360 Header Problems ??

Its been written about a lot so worth doing a search. Much about the subject also dates right back to the F355 where its been a carry over headache ever since. The US spec headers have been a cause of considerable hassle because not only do they crack they also have pre-cats in them which loose around 15-20hp and when they fail can destroy the engine. European cars didn't get them so they drive better and have more power and less weight. Fabspeed and others do replacement headers which can gain 25hp (indy style collector and no cats) which are very worth considering as a preventative measure against engine failure (oh and improved performance benefits too).

For cost, sound noise level emissions and manufacturing reasons the stock exhaust system is very very heavy, with a large proportion of that dead weight suspended directly from the headers themselves. There is a lot of weight being jiggled around. How much exactly? Well basically the full exhaust system on a 360 is a heavy old anchor, even more so on US spec cars. Its approaching 130lbs with a large proportion of it suspended by the manifolds!

To help improve matters the exhaust itself isn't completely ridgidly mounted (by design) but still it causes stresses on the headers. On the back of the stock back box mounting there is a flexible section of metal that is designed to bend and flex with movement. So while Ferrari engineers did try to prevent engine movement causing cracking they unfortunately haven't truely cracked it (exuse the pun). For instance the headers do use spring loaded bolts where they affix to the main cats as well as the described backbox flexible mounting plate.

Some people have argued the thin wall of the headers isn't strong or thick enough to stand the stresses. Overall my opinion is its that the biggest issue is to consider how much weight is attempting to be suspended from the headers and how much stress they must come under during movements. When the engine is rev'd hard up and down the box this causes movement on the mounts (inevitably) and the described springing is designed to help keep things in check however ultimately all that movement is still going to place stress on the metal and eventually fatigue the metal to the point where it cracks. Especially under hot/cold heat cycles where the metal heats up from very cold quickly. Its a ticking time bomb.

Its worse than that too as even when welded up they just keep cracking, its almost impossible to fix them once they 'let go', hence its prudent to keep a spare set for when they do fail. There are preventative measures you can do though such as fit a lighter set of cats and exhaust system.

The easiest and most cost effective solution lies in lightweight cats and a lighter exhaust backbox as this lessens the effects of fatigue. They are substantially reduced because the lower overall weight places much less stress on the metal so they last a lot longer. So the happy consequence of upgrading to race cats (apart from performance, sound and throttle response ) is that they really help to prolong the lifespan of your manifolds. A win win...