luvmuzik66

What can you say? Let's gather some ideas and maybe we can come up with something nice. Porting and polishing the head is good for the engine as long as it is done right. We are talking STREET application here, not racing...
...so...who wants to start?

Bigdot

its in the process...................... its been like 9 weeks now.
had to replace the camshaft, and i got larger fuel injs. and an adjustable emgine PSI guage.

Mark

luvmuzik66

What type of bumpstick are you replacing it with. I know a good Italian fuel pres. regulator. What are you getting ang who's doing your cylinder head?

TheDoughboy

Well if you going to work the cylinder head & do a cam, you will need more to make it work. You have the injectors and fuel reg already. You will want a better air intake, and a free flow exhaust. Although I read the factory exhaust is pretty free flowing already.

A header setup will be nice $$. So maybe some work on the stock mainfolds is in order, like an extrude hone www.extrudehone.com

It would be nice though

Bigdot

i alredy have a nice free flowing eghaust system

as for the other things, i have no idea, my machanic/ friends got all of the "goodies" and the guy who is porting it and polishing it, wrights articles in several hot-rod magizies in the US. and the manifold got "extruded" in GA, so i got that taken care of aswell.
Mark

neanderthal

103s dont have electrical fuel injection so gains would be minimal if you ask me. it would need recalibrating the fuel system with a new baseline for flow to optimise it. i think.

104 and 119 engined cars would certainly enjoy a performance boost.

Kestas

I did some mild porting on my 71 Olds 350. Everything else was kept stock. After I finished, the carburator had a lean backfire and I had to drill the main jets for 10% more flow to get rid of the backfire. So neanderthal has a point that porting will change the flow requirements of the engine. But who knows, it may be within the ability of the computer to compensate for the changes. After all, porting an engine simply allows more air into it. Fuel injection adds the required amount of fuel until the O2 sensors says it's enough.

luvmuzik66

Well, I think a mild port job will work...you know...some gasket matching on the intake side a a little mismatch on the axhaust. A pocket port job is the best way to go. We really don't want to get too excited with that porting tool and making the ports too big or we'll end up loosing power or throwing away a cylinder head.
We want to do some bowl blending and concentrate on the area just below the valve seat and...be carefull not to mess up the short side radii. This part is very critical.
This would probably help...mileage wise and I think porting is making the head more eficient, don't you think?

neanderthal

it all depends on how well mercedes designed the heads in the first place. some cars you can port as much as you want to, but the power gains arent there coz it was **** from the get to. it might be the case with your car.

as i said, 103s and early 119s dont have electronic fuel injectors. i dont recall the specifics of the Bosch KE, but i seem to recall it being rather more mechanical than electrical. so im not sure that it will compensate for the extra flow. if it doesnt then all that porting will be in vain. you will need someone with intimate knowledge of the sytem to tell you definitively.

luvmuzik66

If that is the case, why do they need the O2 sensor? What's the use of having one?

luvmuzik66

Can anyone help us out over here?

neanderthal

what has that got to do with anything. the injectors are not electronic. that doesnt mean that you cant vary the injection. if you couldnt you wouldnt be able to accelrate and all that.

my post meant to say that i think the system is mechanical. if that were the case, then possibly, you have to make adjustments in the fuel delivery system to adjust for the better flowing head. with electronic injection it just adjusts by itself, but thats a built in facility. ours IIRC have a mechanical plunger connected to the intake flaper thing you see when you take off your air cleaners lid. it may, or may not, compensate for the extra flow

again, i dont know. you have to talk to someone who knows the injection system a lot better than i do.

lkchris

Those are VERY short passages in the head. The intake manifold runners are lots longer. Be surprised if you could make even a 1% improvement. Best way to get more air flow is to ASK for more airflow, i.e. change the camshaft and/or the displacement and/or valve sizes. If you don't ask for more, seems unlikely you'll get more, and, besides, all the "hype" about strangled engines applies lots more to slow-running 3rd-world motors like American iron and not to high-rpm, sophisticated autobahn runners like Mercedes.

Kestas

Now that I think about it some more, perhaps this exercise is less of a problem than we may expect. The O2 sensor adjusts the fuel delivery on an engine, but it only feeds into the Lambda unit, which ultimately adjusts the fuel delivery. I believe the Lambda is adjustable and can be tweaked for optimum performance.

Closed loop (warm-up mode) operation may be a different matter.

luvmuzik66

So, it means it is possible. Right? Closed loop operation is letting the cpu/engine tune by itself, correct?

pifcat2

My engine was modified to 3.6L with performance camshaft and ported/polishedcylinder head by RENNTech:

Stock Horsepower: 177 @ 5800 RPM Stock Torque: 188 lbs.-ft. @ 4400 RPM

RENNTech 3.6 Horsepower: 255 @ 5800 Torque: 264 lbs.-ft. @ 4400

They will unlikely tell you their tuning secrets. There's a Tech in Santa Cruz who was selling this in April:

Mercedes Immaculate Rare 5 speed - $9000
Diamond Blue very fast rare 5 speed 87 300E Mercedes. MB Technician owned. Race ready or sunday cruise. Equiped with Renntech port polished head an Cam. Large throttle body, jacobs Ignition and wires. K&N air filter. Custom made Carlson racing camber strut brace. Momo exhuast, Eibach springs, Momo sway bars and bushings. New AMG Mono block wheels. Bridg. RE930 tires. Momo shift knob, premium sound and thats just to start. just smoged car...have all receipts and service records. Sacrificing because of new baby. over 40k invested in car serious inquires only.

Kestas

Yes. But I made a mistake in Post #14. Open loop mode is the warmup mode, when the engine is cold. Closed loop is when the engine is already warm.

luvmuzik66

This operation is used to get baseline tune for cars equipped with programmable ECUs. You input values for the the ECU to target. On OEM ECUs, it is dependent on the O2 sensor, but very minimal adjustments, mostly only at idle speed.