Welding AN fittings onto fuel rails, is this OK or dangerous?

**HKS_TRD** · 21-05-2011, 08:41 AM

I have a factory 7M-GTE aluminium fuel rail and at the factory inlet location I have had a -8 male AN nipple welded (ID of nipple is smaller than ID of factory thread) on but I have been told that you shouldnt really weld anything onto a fuel rail? Is this really a big no-no or as long as the weld is decent its fine?

I have attached pics below

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**wilbo666** · 21-05-2011, 11:10 AM

I think the concern is that Aluminum weld can work harden and then crack resulting in fuel spraying inside the engine bay...

Cheers
Wilbo

**jeffro ra28** · 21-05-2011, 12:32 PM

So long as its not a duckshit weld its perfectly reliable and suitable. I would have no doubts to its function.

**HKS_TRD** · 21-05-2011, 09:13 PM

Its done by a shop that does all top shelf fabrication.

Originally I was going to tap the thread so I could run a -8 screw in fitting that retained a constant ID but they welded the nipple on instead. I only got alerted to the prospect of that not being a good idea recently

I could probably carefully remove the nipple and go back to my original plan of tapping the thread, either to M16 with a washer seal on the face or maybe to a -8 AN ORB fitting that seals with an O-ring.

Welding the fitting on was alot neater but I got a lot of hate for it

**Suavemechanic** · 21-05-2011, 10:22 PM

looks sweet ! if you are really worried use a few inches of flexible hose at that join... no vibration .no cracking

**beerhead** · 21-05-2011, 11:53 PM

Good tig welds are almost as strong as the metal they're welded to, the weld doesn't look too bad either, plenty of heat and penetration. A mates supercharged Porsche had a very similar mod to this to link the 2 fuel rails as the charger plumbing fowled with the factory lines. That weld will outlast any rubber line that bolts to it.

**HKS_TRD** · 22-05-2011, 10:16 AM

Originally Posted by Suavemechanic

looks sweet ! if you are really worried use a few inches of flexible hose at that join... no vibration .no cracking

I was planning on running at -8 120 degree hose end and then atleast 6 inches of braided line from there to the new -8 hardline going in the car, so there would be no issues with engine flex etc

Originally Posted by beerhead

Good tig welds are almost as strong as the metal they're welded to, the weld doesn't look too bad either, plenty of heat and penetration. A mates supercharged Porsche had a very similar mod to this to link the 2 fuel rails as the charger plumbing fowled with the factory lines. That weld will outlast any rubber line that bolts to it.

When I polised the rail after the welding I was sure not to rub back the weld or anything and took it easy with the buffing wheel around there, though you can still see the welding lines which is prove I didnt eat anything away.

I am considering cutting the nipple off and then going back to my original plan of tapping the thread (you need to go to a larger than stock thread for the AN adapter to maintain a constant ID) as I suspect the nipple is sitting over the entire washer sealing face so it'd still be intact, or I could go to a -8 ORB thread, though can you get a tap for that? The cold start injector port I had to get tapped to a -6 ORB on a CNC (wasnt cheap) and then screw in the ORB grub screw as there is no fancy bolt available in a M12 metric fine thread :-(

I'm trying to get everything right with the car and not have to muck around with it once its put together this time. So far I've done everything twice during the build but thats my fault for changing my mind on stuff and thats OK before its all put together, but once its actually running I don't want to have any potential issues sitting in the engine bay.

**dnegative** · 22-05-2011, 03:57 PM

It will be fine

**beerhead** · 22-05-2011, 07:09 PM

Don't worry, the biggest potential issue in your engine bay will be your 7M Head gasket

**HKS_TRD** · 22-05-2011, 07:56 PM

lol good point

I have been considering going to a billet dual entry rail if mine was OK and I could sell it. I dont want to sell someone a time bomb

**beerhead** · 22-05-2011, 08:39 PM

If the work was carried out by a legit workshop, and you have the receipt for the work still in your possession then the liability if the part fails is on the person who modified the part.

Dual entry rail is great for big power and even fuel flow under batch fire, but if you're going big injectors and sequential injection there won't be any real world gains from a twin entry rail.

It sounds like you can't be convinced that the rail is sound, so the only way to be 100% sure is if you get it X-rayed to make sure there isn't any hairline cracks in the weld. If the Xray comes back good, I bet that barb will be there in 20 years when that rail is melted down in china as scrap

**1gjet** · 23-05-2011, 06:28 AM

I'm running something very similar with my build, I have been assured that it's fine

**LeeRoy** · 23-05-2011, 01:39 PM

Originally Posted by HKS_TRD

I have a factory 7M-GTE aluminium fuel rail and at the factory inlet location I have had a -8 male AN nipple welded (ID of nipple is smaller than ID of factory thread) on but I have been told that you shouldnt really weld anything onto a fuel rail? Is this really a big no-no or as long as the weld is decent its fine?

I wouldn't worry about it - looks strong enough.

As for the ID, do remember they typically run a banjo bolt, and that would be significantly smaller than the fittings ID.

**George** · 25-05-2011, 12:37 PM

Think the part is ok . My custom steel fuel rail survived 2 years of driving around, it didn't show any cracks etc (was then sold along with the engine). Aluminium welding may crack if different fusions are to be welded together, but qualified welder should be aware of that situation. However you may want to run automatic fire extinguishing system under the hood, just for the case ) They are not that expensive and are quite easily installed.