Fuel line to AN fitting size

[redfogo]

Does anyone know what size the fuel lines are? I am looking at using PTFE fuel lines so I will need to convert my fuel system to all AN fittings. Are the fuel lines 3/8th or are they smaller. Seems everyone sells 3/8th size to -an6 but want to make sure before I buy a bunch.

I am wanting to get these as they seem like the most secure type of fitting. http://www.summitracing.com/parts/rus-644123

[Mechie3]

I like to use getfast1.com for my fittings. Made in USA, less expensive that most name brand. -6 is a good size.

[redfogo]

I like to use getfast1.com for my fittings. Made in USA, less expensive that most name brand. -6 is a good size.

Thanks for the link I will check them out. Are you using 3/8th to -an6 fittings on the OEM fuel lines on the fuel pump assembly and engine hard lines? Or are the OEM lines smaller?

[russelljones48]

Line size depends on the fuel requirements for the engine you're using. That said my Coyote will use AN6 (3/8) line for both supply and return. I am using Ford connector to AN on the tank and on the engine - available from several sites and vendors..

[Rasmus]

I like to use getfast1.com for my fittings. Made in USA, less expensive that most name brand. -6 is a good size.
Bookmarking that! Thanks Mech.

[redfogo]

Line size depends on the fuel requirements for the engine you're using. That said my Coyote will use AN6 (3/8) line for both supply and return. I am using Ford connector to AN on the tank and on the engine - available from several sites and vendors..

I am asking what size the OEM hard lines are so I can run the correct adapter to convert them to an AN fittings though.

[Rasmus]

OEM fuel hard line on the manifold are .310" Outer Diameter. If the wall thickness was .030" (~1/32") the I.D. would be .250" exactly. AN4 would seem to be a better choice to match the OEM I.D.

[Rasmus]

Yep
http://i.imgur.com/TM6Cnej.jpg
AN4

[redfogo]

OEM fuel hard line on the manifold are .310" Outer Diameter. If the wall thickness was .030" (~1/32") the I.D. would be .250" exactly. AN4 would seem to be a better choice to match the OEM I.D.

Awesome thanks sounds like I will need 5/16 fitting to AN or swap to larger piping then. Thanks for the help.

[Mechie3]

What exactly are you doing? OEM fuel rails, just AN fittings up to the quick release ports?

I'm using -8AN on my stuff. No reason except when I bought the parts for my WRX (used, but new) they had all -8AN fittings. To save money (in the short run) I just went -8. Waaaay overkill, but doesn't really hurt anything except the wallet (and it's harder to pack -8AN fittings next to the AVCS solenoids).

[Bob_n_Cincy]

Does anyone know what size the fuel lines are? I am looking at using PTFE fuel lines so I will need to convert my fuel system to all AN fittings. Are the fuel lines 3/8th or are they smaller. Seems everyone sells 3/8th size to -an6 but want to make sure before I buy a bunch.
I am wanting to get these as they seem like the most secure type of fitting. http://www.summitracing.com/parts/rus-644123

I used the RUS-644113 fitting to attach to the engine and my Subaru pump assembly.
5/16 quick connect to -6 AN fitting.

53574

53575

On another note:
I bought the Sum-220985 PTFE hose and the SUM-220141 PTFE fittings.

Read the reviews on this fitting. They were very difficult to install onto the hose. I sent it all back.
Bob

[redfogo]

I used the RUS-644113 fitting to attach to the engine and my Subaru pump assembly.
5/16 quick connect to -6 AN fitting.

53574

53575

On another note:
I bought the Sum-220985 PTFE hose and the SUM-220141 PTFE fittings.

Read the reviews on this fitting. They were very difficult to install onto the hose. I sent it all back.
Bob

Yep I was looking at RUS-644113. I was planning on those fittings and then buying premade PTFE line from ANplumbing.com. I rather get ones that are crimped assembly similar to SS brake lines. I just want them to be very secure. https://www.anplumbing.com/extras/premade-6-hose.html

I have tried the ones you were talking about from summit and I also had troubles getting a good seal in the past.

[Hindsight]

I used ptfe braided line and various -6AN fittings on mine. Pics in build thread. I think pump output was 3/8 for feed and vent, and return was 1/4" but i could be wrong. Have nit had leaking issues yet.

[Rasmus]

I'm using -8AN on my stuff.
Nitromethane here you come! No longer do you need to rely on that Hello Kitty turbo and air pressure to push air into your engine. Just pump oxygen in molecularly bonded to the fuel and your set!

MPG?: Maybe!

[Loring]

I'm running -8 feed and -6 return. 'cuz e85.

[tirod]

The OP is making a good decision to use fuel rated PTFE line. Typically AN hose is underrated for modern fuels now.

Preassembled crimped fittings from vendors are a standard for reliability. That and the responsibility for the connection falls on the one who made it. In Life Safety considerations the AN fittings are less so - as they are user assembled. The track record here on Roadsters is tarnished because they have contributed to fires.

AN is a standard in hot rodding because it was sold off as surplus post WWII in Southern California when large aircraft plants shut down. One of it's main features is that it can be hand assembled by a technician anywhere the equipment is, in nearly any conditions, which works well if you are in, say, Burma on a grass airstrip on the long end of a military supply chain that can't and won't have a crimping machine or the power available to run it. Hand assembly is a good asset - the drawback is hand assembly involves the risk of doing it wrong, too. In DOD you have to be trained and certified to do it, with the operation documented. If something falls out of the sky and it costs the taxpayers millions of dollars, it's carefully researched to find out why.

We just read posts on the car burning to the ground and move on. The insurance company is the one to say who's at fault and makes a decision. AN works - if properly assembled by knowledgeable users. When improperly assembled it's risky and one of the reasons why no auto maker uses it on production cars - along with cost. A crimp fitting does it cheaper and safer.

In previous discussions there are those who have built cars using other methods and it's based on the idea that automotives run hard lines secured to the chassis to transport fluids with flexible hose limited to the few places where it's needed - in this case, fuel tank and engine. If AN is the goal then that's up to the builder, the important issue is to be fully informed to make a considered opinion knowing all the facts. Nobody should gloss over safety when the result is fire being fed by an accelerant under pressure.

[Bob_n_Cincy]

Yep I was looking at RUS-644113. I was planning on those fittings and then buying premade PTFE line from ANplumbing.com. I rather get ones that are crimped assembly similar to SS brake lines. I just want them to be very secure. https://www.anplumbing.com/extras/premade-6-hose.html

I have tried the ones you were talking about from summit and I also had troubles getting a good seal in the past.


Redfogo,
The pressure line coming out of a Subaru pump assembly and the fuel connections at the engine use a 5/16 OD tube that has a ridge in the metal about 3/4" from the end.
See this picture.
53942

Here is a picture of the RUS-644113 fitting.
53943

The body of the part has an O ring in it. Slide it over the end of the tube as far as possible.

Then put the slotted bushing on the tube and screw it into the body of the fitting.
The ridge of the tube will be trapped in the fitting.

Let me know if this all makes sense.
Bob

[Hindsight]

Those are what I used and they have worked great so far.

[redfogo]

Redfogo,
The pressure line coming out of a Subaru pump assembly and the fuel connections at the engine use a 5/16 OD tube that has a ridge in the metal about 3/4" from the end.
See this picture.
53942

Here is a picture of the RUS-644113 fitting.
53943

The body of the part has an O ring in it. Slide it over the end of the tube as far as possible.

Then put the slotted bushing on the tube and screw it into the body of the fitting.
The ridge of the tube will be trapped in the fitting.

Let me know if this all makes sense.
Bob

Thanks Bob_n_Cincy, I found out that that I received a badly machined fitting it was slightly smaller then the other 5/16th fitting. I found another one and it fit correctly!

[mikeinatlanta]

To be clear:
AN refers to the 37 degree flared area where the two connectors or tube interface. It does not refer to the method by which the connector interfaces with the hose. AN connectors have many different hose connecter interface designs including crimped. Issues with leakage are most often caused by improper assembly or using a hose that is not compatible with the specific connector. While all AN is supposed to be interchangeable, the hose and connectors are not. You cannot mix and match hoses and connectors just because they are both AN. You can mix and match brands at the fitting or tube interface. In other words: You can put a Earls 90 elbow on an Aeroquip hose connector, but you must use Earl's hose on an Earls connector.

I have bought same brand connectors and hose (Fragola) from Summit that were most definitely not compatible, so even when using same brand you must be very careful that the hose and connector are compatible.

[Scargo]

I would like to add my experience to this discussion and perhaps it will help someone or clear the confusion a bit.
FPR's (fuel pressure regulators) that come on Subarus are good for more horsepower than most anyone will want to make. You have to get above about 360HP, at the rear wheels before you need to go to a better, more accurate, way of controlling the increase in volume of gas needed. I am talking 93 octane pump gas.
I'm not going to discuss the needs of those running E85 fuel. The only reason to run E85 would be if you want over 400WHP and more torque than 93 octane can deliver. It's basically not worth discussing here because of the power to weight ratio of the car. Most people cannot justify that HP (and mods required) because stock WRX drivetrain parts will break. Given that caveat, I will continue.
It doesn't hurt to upgrade to a good FPR. Put a liquid-filled gauge on it so it doesn't rapidly vibrate to death. Aftermarket, top mount, fuel rails are nice and, when you are making a fair amount of power the stock rails have been thought to cause a lean condition on one or more cylinders because of their routing.
I like Boomba's.
63063
They are quality and they are only $150! They use AN ORB fittings (with o-rings) and they come with a fuel distribution block. Do not get cheap rails with nipples made into the rail or pipe threads for barbs. You will then be using hose clamps and have a greater risk of leaks. I've seen Perrin's of this style leak.
Other fuel rails have an ORB fitting on each end, like Cosworth's, but I have one issue with this style: one end is very near the turbo. That end and the line coming off will be warmer than the rest of the areas. That line, however, can be insulated/shielded.
You do not need more than -6 AN hose. You can make well over 400 WHP with -6, which is 5/16" nominal ID. AN fittings I've measured are .295" to .310" ID. The steel supply line on my STi is 8mm OD. You end up with a nominal .270" ID. We know from experience that you do not need to upgrade the feed line in an STi unless you run E85 and/or are making 600 CHP. So, -8 AN hose and fittings are excessive.

I suggest you do not cheap-out on fuel line and fittings. Chinese fittings are out there and there is fuel-resistant hose without a PTFE (teflon) lining but then you are living dangerously. I use stainless steel braided, -6 AN, PTFE hose and use Aeroquip or Russell fittings. Hoses need to be sized according to the hose end fittings used. Russell's and Earl's (Holley) can take a larger OD hose than Aeroquip. OTOH, Aeroquip hose ends can deal better with a larger ID hose than a Russell hose end. Summit is quite good about listing the ID and OD of their selection of hoses. Also, if you stick with Aeroquip fittings and Aeroquip hoses you can't go wrong! Russell hose is not rated for as much pressure as Aeroquip or Summit's braided hose. As a side note, I don't think I have ever used anything "Earl's" and from looking at their hose-end options, I doubt I will.

The dampers are an important part of the injection/fuelling system. They smooth out pulse frequencies or harmonics that can cause a low pressure or resultant, lean condition at the injector if the firing of the injector coincides with the low pressure wave. This is usually an issue seen at lower RPMs. I had one stock damper on my 500 CHP engine, where I used 1000cc Injector Dynamics injectors, and it ran fine. I left dampers off my next "big" motor with ID 1300's and it was rough running, or unstable AFR's, between idle and 3K RPMs.

Please ask me anything and understand that this is my experience with these products. I've only done a couple of iterations of engines with these parts and am working on my third. However, I feel I have read what many have done and experienced and am fairly selective (anal) about things like this.
Glyn

[SixStar]

AN is an outside measure of the tubing/hose in 1/16th of an inch increments.

I'm asked daily what size fuel line we use for our -6AN fuel line kits and they never realize they already know the answer. -6 is 6/16th of an inch, so 3/8th. -8 would be 8/16th or 1/2" and so on.

Some more information - https://en.wikipedia.org/wiki/AN_thread