Bambam7

Just wondering if there is a difference between the TII and N/A FPR.
I've heard (only from one person- though a reputable source) that the TII FPR increases pressure with boost, and the N/A one only decreases it under lotsof vacuum (economy)

Is this a fact? I'm just leaning out a bit at anything over 11 psi with the stock fuel system (TII pump, 4 550's).. looking for reasons/solutions.
I havn't done the relay/rewire on the pump yet. Does it really make a difference?

Bambam7

Or am I just an idiot thinking that the stock fuel system is enough for 12-13 psi?? (Only in 4rth)
I'm new to the turbo area....
The S-AFC helps a bit though, but will still only open the injectors to the max ECU controlled duty cycle.

Aaron Cake

iTrader: (1)

The TII FPR is boost depandant. Fuel pressure increases with boost.

Have you considered the FD fuel pump? Flows more then the TII unit by about 30%.

Six Rotors

iTrader: (17)

Well on my factory TII,the fuel pressure regulator maintains fuel pressure in the fuel rail at a constant pressure,except when at idle .Then vacuum is applied to the regulator to reduce rail pressure.Exception is during hot start.In the 1987 New model Training manual Mazda say that the only difference in the regulators is the strength of materials in the turbo one -for reliability.

Icemark

I would agree 100% with that on the S4 cars, not sure on the S5 cars though.

HAILERS

I've put a inline mechanical fuel gauge on both the 87n/a and the 87turboII and I'd bet money they are the same animal. The reason why I say that, is, that at idle they both read the same(something like 28-32psi) and if I apply 10psi of air pressure to EITHER one, they both react exactly the same........the fuel rail pressure goes up to approx 50psi. I know the n/a will never see boost pressure, but it reacts just like the turboii fpr and raises the pressure to approx 50psi.

Don't take what I just wrote to dispute any of the remarks by SixRotors or THE ICEMARK. I know nada about series five or the makeup of the materials inside the fpr.

j9fd3s

iTrader: (3)

the s4 regulators mount differently, they all seem s4 &s5 to work the same.
HOWEVER, you need to look at the vacuum circuit, the regulator only sees vacuum/boost for 30 after start up, so in the us market cars it is NOT setup to be rinsing rate. if you bypass the solenoid then it will be a rising rate, and it works well too

mike

HAILERS

Oh boy. Conflict here. j9fd3s The fpr sees vacuum and or boost 99.9 percent of the time. The fpr solenoid vents to atmosphere for those thirty(fifty?) seconds on startup and gives a slightly higher fuel pressure for those few seconds on start up. Then vacuum is applied when the solenoid de-energizes and the fpr sees whatever is in the intake manifold.

Sorry, I did not mean that they mounted the same. They just react the same on a series four. The turboii's fuel rail pressur does indeed rise when you go into boost. Been there and seen that while driving with a fuel pressure gauge attached to my windshield wipers at full boost. Goes to almost fifty psi when I'm at full boost. Can't say for the N'A car though since it does not boost at all, but have applied pressure to its vacuum/ air pipe while in the driveway and seen the fuel rail pressure go to approx fifty. Thats what I meant when I said they seem to be the same animal (not really true since Six Rotors says the material is different). Just act the same.

HAILERS

Oooops. I no sooner logged off than I realize I may have put my foot in my mouth. What a rising rate fpr is, is not what I just described, is it?????? What I described is a fpr that is maintaining the differece in b/t the fuel rail pressure and atmospheric pressure, isn't it. A rising rate fpr would have risen as described, but higher, right??? What I described is a fpr that is maintaining a forty psi difference b/t the rail pressure and the atmospheric pressure? Not a rising rate fpr. Ok. I admit it. I don't know the true meaning of a rising rate fpr. If you can describe the difference b/t what I described in the earlier post, and a rising rate fpr, have a go at describing it. Thank you.

j9fd3s

iTrader: (3)

hmm your right hailers, i always thought that the fpr was hooked up so that it saw no signal except when the solenoid was on? i guess i need to go look at the diagram. i also know that the jdm fc's and jc's dont have the solenoid at all

mike

Samps

Here's my go!

The FPR adjusted fuel pressure to 50 psi when you applied 10 psi of boost. But it would have done the same had you applied 20 psi of boost. In an RRFPR, the results would have been higher or lower depending on how much boost you applied. I'm sure you already knew that much, but that's all I know.

HAILERS

If I apply pressure to the fpr incremently, the fuel rail pressure goes up incremently. IF I apply five psi, I might see forty five psi fuel pressure. If I go to six psi at the fpr, I'll see forty six psi and on and on till I apply approx 10psi and get a fuel rail pressure of approx fifty. If I appy a lot more pressure, the fuel rail pressure won't rise above fifty. I think thats because thats as high as it was designed to go. Its maintaining forty psi fuel rail pressure vs the intake air pressure. I THINK a rising rate fpr would do more than maintain a forty psi fuel rail pressure. It would give me the forty psi difference and a little more than a forty psi rail pressure as I applied more boost. I think thats the way it works. Thats kinda muddled thinking, but I think thats the way it works.

I guess I really don't have a need to know since my car is just a run about, not a racer. So I don't need a rising rate fpr.

Scott 89t2

I'm pretty sure that is the defination of a raising FPR. if it goes up with boost even if it's the same amount. because for example when you go haltech with a after market one, people use static ones so even under boost the FP stays the same. you just open the injectors more instead.

now you can also get an "adjustable raising FPR" which allows you to set how much it goes up by. like 1.5x or 2x. which would raise FP by 20psi for 10psi of boost etc.

Scott 89t2

and bambam I guess they could be the same... I told you the turbo one goes up with boost. but I never really thought about how maybe the N/A one could aswell if given the chance it just never does on the N/A car

von

So when doing the turbo swap as bambam has done , we really dont need the turbo FPR ( or black thing on the shock tower) ???

Then why does bambam not have enoughf fuel with 550 , T11 pump and Maxed out S-AFC and only 12psi?
Tecknically that should soport over 300rwp im sure

Bambam7

I see up to 13 psi in fourth...
My problem is a few combined things.
1- The engine isn't a stock TII motor, it has almost 10:1 compression, and is also street ported- This increases the power of the engine- requiring more fuel.
2-The higher compression requires a richer fuel mixture (and retarded timing) in order to prevent detonation than a lower comp. regular TII would.

I also have fully modded everything else on the car.. intake, exhaust, etc.
Everyone else I have spoken to in the last few weeks says that any TII running 13 psi would need fuel upgrades... so with my engine I should need those even more!
Damn it flies though... even with the one blown apex seal....

Another problem is the ECU will only mantain a max injector duty cycle of about 60%... so that really chops down the numbers you get from "horsepower calculators" and such....

von

Ok that perfectly makes sense. I didnt realize you were making such good power...

Your saying a S5T11 ECU will let you get more fuel via ( knowing your injectors are larger) Exc. 60% with 460cc as oposed to 60% 550cc RIGHT?