Fuel Injection Questions
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Postmaster
Joined: Jun 2004
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From: Riverside, So Cal
Fuel Injection Questions
I need some info for a project I'm trying to develop. I'm hoping that some folks on here have the info or can point me in a good direction. I'm researching a Tuned Port type of system.
1. What is the typical fuel injection pressure (at the jet)? Or, what range of pressure is typically used?
2. On TPI, are solenoids used to open and close a fuel valve, or is the solenoid acting as a piston to inject the fuel?
3. What jet sizes are normal on a stock TPI system?
Thanks.
1. What is the typical fuel injection pressure (at the jet)? Or, what range of pressure is typically used?
2. On TPI, are solenoids used to open and close a fuel valve, or is the solenoid acting as a piston to inject the fuel?
3. What jet sizes are normal on a stock TPI system?
Thanks.
Fleet Owner
Joined: Jul 2004
Posts: 27,303
Likes: 1,062
From: NM
1. (from a web search on Camaro TPI pressure) Should be 40.5-47psi with the key on and engine off and 30.5-44psi with the engine at idle
2. Solenoids pull a pintle off a seat, they don't push fuel.
3. I don't think this is a completely relevant criteria; injectors have multiple orifices (in some cases at least) downstream of the pintle orifice, to create a spray pattern. What is it you are trying to calculate? Flow rate?
2. Solenoids pull a pintle off a seat, they don't push fuel.
3. I don't think this is a completely relevant criteria; injectors have multiple orifices (in some cases at least) downstream of the pintle orifice, to create a spray pattern. What is it you are trying to calculate? Flow rate?
More Turbo
Joined: Jan 2006
Posts: 615
Likes: 6
From: Tucson, AZ
The injectors don't have "jets" per se. The injectors are rated by the amount of fuel they can pass when opened. 19 pounds per hour, 25 pounds per hour, 30 pounds per hour, etc. These are typical values for Ford injectors. Orifice sizes and nozzle shapes are proprietary info as far as the manufacturers are concerned. What you are trying to do is atomize the fuel into extremely small droplets in order to get good combustion in the combustion chamber. There are lots of factors that go into the design of the nozzles because the droplet size is going to effect the flame wavefront, how fast it travels, how much NOX is produced, etc.
That is the reason that the manufacturers went to computer-controlled fuel injection. They could improve the gas mileage and the emissions by direct fuel injection which they couldn't do with carburetors.
Another factor in the equation is the fuel pressure at the injector. Higher pressures will atomize the fuel into finer drops. That is why diesel engines are going to higher and higher injection pressures and there are added pressure systems after the fuel rails to get the fuel pressure into the combustion chambers into the +20,000 psi range. No, there are NOT too many zeros in that number.
My question like ALBUQ F-1 is: Where are you going with this thread?
Phil
That is the reason that the manufacturers went to computer-controlled fuel injection. They could improve the gas mileage and the emissions by direct fuel injection which they couldn't do with carburetors.
Another factor in the equation is the fuel pressure at the injector. Higher pressures will atomize the fuel into finer drops. That is why diesel engines are going to higher and higher injection pressures and there are added pressure systems after the fuel rails to get the fuel pressure into the combustion chambers into the +20,000 psi range. No, there are NOT too many zeros in that number.
My question like ALBUQ F-1 is: Where are you going with this thread?
Phil
Postmaster
Joined: Apr 2004
Posts: 3,005
Likes: 2
From: Santa Clarita
Randy, Classic trucks magazine did a great article on what your looking for. Here's the website.
http://www.classictrucksweb.com/tech/0404cl_tpi/
http://www.classictrucksweb.com/tech/0404cl_tpi/
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