W124 M102 engine power increase

[darkon]

Hi guys, I’m new here and I was hoping that you could give me a couple of ideas on how to increase or restore the power of my ‘91 w124 m102 engine. First of all I am asking you because I didn’t manage to find any useful information in my domestic Mercedes-Benz forum (I’m not from the UK), so it would be great if I can find all the things on eBay. Secondly I would like to let you know that I’m not interesting in making my everyday car “too powerful” so I’m not aiming to make a 200 hp M102 engine. The car is running on LPG and some time ago I heard that iridium spark plugs are performing better than the stock ones. So I bought a set of Denso Iridium plugs and to be honest I did felt a little difference in the “performance” of the engine. I guess that started me up on going better and better. I also found a K&N air filter for the car, and maybe I could try the pulstar plugs, but does Mercedes offer an intake replacement like Vauxhall do with Lexmaul? Or maybe a pair of throttle bodies? I just don’t want go all hardcore with forged pistons and sport camshafts and things like that, so please get me started on “How to get a little bit more horsepower without braking the bank”.
P.S. I want to keep it NA

 

[trapperjohn]

Welcome to the forum darkon.

Sorry I cannot help with the techie stuff. It will be interesting to see what our Techies come up with considering you are running LPG at the moment.

 

[BlackC55]

I really would consider getting a 124 with a bigger engine rather than tuning yours. The power gains are going to be small for relative costs. Consider the E320 as they go very well.

Throttle bodies will set you back £2k with the ECU.

 

[Ian B Walker]

I'm with Ollie here. Best and easiest engine to fit would be an M103 300-24v (1990 engine, pre cat, 231bhp). Minimal wiring loom issues and a direct fit, no dramas

 

[Will]

+1 to the above.

When Mercedes-Benz wanted more power out of an M102, they had a completely new cylinder head designed for the car by Cosworth - two camshafts, 16-valves, totally different exhaust setup etc. No point re-inventing the wheel twenty odd years later

So IMHO you're best keeping your current W124 in perfect running order, or upgrading to one of the six-cylinder models, cheapest power increase you're going to find

Will

 

[darkon]

Thank you very much, at some point I would love to own a 6 cylinder engine especially with a manual gearbox, that would fix my power issue. What about restoring some of the lost horsepower of my M102 engine? I'm pretty sure that the motor was running better 20 years ago, so how can I "bring it back to life" ?

 

[BlackC55]

It just needs to be serviced properly using decent parts and I would consider getting the mechanical injection system overhauled. (this won't be cheap) The gearbox also plays a part too (if it is an auto) so make sure this is serviced too.

 

[darkon]

Yeah about the gearbox, I have a manual, but I think I should soon fix it because from time to time I feel that the gears won't go that easy or smoothly,but if I double clutch it gets a bit better and it sems like it's working, but it's not like that all the time. I hope it's the clutch pump and not the clutch itself.

 

[Will]

As above.

To be honest, I wouldn't spend too much money on looking for work to do on an M102 - just keep it well serviced and in a good state of repair.

You could spend hundreds of £££s on it and it would only make a marginal improvement.

What's the age/mileage of your car anyway, and does it start/run/drive okay?

Will

 

[darkon]

It's a '91 model, around 155 k miles on the dash, it runs fine, it has no problems with starting the engine at all, and it's a daily driver. I have the car since 2009 and I think they were 2 or 3 owners who had it before me, it was bought from Italy and later imported to Bulgaria where I am from 4 door saloon car with LPG, I haven't done much work on it except the usual oil and filters change.

 

[RBYCC]

Thank you very much, at some point I would love to own a 6 cylinder engine especially with a manual gearbox, that would fix my power issue. What about restoring some of the lost horsepower of my M102 engine? I'm pretty sure that the motor was running better 20 years ago, so how can I "bring it back to life" ?

Start with the basics.
Do a compression and cylinder leakdown test.
If the results are not within factory spec then just drive it until you decide to rebuild or shift to another car.

If the compression is within spec then do a smoke test to find any vacuum leaks.

With compression and no vacuum leaks resolved, Finally tune, including replacing plugs, wires, distributor cap, possibly coil, etc and set ignition and fuel to factory spec and it will perform as it was designed !

 

[d w124]

Best and easiest engine to fit would be an M103 300-24v (1990 engine, pre cat, 231bhp).

I`m sure you mean M104 there

 

[Ian B Walker]

I`m sure you mean M104 there

Sorry Dash and others, typo.

 

[d w124]

Sorry Dash and others, typo.

Figured that out already
OP: You could always go turbo route