switching to efi
3/24/22, 08:39 AM
#1
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switching to efi
65 427 sb. I have two options for switching the fuel system to efi. Holley efi fuel tank module #12-305 or Spectra Premium fuel pump and sender assembly #SP169A1H. The only difference between the two seems to be the Holley has no return line and the Spectra does. I don't want to do this twice. Anyone with an opinion would be helpful.
3/25/22, 10:30 AM
#2
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Welcome to the forums!
I found this article which may help a little.
https://www.onallcylinders.com/2017/...m-right-video/
Cliff Notes: The disadvantage of the return system is the pressure regulator, the extra line, the emissions that might come from all that extra plumbing, and the fuel pump runs all the time which may reduce its life. The returnless system is pressure modulated by the ECU/PCM, has one less fuel line, has less complication, and the pump and regulator are in tank (usually), where the return system has the regulator at the engine for the return line.
Returnless systems, at least for the manufacturers of automobiles, will mean a cheaper, easier system. For a restomod? That's... debatable for sure, for lots of times what seems cheaper isn't at the end. Gotchas abound.
Me? I'd look into the returnless, but I have no idea if the returnless module will go in whatever tank you're gonna need/use. But if it does, then the supply is already run to the engine, and after you get the module in the tank and wired up, tada, you're done! If it won't go in the tank, then you're running a return line as you'll need to go with the return system. Not the most difficult thing. Putting the regulator somewhere is probably the most agonizing part of the setup.
But...
This has me thinking... 
If a returnless system is "just" the regulator's in the module and either dumps fuel back in the tank before it ever leaves, or keeps it from escaping through the pump, either way... then there's nothing (I don't think) saying you *have* to run a return from the engine in a return system. You could put the regulator somewhere near the tank/pump and have a nice lil' return line straight back to the tank. Same exact principle as the returnless, less line to run...
Naw, that's silliness. Don't listen to me. (I'm totally doing this if needed though.
) (Unless I'm not, but IDK, it'd be a cool trick to do and I'd lean towards it anyway... Because I fly on a pig, of course. 
)
Hope that helps, just my musings on it. Pressure's pressure, pumps are pumps, regulators are regulators, all that jazz. Mostly a difference in where what is/how it's controlled, but at the end, the engine's injectors are still needing the pressure and flow, regardless of how it's delivered and the packaging thereto.
Good luck with it!
I found this article which may help a little.
https://www.onallcylinders.com/2017/...m-right-video/
Cliff Notes: The disadvantage of the return system is the pressure regulator, the extra line, the emissions that might come from all that extra plumbing, and the fuel pump runs all the time which may reduce its life. The returnless system is pressure modulated by the ECU/PCM, has one less fuel line, has less complication, and the pump and regulator are in tank (usually), where the return system has the regulator at the engine for the return line.
Returnless systems, at least for the manufacturers of automobiles, will mean a cheaper, easier system. For a restomod? That's... debatable for sure, for lots of times what seems cheaper isn't at the end. Gotchas abound.
Me? I'd look into the returnless, but I have no idea if the returnless module will go in whatever tank you're gonna need/use. But if it does, then the supply is already run to the engine, and after you get the module in the tank and wired up, tada, you're done! If it won't go in the tank, then you're running a return line as you'll need to go with the return system. Not the most difficult thing. Putting the regulator somewhere is probably the most agonizing part of the setup.
But...
This has me thinking... If a returnless system is "just" the regulator's in the module and either dumps fuel back in the tank before it ever leaves, or keeps it from escaping through the pump, either way... then there's nothing (I don't think) saying you *have* to run a return from the engine in a return system. You could put the regulator somewhere near the tank/pump and have a nice lil' return line straight back to the tank. Same exact principle as the returnless, less line to run...
Naw, that's silliness. Don't listen to me. (I'm totally doing this if needed though.
) (Unless I'm not, but IDK, it'd be a cool trick to do and I'd lean towards it anyway... Because I fly on a pig, of course. )Hope that helps, just my musings on it. Pressure's pressure, pumps are pumps, regulators are regulators, all that jazz. Mostly a difference in where what is/how it's controlled, but at the end, the engine's injectors are still needing the pressure and flow, regardless of how it's delivered and the packaging thereto.
Good luck with it!
Last edited by houtex; 3/25/22 at 10:33 AM.
3/25/22, 04:12 PM
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I have sent a request to Holley asking how their pump returns the fuel and whether the pump runs constantly. The Sniper efi has a built in pressure regulator. These two systems are identical with the same pump, but somehow Holley has some way of returning the fuel. I have two concerns, first is the longevity of the return setup and if the pump still runs constantly.