What size injectors? X-Post
12-02-2003, 02:54 PM
#35
Is there an opinion on Delphi vs. Siemens? The Siemens are on eternal B/O, the guys words were, yeah maybe sometime before next Christmas! They have the Delphi in stock, any reason not to go with them? I need to order today!
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12-02-2003, 02:59 PM
#37
It appears they were.
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12-02-2003, 10:19 PM
#38
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Matt H,
I've been doing the same search. I've heard the Delphis have different characteristics then Siemens and Rochester injectors.
For what its worth, RC Engineering doesn't sell Delphi injectors, yet they carry Siemens and Rochestor.
From the looks of the Accel injectors it looks like they are made by either Rochester or Seimens. Summit has them in stock. They're ~82/ea.
Anyone else know of a good source for injectors besides Racetronix?
Thanks,
Sean
I've been doing the same search. I've heard the Delphis have different characteristics then Siemens and Rochester injectors.
For what its worth, RC Engineering doesn't sell Delphi injectors, yet they carry Siemens and Rochestor.
From the looks of the Accel injectors it looks like they are made by either Rochester or Seimens. Summit has them in stock. They're ~82/ea.
Anyone else know of a good source for injectors besides Racetronix?
Thanks,
Sean
12-02-2003, 11:19 PM
#39
The distributor in Houston speeddemon is selling the Delphis for like 52 each. I am ordering tomorrow, we will see how it goes.
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12-02-2003, 11:46 PM
#41
The guy asks me, "what the hell are you going to do with those??" He was saying for a Camaro/Corvette to need injectors that large they would have to putting out over 800HP. I said, I have half the cylinders and half the goal!
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12-03-2003, 04:20 AM
#42
Nordschleife Master
Originally posted by Tomas L
The pressure drop over the injectors is still 2.5 bar and their flow capacity is accordingly. The increase in fuel pressure from boost only has effect on the fuel pump's capacity, not the injectors.
Tomas
The pressure drop over the injectors is still 2.5 bar and their flow capacity is accordingly. The increase in fuel pressure from boost only has effect on the fuel pump's capacity, not the injectors.
Tomas
Anyway, when the fuel pressure goes up the fuel pump's capacity is reduced right? If so, what is the meening of having the FPR attached to the vacuum system?
I'm very confused about this... I have a fuel pressure gauge attached to the rail. It shows different values depending on the current vacuum. If so, how can the pressure over the injectors still be the fixed value of the FPR?
12-04-2003, 01:28 AM
#43
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Duke,
The internals of the fuel pressure regulator (one of the two cans on the fuel rail, the other is a damper) is just a valve with a spring (for the fuel pressure at ambient) and a diaphragm (for the manifold pressure adjustment). At idle the spring and vacuum exerts a pressure on the valve that can be overcome by a fuel pressure of 2.0 bar (at an idle vacuum of about 0.5 bar absolute), at 1.0 bar the fuel pressure will be 2.5 bar (spring force only) and at 2 bar absolute manifold pressure the valve will open at the 2.5bar +1.0 bar = 3.5 bar (spring + diaphragm force) fuel pressure.
This way the fuel pressure across the injector nozzle is a constant 2.5 bar and therefore gives a consistent spray pattern and droplet size. So essentially your fuel pressure gauge should show 1.5 bar + the absolute manifold pressure.
As I just learned (from TonyG) all the injectors fire simultaneously and therefore sets up severe pulsation in the fuel rail with potential difficult to control resonances in the rail. The damper is there to absorb these pulsations.
Hope this helps.
Laust
The internals of the fuel pressure regulator (one of the two cans on the fuel rail, the other is a damper) is just a valve with a spring (for the fuel pressure at ambient) and a diaphragm (for the manifold pressure adjustment). At idle the spring and vacuum exerts a pressure on the valve that can be overcome by a fuel pressure of 2.0 bar (at an idle vacuum of about 0.5 bar absolute), at 1.0 bar the fuel pressure will be 2.5 bar (spring force only) and at 2 bar absolute manifold pressure the valve will open at the 2.5bar +1.0 bar = 3.5 bar (spring + diaphragm force) fuel pressure.
This way the fuel pressure across the injector nozzle is a constant 2.5 bar and therefore gives a consistent spray pattern and droplet size. So essentially your fuel pressure gauge should show 1.5 bar + the absolute manifold pressure.
As I just learned (from TonyG) all the injectors fire simultaneously and therefore sets up severe pulsation in the fuel rail with potential difficult to control resonances in the rail. The damper is there to absorb these pulsations.
Hope this helps.
Laust
12-04-2003, 03:24 PM
#45
Rennlist Member
Fuel pressure goes up with boost, but so does the pressure in the manifold, therefore the differential accross the injector is the same. A rising rate regulator raises the fuel pressure at a greater rate than the manifold pressure and will therefore provide more fuel for a given pulse width as long as the pump can deliver the required volume at higher pressures and the injector does not lock up.
There is a point of diminishing returns when cranking up fuel pressure as has been noted here before but as I recall, its at some fairly high pressures and big hp numbers.
I just bough 57# siemens for my vitesse stage II turbo.
There is a point of diminishing returns when cranking up fuel pressure as has been noted here before but as I recall, its at some fairly high pressures and big hp numbers.
I just bough 57# siemens for my vitesse stage II turbo.