Author Topic: Fuel injection systems  (Read 58486 times)

Online Vixen

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Re: Fuel injection systems
« Reply #255 on: November 17, 2019, 12:28:42 PM »
Hello Roger,

Thanks for the brief history and the drawings. It is now clear just how many goes you have had at making and improving each design of pump and injector. The Swiss have a fine reputation for precision watchmaking and that's clearly what's required for a working fuel injection system

I assume the .dwg is the same as the .pdf one. That would be fortunate, as I have an incompatible version of AutoCAD (very early) which cannot open the .dwg file. It's interesting to see all the information on very large sheet. That's the way i do it as well.

It's going to take time to study and try to assimilate your design, as most of the important detail is still in your head.

Thanks

Mike
It is the journey that matters, not the destination

Offline Roger B

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Re: Fuel injection systems
« Reply #256 on: November 17, 2019, 01:46:08 PM »
Mike,

The PDF is slightly trimmed. I have attached an ACAD 2002 version. I can go back to R12.
Best regards

Roger

Online Vixen

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Re: Fuel injection systems
« Reply #257 on: November 17, 2019, 01:51:07 PM »
Hi Roger

R12 would be good for me

MIke
It is the journey that matters, not the destination

Offline Roger B

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Re: Fuel injection systems
« Reply #258 on: November 17, 2019, 02:01:08 PM »
R12 Version
Best regards

Roger

Online Vixen

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Re: Fuel injection systems
« Reply #259 on: November 17, 2019, 02:36:25 PM »
Roger, Roger.   :ThumbsUp: :ThumbsUp:

Thats an even bigger sheet than the .pdf

Mike
It is the journey that matters, not the destination

Offline Roger B

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Re: Fuel injection systems
« Reply #260 on: November 17, 2019, 03:57:50 PM »
Having reassembled the test setup I tried once again. The initial trials were not very good with sideways squirts rather than atomisation.


As an experiment I tried lapping the seating to the needle using 1 micron diamond paste as before. This has it's risks as I can't keep the abrasive away from where the shank runs in the nozzle and properly cleaning the orifice will be difficult especially in the smaller sizes. The initial trial looked better with more atomisation and less side squirt  :)

Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #261 on: May 19, 2020, 05:39:02 PM »
I have come back to this topic as I know I need to do some more work on the injector nozzle seatings to get good atomisation. Unfortunately as mention in the carb thread my stocks of the key 1.5mm diameter silver steel are no good and I will have to wait for some more. I think I had reached a reasonable compression ratio and will modify the cast iron head to the latest dimensions.
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #262 on: May 19, 2020, 07:15:44 PM »
I tried a couple of the old nozzles and the pattern was not good  :( One was not too bad so I tried igniting the jet (with alcohol). I had a wet towel to hand and a fire extinguisher by the door (run away!!!)




Best regards

Roger

Online Vixen

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Re: Fuel injection systems
« Reply #263 on: May 19, 2020, 07:48:02 PM »
Hello Roger,

That short jet of flame in the video looks very impressive.  :ThumbsUp: :ThumbsUp: :ThumbsUp:

Would you expect the jet to bounce off the piston and cylinder walls to fill the whole combustion chamber with burning fuel, or do you need to develop a broader fan shaped jet.

Still following with the injection and carburetter developments with great interest.

Mike
It is the journey that matters, not the destination

Offline Admiral_dk

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Re: Fuel injection systems
« Reply #264 on: May 19, 2020, 09:44:27 PM »
Looks like your spray pattern would work nicely in a bigger engine  :thinking:

Offline nj111

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Re: Fuel injection systems
« Reply #265 on: May 20, 2020, 09:38:58 AM »
That's great I really like your experimentation here!
Nick

Offline Roger B

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Re: Fuel injection systems
« Reply #266 on: May 20, 2020, 05:18:50 PM »
Thank you all  :ThumbsUp:

The injection will take place into air compressed to hopefully 30 Bar or more so the density will be much higher and the range of the jets much less. This is one of the great unknowns  :headscratch: The injection pressure must be more than the compression pressure but how much more  :thinking:
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #267 on: May 22, 2020, 07:44:14 PM »
Starting off on some new mushroom injectors. I have tried to reduce the internal volume as much as possible as the current versions are difficult to prime. If the air space within is much more that the pump volume it is difficult to get the air out.
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #268 on: May 23, 2020, 04:37:47 PM »
The rest of the operations went without problems. The bore was reamed to hopefully give a good seating for the needle.

The injectors are gradually getting smaller, I think I will concentrate on the mushroom design. There are too many compromises in the needle version.
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #269 on: May 26, 2020, 05:13:23 PM »
Next up was the valves for the injectors. These were made much as before, the longitudinal slide was set true with a couple of trial cuts, the 1.4 mm section was parallel within a couple of hundredths (mm). I have reduced the cone angle from the first experiments to 10░ and 15░ included to see if I get better results.
Best regards

Roger