ok so i know that my max power is at 4200 rpms so should i shift so i end up right in the middle of the band or right before. i want to know about when to shift so i get the best acceration.

 

1st off... ur max power is not 4200, if it is, your car has problems.... shift at 5200ish.... but everycar is differant... i dont even no what i shift at... i do it by feel...

 

was it dynoed at that?

i use to shift at 5500 with similar mods

 

It may only feel like the car is producing power until 4200 rpm, but them the power plateau's and stays at max power for a while, (usually until about 5k give or take a couple hundred RPM) (<on a basically stock 5L) So you want to shift right before the power starts to fall off. The only real way to know when that is, is to either A: Get the car dyno'd so you can physically see where the power drops off OR B: You can take the car to the track on a test n tune night, and play with your shift points. When the MPH starts to slow down (the higher the RPM's you shift at) means that you have reached the end of your power curve.

I know it sounds confusing, kind of hard to explain in words. But I hope you get somewhat of a picture.

 

My max power was made at 4900 rpms...I had it dynoed. I set my shift light to come on at 4800 so I will shift at around 5000rpms.

If you make max power at 4200, shift right around that.

 

A prettystock car should be shifted around 4500, maybe a little higher but not much. I doubt headers raised your power band at all.

 

mines bone stock i get max power at 4326 rpms.Sometimes i can go up to 5200 rpms in some gearssometimes i cant .

 

On my car after I did exhaust and played with my timing it pulls to 5500 pretty evenly,on myThunderbird Turbo Coupe the power felt like itdropped off at 4k but if I ran the gears out all the way it would run a faster1/4 time as opposed to shifting when it felt like it reached it's max.In other words do what 91hatchGT said and take it to the trackto test it out.