Author Topic: 917 180 degree V 12  (Read 42989 times)

Online steamer

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Re: 917 180 degree V 12
« Reply #225 on: April 11, 2018, 11:22:49 AM »
Thanks for that Rodger!     It sounds wonderful!   I remember my Dad telling me a story about his trip to Detroit Diesel.    He was a Fire Department Master Mechanic with many years experience all the way back to WWII.    He told me that the technician at DD Brought out an injector assembly in a beaker of fuel.   Took it out and showed him how smooth it was, took the piston out put it in ect.   He then held the piston in the palm of his hand for about 5 seconds.   It would no longer fit in the barrel of the pump.    Put the whole thing back into the beaker, and a minute or 2 later,  It slipped right back in......33 millionths clearance or some such number....

OK   I'll keep my eye on it...though I don't mind saying....it terrorfies me to think of trying to tackle something like that...

Dave
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Online Vixen

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Re: 917 180 degree V 12
« Reply #226 on: April 11, 2018, 12:14:03 PM »
Roger, Dave.

This thread has developed into a very interesting fuel injection sub topic.

As Roger will agree, direct diesel injection is hard enough, requiring precisely controlled squirts of diesel fuel at very high pressures.

Indirect petrol injection can be achieved at much lower pressures but adds yet another control dimension. That is the additional need to maintain precise control of the fuel air mixture. The explosive limits for a petrol (gasoline) air mixture are very narrow (typically  15:1 by weight). The Methanol/ air ratio is somewhat wider. Add some nitro methane and the limits are wider still, almost any mixture will burn.

The petrol injection system required for a road or race car needs to map and control the fuel flow to the mass air flow ratio for all conditions of engine load, engine speed, throttle setting, acceleration, over-run etc. etc. Clearly we are not going to be able to achieve this level of mapping and control at model scale.

It looks like the Schilling injection set up is both simple and actually quite cleaver. It only attempts to match the fuel flow to engine speed at one point on the map. It looks like they set the throttle position, run the engine up to speed with that huge electric motor, then they adjust the bypass valve, by hand, to give the correct fuel flow (pressure) for that one engine speed condition.  In much the same way as we adjust the needle valve on a big model aircraft engine, to set the mixture for wide open throttle running condition.

Et Voila, we demonstrate a running petrol injected model engine on the test bench.

We should therefore think of the Schilling injection system as a big pressurised carburetor (which is just what the translation tells us).

Well, that's my take

Mike   :noidea: :noidea: :noidea:
« Last Edit: April 11, 2018, 12:22:49 PM by Vixen »
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Online Roger B

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Re: 917 180 degree V 12
« Reply #227 on: April 11, 2018, 12:23:56 PM »
I was surprised at the rev range I was able to get with a fixed injection pump stroke. The speed dependent leakage past the plunger may have had an effect. I am currently refitting the helix controlled fuel injection system to my horizontal engine to repeat the trials from last year when, as I found later, there were other problems with the engine.

http://www.modelenginemaker.com/index.php/topic,7701.0.html
Best regards

Roger

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Re: 917 180 degree V 12
« Reply #228 on: April 20, 2018, 02:33:44 PM »
A little inspiration.....


Dave
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Re: 917 180 degree V 12
« Reply #229 on: April 28, 2018, 01:32:52 PM »
That diagram brings up memories of the Tecalumit Jackson injection system for Mini Cooper engines amongst others.

Interesting read!...
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Online steamer

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Re: 917 180 degree V 12
« Reply #230 on: April 30, 2018, 12:34:37 AM »
Actual progress in this area....found some new pictures, and have a lot of design done....nothing to show just yet....still getting the layout and specs but..

25.4 bore
20 stroke
ball bearing crank
split rods
DOHC 2 valve/cylinder   same size
2 rings   1 compression 1 oil....
dry sump
1 oil pump   6 scavenge.
Carbureted....and TBD.
Air cooled....
dual ignition with dual spark plugs...per original   ( 10-40 rimfire plugs)
Lemans era exhaust.....


Its going to be a while before I can start this.....that Wallaby needs to get done and before that happens, I need to heal up....but I'm on a better course...

Probably time to move this thread.....out of Chatterbox...

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Offline 90LX_Notch

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Re: 917 180 degree V 12
« Reply #231 on: April 30, 2018, 12:38:32 AM »
Don't you have a "Tiny" to finish also?

-Bob
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My Engine Videos on YouTube-
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Re: 917 180 degree V 12
« Reply #232 on: April 30, 2018, 12:39:12 AM »
I need to model up the cam cover on the right side intake to include the injection mount....I found a picture of one..

And a couple of section views...
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Online steamer

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Re: 917 180 degree V 12
« Reply #233 on: April 30, 2018, 12:39:42 AM »
Don't you have a "Tiny" to finish also?

-Bob

Yup....Its there for when I need a break from the other two..... 8-)

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Offline b.lindsey

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Re: 917 180 degree V 12
« Reply #234 on: April 30, 2018, 12:46:00 AM »
24 spark plugs  :o. You gonna make em Dave or go with bought ones?

Bill

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Re: 917 180 degree V 12
« Reply #235 on: April 30, 2018, 12:49:33 AM »
24 spark plugs  :o. You gonna make em Dave or go with bought ones?

Bill

The plan is the 10-40 rimfires    purchased
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Offline crueby

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Re: 917 180 degree V 12
« Reply #236 on: April 30, 2018, 12:59:34 AM »
Wow. Just, wow.

The 3D model alone is impressive, cannot wait to see it actually made!

 :popcorn:

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Re: 917 180 degree V 12
« Reply #237 on: April 30, 2018, 01:14:18 AM »
Wow. Just, wow.

The 3D model alone is impressive, cannot wait to see it actually made!

 :popcorn:

Well    don't hold your breath.   The last 3 years my life has not been my own   Two start ups, a daughter with cancer and being unable to walk for the last 3 months don't promote productive shop time.   I had a lot of time sitting on my butt...so I drew it up.   It needs to be detailed and some areas aren't designed yet...so it will be a while.     But   I don't care..and last time I checked I was the only one who mattered...so I'll get to it   and I'll publish it here
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Offline b.lindsey

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Re: 917 180 degree V 12
« Reply #238 on: April 30, 2018, 01:17:27 AM »
Not to mention crew chief for a budding RC racer :)  Let's hope the next three years go better Dave. Just glad things are getting back to normal even if slowly.

Bill

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Re: 917 180 degree V 12
« Reply #239 on: April 30, 2018, 01:20:33 AM »
And im not starting this till i have prints..
"Mister M'Andrew, don't you think steam spoils romance at sea?"
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