puma

iTrader: (2)

ok guys, i spent an hour on the search to find it.

now i understand the difference between a RRFPR and a 1:1 regulator, i personnaly feel that i don't need a RR and i don't see why people would but that is an other debate.

my question is: is there really an advantage of changing to let say a SX FPR (which seems to be the most popular) on a car that has all the basic bolt on still on stock twins?

Is it exactly like the stock one except it can flow more fuel?

what is the difference and its advantages over the stock one.

thanks a lot

puma

puma

iTrader: (2)

anyone?

RX7Elmo

i have the SX reguator coupled with a cosmo pump on my car.

I have the 1:1 ratio part number , SX just released a RR unit though. The thing with 1:1 is that it's just that, it'll just increase that ratio from then out. The RR ones can go up to 6:1 which is a lot! So by like 15psi you are pouring gas into the motor.

The advantage is more fuel. With an increase in fuel pressure, you technically squirt more fuel into the chamber for any given pulse width or duty cycle. So say at 80% duty cycle, with say 40psi vs 45psi of fuel, the higher pressure puts in more fuel. Of course there is a limit to this as you do not want to strain the pump, fuel lines, and injectors with so much fuel pressure.

The stock regulator is 1:1 too. The aftermarket is simply adjustable. If you do this, spend the money on stainless fuel lines, fuel filter relocation, and the "an" fittings.

Danny

puma

iTrader: (2)

ok but what is the advantage of the sx 1:1 compare to the stock one beside using cool SS lines?

mjw

iTrader: (1)

Reliability, who knows when that stock fpr or pulsation dampener is going to give out resulting in either a rapid decline in fuel pressure or an engine fire. Having an aftermarket fpr with some stainless lines and AN fittings takes that worry off my mind, and most of the regulators have a port to attach a fuel pressure gauge to keep an eye on that. It just adds another level of tuneability to the car. I know there has been some debate on whether the pulsation dampener is needed or not, personally I think it is not and have removed it from 3 boosted cars now with no ill effects to report. The documentation on the SX regulator states that is has pulsation dampening abilities designed into the unit. The main concern I have with a rising rate unit is the added stress it puts on the fuel system with such high pressures, especially on the fuel pump.

Matt

puma

iTrader: (2)

now that is the kind of answer i was waiting for, thanks for sharing.

anyone has other opinions they want to share?

thanks to both of you

rx7will

iTrader: (6)

If you are running a high flowing fuel pump and if you rewire it to run battery voltage, at idle the fuel pump may overpower the stock fpr. I did this on my 87 II and my fuel pressure at idle was 60 psi and sometimes it had hard starting problems because during cranking the fuel pressure was way too high. So yes the aftermarket adjustagle fpr is good when use with other fuel mods, but putting it on a stock car would be pointless. I rather use the 1:1 regulator vs the adjustable rising rate ones, i rather tune my car with the 1:1 than the rising one. But i guess if you just wanted a little mroe boost a rrfpr would be okay. Thats why all the na cars that are turbo charged use the rrfpr as a entry fuel system to run boost.

jspecracer7

You can turn the fuel pressure up from stock and tune from there. In other words, you can push the limits of the stock fuel system with fuel pressure vs. fuel injectors.

coop

so the rrfpr allows you to add proportionally more fuel to the mix without having to increase the duty cycle of the injectors as much as you would have to with a 1:1 fpr...?

mcf

I may be wrong on this... but doesn't the regulator change the flow characteristics BACK to the tank and serve only to apply an even/ appropriate pressure only?

Why wouldn't the flow rate of the injectors stay constant - isn't that part of the equation that creates pressure in the first place? I know my logic must be flawed, it just seems wrong that you can "create" a bigger injector/ more flow than you already have by adding a FPR.

maxcooper

1:1 regulators maintain a constant "effective" fuel pressure. The injectors will flow according to the difference in pressure between the fuel rail and the manifold pressure. So, if your boost gauge says 15 psi and your fuel pressure gauge says 55 psi, the effective pressure is (55-15) = 40 psi. Under vacuum, you'll get a reading of less than 40 psi on the fuel pressure gauge, but the injectors are still flowing according to the 40 psi effective pressure because that is the difference between fuel rail and manifold pressure.

Adjustable rising rate regulators increase pressure by some multiple of the boost pressure. You can adjust the multiple. For instance if you had a RRFPR set to 3:1 with a 40 psi base pressure (fuel pressure at zero manifold pressure), the effective pressure at 15 psi boost would be (40 + 3 * 15) - 15 = 70 psi. That would increase the flow over the base pressure by SQRT(70/40) - 1 = 32%. Note that you need a MUCH beefier fuel pump to flow a lot at 85 psi (yup, the pump must push against the gauge pressure). Very few pumps can flow enough to make decent power at 85 psi.

Advantages of 1:1 regulators over stock regulator:
- hopefully does a better job of maintaining the set pressure
- you can adjust it to get a little more capacity out of your injectors
- some say the spray pattern of big injectors sucks, increased fuel pressure would probably be an improvement
- flows more to avoid pressure rise at idle with mongo pumps

-Max

KevinK2

stock fpr is 2.5 bar. going to adjustable 1:1, set to 3 bar, gives 10% more fuel for all conditions, just like going from 550/850 to 600/930 injectors, assuming pump keeps up.

with full set of mods with stock ecu and turbo, and held to stock boost limits, could be at 300 fwhp and 15% leaner. 3 bar would richen things up again, but not as rich as the stock setup. more margin against detonation with stock ecu.

rrfpr is usually crude attemps at throwing buckets of fuel at engine when inj's max out on duty cycle or maf early.