This should be a sticky...

 

I'm not asking your advice.

It is a good idea to put the pump in, for all the reasons you have stated. Correct, and agreed.

I'm just stating that adding a pump alone will not make your car run rich. It is important to get the facts straight, that's all. The statement about the regulator not being able to keep up with the extra flow from the pump is wrong, and should be noted as such so that nobody gets incorrect information from the forum.

Just my .02, please nobody take it personal. I'm not trying to attack anyone, I just want to see accurate information on the site. That's why we all come here.

 

Your 2 cents are noted - and incorrect

The replacement of the pump will cuase your car to run richer in the upper power band

Again - we will have documantation of this in a few days to quantify specifically the change

Finally - I would kindly suggest that you voice your concerns over on the Vishnu area of this forum as I am growing tired of responding to your differences with my opinion. If you disagree - thats fine just please do not repreatedly post the same thing over and over again in my section of the forum - you are free to post in any of the dozens of other areas of this web site to your hearts content - thank you

 

I have datalogged before and after the walbro pump install at WOT. The O2 voltages before the fuel pump where .96 ot .97 volts at anything over 5 psi of boost pressure. After the Walbro install the O2 voltages where 1.00 volts at anything over 5 psi of boost pressure. This was a consistent pattern. For those of you who clain you can't tell anything from O2 voltages. Go tell all that to Buschur, because that is how he told people to tune there SAFC's. Well at least its in their instructions.

The Walbro fuel pump does indeed increase fuel pressure in the 3500 RPM and up under boost. I know this for a fact. 100% chance of it.

The reason the stock fuel pressure regulator cant return enough fuel is because the return ports area is not large enough. A specific sized orifice will only flow a certain amount of volume per given unit of time at a given pressure. Go get a fluid dynamics book and read it.

Brian

 

Listen up Al. As an evolutionm.net user, I am free to participate wherever I wish, in any forum. Unlike yourself. I see no reason for your brash posting, I was not attacking you. And just because I have Vishnu parts doesn't mean that I am "follower", I bought those parts because I liked them for my car, in my application.

The fuel pump AFR effect argument may not be the most important in the world, but I just find it important that these sort of things be accurate. A lot of people come to the site to learn, including me.

As for whether I am wrong or not, if I am I'll own up to it. I'll be anxiously awaiting the results of your testing since I do not have the facilities to do it myself, or I would have already. Please post your findings.

 

Orifice size, Time, and Pressure being the variables determining the rate of flow from the FPR bypass back into the tank. If you increase any of the variables in the equation, such as pressure, you will have increased flow. It is certainly not a linear effect, as there is a diminishing point when the orifice size reaches it's maximum volume, but that would be far beyond what the new pump ( which is only about 25 LPH more volume ) could actually flow.

So you are correct in your statement above, but it is misapplied because you will be changing the "given pressure" part.

 

Since ou are so fixated on this subject - perhaps you care to share your story regarding how you chose to select a upgraded fuel pump along with your x flash and also IF you have a custom tuned X flash and what fueling corrections - IF any were made to correct for the larger pump ???

 

I had my pump and custom tune done the same day. During the custom tune, the varience from start to finish was off at most by like .4. So, not much of an adjustment was needed. Maybe Shiv could shed some light on it for you, since he was the one that tuned the car not me.

 

Ditto for high altitude ... the stock Evo pumps seem to fail if pushed at higher elevations (eg. Colorado )

l8r)

 

Runs 15 and 16 are the stock pump with the through the mail tune

Runs 17 and 18 are after we swapped the fuel pump with the Walbro 255

Mods are HKS suction intake - 3" exhuast - Boost controller and now a fuel pump

Not only did the a/f turn significantly richer - BUT - in the process it lost almost 10 whp average

I think this proves my thoery that the walbro pump flows more fuel and make more fuel pressure on high speed of the ecu and therefore makes the car run richer

Therefore - you need to re-tune your Dyno Flash for optimal perfromance after you change to the Walbro 255 lph pump

It seems the Vishnu camp that has been harassing me for the past week are dead wrong

We have not rulled out of course the possibility that low whp tunes may be effected differently by the pump swap. Since we make significant whp figures on the Dyno Flash we usually strech the capacity of the stock pump - even on otherwise stock evos. With other tuning devices your results may vary.

Next up - we are going to do this test on a bone stock evo.

 

Bigger

 

That car is mine and this is the end result
http://gallery.evolutionm.net/data/5...oduct2-med.jpg
Thanks Again
AL

 

Look at how smooth those gains are and how steady the A/F is

again Al
THANKS
see you next month

 

Ah - you got special treatment they made you the 3 way dyno sheet - great !

Looks great - YOU KNOW - that car was a real challenge to tune - it took a LOT of passes to get it dialed in - sometimes we get lucky and the cars follow our base maps and other times it can take many corrections to dial in the tune just the way we like it

Sorry I had to leave so quickly when we got it done but my wife was ready to kill me after I had promised it would only take me a few hours today to tune 3 cars and I wound up staying till 6:00 p.m. and also being 45 minutes late to meet her for dinner !!!!!

I wish I had a chance to drive it after the tune - it must have felt real strong! Enjoy it

 

This looks like the stock pump was just not flowing enough to start out, and then you were able to reach the correct AFR after putting the pump in. Or, you made changes between runs to affect the AFR.

A bone stock EVO without any re-flash would be a much better test, and probably the only way to really tell for sure. Since this car is at the level where it needed a pump already, this test doesn't really prove the point. You said it yourself that this is the level of power output that a higher flow pump is needed at.

All this proves is that this car in fact needed a pump, to be able to flow enough fuel to meet the correct AFR. Which means that your mailin flash with out a higher flow pump, would run lean in this case.

Try it with a stock EVO, and no flash changes in between. On this car the mods would have affected his stock fuel system's ability to produce enough flow anyway. The point was to find out on a car that was already producing enough flow, if the pump would add even more making the AFR richer. Effectively I guess the question at hand is wether that extra 25'ish LPH would be enough to overun the stock pressure regulator, and cause the car to run richer than previous.

This doesn't really prove the point, but way to go at stepping around the question.