Well, my gas mileage started to drop and I heard an exhaust leak on the driver side... I wasn't able to look at the exhaust for nearly a month and during that entire time, my fuel mileage dropped about 2 mpg less than normal.

I opened her up yesterday and sure enough, my header was cracked. Well, being a tight wad, I decided to weld it instead of replacing it... hoping it will last for at least a year. Anyway, I just filled up my jeep and I will see if there is any difference in my fuel mileage.

That said, if a tiny crack impacted the performance of my jeep significantly enough due to a change in back pressure... I don't see how headers will improve horse power or performance.

Just as and FYI... I do have a superchip programmer and I would have thought the jeep would learn and adapt to the change it back pressure but it does not appear to do so.

 

What does the exhaust leak sound like and how big was the crack on your headers?

 

the crack was about 4 inches long and it sounds exactly like an exhaust leak. Sounds like gases are escaping out the front of the jeep versus the back if that is any help.

Has anyone tried welding the header before... how long did it hold?

 

Headers use the exhaust pulse waves from adjacent cylinders to create extra backpressure at low RPMS, and a vacume at higher RPMs. It's not all about low resistance flow at all with a tuned long tube header. The tube length is adjusted to move the power band up or down. Longer tubes generally equal more torque and power at low RPMs. Because V6's fire less frequently than a V9 and you have less pulses to work with, you need a longer tube to get the same affect you would with a V8 block.

 

I always thought the idea behind the long tube headers was about reducing back pressure so you have greater draw on the intake. This is why headers are so effective with older muscle cars. Headers and a larger carb equals more power. Headers alone, don't really add a lot of hp... but combined with a larger carb, and you can jump the hp. A 2+2=5 type deal.

is my thinking that far off?

 

The reason that your gas mileage went down is that the crack in your header was allowing air into the exhaust and the oxygen sensor was seeing that yor were running lean and was telling the computer to richen the mixture. If the leak is stopped, your gas mileage should return to what it was before the leak

 

Good to know... thanks