Direct Injection injector options?

[Anonymous]

Going off on a tangent here, but have been thinking a lot lately about fuel injection.

Can anyone tell me what the thinnest diameter injector is that they know of that can flow sufficient amounts of fuel to feed a single cylinder for one of our small sixes? (Length should be an issue, diameter is though.)

Also, is a "mega-squirt" system capable of driving direct cylinder injectors?

I have an idea...

 

[XPC66]

Pencil

Yes

 

[Anonymous]

XPC66:

Do you happen to have a manufacturer name and part # at all?

Really appreciate the help. Trying to work something out that has been bugging me for about a week now. One of those "need to know" things.
I need to know if I should either go forward, or just forget it...

Thanks again!

 

[Bort62]

Direct injection on one of these motors?

Why? Usually I scoff at such "pie in the sky" ideas... but for some reason not right now.

It's sane and accomplishable enough to not get the knee-jerk response, now justify to me (and others) why it would be a significant improvement over port injection (which is a big improvement over carburetion or TBI in the first place)

 

[Anonymous]

Well, from a "novice" stand-point, here's my thought:

Bosch has patented a combination injector / spark plug unit for various undefined engines (2004-2005?). However, the piece is large and cumbersome based on drawings I have seen in my research, and it would cost a fortune to replace at tune-up, as well as take a lot of time.

But, wouldn't it be just as easy to find the smallest injector possible to carry the load of 1 cylinder, and then make an adapter to fit the 13/16" plug hole in a typical small 6 that could house a small injector and a 5/8" plug?
Would prefer to come up with something that could position the plug at top of cylinder (furthest from piston travel area) and then have an injector slightly recessed right below it. That way the "adapter" could be 1-piece machined with both components at about a 45-degree angle from each other (maybe more, maybe less...) and you could thread it into the existing plug hole as a retro-fit item.
To avoid "Custom" component issues, the easiest thing to do is to use the smallest adequate plug acceptable, and the smallest injector housing, and work from there.
Once the component sizing is determined (plug and injector), it would simply be a matter of setting up the ignition and injection controller (MegaSquirt?) to handle the timing of both (initial spark, timing, and advance, as well as injector timing and duration/volume relative to RPM) at the same time.
This would allow you to do a "standard" tune-up without injector removal (and subsequent disconnection from fuel rail, time = money...) without too much more grief than a standard plug change.

Just trying to think out of the box a bit here...

 

[aussie7mains]

Id say put that idea away in the way too hard basket, many oems have tried without succes and from my expeience with diesels and spark ignited gas engines the direct cylinder injection of petrol is very difficult. Just consider how nasty the firing cylinder is, hot turbulent corrosive gas flying about at high pressure. its hard enough with diesel injectors and theyve been around for nearly 100 years. No electronic injector that is currenty available is going to work, BTW pencil injectors are used by the likes of John Deere and they are diesels with jerk type pumps at high pressure that wont work with petrol as the diesel is self lubricating and petrol is not.
Consider what you would drive such an injector with, hydraulics, electromechanical or what?
Exactly what advantages would you expect? you might just as well convert the engine to compression ignition and turbo on diesel fuel and simply supercharge it until the crank falls out under strain.
A7M

 

[XPC66]

Try Hitachi

 

[Anonymous]

aussie7mains:

I actually DID consider compression based ignition. But, the CR would have to be so high that you would need a forged crank and rods, pistons, and main caps, and even that still might not be sufficient on a stock cast block. The good thing is the 7 mains on the 200 and 250, but that's still a lot of grief. Plus, I am aware the injectors would have to be fuel lubricated under the kind of pressure necessary, because it would have to be capable of overcoming cylinder stroke pressure close to TDC, not on the intake stroke. I used to be a heavy line diesel mech at a bus company (MCI-7's, MCI-9's, MCI-10's, Prevost, old GMC 4908's, etc, most had 8V-71's), so I am familiar with diesels and their injectors.

But, all of that gets away from the original thought.
I was just trying to figure out if we could get a properly timed and proportioned fuel delivery directly into the cylinder of one of these old log heads efficiently that could draw into the cylinder on the intake stroke instead. If we could make an adapter and use existing parts I thought it would be reasonably inexpensive, and should certainly be a more evenly proportioned fuel charge than what FoMoCo came up with 48 years ago.
Now, throw a turbo on there to pressurize the air delivery, meter the fuel delivery and timing through a modern computer control system, and wallah!

At least, that was my thought...

 

[Bort62]

Well -

First off I think you are going to be real estate restricted trying to fit an injector AND a spark plug through the existing spark plug hole.

Secondly, the familiar (around here) expression of polishing a turd comes to mind... that is a LOT of work on an old crappy log head.

Lastly, any gains you saw would most likely be more easily accomplished through port injection on the log itself... I do not see direct injection being THAT much better (if at all).

 

[Anonymous]

Bort62;

Thanks for the reply and input.

I know that "real estate" is at a premium, which is why the question in my initial post as in what the thinnest injector possible was. It could be a small one, as it would theoretically only be feeding enough fuel for less than 35 c.i. (assuming an over-bored 200 engine, 1/6th of that load).
The idea being that the 13/16" plug hole could be adapted with a 5/8" plug to the top, and a really small injector coming in at the bottom at an angle (somewhere between 30 to 45 degrees from relative axis of the plug I would assume). Again, a thin injector housing is the only possibility for this idea.

As far as whether the old log head is worth it or not is kind of irrelevant to me in the long run. IF it could be done, I would have to assume that it could be done on almost any engine with a 13/16" plug hole, but ideally you would be able to use this on the AL head or an Aussie head as well.

You're probably right, it may be an effort in futility for minimal gain, and port injection may be the way to go.
It was just something I had bugging me, and I was looking for input. My initial thought was an injector with the plug built into the circumference of the adapter ring, and that would probably be easier from an installation and space stand-point, but the cost of the plug ring in low quantity to be custom produced is prohibitive. It would be a lot more feasible if the adapter were a simple steel adapter with two threaded holes in it, versus a steel ring with a porcelain inner sleeve with imbedded electrodes on it. Plus, I don't think there would be sufficient width for a reasonable porcelain shield from a durability stand point.

Again, just something I was pondering. If it turns out to be unrealistic, then life goes on, but it is a question that my warped little mind requires an answer and closure to. 8)

 

[melavery]

Try looking at benbix. They had direct injection in the big round aircraft engines toward the end of ww2. If I rember correctly it was into the top of the head with the two spark plugs on either side. Supposed to have worked well. It was all mechanical. Those old engines had a cr 6 or 7 to 1. Lots of displacement and hgh boost. Maby look into the older VW injected engines, they had mechanical injection. Maby this will give you some more ideas.


Mel

 

[Jmonty]

There is a prototype injector/ignitor combo that is being used in Hydrogen boosted conversions to inject alternative liquid fuels directly into the combustion chamber while hydrogen is being input thru the intake port via a directed hard line. This injector/ignitor combo device screws into the spark plug hole.

I contacted the guys at http://www.knowledgepublications.com to find out where they could be purchased & unfortunately they are not in production. There is a converted Geo Metro on the site that you can view video of.

I am a machinist whose boss is a mechanical engineer. We offered to sign a nondisclosure agreement & make some but they apparently are either not serious about moving forward or they just want big time investors, not little guys who want to DIY. Perhaps with enough interest they would be willing to get some more made.