Jim’s Garage – Saturday Project

A couple of weekends ago there was another project at Jim’s Garage.  This time it was a 2006 GTO.

Way back in 1966 my father bought a new GTO.  It was a very good looking car and, even though I didn’t have a driver’s license, I lusted for that car.  I had seen my first GTO just a couple of years before.  It was a 1964, the first year of the “Goat”, as they became to be known.  In a Pontiac Tempest body was put a V8 and the muscle car era was born. 


So when my father pulled into the driveway with a GTO I was stunned with delight.  There was young guy in the village that also bought one.  His was a four speed on the floor with triple deuces.  My father’s engine was the same size, but he had the Quadra Jet four barrel carburetor and a Turbo Hydromatic automatic transmission (a concession to my mother, she would drive it, too).  While the triple deuces was the hot setup, my father’s GTO was no slouch.


It had a break-in period of 500 miles to go through before you were to “open it up” so I counted the miles on the odometer waiting for that time when my father would be able to really see how powerful that car was.  A couple of times he and I would take a long ride almost to Boston, just to get more miles on the engine.

The first time he was able to tromp on the accelerator the sound was amazing.  The Quadrajet carburetor was a unique design.  It had four “barrels” or throats to the carburetor, but not all of them worked at the same time.  For some semblance of economy the first two intake throats were small, about the diameter of a pair of quarters.  The second set would only open up if you had the gas pedal to the floor and they were the diameter of a couple of silver dollars.  When they opened up there was this huge sucking sound and you expected the hood itself to be inhaled.  The transmission would kick down and the tires would squeal as that V8 would launch the car forward.

This Saturday Jim’s Garage had the current version of the Pontiac GTO drive up on the lift.  It is a derivative of the Australian Holden Monaro and 2006 is the last year of the GTO name plate.  This one has a six speed and the Chevy LS2 engine that is rated at 400 HP and 400 lb./ft. of torque.  This is rear wheel drive (yeah!) but is a little tubby at 3725 pounds of curb weight.  The Australian version was sorted out for handling, but the brain dead executives at Pontiac felt that the suspension needed to be Americanised so it ends up soft and a bit vague. 

Fortunately there is a huge following that is determined to modify their cars to the level of performance that the car deserves – dam the executives.

Tim had put aftermarket mufflers on his GTO and wanted to further improve things by replacing the front resonators with an “H” pipe.  To do this we unbolted the mufflers and then unbolted the rest of the exhaust system from just before the resonators. 


The most difficult part was unbolting the resonator bolts because they were so close to the drive shaft’s U-joint that it was tough to get access.  This was further complicated by the lift itself that had a brace near that same location.  But we over came the impediments and then measured where the exhaust tubing would be cut.  I had picked up a tubing cutter for that purpose from Car Quest and it did a great job.  Faster and cleaner than any other method.  Unfortunately the handle broke off the new tool, but Car Quest replaced it as new defective without any hassle.

The new H-pipe came with some great clamps that ensured there were no exhaust leaks at the connections.  We bolted up the mufflers and aligned everything with no problems.  We started up the car while it was on the lift so Tim could check for exhaust leaks.  The only ones were small and from the old gaskets at the muffler end.  Tim would remedy those later.



Another project completed at the garage.  Tim was off to see how the sound was and would later decide to try it with the stock mufflers back on (a drone at highway cruise).  The H-pipe provides a nice balance to the exhaust pulses and improves HP and torque.

These are interesting cars.  I wish they were lighter weight, like the original GTO’s were, and I wish the handling was more in line with what today’s drivers expect out of a car, American or not.  The sound of that LS2 is great!

This entry was posted in Automobiles, Car Stuff, Cars, Modifying Cars. Bookmark the permalink.

4 Responses to Jim’s Garage – Saturday Project

  1. Noel says:

    Sounds like a fun car. Nothing quite like RWD and 400 HP, even if the car is 500 pounds too fat. I wonder what it takes to get some springs and suspension bits from Oz to make the car work right. And knowing GM, they probably have a different steering rack or at least different valving in the power steering pump, on the Down Under version.

    But I have to say, almost every time I see a new GTO in the states it’s being driven at or below the speed limit. Makes me wonder who is buying them and why they bothered.

  2. Tim Supples says:

    Thanks for the writeup Jim, it’s always fun working on a car with another gearhead.

    Noel: It takes about $1000+ to do it right. I have about 1/3 the parts necessary right now: a handful of bushings and front struts. I need rear shocks and springs all around, with a couple more bushings, and should be good to go. Add to that a $300+ front & rear cradle alignment + 4 wheel alignment. I haven’t heard of a different steering rack, but an aftermarket one is available with better tolerances and just general tighter steering. Pedders is the name, pretty much the best stuff for 04-06 GTO’s: http://www.peddersusa.com

    And I’m generally not below the speed limit for too long… 😀

  3. Patty D says:

    Nice mods Jim, lookin to do the same to my 06 M6 Goat. How does the H-pipe swap do for weight reduction? Man, Id kill for a genuine Aussie-built Monaro. Probably just a few squirrels, but Id kill nonetheless. Theres a good video of an old fat British guy testing the LS2 Monaro, and he tops it out at 180mph, with ZERO effort on the engine.

    Noel, just so you know, im 23 and just bought my Goat. The only reason we’re at the speed limit so often is because the 5-0 are just aching to pull us over and impound our rides. Other than that, highways are free-reign, and few cars compare to the Goat in terms of power, comfort, and the ability to leave cars that cost twice as much in the dust.

  4. jimsgarage says:

    Patty –

    It looks like you might save up to 10 pounds of weight with the change. We have found that we ended up with leaks at the clamps. The clamps themselves appear to be very high quality so It may have been the installation crew that failed 😛

    The owner is going to dispense with the clamps and get it welded.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s