I have a set of injectors on my NA 616 1983 mercedes 240d. Im going to take a drill bit, that is a tiny bit larger than the pintle hole is, and bore it out ever so slightly. Then i will carefully grind it to a flat and deburr it to help it flow better. After this, i will take some valve lapping compound, thin it out as thin as possible and lap the seat of the nozzle. I will also be doing some minor headwork as well. I will be enlarging the precombustion chamber holes as well. Wish me luck.

Good luck. How will you get the air needed to use any more fuel?

Your injector is going to pee like a boy writing his name in the snow after that. I am going to send mine to be professionally modified. ;)

I like your "out of the box" thinking but the "ever so slightly" you plan to bore out the nozzle probably equates to a 50% increase in area, lower pressure at the nozzle and very poor atomization resulting in lots of black smoke and high temps...

I would turn the pump up first then look at doing something like having the injectors extrude honed. Not so much for increased size but mainly to de-burr and smooth the opening.

Oh yeah, you do have gauges right?

...then look at doing something like having the injectors extrude honed.



That is what I will be doing to mine. They will be opened up 15 thousandths over stock. AFAIK nobody has enlarged injectors for MB IDI engines, and not many people have done it for ANY IDI engines, so it is not really known what the results will be.

Sorry to come off as rude, but my original point was that these injectors require much more precision than can be obtained with a drill bit.

I'd be willing to guess too, that the injector tips are extremely hard and will destroy a drill bit in short order...

EDM machining could also work.



"wire burning" can yield a surface finish on par to that of a surface grinder.



Coating might also be worth it. the entire nozzle face could be coated (evaporation method) to be smoother than possible with grinding. TIN coatings and such arnt that expensive anymore

what a joke

On a non turbo? You MUST have more air to burn the fuel. This will do nothing if you are able to make the "hole" bigger except billow black smoke.

Where I used to work they bought a nozzle regrinding setup (for direct injection nozzles) when they lapped the pintels to the new seat they used 1200 grit lapping compound to lap the pintal seats. Filne valve lapping compound is around 220 grit.
Also even with the the machinery they bought they had a low success rate.
Think off your injector spray nozzle as if it was a nozzle on your garden hose. When you make the hole in the nozzle bigger what happens to the stream of water that comes out?

guys guys i understand that i need more oxygen to burn lol. Im simply doing this to see what the results will be. i have a spare head and engine so i have nothing to loose. (These will not be going into my good engine) Extrude honing sounds good, but wouldnt that also enlarge the diameter of where the nozzle rides inside the hole? I guess it doesnt matter as long as it seats well.

Where I used to work they bought a nozzle regrinding setup (for direct injection nozzles) when they lapped the pintels to the new seat they used 1200 grit lapping compound to lap the pintal seats. Filne valve lapping compound is around 220 grit.
Also even with the the machinery they bought they had a low success rate.
Think off your injector spray nozzle as if it was a nozzle on your garden hose. When you make the hole in the nozzle bigger what happens to the stream of water that comes out? Sorry for the double post, but isnt this why we have IDI engines? the small "ball" for the lack of a better word, inside the precombustion chamber is suppose to deflect and cause more entropy inside the comubstion chamber correct?

If I were you....I would not do that. Just free advice, do with it what you like.

Sorry for the double post, but isnt this why we have IDI engines? the small "ball" for the lack of a better word, inside the precombustion chamber is suppose to deflect and cause more entropy inside the comubstion chamber correct?


You do still have to have a good spray pattern, but I'm not sure the garden hose analogy is a good one. You can have a good spray pattern that still flows more (in both garden hoses and fuel injectors).

Hey Cerven,
I think the critical insight here is to realize that an injector nozzle is Not like a carb jet. Increasing the area that the fuel flows through will only decrease its velocity. The fuel volume is controlled entirely by the injection pump plunger volume. If you want more fuel, that is where you have to start. My turbo 240D is shooting about 100 cubic mm per shot. The stock setting is 41.5 cubic mm. The IP seems to have no trouble shooting this much fuel through stock injectors set at 135 Bar. Cheers, CHris

Thats because its only now getting close to stock turbo settings. Much more than that and the injectors ARE a restriction.

Increasing the area that the fuel flows through will not just decrease its velocity, it increases the volume the nozzle can flow. If there were no gains then performance injectors for the pickups and TDIs would not exist.

why dont you try fooling with the injection pump, If you said you have a engine to play with fool with the injection pump. Open it up and see what its all about and try modifying that.

Hey Cerven,
I think the critical insight here is to realize that an injector nozzle is Not like a carb jet. Increasing the area that the fuel flows through will only decrease its velocity. The fuel volume is controlled entirely by the injection pump plunger volume. If you want more fuel, that is where you have to start. My turbo 240D is shooting about 100 cubic mm per shot. The stock setting is 41.5 cubic mm. The IP seems to have no trouble shooting this much fuel through stock injectors set at 135 Bar. Cheers, CHris

That pretty much sums it up. The nozzle isn't restricting how much fuel you get, its the pump.

Thats because its only now getting close to stock turbo settings. Much more than that and the injectors ARE a restriction.

Increasing the area that the fuel flows through will not just decrease its velocity, it increases the volume the nozzle can flow. If there were no gains then performance injectors for the pickups and TDIs would not exist.

This is true, but think about what pressures these nozzles are designed for and compare that to our IDI nozzles (20+kpsi vs 2 kpsi). The nozzle area is very small in the DI case therefore increases in flow are matched with very large increases in pressure (or very long duration). In our system, the increase in pressure with flow would be much more gradual. Wouldn't it be easier to just put in a non-throttling type nozzle if injection duration is a problem?

This is true, but think about what pressures these nozzles are designed for and compare that to our IDI nozzles (20+kpsi vs 2 kpsi).

Incorrect. You are thinking of the common rail engines, not the pump fueled engines.

You're right I was thinking of common rail engines. The point remains, it would be easier to just swap in a nozzle with the characteristics you want. Most bosch design nozzles will swap from one body to the next, just match up the spray angle and find one that will deliver more fuel (go with a 265 nozzle for example). I still doubt its much of a bottle neck no one has ever measured it to know for sure.

I still doubt its much of a bottle neck no one has ever measured it to know for sure.

Those that have messed with the delivery valves know there is a LOT of extra fuel delivery to be gained other besides internal pump adjustments.

Those that have messed with the delivery valves know there is a LOT of extra fuel delivery to be gained other besides internal pump adjustments.

Wait till I get the Floyd-kit. Element, delivery valve and nozzle. All for more flow.
At least the nozzle is custom made with 3 flats on the needle.
Should arrive tomorrow or next few days.

Tom

Wait till I get the Floyd-kit. Element, delivery valve and nozzle. All for more flow.
At least the nozzle is custom made with 3 flats on the needle.
Should arrive tomorrow or next few days.

Tom

Wow can't wait to see a picture or two!

Yeah, I'm eagerly awaiting news on this as well! But Tom knows that... :) This kit might just take care of the fueling side of the performance equasion.

What is a Floyd kit? Is Floyd the one who made it?

What is a Floyd kit? Is Floyd the one who made it?

Floyd is the brother of Holly :D
Just to give things a name.
It is me who combined elements, suitable delivery valves and nozzles.

Tom

Those that have messed with the delivery valves know there is a LOT of extra fuel delivery to be gained other besides internal pump adjustments.

This was never clear to me. How does a pump barrel/piston deliver more fuel with post pump modifications (delivery valve, nozzle ect)? Is there a pressure relief valve somewhere in the pump? Otherwise, the volume put out by the pump is what comes out the nozzle. Now I am neglecting bypass flow in the nozzle, this is the only parameter no one talks about. By altering the specifics of the nozzle, this parameter could easily be altered.

Sorry for the double post, but isnt this why we have IDI engines? the small "ball" for the lack of a better word, inside the precombustion chamber is suppose to deflect and cause more entropy inside the comubstion chamber correct?

I did not see this until now. To the best of my knowelege Mercedes is the only one using the Ball Pin in the Pre-Chamber.
On most Injector Nozzles the smaller the hole the Fuel is injected out of the better the atmoization is.
Also a bigger hole on a Pintle type Nozzle allows more room for combustion gasses to try to get passed the Pintle/Nozzle seating area.

Another thought is that Bosch makes a lot of different Pintle Nozzles for a lot of different Engine applications. Somewhere in all of those Nozzles must be at least 1 that is already made with a bigger hole and will fit into the Mercedes Nozzle holder.

increasing bores must go together with increasing the flow.
Otherwise the atomisation gets down. Same with bores of the PC, you need the velocity of the gases.
I personally tend to increase a little more the flow to improve atomisation.
Looking at the nozzles there are so many parameters and even more personal requirements that the thing is to try and report.

Tom

Hi everyone,
One more thing to consider on the the nozzles is that the fuel pressure acting on the face of the pintle is what pushes it back against the spring. If you are flowing more fuel, the back pressure from the orifice will increase, thus pushing the pintle further back in the injector body and pulling the pintle further out of the orifice thus opening up more area. The injector is basically self adjusting to the volume of fuel flowing through it.

By the way, according to the fender stickers I've seen on 300D turbos, the Stock injection volume on a 617 is 51.5 cubic millimeters, and on NA engines
(616, 240D and 300D non-turbo) its 41.5 cubic millimeters. Forced Induction said that 100 cubic millimeters was just approaching stock volumes for the turbo engines. I'm assuming he's talking about some of the later model engines. 100 cubic millimeters is twice the stock 617 turbo output, and its atainable with a stock pump just by removing the start/run lockout bar in the IP.
CHeers, CHris

Hi everyone,
One more thing to consider on the the nozzles is that the fuel pressure acting on the face of the pintle is what pushes it back against the spring. If you are flowing more fuel, the back pressure from the orifice will increase, thus pushing the pintle further back in the injector body and pulling the pintle further out of the orifice thus opening up more area. The injector is basically self adjusting to the volume of fuel flowing through it.


You are correct...
until the pintle course it at the end... (something about 0.72 mm)
Then the orifice is the bottleneck.
I got some comparison flow values of the Floyd nozzles. 10% more flow at the same pressure!!! The effect is identical as for the larger elements (not this much). This also reduces the injection time at the same volume or more fuel within the same time. Plus the spray pattern is symmetrical due to 3 flats.


By the way, according to the fender stickers I've seen on 300D turbos, the Stock injection volume on a 617 is 51.5 cubic millimeters, and on NA engines
(616, 240D and 300D non-turbo) its 41.5 cubic millimeters. Forced Induction said that 100 cubic millimeters was just approaching stock volumes for the turbo engines. I'm assuming he's talking about some of the later model engines. 100 cubic millimeters is twice the stock 617 turbo output, and its atainable with a stock pump just by removing the start/run lockout bar in the IP.


Again, it is not only the total volume but the duration. Increasing the amount of fuel on a given element seize will enlarge the duration of injecting.
Begin is fix, end of injection moves towards late and the additional fuel can't burn completely (black smoke and heat).

Tom