Originally Posted by kuzican

well not for me = D I'm looking forward to the new car



you mean a cutout?



i only get 13, and thats on a good day



I will talk to you about regearing later



dont worry I got him a 24 pack to give to him today = D




me? or another one?

Originally Posted by kuzican

you mean a cutout?

Originally Posted by Green2000

Cutout/dump same difference. My circle always calls them header dumps, cutouts are what we do to cat converters. Cut a test pipe and press it through the cat, its the "emissions legal" cat bypass

Originally Posted by jimmy21669

I'm going to try to cover this without getting too technical.

The stock exhaust is a compromise between efficiency, power and quietness and does have a considerable amount back pressure. In this case, the back pressure actually aids in quieting the engine, but decreasing the torque.

Back pressure is not an engines friend as it causes hot exhaust to remain in the engines exhaust port for a longer period of time. Granted, it just for a fraction of a second, but that's all it needs.

A well balanced exhaust system will have a 'tuned' exhaust manifold, exhaust pipes of sufficient diameter to maintain exhaust velocity and cat and muffler with minimum restriction.

A 'cat back' system generally refers to the components after the catalytic converter. Reducing the restrictions of the muffler and tail pipe will improve engine torque. But, the cat still remains as a restrictive device and can be solved by replacing the stock converter with a high flow version.

The stock cat has sufficient restriction to maintain the burn in cleaning up the exhaust. This is probably more true of the '97 and newer XJs with the dual O2 sensors. However, a high flow cat is designed so that the exhaust has less restriction while doing a proper burn.

A tuned exhaust manifold is designed so that as the cylinder releases the exhaust gas it aids in pulling in the next air/fuel component, called 'scavenging'. It does this by having timed equal lengh exhaust tubes.

To clarify this, as one cylinder pushes out the exhaust, the next cylinders exhaust won't collide with the previous going out the exhaust pipe. For illustration, look at the following manifold. You'll note that cylinders 3 & 4 are closer to the exhaust pipe port than 1 and 6. In a factory manifold, the exhaust is just dumped into a common pipe and the exhaust exists the best it can. With the referenced manifold, each pipe is designed in length and diameter to reduce exhaust collision and exit freely.

That's all I'm going to get into here. If you want to learn more here are two excellent articles (and not too complicated) that explain in detail the exhaust flow.

http://www.veryuseful.com/mustang/te...Scavenging.pdf
http://www.bigcitythunder.com/pages/...ng_exhaust.pdf



A restrictive (too small) pipe, will cause too much back pressure and impede free movement of the gasses. The pulses begin to overlap, and you lose HP.

You want to minimize backpressure, but keep just enough so as not to have free flowing gases that remain in the exhaust system and not remaining in a line of pulses that aid in expulsion. For this reason, too large of an exhaust pipe is not desirable.


I highly recommend for a GOOD well tuned XJ exhaust system you keep the 2.25" piping, but get mandrel bent downpipe and tailpipe as well as a free flow cat/muffler to increase and smooth out flow. Going to 2.5" piping CAN actually be counter productive.

Hope this helps SOMEONE since I have been seeing a lot of talk on the subject lately.

Also, unless you get a header with a 2.5" exit at the collector, you won't achieve a true 2.5" exhaust.

STOCK tailpipes are only 2" as an FYI...it narrows after the muffler....

Originally Posted by Green2000

2 bottles of fluid per diff?

Originally Posted by pulltabmike

Hay Jake,
Forget I own a renix also
Problem #1 - Sensor for Electric fan shot
Problem #2 - Looks like he has baby **** for coolant

He pulled into my buddies driveway yesterday and she blew. Only lost 1/2 gallon of water. Im not convinced that it is the water pump or t-stat, thinking more along the lines of blockage.
Fan Clutch worked OK also....

Originally Posted by dukie564

Scott you have a pop rivet gun and some rivets you can bring Sunday by any chance?

Originally Posted by nowhres

Just shy of two bottles

http://www.4x4xplor.com/diff-service.html