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Old 10-12-2006, 07:35 PM   #1
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Hey ya`ll...
I've been reading the posts here for a couple weeks now and have a sorta simple question for everyone.

How do you adjust the timing? It seems like the bipes or some plugin can adjust the timing based on the boost that youre putting out, but how do you adjust the baseline? The timing at idle?

Also - I gave a quick read through "maximum boost". He keeps talking about rising fuel pressure regulators (or something like that) that supply much more petro once boost kicks in but doesnt affect the car at idle. A lot of people round here seem to be installing the walboro 190hp pump. These arent the same thing correct? The walboro pump works all the time? So wouldnt that make the car run wicked rich when youre not boosting? I'm a little confused about this (among several other things - but those are for another time)

Haha - I dont have a mazda and it doesnt have a turbo, but I think it'll be my next car. I learned to drive on my old mans miata and I've got a soft spot for em. I also love projects like this, wrenchin, and torque, so it seems perfect.

Thanks
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Old 10-12-2006, 07:42 PM   #2
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The rising rate FPR is down line from the factory fuel pressure regulator that is mounted on the fuel rail. It raises fuel pressure under boost by blocking off the return line more and more as boost rises. Think of putting your thumb over the end of a garden hose. You can feel more pressure against your thumb the more of it you block. The Walbro pump that are used(the HP models anyway) are capable of higher fuel pressure and flow than the stock unit. These do not cause the car to run wicked rich because the fuel pressure regulator(factory on the rail...not RRFPR) allow fuel back to the gas tank to maintain fuel pressure in the rail.
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Old 10-12-2006, 07:52 PM   #3
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Quote:
Originally Posted by Anotherskait View Post
How do you adjust the timing? It seems like the bipes or some plugin can adjust the timing based on the boost that youre putting out, but how do you adjust the baseline? The timing at idle?
Not exactly plugin, but a few wires a solder. Set your timing as usual, via rotating the CAS, then set the controls of the Bipes unit to retard your desired amount. Very simple, very effective.

Quote:
Also - I gave a quick read through "maximum boost". He keeps talking about rising fuel pressure regulators (or something like that) that supply much more petro once boost kicks in but doesnt affect the car at idle.
Correct. As boost enters the FMU it clamps down on the return line effectivly raising fuel pressure. Good for boosting without an ECU replacement up to a certain extent.

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A lot of people round here seem to be installing the walboro 190hp pump. These arent the same thing correct? The walboro pump works all the time? So wouldnt that make the car run wicked rich when youre not boosting? I'm a little confused about this (among several other things - but those are for another time)
No, not the same thing. The reason we upgrade our pumps is because the OEM pump cannot provide enough flow after 75-85psi of fuel. The 190HP can supply plently of fuel past the 120psi mark. It does not effect your idle pressure as the OEM FPR still functions as normal. Larger 255 pumps can overload the OEM FPR and rasie your idle pressures and dump way too much fuel.

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Haha - I dont have a mazda and it doesnt have a turbo, but I think it'll be my next car. I learned to drive on my old mans miata and I've got a soft spot for em. I also love projects like this, wrenchin, and torque, so it seems perfect.
Most important thing is understanding what you are doing. If need help we are always here to help! Plus have fun.
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Old 10-12-2006, 07:53 PM   #4
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you didn't say whether you have a 1.6 or 1.8. I don't know anything about 1.8s, but on 1.6s you get it to temp, ground the diagnosis box and loosen the cam angle sensor on the back of the head, and turn it while using a timing light.
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Old 10-12-2006, 08:26 PM   #5
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Quote:
Originally Posted by turbored View Post
you didn't say whether you have a 1.6 or 1.8. I don't know anything about 1.8s, but on 1.6s you get it to temp, ground the diagnosis box and loosen the cam angle sensor on the back of the head, and turn it while using a timing light.
Right now, I don't have a 1.8 or 1.6, I have a 4.0 jeep cherokee
I'm thinking about picking up a miata and figuring out how turbos work in general.

So if I understand correctly - You have a fuel pump and thats great stock. when you start upgrading - you add one of these walboro pumps that adds pressure to the entire system BUT theres a pressure regulator somewhere so excess fuel doesnt create a rich condition, it just heads back to the tank.

Where does the rising fuel pressure thing-er come into play? Is that after the walboro is maxed out? Or is it something different entirely?


And what are all these abbreviations? (RRFPR, FPR, FMU)

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Old 10-12-2006, 08:32 PM   #6
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cas = cam angle sensor (on the back of the head i think)
oem = original equipment manufacturer
fpr = fuel pressure regulator
rrfpr = rising rate fuel pressure regulator
fmu = fuel management unit (im pretty sure this is right)

i think that covers all the ones in this thread. A rrfpr is like a fpr in that it regulates fuel pressure, but it has another function in that it increases the pressure linearly with the increase in boost from your turbo. That way, as more air is forced into the cylinder, an increasing amount of fuel is in turn forced into the cylinder.
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Old 10-12-2006, 09:01 PM   #7
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Quote:
Originally Posted by neogenesis2004 View Post
cas = cam angle sensor (on the back of the head i think)
oem = original equipment manufacturer
fpr = fuel pressure regulator
rrfpr = rising rate fuel pressure regulator
fmu = fuel management unit (im pretty sure this is right)

i think that covers all the ones in this thread. A rrfpr is like a fpr in that it regulates fuel pressure, but it has another function in that it increases the pressure linearly with the increase in boost from your turbo. That way, as more air is forced into the cylinder, an increasing amount of fuel is in turn forced into the cylinder.
just to ask to very simple question, Ive seen people say FMU when talking about rising rate fuel pressure regulators, were they wrong or is a RRFPR also a FMU?
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Old 10-12-2006, 09:03 PM   #8
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IMO (in my opinion :-P) any extra device that controls fueling is a type of FMU. People normally refer to simple controllers like what the greddy kit comes with as an FMU though. Something more complex like the RRFPR deserves its own acronym.
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Old 10-12-2006, 09:45 PM   #9
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Calling a rising rate fuel pressure regulator a "Fuel Managment Unit" is like if we started calling the Bipes a "Standalone Ignition Controllerl"

Not true or accurate. No doubt Vortech sold a lot more RRFPRs because of how sophisticated the name makes it sound.
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Old 10-12-2006, 10:15 PM   #10
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Everything you ever wanted to know about Miata timing.
http://www.miata.net/garage/ignition.html#timing
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Old 10-13-2006, 09:53 AM   #11
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A rising rate fuel pressure regulator and fuel managment unit are the same thing.

anyone refering to a FPR, AFPR, RRFPR, FMU on a FI application are typically all refering to the same thing.

There are slight variations between some. Typically a FMU uses a static rise ratio, so say it can only rise 12:1. 12 psi of fuel added for every one psi of boost it sees. Replacing the disc inside the unit can chage the rate of rise from anywhere from 2:1 to 12:1.

An Adjustable FPR can be adjusted on the fly. You can set your base idle pressure above that of which the OEM FPR idles at. Plus you can adjust the rate of rise on the fly, via a needle valve.

There is also a SUPER FMU or Multi Role Regulator, that can take the place of the OEM FPR and function the same as a AFPR.
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Old 10-13-2006, 10:03 AM   #12
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Quote:
Originally Posted by Anotherskait View Post
So if I understand correctly - You have a fuel pump and thats great stock. when you start upgrading - you add one of these walboro pumps that adds pressure to the entire system BUT theres a pressure regulator somewhere so excess fuel doesnt create a rich condition, it just heads back to the tank.
Correct, the stock pump is adaquate to fueling your ride without a turbo. Dropping a 190HP in your tank without an AFPR/FMU/RRFPR will not change your fueling one bit. But with boost comes more fueling demands. An easy way to get more fuel is by raising the fuel pressures in the rail. When the fuel pressures rise, so does the flow, to a certain extent.

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Where does the rising fuel pressure thing-er come into play? Is that after the walboro is maxed out? Or is it something different entirely?
That an FMU allows you to get is higher fuel pressure levels in the rail, by clamping down on the return line (garden hose effect). It allow is activated by boost. The boost source pushes down on a piston that rasies the pressures. That's why you see terms like 12:1 or 8:1. For every one psi of boost you add a certain amount of fuel. So a 12:1 FMU would be 12psi of extra fuel for every one psi of boost.

How you determine how much fuel pressure you'll get is easy.

BOOST x RISE + *0 ~Hg. PRESSURE = Fuel in Rail at Full Boost
*It is import you calculate the fuel pressure at 0~hg. because that will be the spot that the fmu will start adding fuel. Otherwise at idle 20~Hg. your fuel pressures are about 5-7psi lower. Anyways


So, 8psi X 12:1 + 48psi = 144psi of fuel in the rail

Which is way too much, but that's another story.

The reason turbo miatas tend to use FMUs is because it is easy and fairly effective. Plus it typically does not require the use of aftermarket engine management to control the fuel. Is one way better than the other, not technically, cause the job gets done. Is one more effeicent and easier to tune, yes. Once you get your computer on board you can run larger injectors are lower pressures and control when/where/how your fuel is added or removed.

Another Story:

You typically don't want to run more than 100psi of fuel in the rail. Your hoses and injectors will appreaciate it. The "failing" point of injectors is rated at 100psi, but some tend to disagree to that. Plus the is high potenial that the lines can burst or slip or leak (it's not fun, and yes it does happen).

So with that said, you tend to tune for 100psi of fuel in a miata with an FMU as a general point. But your injectors can only flow so much at 100psi of fuel.

How much you say? This much:
PSI in the Rail / 43.5 = New Flow Rate

Square Root of NFR x injector size = new cc level

Example:

100 / 43.5 = 2.299

√2.299 = 1.516

1.516 X 203cc (stock 1.6L injectors) = 308cc
What does this mean to you? Well it means your small 203cc injectors when given 100psi of fuel can flow 308cc (42HP) each. So around 170BHP or so.

Last edited by Braineack; 10-13-2006 at 10:27 AM.
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Old 10-13-2006, 11:16 AM   #13
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So if i understand correctly:

Installing a AFPR (adjustable fuel pressure regulator) or an RRFPR (rising rate fuel pressure regulator) and a new diaphram on the stock FPR (fuel pressure regulator) its good for boost, but not enough because the stock FP (fuel pump) just cant handle the pressure.

Installing a new fuel pump by itself is worthless because the stock FPR will just dump the extra pressure.

So really - ya need both.

Now that I think I understand that - who makes AFPR's,RRFPR's, FMU's etc?
I know Bipes is timing retardation, walboro is the fuel pump.. etc..

Thanks for all the info braineack
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Old 10-13-2006, 11:35 AM   #14
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Quote:
Originally Posted by Anotherskait View Post
Installing a AFPR (adjustable fuel pressure regulator) or an RRFPR (rising rate fuel pressure regulator) and a new diaphram on the stock FPR (fuel pressure regulator) its good for boost, but not enough because the stock FP (fuel pump) just cant handle the pressure.
Correct, installing a FMU (let's just stick with that term) will only work as good as your pump can output. That being said I made 170rwhp on the stock pump.

Nothing needs to be modified on the OEM FPR, it will allow for a 36psi idle and 48-50psi of fuel at the transition into boost. The FMU works in conjuction with it to raise fuel above that point.

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Originally Posted by Anotherskait View Post
Installing a new fuel pump by itself is worthless because the stock FPR will just dump the extra pressure.
Basically, the OEM FPR only raises the pressures by so much in less vacuum.

Quote:
Now that I think I understand that - who makes AFPR's,RRFPR's, FMU's etc?
The best of the best in FMUs would be the BEGi adjustable unit. It allows for higher base pressures if desired, plus the gain is adjustable from 12:1 to 1:1. So with a Fuel pressure gauge you can tune it exactly for each level of boost you upgrade to.

The most common here is the Vortech FMU. It uses different size discs to change the gain. There is no adjustablity other than swapping out disc sizes.

Obviously the BEGi unit is a better choice due to the amount adjustments you can make for a particular tune. However, if you do your math right the Vortech unit does as demanded apon. Plus bank account plays a big factor in each, where the vortech you can pick up for 80-100 used, the BEGi unit can be found anywhere from 100-200.
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