Originally posted by Sh*tBox
The only way you could run 12s would be with a swap and turbo. Or at least a heavily boosted sohc. Turbo cars suck for autocross.
Exactly why I think the whole concept is nuts.
Some turbocharged cars do well at the autocrosses. Example, the RX-7 Turbo II. On stock boost levels, they are not too crazy and spool pretty quick with a decent power band. Once you up the boost, it becomes more and more difficult to control the car, in this case throttle oversteer will kill you unless you spend quite a bit of time and money in the suspension, and even more time doing the "P" word... practice.
N/A engines are much more forgiving, but you're not going to get into the 12's without a crazy-built ($$$!) engine with very peaky horsepower and torque curves. This is not good while trying to maintain precise control of your car.
You may want to participate in some autocrosses first, and build the car as you see fit. Just don't think that because a car is faster in the 1/4 it will be faster in the autocross... there is no solid connection between the two.
On a final note, car choice is everything. Civics can be built into some amazing creatures, but you have to keep in mind your performance goals. You sound like the kind of person that should use your Civic as a daily driver and buy an older car to convert into a track car. That's up to you.