I have a question regard fuel flow rates as affected by fuel supply plumbing. I’m in the process of installing a supercharger on my 496 HO. It’s a complete rebuild with appropriate internals.
It was recommended that any 3/8” fuel line from the tank be replaced, and any restrictions like check valves or screens be removed. What was not specifically addressed was the fuel tank fitting and pickup. As would be my luck, these are in fact all 3/8”. I’m looking for feedback on what others have done and or any issues. Obviously the easiest thing to do is simply replace the line from the tank fitting to the filter. What I have not yet determined is the difficulty in changing the pickup tube to 1/2”. I suspect it’s likely possible with out changing the tank fitting, which is really at the heart of my question. From what I’ve read, it is an involved modification to change to a 1/2” fitting at the tank. From the little I understand about fluid dynamics, hoses, and fitting, the ID and hose lengths effect flow rates. I believe, if I’m correct, that a single 3/8” fitting in a 1/2” system would have minimal impact on flow, and that even leaving the 3/8” pickup installed might still render enough flow increase considering the line from the tank is now 1/2”. Opinions or advice are appreciated.

2007 Baja 26 Outlaw 496HO

If you're worried, contact Eddie Young - he can make the pickup for you.

I'm setting up mine similar to how you've described though I'm in the 600 HP range, NA. Supercharged is another story. At minimum, you might want to remove the anti-siphon at the tank fitting. Looking at parts diagrams - Merc's SCi engines use 3/8 lines to the fuel rail.

I'm sure someone with more knowledge will chime in. You might want to include a little more information regarding the supercharger, dyno results, etc.

TZ

Yeah, I ran into this with my 496/600's. It was either Teague or CP Performance that makes custom 1/2 stainless thin wall pick-ups with the smaller fitting. Its 100% available! I ran 1/2 braided AN throughout and 3/8 braided AN returns. Then make sure you or the person rigging it runs the adequate pickup and return lines. Get the BIG NAPA marine screw on fuel separator mount fitting & can mounted down low. I opted for all Aeromotive fuel pump and regulator, Mount the fuel pump down low on the stringer as well. Set the adequate fuel regulator settings and set her up with an O2 meter and tune.

Thanks for the feedback. Dyno results TBD. Last week we were still waiting on pistons. You hear all the talk about long lead times on outboards, but parts don’t seem much better.

I’m going to reach out to the contacts provided and hopefully have a solid fuel supply system. The supercharger horror stories I’ve read all seem related to detonation issues and weak internals. I’m working to identify all the potential weak links in the system, as much as possible, and mitigate them. Whipple seems to have a great package, and includes the new fuel pump, filter, and regulator.

I waited for pistons a few months not long ago. I ran into the same questions when I upgraded a 502 to a 540. I left in my factory pickup. I replaced the anti siphon valve with a quarter turn shut off fitting. Half inch fuel hose from that fitting to an FST fuel water separator. I am running a carb setup now and went with a Weldon A600 fuel pump after the separator. I am also running a Weldon return regulator and 3/8 line back to the fuel fill.

Thank you so much for the detailed feed back and photo. For sure I’m get the fitting changed to remove rectrictions

I did the same on my 242 with a blown 454. No issues doing it that way.