[jimmyrp]

With stock turbos, most tunes have a lot more torque in the midrange, resulting in a hp curve that is more logarithmic (even falling off in the last 500-1000rpm), instead of being linear.

I couldn't find anything, but are there any examples/dyno charts of an n54 tuned with a very flat torque curve, that holds torque all the way up to 7k? This would obviously be slower, losing a bunch of potential midrange torque, but I'm curious if anyone's done this.

Would there potentially be any drivability issues with this approach? Would a piggyback like jb4 be better or worse than a flash tune for this?

[lowrydr310]

The stock tune is pretty flat. The real issue is that on stock turbos or even mildly upgraded turbos they're not very efficient at high RPMs so there's no point trying to push more boost there; the engine makes more torque before redline. There's also the issue where very high torque at low RPM isn't good for the engine internals, specifically the rod bearings. Again, not an issue for mild tunes, but that's why you'll see the power delivery that you described above in any of the aggressive tunes running high boost.

[jimmyrp]

Yeah, I'd be looking at just adding boost up top, but smoothly, so that the torque curve matches an n/a engine. Haven't seen this done on turbo cars with stock turbos.

For example, here's a dyno chart I found, showing stock vs tune.

Here's what I'd like for the torque curve to look like.

View post on imgur.com

Any reasons something like this wouldn't work?

[whyzee125]

My track/winter tune probably looks like this though I've never dyno'd it. It's a pretty conservative 93oct Wedge tune for FBO + inlets, 6 deg timing and 14psi to redline.

It's way less aggressive than my 21psi full e85 tune that I normally daily but it honestly still pulls well and is very smooth, doesn't feel like it tapers at all by 7k.