Make a fuel rail

[siteunseen]

Here's what mine turned out like using his measurments. No CSV or pressure gauge though. Kept it simple on 1st try.

[siteunseen]

And where I messed up was not checking levelness between holes I tapped. The 1st 3 are straight up and down but the last 3 are slightly tilted. Slipped in the vise between the wood. Nobody knows until now.

[Zed Head]

The fins are great for transferring heat from hot to cold. In the engine bay, hot is the engine and cold is the fuel rail. The fins will result in hotter fuel not colder.

Just something to think about.

Considering the recent heat pipe cooling theory by Fastwoman on the hot start problem, fins might actually be the way to go. It's a dilemma, since when the engine is running you'll be taking heat to the fuel tank, but when the engine's stopped, you'll be cooling the injectors. Assuming the theory is in play. More work is needed (this is the statement with which almost all research presentations end).

[siteunseen]

I think fins would help. My go karts had finned heads to catch air.

[black gold man]

Fins would help if the gas was hotter than the engine bay. The fins would transfer heat into the rail.

[FastWoman]

Gold, after you shut down your engine, I think that IS the case, that the engine is hotter than the surrounding air. After fuel flow stops, the injectors and the fuel inside them are probably heated rather quickly to the temp of the cylinder head and underlying exhaust manifold.

On another note, I notice that Blue suggested a two-hole fuel rail design, above, whereby one hole is the supply and the other hole is the return. Although this sounds like a good idea on the surface and certainly neatens the engine bay, it would not be a good idea with respect to cooling the fuel rail with fresh fuel during startup. A two-hole rail would essentially become a countercurrent heat exchanger. Cool fuel entering the rail would be warmed by hot fuel exiting the rail, resulting in a somewhat static heat gradient between #1 (cool) and #6 (hot). If hot fuel is tapped off of the #6 end instead, and returned around the back end of the engine, it does not have the opportunity to transfer heat back to the incoming fuel.

BTW, countercurrent heat exchange is how a duck can go paddling around in ice-cold water with its big, webbed feet and not lose its body heat to the water. Blood flowing to the feet is cooled by returning blood, which is re-warmed before re-entering the rest of the body. The duck's feet are ice cold, and there's very little body heat to be lost. Lessons from nature!

Edited May 4, 2014 by FastWoman

[mjr45]

What about taking 2 -6 D shaped rails and welding them together, using the curved side for the injector ports? Would there be enough metal between the two to offset any "hot" fuel problems? Just wondering, but I suspect the height of the 2 rails would interfere with the throttle linkage.

Edited May 4, 2014 by mjr45

[FastWoman]

With a solid weld? No. There would be very efficient heat conduction through the aluminum. However, you could attach two rails together with a few brackets (perhaps a welded assembly), so that there's mostly air between the two rails. That would work fairly well. Or you could bracket a return tube below the rail.

[TomoHawk]

I still have my factory 1978 fuel rail. It's a little dirty or rusty, and sitting in the parts box.

[FastWoman]

Hey, if anyone's interested, I ran across this water-tight 12-pin electrical connector on ebay that looks like the one I used as a main disconnect for my 6 injectors on my fuel rail:

1 Sets 12 Pin Waterproof Electrical Wire Connector Plug DT04 12P and DT06 12S | eBay

This allowed me to create a fuel rail wiring harness, bound tightly to the rail, with one large pigtail coming off of it to attach to the main EFI harness.