# Small fuel injector source?



## keith5700 (Dec 4, 2011)

Anyone know what the smallest commercially available petrol fuel injectors are, or to what they are fitted?
I need a couple to fit to a 1/4 scale v8, but I'd really rather not spend weeks and months developing something if I can get them off the shelf.

I've been searching for days but come up empty handed. There are some references to them being used on chain saws and lawn mowers, but I can't find any sizes or manufacturers
I'm looking at a max. overall length around 30mm, 1.25".
Cheers.


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## crankshafter (Dec 4, 2011)

keith5700 
First I have to say, your V8 build is the most butifull engine I have ever seen. So nice and klean finnish.
Regarding fuelinjectors try this guys mybee they have something for you.
http://www.chinese-parts-canada.com/turbocharger_fuel_injection.html

Best Regards
CS


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## agmachado (Dec 4, 2011)

Hi Keith,

I also look for small fuel injectors, but I can not find... in fact I am thinking to developing one... for that I am studying about the pressure it must support, also the flow, etc...

Maybe we can develop together... what do you think ?

Cheers,

Alexandre


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## rustyknife (Dec 4, 2011)

How hard could it be to develop? I've envisioned such an idea, A small orifice, a spring loaded plunger made of ferrous material to keep it closed, a coil of wire with and a pulse width modulated signal to it to vary the duty cycle

something like an Arduino board should be able to be programmed with the inputs such as a crank trigger, and you could use an old speed density type of setup like the older early 90's Fords to calculate fueling based on Manifold absolute pressure.

Ahhhh if only I had more free time.

http://www.arduino.cc/

The boards themselves are only 35 bucks and can be programmed and reused repeatedly for any application, all of the software is open source. They have bigger boards with more inputs and outputs if needed. And after you get it right, it just requires a 9v plug to run independently

I've downloaded 3 books to my kindle to start learning the Arduino software but I have not started yet


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## MachineTom (Dec 4, 2011)

Look into motorcycle injectors, quite small, the electric connectors are the largest piece or it, fuel at around 60psi, a common 600cc bike each injector fires 150cc and if my calculation are correct you are around 250cc for 8 cylinders, use two injectors. Your would need to do some work on electronics or wire in the MC controller. 

These bikes are wrecked at a very high rate, a least in NJ, so they are parted out all the time, look at older 2003-6 stuff, its cheaper.


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## agmachado (Dec 4, 2011)

MachineTom  said:
			
		

> Look into motorcycle injectors, quite small, the electric connectors are the largest piece or it, fuel at around 60psi, a common 600cc bike each injector fires 150cc and if my calculation are correct you are around 250cc for 8 cylinders, use two injectors. Your would need to do some work on electronics or wire in the MC controller.
> 
> These bikes are wrecked at a very high rate, a least in NJ, so they are parted out all the time, look at older 2003-6 stuff, its cheaper.


Maybe it's a possibility...



			
				rustyknife  said:
			
		

> How hard could it be to develop? I've envisioned such an idea, A small orifice, a spring loaded plunger made of ferrous material to keep it closed, a coil of wire with and a pulse width modulated signal to it to vary the duty cycle
> 
> something like an Arduino board should be able to be programmed with the inputs such as a crank trigger, and you could use an old speed density type of setup like the older early 90's Fords to calculate fueling based on Manifold absolute pressure.
> 
> ...



Yes, I've been thinking the same thing. 

I already have two boards... a Arduino Uno...






and a Arduino Mega...





I've manipulated digital signals, servos and stepper motors ... and of course, also the analog signals.

I did a wireless remote control using two XBee Shield, one on each arduino board. This knowledge will can help us to make a control panel wireless, with graphic gauges, etc.

Maybe we could form a team build to make these ideas into reality!

Cheers,

Alexandre


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## mu38&Bg# (Dec 4, 2011)

There is this project. But he doesn't get into the details of the injector design. http://www.f1-2000.co.uk/index.php?f=fuel_injectors Now if you want to run one or two injectors, you wouldn't have to be this small. The smallest Bosch injector I know of is still 2" long.

Greg


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## keith5700 (Dec 5, 2011)

Crankshafter, that Canadian site looks good. I will contact them to see if they can measure the injectors, they look small but it's hard to get a sense of scale from their pics.

Alexandre, If I end up having to make the injectors then we can combine resources if you wish. I don't mind doing all the manufacture etc. but have limited time at the moment for researching coil types and valve arrangements etc. and not enough knowledge to play with Arduino boards. 
As I say, I would much prefer to buy a couple of injectors and plug them into a Megasquirt, and be done with it.
Let's see how it goes.

MachineTom, I reckon my engine will be about 40cc. I couldn't find any details on bike injectors, but maybe I didn't look hard enough.

Greg, I've seen that 1/4 scale F1 engine, and his injectors, which are incredibly small, but as you say, no details on construction etc. He seems to have disappeared of the face of the earth after finishing one injector.

Cheers, Keith


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## gbritnell (Dec 5, 2011)

Gentlemen,
 While attending on of the early NAMES shows at the Yack arena the now deceased Lee Root had a fuel injected inline 4 cylinder engine. 
 It was a throttle body type meaning that it had one injector feeding through a carburetor like unit. As Lee was not very forthcoming with information about his projects the specifics of the system went to the grave with him. 
 I'm not sure but I think Paul Knapp of Rimfire spark plugs has this engine either personally or as part of his engine display which is now at the Sherline Craftsmanship Museum. 
 Maybe someone close to Mr. Knapp could get more information on it.
gbritnell


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## MawitÃ¶ (Dec 5, 2011)

Hi guys, i offer myself to help, i know nothing about how an injector works, but i know how to use arduino and how to code, so if anyone find himself with no time that's something that i have too. 

Also for the arduino newcomer i recomend this book.
http://www.amazon.com/dp/0596802471/?tag=skimlinks_replacement-20

That's a nice book wich covers a lot of stuff and has a really interesting chapter on memory management and advance coding.

Mawito


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## agmachado (Dec 5, 2011)

dieselpilot  said:
			
		

> There is this project. But he doesn't get into the details of the injector design. http://www.f1-2000.co.uk/index.php?f=fuel_injectors Now if you want to run one or two injectors, you wouldn't have to be this small. The smallest Bosch injector I know of is still 2" long.
> 
> Greg


Very nice this web site... the last update ocurred at november, 2011... I will send a e-mail to try obtain some information!



			
				keith5700  said:
			
		

> Alexandre, If I end up having to make the injectors then we can combine resources if you wish. I don't mind doing all the manufacture etc. but have limited time at the moment for researching coil types and valve arrangements etc. and not enough knowledge to play with Arduino boards.
> As I say, I would much prefer to buy a couple of injectors and plug them into a Megasquirt, and be done with it.
> Let's see how it goes.


Ok, but before to play with a arduino board we need to develop the small fuel injector... I think that's the first objective, because also will be necessary to know the volume of the injector to set the parameters in the MegaSquirt module.

If we define approximately how it should be this injector, I can search coils to the solenoid... I think that the coil can work between 6 or 12 volts... Do you agree?

I'll try to think of something, put into CAD and share with us.



			
				gbritnell  said:
			
		

> Gentlemen,
> While attending on of the early NAMES shows at the Yack arena the now deceased Lee Root had a fuel injected inline 4 cylinder engine.
> It was a throttle body type meaning that it had one injector feeding through a carburetor like unit. As Lee was not very forthcoming with information about his projects the specifics of the system went to the grave with him.
> I'm not sure but I think Paul Knapp of Rimfire spark plugs has this engine either personally or as part of his engine display which is now at the Sherline Craftsmanship Museum.
> ...


Very cool your information... thanks!

Cheers for all,

Alexandre


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## gbritnell (Dec 5, 2011)

Here's a link to the Paul Knapp/Sherline engine display. It has Lee Root's engine with the fuel injector.
gbritnell
http://www.craftsmanshipmuseum.com/images/k104-RootDOHC2.jpg


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## agmachado (Dec 5, 2011)

Yes... very cool... a single point injection... very nice!!!

Thank you George.

Best regards,

Alexandre


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## atheras29 (Dec 5, 2011)

I wonder if this link is gonna help. 

http://www.findsminimodelhotbulbengines.dk/Side1.html

They have some nice small injectors


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## HS93 (Dec 5, 2011)

OS do this engine so the injectors will be avalable as spares.

http://www.ebay.co.uk/itm/ws/eBayISAPI.dll?ViewItem&item=110659657076&ssPageName=STRK:MESELX:IT

Peter


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## HS93 (Dec 6, 2011)

this may help

http://manuals.hobbico.com/osm/fs91-ii-fi-manual.pdf

Peter


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## agmachado (Dec 6, 2011)

HS93  said:
			
		

> this may help
> 
> http://manuals.hobbico.com/osm/fs91-ii-fi-manual.pdf
> 
> Peter


I did not know that it existed... very interesting...

Thank you Peter!

Cheers,

Alexandre


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## mu38&Bg# (Dec 6, 2011)

The OS engine is a solenoid valve arrangement. The tank is pressurized by crankcase pressure through a check valve to less than 9psi. There is a patent for this design where you can read about it. I actually own one of these, but haven't run it. There was a product offered by a company in 1995 or so that used throttle servo position and EGT for feedback to operated a valve and pressurized tank setup.

This does bring up a point. You probably don't need a high pressure fuel system to do what you want. This greatly simplifies the design requirements. You can probably even buy off the shelf pumps and valves to do the job. I'd have to dig through my bookmarks to find the pump and valve components, but they weren't hard to find in internet searches. I've researched various EFI ideas for model airplane engines and there are various systems in existence for small engines, but nothing that can be purchased off the shelf, most of these companies are looking for OEM applications.


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## keith5700 (Dec 7, 2011)

I have seen the OS injection system before, but not read much on how it works. 
If the check valve is 9psi then this is obviously a low pressure type system.
It also looks a bit basic in how it meters the amount of fuel, as it says you may have to trim more fuel in as the daytime temperature increases.
I'm not sure if it uses exhaust gas temp to trim fuel, within itself.

The good bit is that it seems like it would be fairly straightforward to make a simple solenoid valve for the injector.
Full sized ones are quite big, but then they've got to perform for 100k+ miles, and meet emission specs, etc.

Greg, with me wanting to feed 4 ports from one injector I think high fuel pressure would be best, as I reckon I'd need good atomisation to spread around the inlet manifold before the mixture is pulled into the inlets.
I've got 60psi+ in my mind at the moment.
Cheers.


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## Noitoen (Dec 7, 2011)

To get the pressure without a pump system, you could pressurize the fuel tank. Such a small amount of fuel can be pressurized with CO2 and work like a spray can.


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## HS93 (Dec 7, 2011)

Its only like like single point injection that they used on cars some years ago Ford Fiestas in the UK where one single butterfly and I don't even think they had a plenum .

Peter


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