General ? about FPR psi on 450cc's.

[SnowBird]

Im still a newb to tuning and everything (I am not planning on doing this or any serious modding until I can log and tune), but doing some research on swapping out FPR's from a N/T 47psi, or Turbo auto 43.5psi, I come up with the math the N/T will make the 450's flow like 562's?

My confusion is can the 450's flow that much? It doesnt make sense to me, I dont understand how they could flow that much more, I mean, whats the cut off? I know you just couldnt get an adjustable FPR and crank the PSI sky high turning 450's into 850's, so whats the deal? Is it too much for me to even understand at this point?

 

[GSX93DSM]

There is no way 450's can flow that much. That would mean nobody would need to upgrade to larger injectors. If you did have a fpr that does change a thing with 450's. Adding more fuel will just override the 450's.With a 16g and right amount of psi 450's are worthless.

 

[jerseydiver84]

you wanna run a larger turbo, more boost, there isnt a way around getting larger injectors, you need to do fuel management, get a fpr, get larger injectors, fuel pump, gauges to tune off of a wideband or even a egt and boost gauge, something to tune off of like an safc, you want more power you have to do supporting mods.

 

[1992awdlaser]

Running more pressure will increase the amount the injectors flow. Where does it stop? I have no idea.

 

[SnowBird]

you wanna run a larger turbo, more boost, there isnt a way around getting larger injectors, you need to do fuel management, get a fpr, get larger injectors, fuel pump, gauges to tune off of a wideband or even a egt and boost gauge, something to tune off of like an safc, you want more power you have to do supporting mods.

Sorry, thats totally not what I was asking in my post, I stated I had no intentions of doing this or wanting more power, or boost, or turbo.

Running more pressure will increase the amount the injectors flow. Where does it stop? I have no idea.

Thank you, thats what I was getting at. Ive read endless threads about people using N/A FPR on turbos, and people claiming it will make the 450 flow like a 550, but I didnt see how that was physically possible, and if it was what the cut off was.

I get exactly what you are saying, its a shot in the dark, they will flow more due to more pressure but its not specific or anything to work with.

 

[tkelly27]

RC Fuel Injection

You can do the math. One thing I've never understood was if the 1g's are 450cc's at the stock 1g fuel pressure (37.5?) or if they flow that at the standard 43.5psi. Even if you go from [email protected] to 47psi you are only getting about 503cc/min

As you increase pressure the amount the fuel pump can supply goes down, and not an insignificant amount. The first image I could find on google is this one
http://www.expressfuelpumps.com/images/F20000169chart.jpg

Depending on where you bump it up at, an increase of 10psi base pressure can drop flow dramatically.

 

[steve]

One thing I've never understood was if the 1g's are 450cc's at the stock 1g fuel pressure (37.5?) or if they flow that at the standard 43.5psi. Even if you go from [email protected] to 47psi you are only getting about 503cc/min

The injectors are rated at 43.5 psi (3 bar), at that pressure they spray 450cc/min. At the stock 1G manual fuel pressure of 36.3 psi they spray about 411cc/min.

There are limits to how high and low you can go usually because of spray pattern but the injector deadtime also changes with pressure and at some point they just can't open against the pressure anymore.

As pointed out the fuel pump imposes limits too. Flow rates drop off as pressure increases and there is a relief valve the limits the max pressure at the pump. Remember that there are pressure drops in the lines that cause the pressure at the pump to be higher than at the regulator. You need to take then into consideration.