Russian

so i was driving lastnight and heard a familiar sound that went clank clank clank(muffler dragging on the ground. well i seen what happened so i stopped and kicked it off the rest of the way. now when i did this, it made the jeep sound pretty bad *** and loud. would running an exhaust like this be bad?one with not too much backpressure?

n_a_i_w

I don't know if this is what you are looking for in an answer. I wouldnt recommind doing it for a long period of time. But I cut my cat and muffler of and bought a glass pack from checker for 30 bucks. It sounds better and runs better. but I dont have to worry about emmisions either.

JerseyJeeper

You need to read this:

https://www.cherokeeforum.com/f2/cat...er-laws-24337/

96jeepxj

Yes eventually you will have trouble with the engine. These I6 really need that backpressure. It will be ok for a short while if you take it very easy, but replace it asap. On another note it is illegal.

Russian

lol im more worried about harming the engine than the legality of it lol. eventually i wanna do true duals but for now i guess ill do the cherry bomb. i got one laying around here somewhere now i just got to remember where it went

but it sounds so cool right now lol

OldMan

I have been hearing about the need for back pressure my entire life (which, BTW has been pretty long) and no one has ever been able to explain to me why.

Does anyone out there know a reason for this? I mean really know?

So far, I have filed it under the heading of "myths". Like George Washington having wooden teeth (he didn't).

Russian

ive been searching around and it keeps the valves cool in the engine

UserID6095

^^ Exactly. If you run an 'open' exhasut setup you will burn up the valves.

I sure hope you saved the cat becaue you can scrap it and use that money to buy a new one. I would not drive it with no cat or muffler, dont care how BA it sounds your going to burn a valve in no time.

cw50must

If you were running just an exhaust manifold, then maybe the valve problem could arise. If you are running pipe all the way out the back, just sans xat, its not an issue.
The problem is this site doesn't like talk about removing the cat, so you will be told not to and then the thread will probably be locked or deleted.

superj

you will only burn the valves with a short open exhaust. and the reason is because the cool air will go back up the exhaust and the valves will cool faster then the rest of the engine and crack. running straight exhaust with a normal length pipe will not hurt your engine at all. you don't need back pressure at all. what you need is proper cylinder scavenging which happens at end of the cycle for combustion. the piston is on the upstroke and pushing the exhaust out the valve. as it reaches tdc, the intake opens also ao when the piston is on the down stroke, a new charge is sucked into the chamber. during this time, there is a point when both valves are open together and you get some of the fresh fuel/air charge going out the exhaust valve too. it has to happen or you will not have proper scavenging. that is why in the old days, you could tell if a carb was running rich by smelling the exhaust and you could mount a spark plug in the exhaust pipe to light it and make a flame show for hte girls.

but you cannot ruin your valves with straight pipes. you don't need back pressure.

all back pressure is the burnt fuel charge being kept in the chamber because the exhaust is to small. its ok to have back pressure but it is not required for an engine to run and you will get more horsepower with out the restrictive exhaust.

i hope i remembered all the inner engine stuff properly. been awhile since i was in powerplant training and needing to know about the otto cycle and the brayton cycle

98 JeepJeep

his teeth were made of wool!!

98 JeepJeep

if the vehicle is for Off-road you dont need a cat. Hack away!

OverlandZJ

We dont allow discussion of Emissions Equip removal. Sorry...