Offshoreonly.com - 3/8" fuel line feeding a whippled 454?

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My point as well . In addition to 3/8 inch lines you have to take into account the bends and elbows check valves and partially clogged filters etc. Thats what I mean by what I was saying. I just shot 4500 fixing my motor due to a lean condition. You dont want that. Once you start tearing into it you will see that its not that bad. Greg

600 H.p. Will Need .83gpm At Wot.the S-x Pump Will Do This All Day.but I Repete My Self,if You Do Not Want Any Problems Increase The Fuel Line To At Least 1/2". You Can Run A Return Back To Tank Fill Line If You Do Not Have A Extra Port In Tank.

Quote:

Originally Posted by mrhorsepower1 (Post 2107810)

:eek: Sprag, Let me get this straight........3/8 ID fuel line out of the tank?!? You would never catch one of my engines on it.....It would never support a True 750 HP engine. The only way you may be getting away with this is the carbs are way rich. I have had more "B" and "A" class race engines out on the circuit than anyone and all of them made over 750 HP, all delivered fuel with 1/2" pickup tubes and hose. Theoretical BS does not always work in the real world. You can have pressure at the carb, but not have enough volume to it. The fuel pressure should NEVER drop if the fuel system is correct.

Question: mine is 600hp dynoed, carbs are 1050 dominators,fuel pumps are holley mechanicals 130 gph 1/2 inch.mercury water seperator, original pick up in the tank with anti siphon valve knocked out of it. 1/2 in line from tank to seperator,thru seperator which is not 1/2 inch, 1/2 from seperator there on. Mechanical fuel pressure read from the back of the carb is always 6 to 6.5 lbs. Have been told that this is fine but the pickup in the tank and the seperator has always been a question in my mind. Any comments or personal experiences would be appreciated. Bruce/boatman302

Dean,
I agree that if it is easy to re-rig, use 1/2" lines...no concerns. All I am saying is my system has always been -6 hose from the tank to the fuel/water separators and then a combination of -10 from the fuel/water separator to the CV fuel pump and then -8 from the FP to the log style carb manifold. My long term experience including racing is that this system will support 750+ HP and does not go lean.
I have always run PV's and do believe in setting up the fuel system to be slightly rich at WOT. Last year we set up bungs in some new tail pipes so we could check the air/fuel ratio with the Innovate Motor Sports system in the boat under load. With 1150 CFM 7320's, the jets and air bleeds combination was set to hold at 13.7 to 1 to about 5500 RPM when the front and rear PV's opened. From 5500-6800 RPM the A/F ratio drops to 12.6 to 1 and holds steady.
This might not look safe to some, but it works in my set up.

So, if you have a twin application 650 hp & under & one 3/8 pickup per engine on a supercharged efi setup you would/should be ok with that to the fuel filter?
I have that setup with the return plumbed back to the filter. Everything on the feed side from the fuel filter to the pump is -8 with -6 for the return to the filter. The filter is the stock mercruiser stuff with larger filters.

I don't think you will have an issue, but I wouldn't run any HP application w/o a fuel pressure gauge near the carb. To test your system, set up a simple temporary gauge taped to your seat.
If you can hold FP at WOT, you are good to go...

boatman302
I have some drilled out merc seperators(to 3/8 npt) , drilled out fittings too(1/2 hose to 3/8 npt) ...you can have them for a paint job fix later ;)