlier to protect the engine from fuels of little octane. It has On and OFF position, If you put it in Off you will win compression because it sparks later and therefore it gains compression. You are able to win near 12 hp, but if you do so try to use high octane fuel (98 if possible).


Payson

 

Regretfully all that you are contemplating doing will not return your effort.

The M103 is a period motor designed in the eighties.

It uses a rather unsophisticated engine and fuel management system.

The Bosch KE-Jetronic injection is the first semi-electronic system that Mercedes used.

I would suggest the basics first.
Do a compression test to assure that all cylinders are within specification.
Check your fuel pressure to confirm that your pumps are at spec and your filter is flowing properly.
Do a major tune up which includes points, plugs, wires, timing adjustment.
At this point you then know that you are performing as well as the engine was designed to perform.
You may be surprised at what performance gains you will achieve with the "basics".

From that point you can move on.

Suspension and engine mounts will not give you any more "power to the ground" as far as acceleration with a M103.
Lowering the car doesn't really alter the aerodynamics, but just changes the center of gravity.
Worrying about unsprung weight of wheels and tires also is negligible.
Removing weight from the car as in the spare will not have much overall effect.
Remember that gas weighs 6.6lbs per gallon, so running half a tank will save more weight then what you propose.

A stock, properly tuned M103 will do 0-60 in around 7.5 seconds, with a top speed of about 139MPH
The window sticker on my 1988 300CE M103 indicated EPA mileage of 19-21 City and 18-26 Highway.
These figures I found over nineteen years of ownership to be a bit low.

All things considered not too shabby of performance for 177HP !!!

 

After owning a 78 450sel and then a 87 560sl, the m103 gets more often than not 25 mpg and about 375 miles to a tank with fun performance, I am not complaining.

 

Considering that hondas and the like only get a few more miles per gallon, I would take this type of mileage any day. I have first hand knowledge of the safety that the w124 provides, and I would give up 10mpg to have the solid feel and strength that comes with these cars.

After driving mercedes, well for all of my life, I feel uncomfortable and at risk when I am in anything else, especially on the highway.

 

forget all that "efficiency" crap

find a 5 speed manual. install said 5 speed manual and corresponding differential.
you can use this with taller 205/65-15 tires instead of the standard 195/65-15.

the end.

 

This is very intriguing, I was planning something of that sort. Until someone told me it digs a deep hole in your pocket to get that done.

In other words, how does that justify the cost at the end? Unless you are keeping the car for a REALLLLLLLY long time.

If you have a price idea, please share. Maybe the other person who told me was wrong and I never bothered to confirm it.

 

By the time you are finished the install will cost about what the car is currently worth.

W124 are excellent cars as they stand.

Performance modifications are very expensive because at this time there are few after market parts available.

Unless you have a special car, of which in my opinion, such as a 500E sedan or a solid low mileage coupe or cabriolet, then run the sedans with minimum cash investment.

The 500E, all coupes and cabriolets are the only W124 they are now becoming appreciating assets

 

I my opinion, it would be foolish to go ahead with your proposed changes.
It will only reduce the value of of the car (if there's any left in it) and bring nothing back.
2 years ago, when I made the decision to keep my 1989 260E (over 400K on the clock now), I "invested" close to $5,000. in bringing the car back close to its original condition:
rebuilt suspension/steering front and rear, head rebuilt, complete engine tune-up, engine/transmission/body rubber mounts, brakes, new tires, some cosmestic restoration, (and more)
This was the best $5,000 new/used car I ever bought. I'd do it again.

 

sorry, but the coupes are now appreciating in value? sweet!

 

March 2007 "Mercedes Enthusiast" magazine in the U.K. has a lengthy article entitled "Why the time is right for the W124 Coupe - Full buyer's guide ".

Merc coupes have always increased in value from their low point, which I believe has occured.
However, mileage and overall condition are important to value.

Keep in mind when I bought my 300CE new in 1988 it stickered for $53K.
It was the second most expensive Merc in 1988.
Stickered more then the SL.
Highest sticker was the SEC.

 

the thing about weight reduction is that you can only do a little at a time... but every little bit helps. for the exhaust system... I know it was designed well from factory, but it's heavy! just by changing the muffler, I'm sure a substantial difference in weight would be present
REALLY?!, I definitely have to look for this

the suspension upgrades i proposed was more of a suspension replacement - currently all my shocks/struts are blown and driving around on a tunaboat gives me a lightly sea-sick feeling... so as the car sits now, it squats like asians around a bbq and it dives so hard I have increased my street vision by an extra foot and a half in front of me...

currently, my head is leaking oil and was told that my waterpump is leaking... so machining the head would kinda fall in the category of repairing, but if I milled an extra .25-.5mm off the head and theorhetically raise the compression, would I have better engine response in the long run?
my only thing is that I would be forced to run 93OCT all the time... right now, my car is utilizing 89 very well and I'm eeking about 360mi/fill up and that's usually with about an 1/8th tank left.

as for the 5speed manual conversion, what will make a good donor car to get a 5sp off of that will fit the w124 without too much issue? I've always been interested in that.

does anyone have a parts list for a regular engine tune up?

 

if you're doing this to preserve the environment, then good for you. If you're doing it to save cash, you're gonna lose.

The list of things you posted are going to cost a lot of money. They may save you 2 or 3 mpg. So lets assume you're currently getting 20 mpg, gas costs $3/gal (too lazy to look the national average up), and you drive an average of 12,000 miles per year. Your annual fuel cost would be $1,800. Now, let's assume you squeeze another 3 mpg out of your car from all of this. Using the same assumptions except with 23 mpg, your annual fuel cost will be $1,565, or a savings of $235 per year. The mods you're looking at doing will cost you around $2,500 (very roughly). You're talking about a break-even point of more than 10 years (or 120k more miles). At that point, your car may be ready for the junkyard.

I made some assumptions, but this is what you should consider before doing anything like you're proposing...

 

nice perception bigpete.... good point