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Exhaust Brake

Started by hakcenter, May 26, 2015, 09:26:15 PM

hakcenter

Finally mounted my switches (not going to use a perf switch)


void exhaust_brake() {
  if (turbo_rpm < 55000 && turbo_rpm > 45000) { vane_position = map(turbo_rpm, 55000, 45000, 900, max_position); }
       if (turbo_rpm > 60000) { vane_position = vane_position - 50; }
  else if (turbo_rpm < 45000 && vane_position < max_position) { vane_position = vane_position + 25; }
  if (vane_position <= 900 && turbo_rpm < 60000) { vane_position = 900; }
  if (turbo_rpm > 21000 && turbo_rpm < 35000) { vane_position = map(turbo_rpm, 21000, 35000, 800, max_position); }
  if (turbo_rpm < 21000) { vane_position = 800; }
       if (vane_position <= min_position) { vane_position = min_position; }
  else if (vane_position >= max_position) { vane_position = max_position; }
}


I'll take pictures tomorrow.
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

#1
Looks OK, though I'm not quite wrapping my head around how the exact logic works out while you're driving...

In my boostmap setup, I have a area of the map (High RPM, Low TPS) where I set the boost to 15PSI.. I call it the "auto brake" area... do you think it'll actually build that kind of boost without any fueling?
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

#2
Quote from: Rx7man on May 26, 2015, 10:05:06 PM
Looks OK, though I'm not quite wrapping my head around how the exact logic works out while you're driving...

In my boostmap setup, I have a area of the map (High RPM, Low TPS) where I set the boost to 15PSI.. I call it the "auto brake" area... do you think it'll actually build that kind of boost without any fueling?

The turbo is simply a centrifuge, so if it is spinning fast enough, absolutely will create boost. Whether that goes right out the exhaust is a different matter.

I'm yanking out a bit of the section and tightening it up.. it is working pretty well on my truck too bad I don't have a BP gauge.

I can tell you, 800-825 position does pretty much squat, where as once you get into the 900s small increments really changes how fast it slows your motor down.
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

In my initial test on my method, I'm going to try to not care at all where the vanes actually are at, and just use math to set them at the right position... without an exhaust pressure input it may be hard to do though
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

Did you say you needed a TPS still?  maybe you can get one off an automatic tranny truck
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

Did any p pump cummins ever have a tps ?
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

I'm pretty sure the Auto tranny ones did.. the auto tranny VE pump trucks did like my dad's '92
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

#8
Kinda fallen on this for the brake


void exhaust_brake() {
       if (turbo_rpm > 50000) { vane_position = 900; }
  else if (turbo_rpm < 50000 && turbo_rpm > 40000) { vane_position = map(turbo_rpm, 50000, 40000, 900, max_position); }
  else { vane_position = max_position; }
}


No back pressure, but unloaded truck, sounds pretty good. Really actually brakes very well.. probably make a video here in the future with all the goodies working.
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

cool.. looks simple enough :)

I can't wait to get all the stuff I need to do my truck, and actually get a chance to do real tuning rather than just theory.
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles