[QUOTE=speed_monkey]Wouldnt you have to take into consideration that it's a rotary and not a piston engine? They need more air per horsepower than a piston engine, so they would also need more fuel correct?

my guess would be yes which is why i set the BSFC at .70

and adrock3217 how can the stock fuel pump not keep up with 119lph if it pumps at 180lph?

and everyone i started this thread in reference to light basic power mods (i.e exhaust, ported wg FCD...maybe even an intake) in mind.... plz post with that in mind it would be more helpful

 

Ok, so, lets say I'm at light throttle at 4000 rpm, not under boost..the secondary injectors are indeed squirting, but hm, lets see. I'd say you will be getting a lot more fuel then needed, as you will be putting in more fuel, when the car is in an area of the RPM range where more fuel is not needed (then stock).

Your method can and will work, but it will not work correctly at all RPM's. If you loose boost in the upper RPM, as normally the stock turbo cannot keep up..WOT, 720cc secondaries, lets say you bleed off to 6psi. Hmm, it would appear that you would be injecting a lot more fuel then necessary .......

 

adrock3217 how can the stock fuel pump not keep up with 119lph if it pumps at 180lph?

 

Yes it does actually.

The FPR is a very simple device that cannot respond to upstream changes in fuel pressure from a bigger pump, no matter how small the increase is. If you put more pressure in, you get more pressure out. The proof of this is the 2-speed pump systems fitted to FC's and many other cars. Changing the voltage sent to the pump changes the fuel pressure. The FPR is not their to keep the fuel rail pressure constant, but to maintain a constant pressure differential across the injectors. That's why it adjusts pressure according to manifold pressure.

Your assumption is completely wrong. This works nothing like an air compressor.

Because as boost increases the pump must work harder to maintain that constant pressure differential. Not only does more boost need more fuel, but the pump must push against higher manifold pressure when the injector is open.

You're dead right, which is why a significant upgrade to pump capacity requires an aftermarket adjustable FPR to bring pressures back down. A mild upgrade like the FD pump doesn't make enough difference at low flows to need a new FPR.

Uncontrolled as in no way of tuning the amount of fuel injected, i.e. a fuel controller. Without some form of fuel control bigger injectors will cause overly rich mixtures, which reduces power and increases fuel consumption.

I'm sure it was common a long time ago before fuel controllers were cheap and readily available. These days there's no excuse for such crude and lazy "tuning".

The FD does "overpower" the stock FPR, if by that you mean more fuel gets through that with the stock pump.

You need to take your own advice. Your posts demonstrate a scary lack of understanding of how EFI works...

 

NZ:
It seems as though the topic of the thread has been greatly expanded, and the bashing unrelated to the thread subject.

My reply was to put in larger secondary injectors, a FD pump, along with the exhaust and FCD. I still stand by this economical way of gaining HP with the 3" exhaust, along with the added safety of additional fuel.
Is it as good as a full electronics upgrade, of course not, but not everyone has the resources to do what you suggest is the "correct" method. Some would need to spend more than what the purchase price of the car might be, that's why they use (your term) crude and lazy tuning.

As for the 2 stage pump, it was designed for longevity, not because of flow capacity and the FPR. When fuel not needed, it will run along on 9 V, then jump to 12. People that do a rewire don't have a problem with running a constant 12V, at least the ones I know.

"The FPR is not their to keep the fuel rail pressure constant, but to maintain a constant pressure differential across the injectors. That's why it adjusts pressure according to manifold pressure."

That is correct, but as in my simplistic example, the FPR IS to maintain a certain pressure, whether under load or cruising, depending on the need.

Quote:
Why install a pump if the injectors cannot take advantage either through larger injectors, or better electronics.

Because as boost increases the pump must work harder to maintain that constant pressure differential. Not only does more boost need more fuel, but the pump must push against higher manifold pressure when the injector is open.
Exactly. Read my reply. I was asking why install a larger pump if you don't upgrade the injectors, and have a FCD. You'll see no more flow than what the ecu demands at fuel cut with the 550 injectors. Once again the need for more fuel, larger injectors.Unless you're one of the people that will say, with a larger pump it will force more fuel through the injectors.........

Quote:
Have no idea what you're referring to as uncontrolled upgraded injectors.
I'm suggesting replacing the secondary injectors with 720's and keeping the original ecu. It will allow more fuel without a more expensive system, and he'll have the pump to maintain the fuel flow.

Uncontrolled as in no way of tuning the amount of fuel injected, i.e. a fuel controller. Without some form of fuel control bigger injectors will cause overly rich mixtures, which reduces power and increases fuel consumption

In the late '80's guys would add the larger secondary injectors, RB Turbo system and a FCD. Geez, their cars would kill nearly everything at that time. My cousin had an '88 and drove it this way for 4 years until he traded it. Just remember if larger injectors are used, they are still controlled by the ecu, and will be proportionally more fuel throughout the rpm, but governed by the ecu.
I know in my TII with the GForce ecu upgrade, when accelerating at a normal rate, at the transition to the secondary injectors, it's almost like shoving you’re foot down further to the floor. Even if the pedal is not moved. The car will shoot forward because of the extra fuel. Never had a flooding problem, car passes emissions each of the last 6 years, and pulls hard.

I guess you could say I did a crude and lazy tuning on my S5. Just added the GForce computer, stock air box, stock mufflers with a Bonez high flow cat, Fd pump. I was going to install a Hallman remote to take it up to 12/13, but the 10/11 has been fine.


OUT!!!!!!

 

Nothing wrong with that. People might learn something...

Economic yes, efficient no. The point of adding fuel system upgrades is to increase the capacity of the system so it can keep up with the increased airflow (i.e. maintain a safe AFR) when making significantly more power than stock, not just to make the mixtures excessively rich.

What I'm suggesting is nothing more than a piggy-back fuel controller to lean out the pig-rich mixtures caused by upgraded injectors. You can get a new S-AFC for less than $200. I'm pretty sure most people who need bigger injectors have invested a lot more than $200 in their car.

I know exactly what it's for and what it does. The point is it's been proven with a wideband that increasing the fuel pump voltage lowers the AFR (i.e. richer). The only way that's possible is if the fuel pump is pushing more fuel through the injectors, and there's nothing the FPR can do about it. This is the same reason that fuel pump voltage boosters work so well.

There no problem with doing that, except that it increases low-load fuel consumption for the reason explained above. Rewiring the fuel pump to reduce voltage drop and retain the 2-speed system is easy.

It is NOT to maintain a certain pressure; it's to maintain a constant pressure differential. Very different. Fuel rail pressure is far from constant because it must increase and decrease in line with manifold pressure.

Hopefully by now you can see how wrong you are with this point. Upgrading just the pump will provide more fuel without changing anything else. It's been done and proven. Accept it and move on.

Who cares what people did 10-15 years ago? That's practically the dark ages in EFI terms, we've moved on just a bit since then. There are lots of things we do differently (i.e. better) now because advancing technology and dropping prices allow us to.

The stock ECU has no idea how big the injectors are or how much fuel it's injecting. All it knows is how much air the engine getting (up to the limit of the AFM) and how long to open the stock-sized injectors for that particular airflow to get the right AFR. If you simply add bigger injectors without any way to tune them, you will make the mixtures richer.

More proof you have no idea what you're talking about. If you simply add more fuel, and the mixture gets richer, you lose power. The richer the mixture is the cooler it burns and the less power you get out of it. Simple thermodynamics, long proven in both theory and practice. What ever you think your car does is either because of something else you're not telling us or it's in your head.

The secondary injectors aren't firing when you start or idle the engine so upgrading them won't ever cause flooding.

 

NZ:

I wasn't going to respond, but hey, I'm sitting around the house recovering from shoulder surgery and it gives me something to do.

It's going to be short and will condense all the gibberish into the following. Seems someone can run larger injectors on a stock ecu and NOT flood the engine out. It may be 25 years old ingenuity, but getting it done on a stock ecu with stellar results.

From Rohnert Park, CA.:
I’m running about 300 crank HP out of my S5 engine with the RB 3" exhaust, but more fuel is needed to feed the increased boost.

A SupraTT or Cosmo fuel pump are good choices and quieter than the Walboro. I run the SupraTT, and you'll be best off with some 680-720cc secondary injectors too. I run 800cc secondaries and they are well matched to the 14psi of turbo pressure. I run no fuel control trickery, just stock ECU pulse widths. I used to run 680's with my old S4 setup around 12psi,it was also very well matched with no fuel controllers.

To safely control the increased boost to match your new found fuel delivery, you'll need a boost controller. Don't skimp, get a good one. I run an Apex ACVR with excellent results.

I've run my setup for years and years with very good results and excellent manners from the stock S5 ECU and full smog gear intact.

 

I don't know who's account that is, but I wouldn't trust their opinion... For one, it's amazing they recommend both the Cosmo and the Supra pump, when they are the same Denso part #...

Also his #'s alone go to show how innefficient his setup is... ~260whp @ 14psi is NOT good... I can't even believe you would listen to someone who has such a ghetto trailer park setup... I don't understand why you would not believe NZ or HAILERS, since the information they've given you is all based on pure FACTUAL evidence... It's been tested... It's been proven... Get over yourself and take their advice!

 

Wherever you got that info from the guy is completly ignorant.

Everything NZ is saying is correct.

The reason there is so much misconception is because running rich (especially under boost) is actually a more reliable (although produces less power) than running more near stoichimetic ratio.

Rotaries blow up when they go lean, especially boosted ones. And every engine experiences more wear the more power it produces. So by running excessivly rich you reduce both sources of premature failure. To a point....because when you get VERY rich you cause other problems.

Further your never going to flood the engine out (as NZ already stated) with larger secondarys) its just going to produce less power (and if really rich) missfire like crazy durring WOT high RPM driving.

The down sides of running rich (even if its only high RPMS) other than less power from overly rich mixtures are these. You will foul your plugs faster, and you will destroy your catalytic converter (if you are still running one).

Excessive fuel delivery will not increase boost, actually quite the oposite. Overly rich mixture will reduce the boost created by the turbo....again a source of backing into longevity through lack of tuning.

The reason people swear by adding secondaries is because they by default run too rich and produce less power, both (to a point) increase longevity of the motor and turbo...

 

DUH! Read the threads.
I never said NZ wasn't correct, in fact I agreed with aftermarket fuel controls, but I challenged his statements that a fcd, larger secondaries, RB 3" exhaust, larger pump, would not work, that they make less power. They don't from example. Could the above make more power if a stand alone was used, then tuned properly, providing you don't blow the engine when do so, certainly, but I rest my case, 'cause I've seen guys go this route dozens of times. You'd need to change the secondaries anyway as the stock injectors would be maxed out, but it's a start.

If you want to knit pick, he also mentioned on his first reply, that the 2 speed TII pump was reduced because of volumn and the FPR. When I corrected that and stated it wasn't because of volumn, but it was to ensure pump longevity, he then said he knew that!!!!!!!!!!!!
G Figure

 

Ok, with these statements, I kinda have to step in.


I don't know who's account that is, but I wouldn't trust their opinion... For one, it's amazing they recommend both the Cosmo and the Supra pump, when they are the same Denso part #...

Well, if you tell someone just Cosmo, and they can't find one, they would be like "****, Walboro it is." But if you tell them BOTH, chances are they will be able to find one or the other. That is probably the most efficient way of communication....

Also his #'s alone go to show how innefficient his setup is... ~260whp @ 14psi is NOT good... I can't even believe you would listen to someone who has such a ghetto trailer park setup...

I have for one never seen someone make over 265rwhp on a stock S4 or S5 turbo. So...those seem to be quite excellent numbers...

 

I have seen cars with the stock turbo make power like that on 14-15psi, but it wasn't efficient WHATSOEVER... The logs were terrible and that was with fuel control... The stock turbo simply cannot handle that amount of boost safely, especially without some sort of timing control... Please tell me I'm wrong...

If all you have done is an FCD/exhaust/etc, and you're wondering whether you need a fuel pump, I highly doubt you're running a larger intercooler, which is also a big setback... I wonder if that "300bhp with no fuel control" guy ever got it on a wideband?

 

i realized that the source of the problem with an FCD isnt the stock fuel pumps inability to supply enought fuel but its lack of knowledge of how much fuel is needed. as you all know the FCD tricks the ecu into beliving the boost is lower than it really is. as a result if the motor is boosting at 10 PSI the ECU thinks the motor is only boosting at 7 or 8 PSI and as a inturn gives the engine fuel that is necessary to sustain the fictional 7 or 8PSI instead of the actual 10PSI. while this problem can be solved by installing a larger fuel pump and larger injectors to force an unknown amount of extra fuel into the engine, as many people have said, this is a rather uncontrolled solution and with todays gas prices rather uneconomical. the cheapest, easiest, and safest way to solve this problm is to make sure the WG is ported to a large enough diameter, keep the stock air box, and use either a racing cat, stock cat, or presilencer for back pressure to keep the boost levels at 10PSI or below and wait until you have enough money to properly upgrade with a programable ecu. while you wont be able to ralize the full potential of your boltons for a while, atleast your motor will last until you can get the money to do so.

 

Bingo!

 

Who besides you said anything about flooding the engine? Like I already said, upgraded secondary injectors can't cause flooding.

Get real. There's nothing "ingenious" about it, quite the opposite. Bulk rich mixtures are a cheap, easy and safe, but they're also inefficient in terms of both performance and fuel consumption. Proper mixture control and tuning would make the car faster and still be safe.

I think you need to go back and read a little more carefully nowhere did I say adding all those things would result in less power. What I did say is that if you do nothing other that upgrade the secondary injectors, thus making the mixtures much richer, you will lose power. This is a proven fact.

Again, put your reading glasses on and go look again. I never said anything like that. I brought up the 2-speed system as proof that an upgraded fuel pump will push more fuel into the engine. Nothing more.

No, it is the pump's inability to supply enough fuel. Forget about the EFI side of things for a minute and think about how pumps work. The pic in this thread shows the flow vs. pressure curve for the stock TII pump. You can see that as flow increases the pressure drops. But as manifold pressure rises the fuel pressure also has to rise to match it, so you get to a point where the pump simply can't provide enough pressure and the engine runs lean.

Nope, the MAP sensor has very little to do with calculating fuel requirements. The AFM is the main load sensor and it isn't affected by the FCD, so fuelling is based on the airflow the ECU is measuring. As boost increases so does airflow, so the ECU does add more fuel as boost increases, at least until the AFM's flap is fully open. What the MAP does affect is the ignition timing, with the timing being retarded as manifold pressure increases. So once you get above the FCD's clamp point you have less ignition retard. If the ignition is too advanced (or not retarded enough) you can get detonation, so steps need to be taken to prevent that. Rich fuel mixtures reduce the chance of detonation by lowering combustion temps (that's why the stock mixtures are so rich), and reducing the intake air temp (CAI, FMIC) has the same effect.

 

Jason:
Let me start by saying that over the years that I've been on this forum, I don't believe anyone can match your overall knowledge of the FC. It seems as though you have an answer for any problem, question, or theory that is posted. Reading your answers, one might even believe you were involved with the rampup of the FC. I even have copies of threads saved, with your responses, that I felt might help in certain situations.
Having said this, I certainly wasn't challenging your quick and valid responses, but only suggesting that there was a viable "build up" solution using the poster's parts that would be satisfactory, and nothing more. I've stuck my neck out further than I should, so I'm bowing out, and hopefully haven't offended anyone.