S63tu m5 jb4 + bcm attached logs high altitude vs low altitude

[kennis827]

Hi Folks,

I am running 2014 M5 competition package, stock, jb4+bcm/91octane/100%meth at 2000ml/min running toyo r888r.

I logged my car with map7(25psi peak)with 3500 feet altitude vs 0 feet altitude in the same day, the results are attached.

at 3500 feet (boost drops as rpm increases)


at 0 feet (boost are on target)


When the DME detects its high altitude location, it protect the engine by dropping the boost as rpm increases, because the air is less dense, but as i am injecting a lot meth, the air density should be fixed in this high altitude, i tried increasing the target psi and duty bias with custom map6, but it keeps the same dropping at 3500 feet.

Is there any other way to "lie the DME", or any addon other than upgrading the turbos to keep the boost pressure stable on high rpm?

[TrevorM3]

dump the jb4, and flash the car.

[kennis827]

Originally Posted by TrevorM3

dump the jb4, and flash the car.

which is a good flash that is not so pricey?

[DenverF10M5]

Originally Posted by kennis827

which is a good flash that is not so pricey?

BootMod3 ran me $800+shipping

[kennis827]

Originally Posted by DenverF10M5

BootMod3 ran me $800+shipping

hey thanks for the advise! i guess you live at high altitude too, do you have any datalog using this flash?

[DenverF10M5]

Originally Posted by kennis827

hey thanks for the advise! i guess you live at high altitude too, do you have any datalog using this flash?

I have the same issue you're having. I have a JB4 on top of the flash, so I use it to log. I'm a few psi under target at higher RPM like you are.

[BadGTR]

Your problem is the turbos cannot keep up with the thinner less dense air. You need bigger turbos to compensate for the elevation. I hold 18#s at 6500rpm with a stage 3 flash at 5200' elevation. Turbos can't make anymore.

[DenverF10M5]

Originally Posted by BadGTR

Your problem is the turbos cannot keep up with the thinner less dense air. You need bigger turbos to compensate for the elevation. I hold 18#s at 6500rpm with a stage 3 flash at 5200' elevation. Turbos can't make anymore.

I'm at 5500' and am hitting 22psi at redline, but am targeting more. The duty cycle helps quite a bit, but PWM is definitely getting up there. I had the same issue with Pure Stage 2. You have to love high altitude. It's even worse at the drag strip.

[BadGTR]

Yes, I spike higher boost earlier in the rpm band. But I like to log what the turbo makes up top. My GTR with stock turbos and 100% open waste gates would spike 18#s, but only hold 11#s at redline. Elevation sucks.

[kennis827]

Originally Posted by DenverF10M5

I'm at 5500' and am hitting 22psi at redline, but am targeting more. The duty cycle helps quite a bit, but PWM is definitely getting up there. I had the same issue with Pure Stage 2. You have to love high altitude. It's even worse at the drag strip.

Are you hitting 22psi at redline using pure stage 2 turbos + BootMod3?

do you have any log to share please?

[kennis827]

Originally Posted by BadGTR

Yes, I spike higher boost earlier in the rpm band. But I like to log what the turbo makes up top. My GTR with stock turbos and 100% open waste gates would spike 18#s, but only hold 11#s at redline. Elevation sucks.

hey did you upgraded your m5 turbos? if so, does it making stable boost from low rpm to high rpm?

[BadGTR]

Originally Posted by kennis827

hey did you upgraded your m5 turbos? if so, does it making stable boost from low rpm to high rpm?

Not yet. Would like to do stage 2s.

[TheHouseWon]

+1 for bootmod3