Questions about FI bolt-ons

KingJoseph

Thanks for your well spoken response. I've got a call in to Tony, but I think they're in the midst of a move because they haven't answered my email and I got an auto-response saying something to that effect.

So, it sounds like with less cells on an NA engine, I'd be sacrificing some of the powerband for a minimal HP gain. Am I understanding that correctly?

wstar

More or less this is a correct approximation of the situation. Within reasonable design limits, if you remove some restriction from the exhaust the torque peak moves upwards in revs. Since HP = Torque*RPM, this increases "Peak HP", but that peak will come at a higher rev than before. That doesn't necessarily mean you improved the total area under the curve on the torque graph, depends on a lot of variables whether a given exhaust change does that for the rev range you care about.

Most people driving on the street will dislike a change that pushes the HP Peak up the graph, because they spend most of their time in the lower rev range and it'll feel like a loss. On the other hand at the track I spend most of my important engine time in the 4K -> 7.5K range, and below say about 3K RPM I just really don't care if my torque drops off sharply, as long as I get solid gains in the range that matters to me.

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