Note: I apologize for the lengthy delay between
the Colorado Red articles. I hope you will understand that I moved
my entire family from Oklahoma to South Korea. I did not expect to
be without my computer for so long. Please accept my apologies and
I hope you enjoy the continuing story that is Colorado Red.
Project Colorado Red is coming together quickly.
For those just joining, Colorado Red is a 1989 four door Cherokee
Laredo owned by a geologist in Venezuela. The owner lifted the XJ
using Tomken Machine's 5-6 inch lift and Rancho 9000s to clear 32
inch BFG Mud T/As. He installed Custom 4X4 Fabrication bumpers
front and rear, a Warn 9000I winch, a Con-Ferr roof rack, and a
host of lights. The drivetrain remained stock except for the 4.56
gears and ARB air lockers front and rear. Shortly before moving to
Venezuela, the 4.0-liter motor succumbed to an over heating problem
at about 125K miles. The Jeep was left in storage until I was asked
to take it on as a drivetrain upgrade project.
Motor - Number One Priority!!
More horsepower to pull a camper at highway speeds
in the mountains of Colorado was the order. For this, we called the
experts at HESCO manufacturing in Birmingham, AL. They sent us a
4.7-stroker kit and peripherals to increase the stock horsepower
from 177 to 260+. The engine was removed and taken to Volks Machine
shop in Norman, OK where machinists double checked HESCO's
measurements and balancing. Finding everything within tolerance,
they bored the block for the oversized pistons and line honed it
for the crank. HESCO recommended staying with the stock head and
valve grind for durability. Volks refurbished the head installing
new valves. Once the machine work was complete, the components were
taken to Alan Kennard, owner and chief mechanic of Kennard
Automotive in Norman, OK (405)447-4258. Alan is an expert on the
Jeep 4.0 motor and took special care with our custom engine. He
quickly pointed out a major mistake I made by taking an assembled
engine to a machine shop. Between the location where we removed the
engine and the machine shop, a good 1/3 of the fasteners for this
engine were lost. Luckily, Alan built so many 4.0-liter engines
there were plenty of bolts in the shop to put our motor back
together. Yes, this is embarrassing; but a lesson I will pass on to
help a fellow Jeeper.
Alan
surgically installed the HESCO components in the machined block.
Many folks would like to know just what HESCO is using to make
their 4.7 liter kit. As far as we could tell, the crank is from the
well known 258 cid Jeep engine, the rods appear to be 4.0 liter,
the cam is a RV cam (you can purchase several types through MOPAR
performance or other retailer), but the piston is custom. It is the
piston head that makes the kit special and the power claimed by
HESCO. A double roller timing chain was installed for extended
life.
Next, the head was bolted on. The word from HESCO was "nothing
fancy", just a good quality stock head. We did just that using all
new valves. Since the combustion chamber is larger, HESCO
recommends adding a bored throttle body and 20% larger fuel
injectors. Both of these items HESCO supplies as options to their
basic 4.7 kit. We also opted for an adjustable fuel pressure
regulator to help compensate for fuel quality outside the United
States. Since the engine will be taking in more air, we figured it
best to get rid of it efficiently. This Borla stainless steel
header should do the trick once we attach it to a Summit Racing
free flow catalytic converter and a Flowmaster muffler. The pipe
was kept at 2.25 inches all the way to provide adequate
backpressure. The Borla header is a very good deal compared to
purchasing a stock replacement exhaust manifold from the dealer. It
is only about $30 more, made of stainless steel, comes with a tuned
cross pipe, and has a million-mile warranty. After final
inspection, Alan was ready to stab the new engine in Colorado
Red.
How does it run? Is the power HESCO promised
there? Well anyone who has experience with a new 4.0 liter straight
six knows they take a while to break in. The cam HESCO supplied
makes the Jeep have a definite lope at idle. It may actually be a
bit too much for some people so you might ask HESCO about cam
options. I was able to drive the Jeep for the first 100 miles or so
and can say it feels like a stock Cherokee. What! Are you kidding?
Remember that this Cherokee is turning 32 inch BFG Mud Terrains and
weighs nearly 1000 pounds more than stock. For a "green motor", I
would say that is pretty impressive. I will keep in touch with the
owner and let you know how the engine performs after a healthy
break-in period. Check in next month to see how the new Atlas II
twin stick transfer case installation worked out.
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