Author Topic: Fuel injection systems  (Read 83553 times)

Offline Minh Thanh

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Re: Fuel injection systems
« Reply #375 on: October 15, 2021, 10:01:59 AM »
 Roger .
Thank you very much !
And one question : the pump has 2mm , does it create enough oil pressure to pump into the cylinder ?

Offline Roger B

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Re: Fuel injection systems
« Reply #376 on: October 15, 2021, 11:09:08 AM »
I need a load of 4kg on the end of the 2mm plunger to open the injector, this calculates to around 100 bar. The compression pressure is around 30 bar so it does inject as the running trials show.
Best regards

Roger

Offline Minh Thanh

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Re: Fuel injection systems
« Reply #377 on: October 15, 2021, 11:21:15 AM »
Thanks !
 i'm testing with a 2mm diameter pump, it doesn't seem to generate enough pressure, i'm looking for the cause

Offline Roger B

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Re: Fuel injection systems
« Reply #378 on: October 15, 2021, 12:13:30 PM »
With the small plunger any trapped air will stop the pressure building up. It can take me several minutes to get all the air out.
Best regards

Roger

Offline Minh Thanh

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Re: Fuel injection systems
« Reply #379 on: October 15, 2021, 12:43:15 PM »
 Thanks !
I plan to reduce the bottom diameter of the piston  4mm, making it about 3  or 2mm, I think this will reduce the amount of fuel, for test the amount of fuel ...
 what do you think ?

Offline Roger B

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Re: Fuel injection systems
« Reply #380 on: October 15, 2021, 12:59:08 PM »
The 4mm part is still moving so it will displace the same amount of fuel. Does your 2mm pump work without any pressure? Does it deliver the amount of fuel you would expect? Are you using ball valves? The movement of the ball must be very small with small volumes otherwise it takes too long to reseat.
Best regards

Roger

Offline Minh Thanh

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Re: Fuel injection systems
« Reply #381 on: October 15, 2021, 01:14:37 PM »
Roger !
 I drew it wrong,
this is correct, I'm sorry
 I use ball valve
 amount of fuel :  i think it's fine, but the pressure is weak,     
with a 4mm cylinder, I can be sure it's fine, but with a 2mm cylinder I'm not sure

Offline Minh Thanh

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Re: Fuel injection systems
« Reply #382 on: October 15, 2021, 01:33:01 PM »
   And one more thought:
I use a 4mm cylinder, but I increase the spring force of the needle
  the needle will open when the pressure is at a higher pressure range, This results in less fuel being injected
  This video is I tried with the above method, the stroke is about 0.8 mm
  (that injector is not very good)
  what do you think ?
 
« Last Edit: October 15, 2021, 01:37:28 PM by Minh Thanh »

Offline Minh Thanh

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Re: Fuel injection systems
« Reply #383 on: October 27, 2021, 10:44:31 AM »
Hi All !
It lives,
although still need to improve, but that's what i need right now

 

Offline cnr6400

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Re: Fuel injection systems
« Reply #384 on: October 27, 2021, 12:24:11 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: well done!  :cheers:

Offline Admiral_dk

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Re: Fuel injection systems
« Reply #385 on: October 27, 2021, 12:35:21 PM »
It runs very nicely - stable RPM and sound  :ThumbsUp: :ThumbsUp:

Shame that we can't see the injector and pump in the video ....
So I will have to ask - do you have direct injection or is it into a hot Bulb / PreChamber ?

Offline Minh Thanh

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Re: Fuel injection systems
« Reply #386 on: October 27, 2021, 01:00:00 PM »
   cnr6400 !
Thanks !
   Admiral_dk !
At 20 seconds of the video, you can see the pump
I spray directly
 I put a lot of oil in the engine to prevent damage to the pistons and cylinders when the engine warms up ( I'm not sure  ;D ) because I didn't install the water pipes
so when the engine runs it bleeds oil

Offline Minh Thanh

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Re: Fuel injection systems
« Reply #387 on: October 27, 2021, 01:19:21 PM »
 Hi Roger !
 I forgot this
Your injectors are pretty good, maybe even better than mine
so just focus on the valve, pump cylinder
  If the pump is ok (creates enough pressure) and the valve is closed I'm sure your engine will be fine!

Offline Roger B

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Re: Fuel injection systems
« Reply #388 on: October 28, 2021, 10:10:55 AM »
Congratulations  :praise2: you must be happy with the first runs  :)

I need to find some more time to spend on my engines  ::)
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #389 on: October 31, 2021, 09:50:23 AM »
A little more progress  :) I received some MOD 0.4 rack and pinions for a reduced size helix pump. 0.5 is easy to find 0.4 was rather more difficult  :headscratch: I can now confirm the dimensions and finish the design.

I then tried one of my diamond ball laps on the delivery valve of the test pump (I have a fine Email thread titled Diamond Charged Balls). The instruction said use a little light mineral oil and if possible don't apply any side pressure. I used the floating reamer holder and lapped for a couple of minutes at 500 rpm. After cleaning and reassembly there was no leakage and the system held it's prime for several days  :)  :)

Next I will repeat with the pump from the two cylinder petrol engine before moving onto the diesel.
Best regards

Roger