my 55lbs lockwood wont start

[Dang911]

Classic L-H fueling calls for the injection point to be somewhere near the interface between the intake tube and the front transition cone.

I am about 0.75" back (down the intake) from that location. I do hate the fuel loss, but I have found the best "smooth" running performance there. When I move the injector into the CC I get rough running, and it is harder to start. The engine will run, but at times it will just shut off. Quite annoying. At my current location, I can start it instantly, and it will run till I shut it off.

And I'm sure that the closed tube will work fine, I just like the bragging rights of saying I have a "solid brass high precision aerodynamic radial cryogenic fuel injector"

[kid jansen]

Because of my job it shouldn't be that hard to find a lathe. And if I can't find one, I can still drill the holes in the tube itself.

Just to straighten things out I made a picture with the current placement of my injector on top, and the way I think dang means below. In my opinion that's a big difference, something like 3.5".
First I had the injector even 2" more into the CC, but then it didn't even sound like it could start.

[kid jansen]

Cant you just drill the holes into a tube like you made the sideways swizzle stick from?

You should be able to pinch the tube closed on the end, and then drill the holes directly into the tube immediately behind the pinched area.

That pinch on the end is surprisingly good, aero-wise. I use it myself.

You mean to just smash one end of the tube flat? Is that a good aerodynamic shape? I think a coneshape like the injector dang used is areaodynamically better, and it looks better too, and I just like making things more difficult than necessary.

[hinote]

You mean to just smash one end of the tube flat? Is that a good aerodynamic shape?

It's not that bad--and certainly has a good effort-to-results ratio.

An easy way to make a bullet-shaped end is to find a bolt shank that will just fit inside the tube; after tacking it into place, just use a grinder or belt sander and finish it to your favorite shape.

[hinote]

Because of my job it shouldn't be that hard to find a lathe. And if I can't find one, I can still drill the holes in the tube itself.

Just to straighten things out I made a picture with the current placement of my injector on top, and the way I think dang means below.

I took your drawing and made some changes, to illustrate my point as follows:

Region 1 is a sure failure.

Region 2 is the location most likely to succeed.

Region 3 is a possibility--but I'm betting on 2.

[Dang911]

Sorry to disagree, but I have done a lot of tweaking, and can confidently proscribe this image to my particular engine. Now I do believe you made the same engine I did, so this should work good for you.

At green easy starting, 100% sustained running.

At yellow I have running consistency problems.

At light red, I have very very hard starting, and only short bursts running/running on forced air.

At dark red, fireballs, no running.

Oh and on your pic above, you nailed exactly where I have my injector, good job!!!

The green region is 1.25" but 1" of it is on the intake, and only 0.25 is into the cone.

[Eric]

Nice job Dang, that diagram is exactly right.

The ranges and sweet spots move around a bit depending on injector type, but the green is typically the epicenter for best running.

With an advanced injector those ranges can be doubled, but the best spot for mixing the fuel remains near the intake transition, where all the incoming air will mix will fuel, and you have the best mixing : blowback ratio.

Too far into the combustion chamber and you get less fuel blowback but greatly reduced mixing. Too far into the intake and you wind up with better mixing but greatly increased blowback. If you exceed either extreme the engine will not run.

Eric

[Jonny69]

This thread has possibly been one of the best on the forum about fuelling techniques. I have to say it pretty much sums up everything about fuelling, injector types and injector placement in one easy to find thread.

Thanks chaps, I'm reading and learning.

[Eric]

Heres one depicting the expanded range of a more advanced injector setup. The advanced injector makes things much more forgiving but the basic range is still the same.

Eric

[Dang911]

Do I classify as advanced fuel injector? What exactly do you mean an advanced injector. Through my tubing, I do have a preheat coil, and there should be some expansion/compression cycles....

While we are on the subject, where is the best place to inject water? And does it need to be in fine mist, or because of the heat, can you pump it in at the end of an open tube?

[Eric]

Dang your system is pretty advanced, the propane should be pretty warm when it gets injected, and mixing seems to be pretty good judging by the easy starting / running.

If you could note any discoloration on the injector tip / copper tube that would help determine the aproximate final injection temperature.

To be what I consider "advanced" it has to have excellent heat absorbtion and excellent mixing, and display an ability to operate over a large throttle range and injector position range. There are several styles that I use that get this done... I am in the process of updating the forum that I made while this one was down, and am going to be posting a lot of stuff tonight hopefully.

Eric

[kid jansen]

The post on Eric's advanced fuelinjector

A picture of it:



A how to make description


But Eric probably has more designs, and I think he can better tell about it himself.

[kid jansen]

I got myself a lathe. Tomorrow 9AM at a 'HBO'. I don't know how to call it in English because I don't know much about foreign schoolsystems, but it is a sort of practical school.

[kid jansen]

I'm a really happy man, the result is truelly amazing. That guy who made it for me is really good, very experienced and skilled.
It's hard to make a good and sharp picture of a so small and shiny thing, especially when you have a crappy camera. But it's really good.
Clothes don't make the man, machinery does!

[Dang911]

Looks pretty sweet, debur the holes though..