Regardless of what pump you use, the target rail pressure is about the same (58 - 65 PSI).
The difference is that on the vast majority of OE pumps (if not ALL of them), the target fuel pressure is not met at high demand.
I've see fuel pressures drop to as low as 40 PSI on a known "good" OE pump at 6000 RPM on a 300 HP FI application. I've seen lower than that on my own system and actually lost an engine to it.
Since upgrading the OE assembly with the Walbro pump, I've never seen the fuel pressure drop below 60 PSI, even as I ran on "fumes".

The net fuel pressure is exactly the same on the primary and secondary rails, which have enough flow to supply a little over 4000 cc at 65 PSI each. You wont exceed that on the secondary rail and you definitely wont exceed it on the primary rail.

Retuning will have to be done, but only because the tuning was already "wrong" to compensate for sagging fuel pressures.

 

MM calibration service purchased, Fuel pump assembly has been ordered and my injectors will be sent to kgpart.com for service, flow matched and upgraded.

 

w00t!

 

Well that supercharger isnt any fun sitting in a box. If i am going to get the most out of the norcal dyno/tune day in a few months I better get started working on the car now.

 

You guys need to get cracking on that and set a date!

 

I see . How much difference in AFR have you seen going from stock to Walbro

 

I will head over to that thread right now. I want this thing to happen, the timing would be perfect for me.

 

Oh, I dunno.
I started over.
The target lambda and the actual lambda always line up on my setup.

 

Need to clarify--when i agreed with Team I was reponding to his bypass statement and I was wondering if that changed with the new designed pump assembly in the 09 models.
I have had differences in the fuel rail pressures----when i blew the line connector spacer out!
OD

 

Oh? And what are they?

 

Not enough!

 

So from the above and referencing my own experience at approx. 350whp I could conclude that :
380/480/380 with a Walbro pump is a pretty safe bet if your target is 350whp ......

 

Well, that's net 200cc less then I recommended, isn't it? (And in the wrong positions.)

 

Yes 200cc less - just wanted to point out that if one gets the blues from an AT and juggles things around that 350whp is doable .

380 P1 /480 Sec /380 P2 are the positions you recomended to me the other day

 

No you recommended that.

I said:

If you were just going to add blues, you would have 380/380/480.

The blues go in P2.

Then, you have enough fuel for 350, but you are right at the edge (MAX of 380 or so crank HP).

290/380/700 Gets you over 420 at the crank.

 

which is it ?



My reference point is I ran 350whp with only 290/380/480 and saw afrs starting to lean out due to under capacity .
Add another 200cc by changing out the reds( 9% ) + whatever you get from upgrading the pump and you should be sweet at 350 .

 

280/380/700
or
380/480/700

Those are your choices.

I guess you can do 380/480/480.

 

WHP considerations aside - is there any reason why 380/480/380 would be a bad combo ?

 

Not particularly, though I like having the smaller primary/secondary combo.
But that is TOTALLY personal preference.
There isn't any serious technical reason why 380/480/380 wouldn't work.
You should be able to hit 300 - 320 WHP safely with that combo.

 

I hit 350whp with 200cc less than that (290/380/480)at which point injectors were at 90% and AFRs were starting to go lean up top .
Which is why I made the above statement about 380/480/380 working to 350 - you would have about 9% spare capacity not counting whatever you got from upgrading the pump .
I guess that is still below the recommended 75% max duty cycle so not ideal .

Nevertheless a lot of people have done the swap to AT blues and i'm sure they would like to know how far they can push that combo without going to aftermarket injectors.

 

I run 290/380 and modified blues in P2.

 

Interesting . Do you prefer the modded blues vs aftermarket because of latency issues ?

 

I prefer them because they are cheap and they work.

 

Turns out the rich 'accelerator pump' effect I was getting was more to do with maf scaling than anything else .
Compare previous log to this one and there is no rich condition this time . Injectors still the same as before 380/380/480

Now can conclude that there don't seem to be any issues with running this setup.

 

Fixed.
Don't jump to conclusions.
You'll eventually find the big issue.