[d-unit]

I live in Denver metro and routinely drive between 5 and 10k. I assume the turbo has to spin faster to make the same amount of boost at altitude. Will the plugin boost mods like JB+ and Racechip put too much stress on the turbo at high altitudes? Is anyone using these at altitude or is it safer to get a flash tune that takes the altitude into account?

[bryan_G01]

it will all help, but you can't compare to others that have the same mod at sea level.

[raldenlee]

I live in Santa Fe at 7000' and have used both jb4 and, now BM3, and I've come to conclude that their both worthwhile and make a noticeable improvement, but the limiting factor is the stock turbo. It just can't produce the boost pressure that these mods are targeting at higher rpms at my altitude. I have logs where target is 21 - 22 psi at 6 -7 K rpm and MAP psi is only 16. Boost is much closer to target up to 4500 rpm and then drops off fast. Of the two mods, the BM3 is smoother and more gradual while the jb4 hits harder under wot but sometimes feels uneven and sometimes even jerky.

[d-unit]

@raldenlee Do you know if the ECU monitors the turbo RPM to prevent spinning too fast in high altitude conditions when it can't reach the desired boost pressure? That's what I'm worried about with a boost mod.

[raldenlee]

Don't know if there is some safeguard to prevent such a thing, but Halim at PTF said they were reluctant to increase boost target for me because it would probably only result in excess heat and no real increase in boost due to turbo's small size.

[CapitaineBeaver]

Originally Posted by d-unit

@raldenlee Do you know if the ECU monitors the turbo RPM to prevent spinning too fast in high altitude conditions when it can't reach the desired boost pressure? That's what I'm worried about with a boost mod.

I don't think it does because I read recently a JB4'd F90 M5 recently blew it's turbos running a race map (aka high boost) in Colorado. It was deemed overkill since this map is still considered use at your own risk at sea level.