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The Bacon Hauler (‘12 Cop Charger)
6,033 Posts
Discussion Starter #1
This question isn’t necessarily specific to my car’s tune, but it did arise out of me generating and viewing datalogs from my DiabloSport tuner. It’s actually more about general theory of how the engine works and how it reacts to changes from stock specs. Either way, I figured this section is probably the best place for it, not to mention I figured the folks that can probably answer it are more likely to be watching this section of the forum.

Question: Given that peak VE occurs at peak TQ (as opposed to peak HP), what does it mean to raise the RPM point at which peak TQ (and thus peak VE) occurs?

For example, this screen shot from a recent datalog shows my engine's peak VE (and thus peak TQ, right?) occurs well into the 4K RPM range, despite the engine's stated peak TQ RPMs of 3900 (according to and other sources I've found):
VE DataLog Capture.jpg
NOTE1: This specific instance has the peak TQ/VE occurring at 4421 RPMs, but it is always at least 4400+ RPMs in the other instances from same datalog and other datalogs generated recently.

That ~500 RPM difference seems significant to me...which is why I created this thread.

Anyway, here is my hypothesis on why the discrepancy:
Through various mods and the associated tune adjustments, there was a net gain in TQ, and because of that increased TQ, the RPMs at which it occurs would naturally be at a higher RPM than what is stock spec.

Can anyone confirm/deny my hypothesis here?

NOTE2: I am well aware the odds are just as likely the discrepancy can be explained with a correlation-type explanation instead, e.g. the different-from-stock peak TQ RPM is due to every engine being unique and thus having its own RPM that will naturally differ from stock spec in every single case. Further, the peak TQ RPM will not vary much either direction when performance-adding mods increase (or decrease) peak TQ.

(It may be obvious to those "in the know", but I will readily admit I am starting to get out of my element a little when I go all theoretical like this. But I know some things about this topic, and so I'm just really trying to tie those things in with the things I do not know (for sure). So if I need to be corrected or redirected on anything I've said in this thread, please feel free to do so...with extreme prejudice, if necessary!)

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