Jump to content
Forums Gone... but not forgotten!
Pontiac of the Month

JAH11's 1968 GTO

2024 June
of the Month

  • Rev up your passion for Pontiacs and join our vibrant community of enthusiasts!

    Whether you're a die-hard fan of classic muscle cars or you've got a soft spot for sleek modern models, you've found your home here at Forever Pontiac. Our community is dedicated to celebrating everything Pontiac, from the iconic GTO to the legendary Firebird and everything in between.

    Unlock access to expert advice, stunning photo galleries, engaging discussions, exclusive events, and more!

    Start your Pontiac journey with us today!

    Sign up now! 🏁

Supercharged Grand Am GT

Recommended Posts

Most of you know me. Its just been a really long time. Took the car apart, decided to put it back together. I searched for this specific car in 2005 on autotrader. Found 1 in a 300 mile search. Like 286 miles away, California. I drove out there and got it. Just cant let her go. Put way too much money into this thing. But oh well. Here she is when I first got her.



M45 Supercharger


Long Tube Header w/ 3" collector

High Flow Catalytic Converter

Full 2.5" exhaust

GM Crossflow Muffler


Gunmetal Exel Wheels

Black Housing Headlights

GM Strut Tower Bar

TenzoR Lowering Springs









Here is a video when I had stock pulley and just 2.25" catback exhaust.


Stock I ran 16.7 at I dont know 78mph? Lol. Supercharger 15.6 at 87mph maybe. Now 15.4 at 90mph. Times will improve once I get some mounts and traction. Possibly picking up a meth kit next.

Go to my youtube page http://www.youtube.c...rcraigbwilliams and see my video running at Speedworld Raceway. Subscribe, like, whatever you want.

Also got a whole set of drag radials. Why? Because I can. And I like to match. 225/45/17 BFG G-Force T/A drag radials.






Well here is the fun part. This IS super rare. Supposedly 1 of 5 made. These were the first prototype M45s GM was building for the LD9. Originally they had planned to intercool it but came to the conclusion there was not enough room and that the supercharger can still be as effective and efficient without it. And to save trouble and money, they casted the manifold and supercharger all as one piece. The pulley is somewhere between a 2.5 and 2.6 and should boost up to 9lbs.

What is the advantage to this supercharger? Well I for one like the fact that it is now mine and no one can have it, and its not an option for anyone out there either. It leaves a slim window open for the possibility of intercooling it. And lastly I believe the manifold may be a better design considering this supercharger sounds different. Sounds more like an M62, maybe an M90. Must be higher flowing. I have not full throttled this thing because it scares me. Maybe when I get some race gas back in the car and turn on the wideband and see where the afr is at. Still need the meth kit hooked up too.

I took a picture of every possible angle. You can see how it mounts, how the brackets are different, even the idler is different. The pulley has the protective wall helping keep the belt wrapped. Also, the fact the throttle body bolts to an adapter that bolts to the supercharger, leaves an option for a much larger inlet. Everything had to be gasket sealed since GM didnt design any gaskets for this kit.

















Link to comment
Share on other sites

Tired of these Ads? Register Today!

  • Replies 50
  • Created
  • Last Reply

Top Posters In This Topic

Truly impressive power mod to put on a 2.4L Grand Am. It is truly a remarkable, one of a kind car. Great job! I love the story of the supercharger especially.

Have you got any plans for the interior or the body at this point?

Link to comment
Share on other sites

Thanks fellas. It means a lot to me.

No numbers, but I just raced my buddy with a 3.6 pulley, headers, cai and other little things on his 04 GTP. Dead even. Went from 60mph to just over 100mph. That made my night. He got it on video, dont know how good though. Hopefully I can show that soon.

Link to comment
Share on other sites

I like it imo though I think thicker rims like the cobalt ss/SC would look amazing

My wheel size is 17x7. Same as the 17" on a Cobalt SS. Unless you are suggesting the 18" wheels that are 7.5 wide but Im not interested in hot roddin 18s on this car.

So what do you mean, thicker rim?

Link to comment
Share on other sites

' timestamp='1326073869' post='64495']

The thing I don't like about the GAGT, the wheels don't seem to have much of an aggressive offset.

I agree. But I dont want to end up with wheels that look like they are worth more than the car. Plus Ive ran into options but I HATE multi lug patterns. These wheels I have are only 5x100 and I like it that way.

I also like the color of the wheels. They arent exactly black. They happen to be the same color as my GT badges too. Lame excuse to fight for I know but I admire the accent matching.

Link to comment
Share on other sites

Got the video. My buddy doesnt have video editing program so its a long clip. We left a car show and hit the freeway. Raced a few times but the only one where you can really see me is at 2:40. Hope this will do fellas.

His car is a 2004 Grand Prix GTP 3.6 pulley, headers, full exhaust, overkill pcm, wai, and all the other little things. Suspension, plugs, blah blah.


Link to comment
Share on other sites

I agree. But I dont want to end up with wheels that look like they are worth more than the car. Plus Ive ran into options but I HATE multi lug patterns. These wheels I have are only 5x100 and I like it that way.

that's what kills many of the choices for me. nothing looks worse than multi lug patterns or the fake rivets.

car looks awesome btw.

Link to comment
Share on other sites

Well, I am not happy with my times. Went to Speedworld last night. Wasnt sure the supercharger swap would make a difference but there are I have seen different results. First off, here are my best 2 times at the track.

Reaction- .7135

60ft- 2.1897

330ft- 6.4506

1/8et- 9.8994


1/4et- 15.2404

1/4mph- 91.93

Reaction-. 5779

60ft- 2.2174

330ft- 6.4608

1/8et- 9.8903

1/8mph- 73.12

1/4et- 15.2297

1/4mph- 91.59

After these I think something broke. Engine is fine. I think the trans is fine, but the wheels (I beleive, maybe just one) want to wonder. I was flying down the track in 3rd gear and all of a sudden it just started curving right. I jerked the wheel back and got the car going straight and after that I called it a night. Long drive back noticing it a bit on the freeway, I dont know what it is. Tie rod? Hub bearing? Meh.

Scanned my car with HPTuners. Timing is between 22-29 degrees max at WOT, with xylene in my gas tank no KR, and my AFR is between 11.1-11.5 at WOT. Which is amazing since this is the original tune I had for the old m45 setup with stock pulley and no header. The biggest difference I noticed. Old setup reached 201 degrees intake air temperature. With this setup, highest was 164 degrees. Awesome! This manifold design is better for sure.

Anyways, so thats where Im at. Next, fix the problem whatever it is. Get a larger crank pulley, throw in the meth, hit the dyno.

Here is a video racing my buddies 04 GTP on the way to Speedworld, and then a video actually running at Speedworld. My buddy swapped his pulley from a 3.6 to 3.5 and I had an extra passenger so yeah. I knew I would lose. Enjoy.

Link to comment
Share on other sites

  • 1 month later...

Picked up a OD crank pulley. For those of you who dont know what it does, its bigger than the stock crank pulley, but the revolutions do not change. This will make all the other accessories spin faster. The alternator, compressor, idler, tensioner, and the supercharger. Should be seeing about 3psi more with that. Then I install the meth kit. Then the dyno.

Also think I figured out why the car is slower than it should be and why it feels like its dragging. I have too much advanced timing. Like 10 degrees too much. Need to adjust that on the dyno too.


Link to comment
Share on other sites

  • 2 weeks later...

Overdrive crank pulley installed. Im sure the supercharger is now pushed to its limit. Probably seeing 12psi on stock motor. Faster? No idea. Afraid to floor it. Meth still in trunk. After thats hooked up, dyno time.



Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Tired of these Ads? Purchase Enhanced Membership today to remove them!
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.