where to buy an adjustable FPR? Turbo guys chime in!

[BLINGMW]

I'd like to get an adjustable fuel pressure regulator so my little 318 can be properly tuned and run correctly without an O2 sensor, headers, no cat. Ok, whatever, just something else to play with. I need something not application specific, just an inlet/outlet and a vacuum connection (I guess?). Maybe I don't even need that, it's not like I care much if it runs a little rich at idle. I guess I'd gut my stock FPR that's mounted on the injector rail and run this into that. I see ones out there that are upwards of $300. Screw that. Any ideas on where to get one that won't break/leak right away for less than $100?

[CaptainHenreh]

Alot of the billet FMU's I see on ebay run ~80 bucks and seem to be of good quality.

[.RJ]

Huhu... when does the "nawz dial" get installed? this weekend?

[KPWSerpiente]

I'm extremely confused about your needs.

Why do you want/need an adjustable fuel pressure regulator?

Are you running a larger than stock fuel pump? Are you somehow flowing so much air that your current set up is not able to supply the fuel? And why would you remove an oxygen sensor?

Perhaps you just want the bling?

Alot of the billet FMU's I see on ebay run ~80 bucks and seem to be of good quality.

Why would he want to run an FMU on a naturally aspirated car?

Here is a 129$ universal fpr from full throttle.

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-T

[BLINGMW]

I'm extremely confused about your needs.

Why do you want/need an adjustable fuel pressure regulator?

haha, I can understand your skepticism. And it's entirely possible I'm going about this the wrong way. I just want to make sure that at full throttle, the A/F is around the 13 something that's best for power instead of 14.7 or more. It's possible that just disconnecting the sensor might make the computer err on the rich side and I'll get lucky. But when I goto a dyno, or borrow a wideband, I want to be able to dial in the correct amount of fuel. And currently, I'm not sure I have a stock FPR that's doing it's job right. So I figured if I could spend $50-$100 and get an adjustable, that's not much more than a stock non-adjustable one.

Just trying to learn too, and I like having control over the systems in my car rather than hoping the primitive ECU will figure it out. I do see FPR's like I'm looking for pop up on e-bay now and then, there's one now matter of fact.

I don't even know what the difference between a FMU and FPR is. :oops:

[CaptainHenreh]

Why would he want to run an FMU on a naturally aspirated car?

I don't even know what the difference between a FMU and FPR is. :oops:

Because at 0 psi he could still adjust fuel pressure? My understanding is that an FMU is just an RRFPR, with fewer letters. My point was that I see them cheap, and that if he was looking for cheap, he could do that...cheap.

[Feersty]

:?:

[KPWSerpiente]

I just want to make sure that at full throttle, the A/F is around the 13 something that's best for power instead of 14.7 or more.

This statement makes little sense. Your car will never see an a/f of 14.7 at full throttle. 14.7 is the ideal ratio for cruising, idling...partial throttle situations. Also who says 13.x:1 is good for power? How long do you want your engine to last? If you are seeing 14.7 at full throttle right now...you are melting your engine.

Your car will always be running richer than 11:1 at full throttle unless you are flowing more air than your current fuel system can provide fuel for. And usually you will hit fuel cut before this is possible.

So why do you need to be able to raise or lower fuel pressure? Do you need to provide more fuel than you are currently capable of doing? Do you know what your current a/f ratio is or what your current injector duty cycle is?

Because at 0 psi he could still adjust fuel pressure? My understanding is that an FMU is just an RRFPR, with fewer letters. My point was that I see them cheap, and that if he was looking for cheap, he could do that...cheap.

Under what circumstances is he going to need to adjust fuel pressure vs intake manifold pressure?

I aleady linked you to a decent one that won't run you too much bank. Convince me you need one before buying it.

-T

[Kaan]

well lets just say i'm going to need a FPR and a better fuel pump shortly.

Chan just b00st that pile! its not like you cant get an E30 for cheap... especially you!

[.RJ]

Chan is doing away with his MAF in one of his e30's and replacing it with a potentiometer to send the ECU a resistance signal. It doesnt work for shit to begin with and doesnt do anything over 3500 rpm except block airflow. We were thinking that as long as you get some resistance signal to the ECU that it could idle halfway decent and provide some more airflow above 3500rpm when the signal isnt even used. Chan's already tossed the idle control system and who knows what else fell off on the side of the road Chan, you should just put a pair of carbs on that thing

On the point of FPR's - if you were using something like a VAFC, if you need more fuel its best to have one to bump up the pressure and then use the VAFC to tune it out leaner where needed.

[Kaan]

that sounds like what you are planning on doing lol! well the FI equivalent to it.

[CaptainHenreh]

Because at 0 psi he could still adjust fuel pressure? My understanding is that an FMU is just an RRFPR, with fewer letters. My point was that I see them cheap, and that if he was looking for cheap, he could do that...cheap.

Under what circumstances is he going to need to adjust fuel pressure vs intake manifold pressure?
-T

He doesn't, damn it! But FMU's are cheap and readily available on ebay. He could probably score one for 60 bucks if he really looked. He asked for an adjustable FPR. If he really needs one, an FMU will do what he needs it to do. And then, if he ever wants to turbocharge it, well, he's in good shape, now isn't he? I operate on the theory that everyone wants to their car to be boosted, and if they say they don't, they either haven't found Jesus yet, or they're in denial.

So eat a D, Travis.

[.RJ]

I operate on the theory that everyone wants to their car to be boosted, and if they say they don't, they either haven't found Jesus yet, or their in denial

Now thats funny

[JackoliciousLegs]

NAs at WOT run 11:1 A/F???

[KPWSerpiente]

Chan is doing away with his MAF in one of his e30's and replacing it with a potentiometer to send the ECU a resistance signal. It doesnt work for shit to begin with and doesnt do anything over 3500 rpm except block airflow. We were thinking that as long as you get some resistance signal to the ECU that it could idle halfway decent and provide some more airflow above 3500rpm when the signal isnt even used. Chan's already tossed the idle control system and who knows what else fell off on the side of the road Very Happy Chan, you should just put a pair of carbs on that thing Wink

If this is the case...well then I retract any assistance. If that car ever gets to running right let me know about it.

On the point of FPR's - if you were using something like a VAFC, if you need more fuel its best to have one to bump up the pressure and then use the VAFC to tune it out leaner where needed

Oh yes. Just raise that fuel presure! Tell me why it is better. In fact...tell me what a vafc/safc actually does. And then tell me why your idea of what to do is wrong/impossible if I'm running injectors 50% larger than stock.

He doesn't, damn it! But FMU's are cheap and readily available on ebay. He could probably score one for 60 bucks if he really looked. He asked for an adjustable FPR. If he really needs one, an FMU will do what he needs it to do. And then, if he ever wants to turbocharge it, well, he's in good shape, now isn't he? I operate on the theory that everyone wants to their car to be boosted, and if they say they don't, they either haven't found Jesus yet, or they're in denial.

You're right. What was I thinking. Something designed to set and adjust fuel pressure vs something that is designed to read intake manifold pressure and bump up fuel rate at 5 to 10 times that rate...silly me!

NAs at WOT run 11:1 A/F???

No Jack. Of course not. Why would they run a safe a/f?

-T

[.RJ]

If this is the case...well then I retract any assistance. If that car ever gets to running right let me know about it.

:?:

This is chan's POS e30. It doesnt run all that great, and he cant seem to get a MAF in it that works worth a shit either. So why the hell not? No need to be so negative about it.

Oh yes. Just raise that fuel presure! Tell me why it is better. In fact...tell me what a vafc/safc actually does. And then tell me why your idea of what to do is wrong/impossible if I'm running injectors 50% larger than stock.

Who the fuck said anything about injectors 50% larger than stock? This is getting retarded. You cant add fuel with a VAFC anyways, so you need to bump the mixture up with something if you need it somewhere in the rpm band.

You're right. What was I thinking. Something designed to set and adjust fuel pressure vs something that is designed to read intake manifold pressure and bump up fuel rate at 5 to 10 times that rate...silly me!

If the intake manifold pressure never goes over 1bar (atmospheric) you wont get any rise in fuel pressure with a FMU... so...

No Jack. Of course not. Why would they run a safe a/f?

11:1 a/f is hardly healthy for a N/A motor. 12.5-13.0:1 is more realistic.

[KPWSerpiente]

It doesnt run all that great, and he cant seem to get a MAF in it that works worth a shit either. So why the hell not? No need to be so negative about it.

Ok. Sure. Cool. I think I'll take a few steps backward with my car as well...throttle body injection anyone?

I'm going to try and simplify this.

An SAFC/VAFC is first and foremost a super airflow converter....it converts the signal from the mass air flow sensor (maf/mas) and allows the user to alter this signal vs rpm.

Now how does this benefit the user? It allows him/her to trick the ecu into believing more or less air is coming into the engine and because that variable is critical in the ecu's decision on how long the injectors should be opened it ultimately affects how much fuel is injected into the cylinder.

Now there is a direct correlation between airflow and the ignition timing advance as determined by the ecu. So another byproduct of increasing or decreasing the airflow signal is to alter the amount of ignition retard or advance.

Who the fuck said anything about injectors 50% larger than stock? This is getting retarded. You cant add fuel with a VAFC anyways, so you need to bump the mixture up with something if you need it somewhere in the rpm band.

I said something about injectors 50% larger than stock. You said something about a vafc. When you demonstrate knowledge of how to use one I'll let you figure out why I talked about oversized injectors.

And because you CAN increase the airflow signal up to 50% you can increase fuel delivery with a vafc. But I'm glad we both agree an afpr is critical when tuning with an safc.

Sadly by itself it is not much help unless we are running into over run issues in which the stock fpr cannot hold back the flow of fuel.

-T

[JohnC]

(Just want to say this is an interesting tech discussion - thanks guys!)

[CaptainHenreh]

If the intake manifold pressure never goes over 1bar (atmospheric) you wont get any rise in fuel pressure with a FMU... so...

So, with an FMU, you can get an adjustable FPR, without using the extra increase-fuel-pressure-relative-to-intake-tract-pressure while paying only ~70 bucks, instead of a 125. Just because it has a feature you'll never use doesn't mean you shouldn't buy it.

I'm glad at least RJ understood what I was trying to say, instead of immediately taking the attitude of "If you're not going to do exactly what I say, I just will say everybody else is wrong."

Also, if you do get some kind of air fuel controller I have an *enormous* hotwire MAFS I'd let go for cheap. You'd have to make some kind of plug for it, but it's really the biggest MAFS I've ever seen.

[.RJ]

I said something about injectors 50% larger than stock. You said something about a vafc. When you demonstrate knowledge of how to use one I'll let you figure out why I talked about oversized injectors.

You dont need oversize injectors to benefit from running higher fuel pressure and tuning with a VAFC.