OK here it is. I did this mod and took the time to take pics of it and make a little page describing the process. I open it up for any comments and critisims.
here is the link
http://kayakoutfitting.com/mercedes/intake.html

Eric Z

Great idea except for one thing,the diesel doesn't get ANY benefit from extra air unless you also add more fuel.Unfortunately Nitrous Oxide won't help either,unless thats another mod you want to try?

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Democracy dies in darkness, you have to kick at the darkness till it bleeds daylight

You can richen the fuel delivery a bit by changing the injection pump's start of delivery. Factory spec is 24 degrees BTDC and I have an official M-B 1981 manual entitled "Diesel Injection Service Procedures" part of M-B's Education for Excellence program stating that the start of delivery is + or - 1 degree from 24 degrees BTDC. Meaning that 25 degrees BTDC is within spec and I have gone a bit richer than that when I was experimenting with my engine (up to 27 degrees BTDC, before going back to 25). An independent tech also recommended using a couple of degrees of advance for start of delivery - like 25-26.

I adjust start of delivery using a separate fuel tank (recommended by the Mitchell auto service manual for M-B diesel engines) and gravity feed diesel fuel into the inline fuel filter (removing the fuel inlet line from the inline filter and connecting the fuel line to the inline fuel filter from the separate fuel tank that I hang from the grill). Set up is the same (removing #1 element valve and spring, open throttle to full open, remove vacuum line to fuel cut-off control valve, install overflow pipe, etc.). Then instead of trying to get the one drop per second, I use a fuel flow just stops method by pumping the hand primer pump to get fuel flow out of the overflow pipe, turn the engine until all fuel flow just stops with maybe one drop 10-15 seconds later (this method corresponds to the interior of the IP where the piston just closes the fuel port thus beginning pressurizing the fuel going to #1 injector - the true start of delivery). Both the above M-B manual and the Mitchell manual use the fuel flow just stops with a drop 10-15 seconds later method. Adjust the position of IP so the the fuel flow just stops at the desired crankshaft position (it will probably take several tries turning the engine in the direction of rotation and moving the IP until the start of delivery is where you want it). This method is a lot more accurate and faster, in my opinion.

Turning the IP away from the engine is leaner (fuel delivery is later in the stroke) and turning the IP toward the engine richens (fuel delivery is earlier in the stroke). Richening does not add a lot of fuel, but does add a small amount that may take advantage of the increased air flow from your modifiaction to the air cleaner and the use of the K&N air filter.

Experiment to find the start of delivery position that yields the best performance. Let me know what you end up doing.

Good Luck!
Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.

Tom, So you are saying that only adjusting the "start of delivery" changes the amount of fuel put into the cylinder per charge ? There is no other change you are making to get more fuel per charge,,,like on the IP ? I would have thought that the amount of fuel would be determined by a small piston and that something other than the "start" would have to altered to change that. (?) Greg

Kyle said "the diesel doesn't get ANY benefit from extra air unless you also add more fuel."

I don't claim to have any great knowledge, especially when it comes to diesel, but this just doesn't make sense. If this was the case then there would be minimal benefit from a turbo. A turbo obivously benefits a diesel greatly in mileage and output. According to the Chilton book, a turbo can ram up to 3.5 times the air into a cylinder as a naturally aspirated engine. At the same time fuel mileage is increased not decreased. So signignantly disporportionate amounts of air into the chamber increase volumetric efficiency. This is the bueaty of a diesel in that you are not limited by the lean-ness of the mix as in petrol. Again I don't claim to know but I doubt that when a turbo doubles the air intake that the fuel pump output doubles as well.
If im wrong set me straight. I joined this group so I can learn.
Eric Z

Greg:

From all the reading I've done (100's of pages, including some info from Am. Bosch about the M-B IP), talking to some techs, and my own experimenting, you can richen the mixture a small bit by changing the start of delivery with no other changes to the IP. I am not talking about a lot of difference, but a small bit more fuel into the cylinder before the compressed air ignites it by changing start of delivery to 25-26 degrees BTDC. Recall, the turbo 300D uses a 26 degree BTDC spec (+ or - one degree, so 27 degrees BTDC is within spec) for start of delivery in order to get more fuel into the cylinder before the compressed air ignites it (of course, the turbo IP is made to deliver more fuel to begin with based on the boost delivered at a particular engine load) and it needs to get the additional fuel into the cylinder a bit sooner than the non-turbo engine - at least that is my reading/understanding of how this system works.

Also, an earlier start of delivery will introduce a small bit more fuel before the fuel delivery cycle really starts fighting against the compression from the piston. The injector nozzles have overflow lines to take the excess fuel not used by the nozzle back into the fuel tank. Meaning, extra fuel is delivered by the IP to the injection nozzles that is not all used in the fuel delivery cycle and that the total amount of fuel injected into the cylinder is limited by both the spring strength inside the nozzle and the pressure in the cylinder as the piston compresses the air delivered from the intake manifold through the air cleaner. It seems to me that engine compression will have an effect on the total amount of fuel delivered through the injector nozzle especially as the cylinder pressure increases toward maximum causing a bit less fuel through the nozzle at the end of the fuel delivery cycle and this fuel is passed into the overflow lines.

In the case of the additional air Eric may be getting into the engine with his modification to the air cleaner and the K&N air filter, I believe a start of delivery of 25 to 26 degrees (perhaps a bit more) may add a small bit of power (who knows for sure without using a dyno to run the engine on and make various adjustments). I do not believe we're talking more than a few horsepower here (1-2, maybe 3??) and certainly not enough to shorten engine life. At 77 horsepower for the non-turbo engine, a 1-2 -3 horsepower increase is not huge, but may be possible with these modifications. However, what condition is the engine in to begin with (piston ring sealing, valves leaking or not, compression, injector nozzle opening/closing pressure, etc., etc.)? And, is it in good enough condition that Eric's air cleaner modification will actually increase the air going into the cylinders by a large enough amount that a small increase in fuel delivered by an earlier start of delivery setting will actually increase horsepower? How restrictive is the stock M-B air cleaner assembly and stock air cleaner? Who knows without trying? Eric wants to try and I would like to know what happens.

My $0.02 worth!
Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.

I wish I could have done a good baseline of fuel mileage beforehand to give a comparison. I can say without question though that the throttle response in the low RPM range has been improved. Those first moments as you are pulling into traffic waiting to hit that 2K+ rpm mark so you can start getting positive accelleration used to seem like an eternity, now that sweep of the tach through the lower section of rpm's takes less time for sure. Above 2K I do not feel any tangible difference in the cars performance. I wasn't anticipating any benefit here though other than perhaps less wear on the turbo.
It may be only a horse or two, but it was cheap to do and will be there for the life of the car. If it gets me even 1/2 of a mile more a gallon of fuel it will also be worth it because it only took a few hours and will be there for the life of the car.
Eric Z
P.S. I did a test with the hose today spraying the front of the car aggressivley with it running and no water got sucked into the air box.

Oops!! Eric, I thought you were talking about a non-turbo 300D! Oh well!! Any way, the info about the IP I gave was for the non-turbo, but I did give you the specs for the turbo start of delivery. If you do experiment with start of delivery at 27-28 or more degrees BTDC let us know what happens because the basic premise for earlier start of delivery should work on your turbo. Your engine produces about 120 horsepower, which is a considerable improvement over the non-turbo's 77.

Good Luck!
Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.