Heres the sim on a 97 mustang cobra SAE net 305Hp@5800RPM 300Tq@4800 Sim est 309Hp@6000RPM 304Tq@4500
I haven't read anything on it to be fair, but I have always worked under the notion that headers provide 20-30 FWHP on a stock to mild engine. Much more as you go from mild to wild. Like I said though, if I have seen any estimates from knowledgable sites online, I didn't pay any mind. Just would have been surplus info in my thinking. Now, I don't know that my idea of header increase is correct, I just heard it from the really old-schoolers, way before the net, and took their word. On my engine modeling program, it is dead on what I was told. On computer dynos, they make MINIMUM of 20 HP on any dead stock V8, and that is often before adding a 4v. Then every mod beyond that magnifies the HP offered by the headers. (or the headers magnify the HP offered by further mods, however you want to look at it) In fairness: I never have modeled an engine that was stock and single exhaust, and then put headers on without changing to dual exhaust that instant. It wouldn't make sense to add headers and keep the stock muffler and single exhaust pipe. So in some instances, I am sure the move from single to dual exhaust, while simultaniously adding headers, inflated the gains on some level. And: Although I have modeled engines with 2v carb and headers (dual exhaust), this is not an optimum model. Most folks would run with headers and a 2v carb for a very short period, if at all. Improving intake breathing and exhaust breathing kinda go hand in hand. Not doing both defeats the purpose. So I believe that between headers, duals, and 4v intake/carb, none mean nearly as much without the others. Getting off topic now... sorry.
Well ... we'll see how she runs ... I am leaving my dual exhaust and H-Pipe setup on the car ... just gonna run a pipe from the stock manifolds to the H-pipe ...
I predict it will be quieter, run about 5* warmer on average, and you should notice less butt-meter power. In theory, it should lose a small amount of economy as well.
i ran my sim on the 72stock302 with 1.781/1.460 valves cam specs 368/381(valve lift) duration 270/248 300CFM 2bbl(what did the stock one come with?) dual exhaust w/stock manifold/mufflers(my sim doesn't have single exhaust)
