1JZ Fuel Pressure Regulator Limits

[beasht]

Can anyone tell me what the limits are of the stock 1JZ fuel pressure regulator are?
My power goals will be around the 350-400rwkw region and I will be using a Bosch 044, 650cc injectors and Emanage and probably no more than 25psi of boost.
Im presuming I will need to upgrade with those goals in mind? haha
Would a Sard FPR be enough? Are the Type-R Sard FPR's worth the extra dosh?

[petespipes]

well you would get 350rwkw at about 90% duty cycle [manual gearbox] with 650's at stock fuel pressure based on 550's providing 300rwkw at 90% duty,stock pressure.

90% duty cycle is not considered safe so you may need to go to 720's

This is according to sources i believe are reliable but is not first hand info.

I guess you mean you want to increase the fuel pressure?

I think these are questions for your tuner.everyone has their own story on these details and not easy to get two people to agree exactly on the best method of achieving any given amount of power.Find a tuner you trust and follow his recipe on components used to acieve your power goal.[or copy someone elses recipe exactly]

best of luck with it.

[beasht]

cheers heaps for that Thats the sort of info I needed!
Im using an auto trans so yeh a bit less power than a manual.

I will be using a bosch 044 pump and they are apparently capable of 73psi and if I use a Sard Regulator would it be safe to increase fuel pressure?

Does anyone have any experience with aftermarket FPR's? At the moment I am thinking of going with the Sard Regulator because it can be adapted to the 1J easily and has enough adjustability for my needs.

I agree with you there that these are questions for my tuner. But I wanted to ask on here to find out if I needed a better FPR before I get it tuned because I am 4 hours away from a tuner and I didn't want to make the trip just to be told to come back later

That's why Im trying to cover all bases first and get everything I need done so I can have a one and only tune done when its finished

[Draven]

I'm with pete... I'd get a RRFPR (like the SARD Fuel Regulator Type-R).. in fact, that *is* what I'm getting
$330 delivered from nengun.com
I'd also be looking for some 700+cc injectors for that power figure (I'm also aiming for 350-400rwkw, and my injectors will be 720-850cc)

[beasht]

I thought the standard Sard Regulator was Rising Rate aswell? I'm getting my gear from Nengun aswell haha
I was thinking of the 800-850cc but I have just paid for a set of 650cc from a guy off SF.com.au so I might stick with them and see how I go. Im using an Emanage aswell so that's probably another reason why I'll stick with slightly smaller injectors until I get a full standalone ECU that can handle the 800cc+ injectors better.
I would be happy with a safe tune of 320-350rwkw anyway until then

[Draven]

yep, the regular one is rising rate too

[beasht]

awesome, any particular reason your going with the Type R? Or do you have some bigger plans after you reach 400rwkw?

[Draven]

when I first ordered it I didn't realise both were rising rate, and once I'd placed the order I figured that it'd be better anyway. Realistically, I'm not going any higher than 400rwkw

[beasht]

Can't go wrong with getting that bit extra anyway I guess

[JZA70 R]

Bit of a thread revival here but its better than creating a new thread...

-Do we have any EFI experts in here that can tell me why you do or dont have to mess with fuel pressures when upgrading injectors and the fuel pump.

-Can anyone tell me what the limitations of the factory 1jz FPR is, does it cause a flow restriction, or is the base pressure too low of larger injectors?

[JZA70 R]

Also since ive been reading up on the subject, i thought id share some info ive gathered for those that are interested...



What is a Fuel Pressure Regulator?
Answer 1
EFI fuel pressure regulator’s job is to maintain a constant fuel pressure above the intake manifold pressure.

Answer 2
EFI fuel pressure regulators come in various shapes and sizes but all have the same purpose - to maintain a constant fuel pressure above the intake manifold pressure. The difference in pressure between the fuel rail and intake manifold or differential pressure across the injector should be maintained at a level to suit optimum injector operation.


Why and When do you need to install a Fuel Pressure Regulator?
Answer 1
If you're planning to use larger, aftermarket injectors, it's a good idea to invest in an aftermarket Fuel Pressure Regulator. The installation of an aftermarket FPR allows for the adjustment of fuel pressure to suit aftermarket injectors and other engine modifications. They are also necessary to regulate and flow increased volumes of fuel pumped by high flow aftermarket fuel pumps.

Answer2
The installation of performance fuel injectors or a high-flow fuel pump requires the use of an aftermarket fuel pressure regulator to allow pressure adjustments while maintaining a stable base pressure. They can also be used to maximise a standard fuel system’s ability to cope with minor power modifications.

Answer3
The installation of an aftermarket fuel pressure regulator allows for the adjustment of fuel pressure to suit larger aftermarket injectors and other engine modifications. They are also necessary to regulate and flow increased volumes of fuel pumped by high flow aftermarket fuel pumps.
Fuel pressure regulator, which works with the fuel pump to maintain a steady pressure relationship between the fuel line side of the injectors and the intake manifold.
Most adjustable regulators are still one to one or close to that, however you can adjust the pressure at idle or full throttle for fine tuning. There is one other type of regulator that is used with aftermarket forced induction. These are rising rate regulators commonly called FMU's (fuel management unit). These regulators increase fuel pressure at a multiplication factor of boost. So instead of messing with complicated computers and injection duty cycles, these systems just increase fuel pressure to add fuel. They go inline down from the factory regulators and only start to add pressure under boost. So when you are off boost, you maintain factory tuning and drivability. Only as you get boost does the FMU begin to increase fuel pressure


Return Flow vs Base Pressure
• Ideally a fuel pressure regulator will provide a constant pressure differential across the injectors. Base pressure has been defined as the difference between the fuel rail pressure and the manifold pressure. This is the actual pressure across the injector that affects the amount of fuel flowing through the injector when it is open.
• If the base pressure is constant this will aid in tuning by reducing the number of variables the tuner must account for.
• The fuel pressure regulator should have the same base pressure at a given setting for all return flow rates through the regulator.
• The return flow through a regulator can vary from maximum return flow at idle to approximately 25% of the return flow at full throttle and maximum rpm. For example the test RX7 would return 6L/min at idle and 1.5L/min at 7000 rpm full throttle.
• The base pressure is typically tuned at idle when the most fuel is being returned.
• If large aftermarket pumps (or high volumes of fuel – eg alcohol based) are used this can mean the regulator is causing a restriction in flow at idle.
• This means that when the regulator is being tuned there is an increase is pressure due to the restriction in flow. This is caused by the regulator having to return too much fuel for its design. In effect the base pressure in then being set with a combination of spring pressure and pressure build up due to the flow.
• At higher load & rpm there is less fuel being returned through the regulator and the pressure increase due to the restriction in flow will be removed (as the regulator is designed to flow this flow rate) causing a drop in base pressure under these conditions.
• This drop is because without the restriction due to too much flow the regulator is only using spring pressure to regulate.
• The RX7 tested with twin bosch pumps give a good illustration of this effect with the TREG giving the most stable base pressure and competitors base pressure dropping by up to 4 psi
• Bench testing has also confirmed this relationship between regulated pressure and fuel flow.


What to look for when buying a Fuel Pressure Regulator?
Since the FPR's main job is to maintain an optimum fuel pressure, you should always look for an FPR that can maintain a stable and consistent fuel pressure delivery. Other things to look for are flow capacity, spring and diaphragm design and compatibility with all commonly used fuel line fittings. or alcohol.

[Norbie]

Factory base pressure should be fine for any injectors. The only reason you'd want to play with the fuel pressure is if you're doing something cheap and dodgy. Note that "rising rate fuel pressure regulator" is synonymous with "cheap and dodgy".

As for the limits of the factory FPR, I've never seen any hard data on this but if you invest in a fuel pressure gauge (which is a good thing to have anyway once you upgrade to a big fuel system) it will very quickly become apparent if the FPR needs upgrading.

[JZA70 R]

Are there any members here that are making big power with the stock fuel pressure regulator?

eg big injectors and fuel pump but stock reg and making over 300rwkw?

[manny]

My 1.5JZ when it ran the 1JZ-GTE factory fuel rail, fuel pressure regulator, pulsation damper, fuel lines etc with 800cc injectors, Denso/USDM Supra pump and at 25 psi on pump fuel had no dramas pushing 25psi above base fuel pressure and was making 350+rwkw if that's any indication. Same fuel setup on my 1JZ-GTE at 24psi and 320+rwkw without any dramas.
I've had a SARD FPR sitting on a shelf and ready to drop in if/when the factory FPR ran out out of puff, but I've never had cause to change it on my 1JZ/1.5JZ/2JZ-GTE engines all running factory FPRs.

[JZA70 R]

Wow thats what i wanted to hear.

So how do you know when its time to upgrade?