Ultimate budget build.

[e30s52]

I had that same strut brace but now it doesnt fit. GL with the project!

[Mako18]

Rising Rate Fuel Pressure Regulator.

Its basically acts like you're fuel pressure regulator, but kind of holds the fuel untill enough PSI is built up and then lets it flow to the injectors. At least thats how I understood it. Maybe someone else can chime in with a more accurate description.

Its also known as an FMU.



Of course I am!

Kinda yes... but also no, I think this description can be a little misleading I would like to expand and explain a bit..

Basically a rrfpr/fmu will hold the pressure in the fuel rail by not allowing the fuel to return to the tank freely or at its regular rate, so as a result of basically corking the end of the fuel rail the amount of pressure in the fuel rail is greatly and rapidly increased. How much of a pressure increase is regulated at a set/adjustable level or ratio using a vac/boost reference from the intake manifold, thus increasing the amount of fuel being sprayed into the engine I.E. adding more fuel per every injector pulse (increasing duty the cycle of the injector).

BEWARE!!!!! There is a balance!! You can max out your fuel pump and injectors. If your using smaller/lower flowing injectors than needed you can get a bit more out of them by increasing the pressure in the rail by using a rrfpr or fmu but don't ask to much of them because at a high duty rate lets say 80%, your really starting to tax your stock fuel pump and whatever injectors you have choosen and it could and will eventualy lead to a failor of one of the two. They are rated at certain rate for a reason. If you find your self needing excessive amount of pressure or your maxing the rrfpr/fmu then you probably need larger injectors and a fuel pump just to be safe. This said balance is a calculated rate and it will increase as more power is desired.

Also realize the set pressure is to be adjusted in acordance to the choosen rrfpr/fmu rate. Adjusting the pressure its best to start at part throttle and work your way up to w.o.t. This is where a WBo2 comes in for tuning of a specific rate/pressure setting. Remeber its better to set it a little to high (rich) then a little to low (lean) but again be aware an extreme of either situation can lead to detonation (lean) or cylinder wash (rich) which can lead to a seized engine = bending, breaking etc. DAMAGE. When adding forced induction to a n/a engine or any engine its better to start low with the boost and work your way up while carefully and accurately monitoring your AFR's increase or decrease fuel rate delivery. For better tuning through the rpm range you'll need a fuel controller such as a piggy back or standalone ie apexi neo, hks fcon, or megasquirt, vems, tec3r....etc..

hope this helped.

[Mako18]

here

http://www.rceng.com/technical.aspx

http://www.performancetrends.com/Fuel_Injector.htm

[Danny]

That does help alot Mako.

Thanks!

[Danny]

So we test fitted the turbo today, and as luck would have it, it doesn't fit.

I'm going to have to fab up an adapter tube and plate to lift the turbo and move it away from the motor some.

I did change my thermostat and delete my A/C though, all was not lost.

I also might be looking for a smaller turbo, if someone could point me in the right direction that would be great.

[Dominic49]

pics of the manifold on the motor?

[Danny]

Ahh, I didn't take any.

Here is someone else's:



And here is what I have to do:

[SamE30e]

If you were closer to where I was staying I could help. Turbo's are kinda my thing haha.

[nando]

are you doing this on stock injectors?

I believe the M42 has 19# injectors stock. I would put at least 24# in there. The RRFPR will help some but injector flow rates do not increase linearily with respect to fuel pressure. how will you know where to set it? without a wideband you are left to the sniffing your tailpipe method. and all that really does is give you a headache.

the second and even bigger problem is you have no way to retard timing under boost. The stock timing map at full load is going to be way too advanced. you would probably want to pull 5-10 degrees out of the full load area at least, but there's no way to tell without feedback on a dyno or from an EGT gauge.

third problem - motronic isn't designed to measure loads above atmospheric pressure. basically the ECU can't tell the difference between 0psi and 10psi. the AFM does measure air mass to some extent, but at WOT motronic actually ignores the AFM and runs off assumed values built into the computer. And it's assuming full load is equal to atmospheric pressure, not boost. A chip programmed for boost can get around this (sort of), it basically sets timing and fuel under boost to a set and safe level. but it still cannot differentiate between 10psi and 20psi, it can only see full load and cruise/idle.

also, that turbo is probably too small; with 10:1 compression, advanced timing and a restrictive exhaust housing you have a recipie for disaster. the CR itself isn't a big deal; with the right cams, (bigger) turbo, and tuning, it can work very well.

there is a reason nobody ever sticks to a budget build for very long. I hope you have a backup engine for when this one explodes.

[Danny]

I appreciate the critiquing Nando, but people have done this before and it worked out fine for them.

Plus if this one explodes I have a line on a cheap M50.

[nando]

I didn't say it couldn't work. But it will never be as reliable or powerful as if it were purpose built for a turbo to begin with, with a turbo sized to the engine, the right cams (especially for the high static CR, you want a lower dynamic CR), engine management and fueling.

I think the biggest hurdle for you to overcome is the ignition map. that part is critical if you want this to last more than a couple days.

and FWIW, the stock FPR is rising rate as well (1:1) - basically for every 1psi additional pressure in the manifold, it increases fuel pressure by 1psi. Yours at the max setting would increase FP by 12psi for every 1psi of pressure in the intake manifold. The stock fuel pump can do about 90psi, so beware of the upper limits of what that FPR can do (not that you'd want to dump that much fuel in anyway, mixtures below 12:1 don't burn very well).

[Danny]

I do agree with everything you said and I think if I was going for a whole mess of power and high boost I'd have alot of problems.

Just for as low of boost as I'd like I don't think I'll be faced with as many problems.

[SamE30e]

Since it is individual coils, I don't think you can run a MSD boost retard box. But maybe it's possible.

And Danny, get the C.O.P setup =)

[nando]

I do agree with everything you said and I think if I was going for a whole mess of power and high boost I'd have alot of problems.

Just for as low of boost as I'd like I don't think I'll be faced with as many problems.

yeah, I'm just trying to let you know what the shortcomings are.

On the M20, and I don't know for sure if this works for the M42, you can disconnect the TPS switch to retard the timing. what happens when you hit WOT is the ECU switches to a WOT map. If the switch is disconnected, at full load it will only be running on the cruise map, effectively retarding timing. unfortunately your fuel is also running on the cruise map, and your idle will suffer without the TPS input.

Since it is individual coils, I don't think you can run a MSD boost retard box. But maybe it's possible.

And Danny, get the C.O.P setup =)

I don't know that there's any real benefit to that other than the cool factor. I don't think the M42 has a cam sensor so it's running wasted spark anyway. if that were the case, M42 coils are probably better suited to that condition than M50 coils which are meant to be fired in sequential mode.

[SamE30e]

The coils for the C.O.P are off the 4.4L V8. The benifit is, it cleans stuff up a bit, also gets the coils out of the way for a top mount turbo. I don't think it's running wasted spark but I could be wrong.