Rail Pressure....
 

Hello all,

I bet this gets a few guys attention (mikey and superduty!) ha ha here is my thought I was reading a post the other day and superduty made a commit about the increased rail pressure VS. fuel flow and showed a formula that I feel was correct and would agree w/ his math...however it only reflected a maybe 10% gain in going from 23k to 27k pressure and like I said the math works....but I am tricking my fuel sensor and I think I am about 26k fuel and it combined w/ the other map mod is making exponential power gains...so why? Is it the truck sees a lower fuel pressure than what is really there and advances timing....and increasing pulse width? What gives?

From Doug Leno's report in the TDR#48 magazine he states theres about 13hp gain per 1k gain in pressure. So by increasing the rail pressure by 3k psi you gain around 39hp. Note, you could be exceeding 26k psi and don't know it because of the voltage saturation on the sensor. It maybe already at the limit. I believe the relief valve will open at around 28k psi.
Doug also mentioned increasing the pressure you are also advancing the timing slightly and decreasing the duration. So with the other mods you have done, like the crankshaft sensor and the boost fooling, you could easily gain 60+hp and 100+ lb ft of torque which is quite noticable.

MikeyB

how does increasing pressure advance timing slightly? is that what's going on in pressure boxes?

using the 13hp per 1k pressure increase formula, a box like the EZ or ZXT would have to increase pressure 5k to achieve a 65hp gain. :o

that seems crazy, there must be something else going on to see these substansial gains people are seeing, otherwise the rail pressure would be insane.

please enlighten me too [duhhh]

Good article on pressure boxes.
http://www.drperformance.com/TDR48.pdf
Explains where pressure, timing and hp comes in.

MikeyB

wow that's a ton of info

thanks mike

Thanks mikey you’re a lot of help! :) I think I must be hitting a point were the timing factor kicks in cause this thing will spin out @ 30mph in forth and slips the clutch at 60 in 5th or 6th gear have not chained her down yet to see what its putting to the rears yet.....I think this would be really cool w/ a tst what do you guys think?

Since the TST does timing and duration it's doable. Maybe a little too much timing with your crankshaft sensor mod. Problem is not only the clutch won't hold, but the turbo is going to get super hot from exceeding it's maximum boost rating, and decrease it's lifespan.

MikeyB

i guess i will add that to my shopping list....new turbo!

But first, get some GAUGES!! ;)

MikeyB