fuel pressure and 4age

[45aken]

hello
just bought a sard rising rate regulator for my fuel system, and im just wondering what a ball park fuel pressure would be to run?
also as the setup will be N/A for the moment, will the rising rate effect anything on the car?
and finally, should i still run the damper on the fuel rail?
thanks

Ps if it helps im running 3/8 feed, stock 4ac feed as return and a walbro 255l/h pump (gss341).

[oldcorollas]

stock fuel pressure is around 35-40psi?

if you will be using an aftermarket ECU, is there a need for a rising rate reg?

[45aken]

nah it's not running an aftermarket ATM, but thanks alot for the stock pressures.

you can still run the aftermarket ecu with a rising rate though, i just threw one in cuz i didn't think the stocker could handle the flow from the pump etc.

plus it looks jun spec...

[ira11y]

So for what reason do you need a rising rate reg? are you running a big turbo with larger injectors? a stock regulator will handle most applications just fine.

[45aken]

i figured a stock reg would 'flood' with the amount of flow the pump is pushing.
regardless of why i bought it though, is this going to cause any problems on N/A setup?

i figured that when im running the car N/A there wouldn't be any boost to actullay make the reg open on throttle (rising rate), so on the NA setup it would just be a normal adjustable reg, which could handle any pump or size lines i threw at it.

just double checkin. ($120 for a new sard reg...i thought why not)

[Starfire]

Run the stock pressure man. There really is no need to increase it on a stock engine - or any engine for that matter.

If you need to increase the rail pressure then you really should be changing the injector timing or fitting higher flowing injectors.

A 1:1 rising rate is essential for a boosted system as it gives you a fixed reference point for the fuel system. If yours is anything other than 1:1 I would be inclined to trade it in on one that is.

The stock reg will be good for much more power than you are likely to be making.

Of course if the sard unit looks the biz then thats always a bonus too

[45aken]

yeah that it, i just wanted to know what the stock pressure was!

the unit is adjustable, so i'll just run it at the stock pressure, and im 90% sure that if a rising rate regulator is used on an NA setup that the 'valve' that rises the pressure will not open because there is no positive vacuum to open it, therefore making it just a normal 1:1 reg.

[Starfire]

1:1 refers to how much pressure is adjusted based on the manifold pressure.

So if you have 40psi of fuel pressure and 10psi of boost you will read 50psi. Some regulators have different ratios, like a 1:1.1 so then you would have 51 psi and so on.

[45aken]

no worries mate,
but since this is going to be n/a for now, all i need to know is if no boost=no rising rate
im pretty sure it does..

[Starfire]

Pretty much,

Especially if the vacuum port on the reg is not connected to the inlet system. That way the fuel pressure will be fixed against atmospheric pressure.

[45aken]

thanks mate, just needed confirmation, rep+ 4 u

[takai]

Oh yeah, and the stock fuel reg will stand up to a pair of Bosch VL-t pumps running in parallel so it woudl have been fine.

[ira11y]

Pretty much as stated above, leave the vacume line off and as long as its set at the factory pressure it will be fine on your NA application.

The standard regulator will handle bigger flow rates without any problem, in fact the pump flow rate wont really affect the stock fuel setup other than returning larger volumes of fuel back to the tank.

Make sure all your hoses and clamps are in good working order and it will be fine.

[cri_ag]

so do we need a rising rate reg on a turboed 4age? can we not just make adjustments to the fuel map if the injectors are suficient?

[oldcorollas]

no-one needs a rising rate reg.
the only possible purpose is for stock injectors which are just out of range and the owner is too stongy to do it properly

the point of a reg is to keep a fixed pressure differential across the injectors, so that their flow rate is known for a given opening time.

usually, a reg is connected to vac in NA so that at idle, the rail pressure reduces so the differential is 40psi (as example). if you don't have it connected to vac, you may have sayy (at 50kpa vac) 47psi differential, so the injectors flow more, and you have less control over your idle mixtures (even with aftermarket comp)

for boost, if you have 1:1 reg, then for 20psi boost, the rail pressure will be 60psi, but the differential is still 40... otherwise you would have 20psi, and lower fuel delivery.

rising rate just increase the rate of rail pressure increase (usually only on boost side) to give you more flow, but this wrks pumps harder...

say you have 1.5:1 and run 20psi... now your pump has to provide 70psi, which is a bit high really... you may end up actually losing fuel pressure because the pump can't provide the volume at the higher pressure...

so anyways, the reg is there to make sure you don't have too much fuel at idle and part throttle, and make sure you do at higher manifold pressures.
it will work for NA if you disconnect it, but you will need to lean out the original map a bit to compensate.