I have a friend who swears that installing an aftermarket ignition system will add at least 15 hp. My knowlege of engines is pretty fundamental, but my gut feeling is that he's full of crap. So, my question is, will a spark system add hp, how much, and if not, what exactly will it do?

 

lol. no. I dont think so. It might make it more responsive, Idle better, better mileage. But not 15 horsepower!

 

Do you have any suggestions as far as brands, type, etc?

 

I put an MSD ignition box on my old truck. It got aweful fuel economy and would not go over 70. I added the ignition and... not too much excitement. I got a little better with fuel like maybe a mile /gallon. I did notice that it could hold it's speed on the hill climbs a little better.

The one I had was the 6a model.

Anyway, basically the box amplifies your spark to make it more powerful. It is intended that the hotter spark will burn all of the fuel and will improve horsepower. Most cars already burn enough of the fuel that this really is not true. The only exception is when cars get ahead of their spark. You have probably seen dyno testing and the horsepower climbs to a point and then drops dramatically, that is because the spark cannot sustain the fuel burning. Dyno testing on the ingnition systems create a later drop off point which since the horsepower is a straight line means that you get improved horsepower and later drop off... at 7000 rpms. And if you are driving at 7000 rpms all the time, you will see it.

 

This was true if you're talking about old point - ignition distributors, but not anymore. Save your money and get CAI (Cold Air Induction). You can gain up to 5% more HP that way. I know that doesn't sound like much, but with today's engines and their electronic controls, getting big HP requires NOS or artificial respiration (super or turbo-chargers).