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Discussion Starter #1
Hi All:

Did some searching but didn’t find anything relevant. Which will flow better, the 45-degree fitting or adapter?

I’m plumbing a smallish (120gph) pusher fuel pump just after the tank, and I don’t have room for a straight shot into the pump, but a 45-degree AN fitting will work.

-8 and 3/8 hose to 3/8 metal lines...

Thanks!


102081
 

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I do not have the facts or anything to back it up but for as long as I can remember the style on the left was always deemed superior. This may have been because a name brand fitting like that back in the day was near $20 each. The style on the right had been around for ages used in all sorts of industrial plumbing and could be had for 1/2 or less than the other piece.
Notice I said STYLE not that specific piece.
 

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Zero difference. Steve Johnson from Induction Solutions did a test. He's got a video out of it. Flow test with cheap 90's and other fittings. NO change...
 

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Zero difference. Steve Johnson from Induction Solutions did a test. He's got a video out of it. Flow test with cheap 90's and other fittings. NO change...
I agree. I saw the same test. I always thought radiused fittings flowed better. Also the fittings Steve used, I believe, were 90 degree comparison. Both flowed the same.

TS1955
 

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I'd pay closer attention to the hose ends themselves. I have a pre-made -8 hose, and the ends have a smaller ID than a typical -6 hose end. I also had some -6 hose ends that had an ID closer to a -4.
 

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Depends on the liquid and amount of flow.
 

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Zero difference. Steve Johnson from Induction Solutions did a test. He's got a video out of it. Flow test with cheap 90's and other fittings. NO change...
This! Good video. Clear as day. No change
 

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I think this is the video:


Fun test.
 
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That video has restricted flow. Would like to see it compared to full flow.
 

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Yes. The hose is so oversized I the restriction is the small hole obviously...

the question is which flows better. The tub style A/N fitting design was brought to racing from the aircraft industry. They have been tested to death and the radius tube style exists for a very good reason. Also, fluid dynamics speaks to radius vs angle fittings.
 

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500 pph is about 1.6gpm which is not a lot of flow. The vid does show that at these “low” flows, being OCD on fittings is not going to reap measurable benefits.

Turn the pressure up to 1 or 2000 psi and up the flow to 40 or 50 gpm and pressure drops for mitered 90* fittings is measurable and needs to be accounted for. Not many drag cars have hydraulic systems like this so it’s just the usual example where it could matter for the OP.
 

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So it seems that everyone refuting the video is talking top fuel level fuel systems, where the video is showing a realistic street strip style carbureted/fuel injected system
 

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Discussion Starter #16
@carlb - thanks for the vid, I spent some time searching his site and YouTube but came up empty. And thanks everyone for the continuing discussion. I've always created lines under the idea that straighter is better and have been able to keep to it for the most part. This was a situation where I second guessed myself since it is the non-pressure side of the pump. I appreciate the knowledge and expertise here!
 

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Depends on the liquid and amount of flow.
What he said.

Years ago I was plumbing a fuel system using Mallory 140 pumps with -8 lines and an assortment of fittings. I had a large glass jar and a stopwatch to test the fitting flow. For the most part there was very little difference running to the 1/2 gallon or 1 gallon fill line with fitting like that. I can sure tell you though, back then some of the producers sure choked down their fittings more than others. You might as well been using -6 lines with a couple of them.
 

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I had a large glass jar and a stopwatch to test the fitting flow.
I'm not saying it didn't happen but the stopwatch is not going to be accurate.

Edit: Let me rephrase you will not be consistent or accurate with said stopwatch.
 

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I'm not saying it didn't happen but the stopwatch is not going to be accurate.

Edit: Let me rephrase you will not be consistent or accurate with said stopwatch.
I don't know exactly what you are trying to say but I've done fuel flow tests as described many times and it was repeatable. The test as described will be MORE than adequate to show any problems. Tests like this aren't exact but you only need enough accuracy to show a potential problem.
 
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