At the risk of sounding stupid, how do you-

[Safe_Cracker]

Find your in-car resonance and once you find it how should you tune your sub higher or lower? Thanks for any and all answers, Polo..

 

[Glowbug]

Get access to a good, calibrated SPL meter, like a Termlab.

Using a sealed enclosure, run sine sweeps until you find the frequency that peaks the loudest on the mic.

I assume you're interested in knowing this for competition purposes?

What kind of vehicle is this?

 

[Safe_Cracker]

This is a 2001 Pontiac Grand Prix. I'm not into competition (ony with myself and local punks ) but I thought maybe it was some kind of information I can use to get louder and maybe gain a little extra in the SQ department. Polo..

 

[xplod1236]

Tuning at the car's resonant freqency will get you more output at that frequency; the port decreases the excursion of the driver, while still putting out the same spl. That means that you can push the driver to the limits of its excursion, and get insane spl. On top of that, add in the gain from the car (the whole car resonates), increasing the spl once again, and you have a competition vehicle. The resonant frequency of cars is somewhere around 50-60 Hz, so tuning above will get you no bass.