Fuel supply and intake cooling are the key areas to address for getting maximum power out of these engines using 185mm, 61/62mm, or stacked pulleys. This thread is about FUEL SUPPLY.

The OEM returnless fuel rail system is great for reducing evaporative emissions by not returning fuel to the tank that has been warmed by the engine. Not much else is great about it. The pressure regulator is far upstream, in the fuel filter back by the tank. The fuel pressure is regulated there to the factory range of 54-60 psi. The actual pressure at the injectors could be significantly lower during high fuel usage (WOT) due to pressure drop from flow restrictions along the fuel line, through the tiny fuel rail inlet, and through the rail itself.

The looped fuel rails help to balance fuel pressure throughout the fuel rail. But they do nothing to address the tiny fuel rail inlet opening or keep fuel pressure in the rail from dropping during full throttle. The more fuel you are using, with larger fuel injectors or larger pulley ratios, the larger the fuel pressure drop problem from the regulator to the rail will be.

I need something better, so I built the Ultimate Fuel Rail.

I welded a new 8AN inlet fitting to the back of the rail centered on the vee between the left and right sides.

Mattsiphone4pictures537_zpsf9ed7574.jpg

I cutoff the ends of the rail and welded new 8AN outlet fittings.

Mattsiphone4pictures534_zps781c3d16.jpg

The new inlet inner diameter (ID) has 168% MORE AREA than the OEM inlet. This will flow a LOT more fuel into the rail, and maximize the fuel delivery from the fuel injectors. I considered dual inlets, but that is futile unless you need dual pumps and supply lines (alcohol/E85?) and would require buying an extra Y fitting and hose ends for use with a single fuel line.

The dual 8AN outlets will be run to an adjustable fuel pressure regulator with dual inlets. MOST AFPRs have dual inlets, one for each cylinder bank’s fuel rail. The regulated point will be AFTER the fuel rail. This eliminates the dangerous risk of running lean from fuel pressure drop at the rail when the injectors are running at a high duty cycle. It will be a true return-style fuel rail, which is tremendously better for performance and is cheap insurance from running lean and ruining an engine.

I decided to leave the OEM inlet fitting intact for future use (gauge, datalogging, etc.) or to be able to return to a stock configuration by simply installing 3 8AN caps on the new fittings. The OEM inlet fuel line will be plugged.

Mattsiphone4pictures529_zps7bb213f3.jpg

If you want an Ultimate Fuel Rail modification as well, I can modify your fuel rail and ship it back to you. This winter is a great opportunity.
I can do it for $175 plus shipping.

Ultimate Fuel Rail Details:

 

OK.....I will get my rail and take at look at what you did. So with all this new volume you see no need for the loop....or am I missing something...

 

have you mocked this up? an8 fittings tend to hit the recirc valves in front of the line. the biggest i could fit was an an6 with a hard 90* bend pointed down at the bottom of the supercharger.

 

boostmonkey, have you done any real testing and logging? Any pictures of how this fits on the car?


+1. I also switched to an6.

 

Subscribed. And just my $.02, but TIG would be the only way I'd want to have this Mod done.

 

I have -8an inlets and -6an outlets on my rails (stock rail cut in half). A 45deg fitting on the passenger side is perfect, and a short 90deg works on the drivers side. Install the air valves after the fuel rail and you should be fine.

 

Below is my plan for the fittings. I measured everything up and it should fit well.
Mina is in the barn for the winter, so I won't be installing anything until spring.

Ultimatefuelrailfittingsschematic_zpsfe6e63d3.jpg

 

It will cost more than $.02 for you to buy me a TIG, but I'm game.

 

I bought 6AN weld bungs as well, but the 8AN bungs were a better fit for welding to the rail. I am actually going to use 8AN to 6AN reducers for the return lines; my APFR has 6AN inlets. My check valve after the Walbro fuel pump has 8AN fittings, and I will run a 8AN supply line from the check valve to the rail inlet.

 

Those having done this......what's the ID (internal) of
- the rail &
- the fuel line from the tank?

eg: at 8mm ID, line velocity at 200L/hr is 1.2m/s

 

Yes, though it actually will be looped, through the AFPR.

 

matt i hope to save you some hassle but an8 male fitting with a an8 90* fitting WONT fit behind the recirc valve. rememebr i had 3 of these rails on my car from an to an6 using different styles of 90* fittings. the only way there was enough room was to cut the rail at almost the injector hole and tig weld the male fitting. add a 90* after. its a major tight fit. its easier on the pass side if you leave the bend in the rail .

weld away but i dont know of a single fabricator that uses mig on a fuel system. the only way to properly control the heat is to use a tig

something to consider is how my new fuel system will be routed. out of the tank with an8 splitting into 2 lines to the filters then a y to a single an8 to the rails and using 2 rails split again and feed each rail individually. back thru a y into the fpr and a an6 return line to the tank

 

Next thing you guys are going to tell him is to build it out of silver, even it cost 5 grand. Obviously he owns what he owns (MIG), and I don't see people lining up to build these at an affordable price.

I read that some guys are using silver solder on the rails and they hold 100psi. Here's mention of it: Welding a -6AN fitting to a Steel fuel rail??? - Honda-Tech I would think that brazing/soldering would be cost effective if you decide to go a different route.

FSAEUNH.jpg


Whatever you do, don't let it look like this: http://forums.vwvortex.com/showthrea...FI-conversions

fuelrail015.jpg

 

by your theory may as well just use a garden hose to run the fuel. my .02 was tig was what the pros use and who wants fuel to leak at the injector? i know matt has a mig and from looking at the welds he has miles to go before i would trust the welds to hold. again this is just my .02 and i think matt is an awesome wrench

 

I machined steel fittings to press in the ends and used silver solder.

 

I can't believe that actually works lol. That's crazy. It makes sense though, the melting temp would be pretty high and it would be pretty damn strong...

 

It's nothing new.

 

Hmm, learn somethin new everyday.

 

It's a heck of a lot quicker and cleaner than welding IMHO.

 

Oh yeah, easier, faster. Since I solder all the time all that stuff is ready to go, so for people like me there would be no setup time. I agree that it would be cleaner too.

I think the propane torch would be overkill, I would probably just use the little butane torch that's on my soldering iron but that is a damn good way to come up with modifying the rail cheap and clean.