Dear Jim, I don't yet know if I'll ever buy a coach, but before I do I was to understand these things as much as I can and understand how much I''m going to be able to do to maintain a coach. 77-year old ladies have to be careful about stuff like this. Thanks for all your comments & advice; you put things in simple, easy to understand terms and you don't overwhelm mr with technical jargon I wouldn't understand anyway. Good job, well done. Keep it up.
Thanks Jim. I am comfortable working with Qjets but you have given me a reason to consider going to fuel injection. I like the idea of monitoring the sensors that a computer can display.
Hi Jim. I have a Bosch FI system in my 1989 Porsche and a 1995 GM FI system in my GMC. Both systems learn and adjust to try and maintain stochiometric combustion when in closed loop, just like the FiTech. I'm not sure I understood the part about fuel injection adding pressure to the air/fuel mixture entering the combustion chamber. Does that decrease the manifold vacuum then? By how much?
Bill: I don’t think Jim said that the air/fuel mix was pressurized as it enters the intake manifold, but instead that the fuel is pressurized when it enters the injectors, and the pressure of the fuel as it passes through the injectors atomizes the fuel better and finer than the Venturi inside the carburetor. Once atomized and mixed with air, the mixture is at the same atmospheric pressure than the output of a carb. Pretty sure that remains the same.
@@tiagosoromenho1868 Ah.. that makes more sense. I can see that the atomized ethanol fuel particles turn to vapor sooner after leaving the injector than non-ethanol , since the vapor pressure of ethanol fuel is less - but I would submit that both fuels turn completely to vapor long before reaching the cylinder whether they're delivered by a carb or by fuel injection. Where EFI shines is that vaporization is suppressed (due to fuel pressure) _before_ the fuel reaches the injector.
@@billvanvlack117 I see what you are saying. Even if the Venturi action doesn't fully atomize the fuel within the carburator itself, the trip down the intake manifold will achieve full vaporization. And Yes, totally agree: the vapor lock issue is much less likely (if at all) to happen when there is a single, non-return, high pressure line to the injector housing (and the injectors themselves) -- I've done the test of turning off any flow to the engine from the pump (disconnecting the high pressure pump's power supply) and the amount of the time the engine goes on running is pretty impressive: About 1-2mins. Partly that might still be the residual pressure on the line, but a lot of it is just the fumes. Squirting some aerosolized starter fluid into the intake manifold also results in 5-15 seconds of running. Having vaporized fuel in the line isn't so much the issue as having the vapor flow fast enough to achieve proper stoichiometric mixture.. and a high pressure pump needed for FI applications will certainly achieve that. (imho)
Dear Jim, I don't yet know if I'll ever buy a coach, but before I do I was to understand these things as much as I can and understand how much I''m going to be able to do to maintain a coach. 77-year old ladies have to be careful about stuff like this. Thanks for all your comments & advice; you put things in simple, easy to understand terms and you don't overwhelm mr with technical jargon I wouldn't understand anyway. Good job, well done. Keep it up.
Thanks Jim. I am comfortable working with Qjets but you have given me a reason to consider going to fuel injection. I like the idea of monitoring the sensors that a computer can display.
Are you able to get the fitech under the engine cover with the 455?
Hi Jim. I have a Bosch FI system in my 1989 Porsche and a 1995 GM FI system in my GMC. Both systems learn and adjust to try and maintain stochiometric combustion when in closed loop, just like the FiTech. I'm not sure I understood the part about fuel injection adding pressure to the air/fuel mixture entering the combustion chamber. Does that decrease the manifold vacuum then? By how much?
Bill: I don’t think Jim said that the air/fuel mix was pressurized as it enters the intake manifold, but instead that the fuel is pressurized when it enters the injectors, and the pressure of the fuel as it passes through the injectors atomizes the fuel better and finer than the Venturi inside the carburetor. Once atomized and mixed with air, the mixture is at the same atmospheric pressure than the output of a carb. Pretty sure that remains the same.
@@tiagosoromenho1868 Ah.. that makes more sense. I can see that the atomized ethanol fuel particles turn to vapor sooner after leaving the injector than non-ethanol , since the vapor pressure of ethanol fuel is less - but I would submit that both fuels turn completely to vapor long before reaching the cylinder whether they're delivered by a carb or by fuel injection. Where EFI shines is that vaporization is suppressed (due to fuel pressure) _before_ the fuel reaches the injector.
@@billvanvlack117 I see what you are saying. Even if the Venturi action doesn't fully atomize the fuel within the carburator itself, the trip down the intake manifold will achieve full vaporization. And Yes, totally agree: the vapor lock issue is much less likely (if at all) to happen when there is a single, non-return, high pressure line to the injector housing (and the injectors themselves) -- I've done the test of turning off any flow to the engine from the pump (disconnecting the high pressure pump's power supply) and the amount of the time the engine goes on running is pretty impressive: About 1-2mins. Partly that might still be the residual pressure on the line, but a lot of it is just the fumes. Squirting some aerosolized starter fluid into the intake manifold also results in 5-15 seconds of running. Having vaporized fuel in the line isn't so much the issue as having the vapor flow fast enough to achieve proper stoichiometric mixture.. and a high pressure pump needed for FI applications will certainly achieve that. (imho)