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  #1  
Old 01-09-2002, 08:07 AM
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Will porting and polishing cyl head help power?

Will porting and polishing the intake and exhaust ports in the head help the power of a 240D?

I have to take the head off to do one valve, and I figgered what the hey...

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1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
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  #2  
Old 01-09-2002, 12:57 PM
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You would never be able to tell a difference.
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  #3  
Old 01-09-2002, 01:46 PM
Aaron D
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Since you're going to have the head off, I say try it (assuming you can do the work yourself). Maybe a three-angle valve job, a little pocket work and some cleaning up of the ports. Also, port matching might help, too, but you would think any engine built by Mercedes-Benz would be port matched from the factory.

I guess the only thing you really don't want to do is lower the compression ratio.

Aaron
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  #4  
Old 01-10-2002, 03:34 AM
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Interesting question - Would the headwork at least improve fuel mileage, starting etc., even if it does not result in any more noticeable grunt? What could it hurt? Keep us posted.
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  #5  
Old 01-10-2002, 06:44 AM
LarryBible
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This would be an improvement in most any gasoline engine, but mostly a futile effort with a diesel.

The performance of a gas engine is determined by the amount of fuel/air that is pumped into the engine, more fuel/air pumped in means more power pumped out.

The performance of a diesel engine is determined strictly by the amount of fuel injected into the cylinder. The reason more power is gained from a turbo'd or resonance intake system diesel is because the increased air flow, allows the engineers to provide more fuel injected into the cylinders without engine damage. If you inject too much fuel into the cylinders with an inadequate volume of air, you will decrease engine life.

Have a great day,
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  #6  
Old 01-10-2002, 09:02 AM
Aaron D
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But isn't any engine, gasoline or diesel, basically an air pump? Anything that makes airflow more efficient will help overall engine efficency.

I won't argue that any sort of cylinder head work would probably produce negligable results on an engine in such a mild state of tune, though.

Aaron
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  #7  
Old 01-10-2002, 10:04 AM
LarryBible
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Aaron,

Yes any engine is an air pump, but in the case of a gas engine, you are also pumping in the fuel with the air. In the case of a diesel engine, you are only pumping in the air, you are injecting the fuel directly into the compressed combustion chamber.

As far as the negligible improvement of port work, it depends greatly on the ports you start with. Most American engines have pretty poor porting, so there is much to be gained. The German engines typically have very good ports. This is because in Germany, cars are taxed based on engine size. For this reason, they get as much volumetric efficiency as they can in order to produce the best power with the smallest engine size.

Have a great day,
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  #8  
Old 01-11-2002, 04:28 PM
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More power

If it were available, would a cam with more duration and lift than stock coupled with the port work make more power. It seems logical that it would if the intake and exhaust could flow the added volume.

DieselNation
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  #9  
Old 01-12-2002, 07:32 AM
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Sooooo, if I increase the amount of air into the engine, whether it be by efficiency or turbo or super-charging, I need to change the amount of fuel the injection puts in to take advantage of it.

That would mean that the injectors of a turbo 617 are a different size than a non turbo 617?

I am really glad I asked this seemingly innocent question, because porting a cast iron head is really a pain in the *** ! :p
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1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
1981 Yamaha VX920RH (Euro "Virago")
Solex Moped
1975 Dodge P/U camper


"Time spent in the company of a cat, a beer, and this forum, is not time wasted!"
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  #10  
Old 01-12-2002, 09:09 AM
LarryBible
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DIESLNATION,

AGAIN, anything such as cam, porting, etc is done to increase flow. In a gas engine this flow INCLUDES the fuel. In a diesel engine it is ONLY air. These modifications by themselves will have no effect on power whatever. You will increase power by increasing the volume of injected fuel. This is not a backyard hot rodder thing to be messing with, if you get too carried away, You will end up with a fuel hogging engine with a shortened life.

In the seventies there were some people around that would change the orifices in the return system on Cummins engines, this would provide more fuel injected and would up the power significantly. This, however, caused drastically shortened engine life. It was kind of a bootleg thing to do, and needles to say only those people driving trucks that did not belong to them would have it done.

240 Ed.

I don't think there's any difference in flow from a 300D injector, as compared to a 240D injector. The difference, I think, is in the injection pump calibration, or maybe some of the injection pump components.

Have a great day,
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  #11  
Old 01-12-2002, 09:12 AM
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Thanks Larry.

I was wondereing if there was a difference between non turbo and turbo injectors on a 617. Not between a 616 and a 617.

Have a great Sat.
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Ed
1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
1981 Yamaha VX920RH (Euro "Virago")
Solex Moped
1975 Dodge P/U camper


"Time spent in the company of a cat, a beer, and this forum, is not time wasted!"
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  #12  
Old 01-13-2002, 12:55 PM
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Porting and polishing may help a bit, but not much. Diesel engines aren't throttled, so air flow is greatest at fast idle, and drops off due to pumping losses on a NA engine as rpm goes up. There will be essentially no effect on a turbo since you are pushing the air in anyway.

Porting and polishing have the greatest effect on fuel/air stream separation, not an issue on diesels.

The difference between the non turbo and turbo IPs is that the altitude compensator (ALDA) is connected to the intake on the turbo models so that more fuel can be injected as manifold pressure comes up. This provides considerably more power.

Cam duration changes are problematic -- there isn't much space in the combustion chamber due to the presence of that rather large pre-chamber -- valve to piston clearance is only 0.050" at TDC, so having the valves open longer may cause interference problems. Won't have too much effect anyway, same reasons as porting and polishing.

I'm always amazed by how much horsepower MB gets from rather small engines -- the 560 is only a little over 400 ci! On another posting, someone was very proud of the 4.3L Chevy Vortec V6 he had stuffed into a W123 -- ran the numbers and discovered that my 603 has about the same horsepower per cubic inch! Gas engines much higher. He would have done better to stuff in a 300E engine.

Peter
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  #13  
Old 01-14-2002, 12:21 PM
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Injectors

240 Ed,

I have been told that the non-turbo injectors are different than the turbo injectors due to the higher fuel pressure of the turbo fuel injection system.

DieselNation
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  #14  
Old 01-14-2002, 02:02 PM
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The part numbers for the injector nozzles are different for the turbo and non-turbo 300D engines. To me this means the turbo injector nozzles are made to allow fuel flow/spray pattern that compliments the turbo increasing air flow into the combustion chambers. The 240D and 300D non-turbo injector nozzles have the same part numbers.

I agree with all the others who wrote that porting and polishing the head will not gain much, if any, horsepower/torque unless the injector pump is also adjusted to increase fuel flow (and not just richening the fuel flow by advancing the start of delivery by a couple of degrees).

As Larry Bible wrote, the ports on the M-B diesel heads are light years better than Detroit engines (and on a par with the factory ports on motorcycles that I've had lots of experience with). I've ported and polished my fair share of Detroit heads (also lots of motorcycles) and I believe the small gain you will get by porting and polishing your diesel head could be better applied to other things to bring your engine up to its maximum potential. This does not mean that a good de-carbonization should not be done (sorry about the double negative - you should de-carbonize the ports and manifolds), and if the valve guides are within clearance spec. (0.105mm) then a light lap job on the valves should be done to re-fresh the contact/mating surfaces between the valve face and valve seat (emphasis on very light lapping using fine grit lapping compound), provided the valve seat width is not too wide (intake 1.3-1.6mm, exhaust 2.5-2.9mm) . If the valve guides show too much wear, then they need to be replaced, valve faces re-surfaced or replaced as needed, valves lapped to the valve seats, check the protrusion of the valve head when the valves are seated to make sure the valves will not contact the pistons, install new valve guide seals, other steps as M-B calls for, and you should have a head that will provide the best performance possible.

My, very cheap, $0.02 worth!
Good Luck!
Tom
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  #15  
Old 01-15-2002, 11:37 AM
Bill_Greenwood
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Why would you even want to consider increasing the power of a 240D through engine modifications? It's kind of like that old ketchup commercial, "Benz is so patient!" It's the only car I've owned in recent years that allows me time to fully examine, choose and collect roadkill in one pass without having to turn back around. I hope you realize I'm just kidding--sometimes I do have to slow down in that first pass!

Seriously, I don't think you'll safely extract more power from it without great compromises. Enjoy smelling the roses or get a turbo 5 cylinder.

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