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| North American Grand Cherokee Association | ||
| Your one stop source for Jeep Grand Cherokee Information | ||
Kolak 3" Exhaust System Installation
By Adam J. Sycz
For the longest time a perfect exhaust for me was a one that you could not hear. If the car moved as if on air - that was it. Stock 4.7L WJ is not far from it, though it eminates a pleasant exhaust hum while cruising on the highways. On the streets it's also almost unnoticable. Well screw that, I want some deeper tones to go with the character of this baby, and a few extra ponnies wouldn't hurt either.
If you mention Kolak Exhaust to someone outside of Jeeps Unlimited forum, they look at you as if "what is that?". The system is named after some cool dude who supplies these puppies in ready to selected configurations perfectly suited for one's Jeep. It consists of a 3" hi-flow muffler and catalytic coverter, mandrel bent tailpipe and a choice of tips. Since I wasn't sure how "deep" I wanted to go I had selected a 70 Series Flowmaster SUV muffler.
Stock Exhaust Removal
I decided to save my stock exhaust system since it had barely 1,500 miles on it but in a
nutshell simply choping it off at the Y-Pipe does the trick.
There are 2 kinds of WJ exhaust systems: Regular and LEV (or CA emissions) which contain 2 precats on the Y-pipe itself. It's both good and bad. The bad thing in my case was that the shop which performed this installation did not have a pipe bender. Bending had been necessary to connect the Y-pipe to the cat. The good thing is that I did not have to relocate the O2 sensors.
My old exhaust was chopped off about 2~3in before the catalytic converter. Ideally I wanted to have a 3" tube go to the y-pipe thus alowing for maximum flow all around.
New Cat and Muffler Installation
Since I was attaching the new 3" system way after the Y-pipe on the 2.5" outlet
I needed an adpator which would take me from 2.5" to 3". Most every auto parts
store has such adaptors for a couple of bucks. The adaptor is then connected via a piece
of 3" tubiung to the cat and clamped together. After that another short piece of
3" tube connects the cat to the muffler. These two pieces fit perfectly in stock
locations even though the Flowmaster muffler is larger than stock and the guy at the shop
gave me a "this ain;t gonna fit buddy" look at first.
Tailpipe Installation
The tailpipe was mandrel bent to the specs (well sort of) so it does fit, but the WJ has
very little room to play and with now 1/2" larger tube one has to be careful in
positioning the tailpipe to avoid rattle or constant contact with the frame under
compressed suspension. We have tried diffrent suspension states (flexing) to determine the
best position for the tailpipe. I should mention here that even after all that I noticed
some rattle when I started the Jeep up the next morning. Seemed to have been quiet as the
components got hotter so it didn't bother me too much. One of the critical points would be
the rear sway bar links. That is where my tailpipe rattled. After TeraFlex 2" lift,
rattle disappeared completely though.
The reason I said the tailpipe was sort of bent to specs was because the end of it came out at an upward agle such that I would have had to trim the bumper at least 2~2.5" upwards to allow for straigh exit of the exhaust tip.
Exhaust Tip Installation
If your tailpipe comes out straight or slightly pointing to the ground, no problems there.
Just weld it over the tailpipe. Mine unfortunately came out so high that it was either to
trim the bumper (not very happy abount that) or make the tip exit at an agle. I chose the
second option. The tailpipe was also sort of short so we had to utilize the original
exhaust tip for a connector, then cut at about a 10 degree angle and slip and weld the new
plated tip over it. Initially I wasn't too thrilled about that idea either but I do like
it because you don't see the ugly tailpipe at in the back.
No-Precats Note
I'm not exactly sure about that, but non-LEV systems will require you to relocate the O2
sensor onto the new 3" tube if you choose to make it 3" all the way to the
Y-Pipe joint. You will then need an O-ring to weld into the 3" tube and then put the
old O2 sensor back in. You also might be able to use a straight 3" pipe to go from
the cat to the Y-Pipe since the Y-pipe outlet sits a bit closer to the frame than that of
the LEV version WJ. But I'm just guessing here.
Final Touches and Testing
For safety reasons, you should touch-weld all the joints between pieces of tubing so that
nothing moves on you. Clamps by themselves might not be enough to compensate for expanding
and shrinking metal.
I was a bit hesitant before turning the ingnition for the first time, but then...vroooommmmm! Incredible is not enough of a statement. It now was a deep, throaty, gargle-like sound which if anything complemented the off-road character of the Jeep. I sat there and listened to it for good few minutes before I was kndly asked to cut the damn thing out.
I found myself going the 10 mile distance from the shop, which would have normally taken me about 10-15 min to cross, took me a good hour. No interstate for me. Instead I've taken the slowest routes possible as the sound in 1st & 2nd gear @ ~1,500-2000 was just unbelivably sweet.
You should check for rattle under various conditions such as rapid accelleration, going over bumps, or starting cold.
North American Grand Cherokee Association
www.nagca.com
©2000 by Adam J. Sycz