[pleasanton335]

Can somebody please explain overboost to me? How is this different than peak boost? Shouldn't the full amount of psi always be available, provided that you dont stay in peak boost for more than 5-10 seconds? I just dont get the "overboost" advertising.

I know that a stock 335i peaks at about 9.9 psi...and that tapers off as rpm's rise...and I know that my Dinan Stage 2 335i hits about 13.5....and tapers off....so how is that different from "overboost"?

TIA

[kyleb350]

Sounds like a temporary increase in peak boost, but I could be wrong.

[Donald-335i]

most likey how porsche dose it with a *Overboost Option*

[carve]

I think the idea is, it's hard on the turbos and engine, & the intercooler would get heat soaked, so they just don't let you sustain it for long periods, like going 150 mph up a mountain for instance. But yeah- boost tapers anyway as rpm climbs, so it'd have to be max load at, say, 4000 rpm without really accelerating to stay at the peak overboost for more than 10 seconds. I wonder if in a 1/4 mile run it would allow 10 seconds of overboost total for the 1/4 mile, or if, as the boost tapers during a shift, if that 10 second clock resets?

The nice thing about this is it's just a BMW software change. I think that's sort of an implicit awknowledgement that the engine can handle more.

I do, however, wonder if the new 322 hp rating represents any engine change at all, or if it's just a more accurate rating of what the engine was already making anyway. That's right in the ball park of what most people estimate the N54 has always made at the crank, based on the 275 rwhp rating commonly achieved.

[JayKay335i]

Because saying "over boost" in advertising is catchier than saying "we increased the maximum sustained PSI of the turbos"?

Makes you feel like that extra $$$$ gets you something more than we already have.

I'm always running overboost

[carve]

You're missing the point: overboost is not sustained. Otherwise it'd just be called boost.