Flow characteristics of banjo type fittings

[F1 Rocket]

Does anyone know how the flow characteristics of a banjo fitting compares to let?s say a 90? AN type fitting?

[bjdecker]

Depending upon the clocking of the banjo fitting, you can expect less flow than through an AN822 or hose 90?. If you clock the banjo fitting correctly, it should be about the same.

I tried this when I was playing around with an Andair fuel valve and seeing which fittings flowed the best and would fit in the space provided in the RV-7.

Cheers!

B

[F1 Rocket]

Originally Posted by bjdecker

I tried this when I was playing around with an Andair fuel valve and seeing which fittings flowed the best and would fit in the space provided in the RV-7.

Cheers!

B

I?m looking to improve the flow through my Andair fuel valve. What I have now are the Andair low profile 90? fittings. I have a feeling these are fairly restrictive. There?s no room in my current install for a straight fitting with a hose 90 or an AN 90. A banjo would ?just? fit.

[bjdecker]

I ended up using the 90? fittings from Andair.

I liked the flexibility of the banjo fittings, but I encountered fairly significant restriction to airflow when installed in the unit -- take them apart and you can see why.

However, if you can tighten/clock the Banjo NPT fitting just enough and line up the holes inside the banjo fitting to the AN side, you should be good to go.

Good luck!

[JonJay]

Helpful hint to get Banjo fittings to seal better. Anneal the copper washers (seals). I have had issues with the copper washers being too hard and taking too much grunt to get them to seal. After annealing, you can feel the difference as you tighten the fitting. If they are not annealed properly, or have aged, they feel smooth. After annealing, they feel "rough", or like they "bite" as you tighten.
Makes a big difference.

[Dustyone]

If you plan to use unleaded fuel in the future, avoid the banjo fittings.
I have them in my -10 and my aux tanks will always have cavitation when using unleaded. If I use Avgas in the same tanks, there is no problem.
My thoughts are that they add one too many directional changes with the unleaded fuel.

I have ordered the 90 degree fittings from Andair to replace them.

[TS Flightlines]

Danny---we use the Andair EF20 elbows on our Duplex installs for SDS/EFii systems. Mainly for the tight clearances around the valves. NO flow issues.

Tom

[F1 Rocket]

Tom,
I have the EF20 fittings on the inlets of the valve. I’ve always had a fuel pressure issue at altitude. Especially on hot days. What happens is the fuel pressure will fluctuate 5 to 10 psi unless I run the boost pump. Engine always runs great but it bugs me that it does this. Don at Airflow Performance thinks there’s too much restriction on the suction side and suggested I get rid of any 90° fittings on the suction side of the fuel system I replumbed everything up to the fuel valve with a set of your excellent hoses late last year. This eliminated a couple of standard AN 90’s. The only 90’s left are the EF20’s. I was hoping the banjos would be a better solution but it looks like that’s not the case.

[bjdecker]

Danny,

Where/how are you measuring the fuel pressure?

I saw a similar behavior that was rectified by changing the length of the hose running from the fuel pump to the transducer.

[F1 Rocket]

Fuel pressure is from the outlet of the mechanical pump. It?s typically not an issue unless I?m above 9000?. Then it will start fluctuating. Pressure is rock steady once I turn on the boost pump.