uh huh.... make your case and i'd be glad to admit defeat, but you have shown me nothing

 

nice write up!

 

I know that you want to believe that back pressure regulators perform ideally, but they often do not. I work with them on a daily basis, and with the back pressure regulators that I use ($800/ea), a 10% increase in flow will cause a 5% rise in system pressure.

Now I suppose its possible that the fuel pressure regulator on the Evo has been specially tuned to be absolutely independent of flow, but I doubt it. The question in my mind is how sensitive is pressure to the flow rate.

 

ok. I was just a bit confused about showing the IDC values. I got the impression you were showing the IDC values as if changing a fuel pump alone will cause the IDC values to change.

 

no, the idc was shown to demonstrate that the tune was identical, thus IDC from the stock pump, and with the walboro before the tune should be the same (or really close to). after the tune, it should change only slightly.

 

i'm going to get a pressure sensor and drill out my fuel rail for it tonight or sometime this week. i'll log it on the zeitronix and show the results. fortunately right now i have the stock 8 pump in my car and i have a few walboros sitting on the shelf as well.

 

although fuel pressure doesn't have as big of an effect on the amount of injected fuel as duty cycle does, if we were to see a increase in fuel pressure at idle and lower loads, we would see an across the board decrease in duty cycles as well, which just from looking at my plots from the 9, that is not the case. i will investigate further though.

 

Yep, its not as sensitive. Flow through the injectors goes roughly has the square root of the fuel pressure drop across the injector, while flow through an injector is linearly proportional to IDC.

Hooking up a pressure sensor would be great. Its better than trying to figure it out based on the results of tuning on IDC.

 

Has anyone really hooked up a pressure sensor to see if the fuel pressure rises with the addition of the Walbro 255 (or any other higher flowing pump) vs. Stock?

I bought a pump becasue a lot of threads say its a good idea (I have a nine) but I am debating putting it in and if I do and it's true you need to lean the mixture due to more pressure then I would need to remap right?

If someone logged before and Walbro install and the A/F ratio changed wouldn't this mean the regulator is not maintaining absolute pressure and is of a design that is relative or proportional to the amount of input it is given?

I'll cut to My chase. I would like to know if I install my Walbro 255 if I will need to remap solely due to the higher output of the pump or will the regulator maintain consistent or same pressure as stock pump? I have heard that it does and does not increase fuel delivery to the engine so someone please set me straight.

I plan on turning up the boost but want to know how this new fuel pump could affect fueling Prior to turning up the boost. I would imagine Mits. engineers designed the fuel system to provide sufficient fuel up to or near 100% IDC so should I just stay stock until I get near maxing the stock injectors?

TIA for any thought and responses to my questions

I found this thread while searching for the answer so I figured I'd jump on this rather than start a new(b) one

thanks for helping a newb to the world of Evo tuning

 

From what AMS has told me, the Fuel pump is perfect with their stage three cars, it works fine unless you go bigger turbo, SWEET!!

 

Of course you do.....

but I think AMS is a better source of information and I believe they have tested the IX pump as well so who are you and what do you have to back up your "suggestion"......(besides the obvious response "i have tuned over 1 gazzillion evos bro)

ams fuel pump test: https://www.evolutionm.net/forums/sh...=ams+fuel+pump

 

Thanks for linking to the AMS test.


I like the walbro but it is rediculously noisey and would gladly consider an alternative.

 

I also feel that it gives you an overly rich condition while putting around town. If you can retain the OEM fuel pump I feel it is better, less back fires and fireballs and better tune IMHO. Adding a fuel pump is not needed even with CAMS on the IX, I love that.

 

I love that sound

 

This is what I was looking for so for around 330 - 350 whp pm a IX a fuel pump is so so needed