What Have You Done To Your Stagea Lately?
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we can only guess exactly what happened from our keyboards, but to me it looks like they were targeting 27 but the wastegate was too small or poorly controlled and the boost crept up, that is quite common -
Good points! Took those for granted - though I *did* actually give an example of winding boost up more than it had been before where I wasn't actually specifically looking for more peak power. The Toyota Starlet dyno plot that I shared and mentioned showed an overlay from the previous tune it had and the one I'd redone, I left the boost targetting the same as the old tune but then after peak power I ramped boost up by a good 5psi or so over what the old tune had at the same rpm. The reason I felt comfortable with this (though the owner of the car had a "are you sure?" moment when I suggested it) is that the setup wasn't turbo limited, it was largely head sealing limited and the owner was a bit concerned as for the last few seasons he'd had issues with head lifting - sometimes not completing an event without having some headgasket issue, so he didn't want to run any more boost than it was. The reasons I was ok with raising the boost a good 5+psi MORE than that was that I left it where it was in the middle, and only increased it where VE (and therefore cylinder pressure vs psi) were dropping hard and I didn't stop the torque from dropping, just reduced the drop. Well, there is that and the fact that the previous tuner had it overtimed by near 7degrees at peak torque - but that's another story haha. I didn't really go into detail about that "turning it up more" thing but now you've mentioned the "not detuning", sometimes the boost *can* be turned up higher than you'd expect if the setup allows for it and you do it smartly. I've tuned things to run 30psi on BP98 "safely" that a few years ago (or still?) people would cry that it was a stupid idea - but given they were well intercooled, low EMAP turbos and only doing that kind of boost where VE is dropping etc I was pretty confident it wasn't as cowboy as it sounded at face value and we never ended up with issues as a result of it. -
they choose the number of psi (27) around 4200? Could it produce more at this engine speed with the same turbo? -
one thing escapes me, if the turbo spool provides the maximum boost and we can't control anything before that, how can the boost be higher by it alone. here around 27 psi at 4200 then up to 32 psi at 6500 rpm how does the tuner do this
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I'm still not sure what you are trying to acheive, but I wanted to clarify something about Lithium's response to your question... Only within certain limits. All of the examples Lithium gave were of detuning for a particular reason. Before the engine/turbo/wastegate combination has hit full boost, you can't increase it....the wastegate is shut and the turbo is pushing as hard as it can Once the combination has hit the target (controlled) boost, you generally have full control over whether it makes more or less boost, because it is being limited/reduced from its potential. This is generally done by controlling the wastegate In the top end, with an undersized turbo, it is possible you won't get to your target boost anymore if the turbo is choking up. In this case you cannot increase boost any more without changing the setup. No change in cost compared to any decent build, other than tuning time to get the engine to make less power than it is able to at a certain point
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