PVC Fuel return rails

So the school I go to I'm in a few of the different CAM classes that they offer. Since being in the classes I've doinked around with the idea of seeing of I could CNC machine some fuel return rails; much like the ones that R and D IDI have for sale. The biggest thing is that they would be made out of 1/2 PVC sheets. Knowing that the original caps are .800 inches tall but after measuring the injectors I think that I could get away with a half inch. Worse comes to worst I can source some 1 inch PVC. I have been also testing the properties of this PVC too,(see pictures below) seeing if it could even be used. So far so good. It looks like its gonna work.


I already know that the holes should be .610 of and inch in diameter for the injectors. My question to you guys is does someone have the exact measurements in between the injectors.This saves me the hassle of taking off my injections lines to measure the distance between the injectors. So any help or advice would be much appreciated, Thanks, Matt

Before you continue with this...

Cut a short piece of pvc pipe.

Lay that on your engine. Lay it between the injectors and the valve cover if you wish.

Drive around until your engine is as hot as it ever gets.

Now while still hot, inspect your piece of PVC pipe...

Selahdoor said:

Before you continue with this...

Cut a short piece of pvc pipe.

Lay that on your engine. Lay it between the injectors and the valve cover if you wish.

Drive around until your engine is as hot as it ever gets.

Now while still hot, inspect your piece of PVC pipe...

Click to expand...

https://www.engineeringtoolbox.com/plastic-pipes-operating-pressure-d_1621.html

Only good to 100 F

Add in an injector that is stuck open....

Put it under a couple lbs of pressure too. I have a story about a plastic pipe, a Fiat, the US border, picking up the car for a dealer and ending up in secondary inspection with a tax bill and no money.

Good project. Probably not the best material. CPVC would be better but then you've got the CoE of most plastics to worry about. Polysulfone might work and it's translucent.

I’ve measured outlet temps from the injection pump above 280*

UPDATE Against all of your advice and warnings I have gone ahead and done it. I know it might not work and its gonna get too hot. But I've tested it in the engine and it seems to take the heat and diesel so I'll post how it turns out.

Good for you, taking the chance! That's how we learn.

I would suggest you don't take any long trips.

Or if you do, be fully prepared with all the parts, to put the correct caps and hoses on, on the side of the road...

Why not source something better while you have access to that awesome tool? Delrin?

He's 16. I'd imagine budget, and whatever was offered for free has some part in his choice of materials.

I probably will but Delrin ain't cheap and I'm kinda broke since I work a mowing job and its the off season, I'll see how these work then when the money comes in I can just buy the Delrin and cut it out. These are Prototype 1.

Delrin is only going to take you to about 200* at best.

Be sure to keep all your design files, you never know when they’ll come in handy one day. That much at least is your intellectual work and could useful or valuable to someone wanting to follow in your steps or to you when at some point in the future you have access to better materials.

Definitely kept your design file. I would say if everything fits on your prototype setup then forget the plastics, and the router table setup your using should be capable of working with aluminum (may have to buy a couple specific milling bits) but them your playing with a Final product that you can depend on. And it is still easy to work with.