In mid-summer 2010 we added the Magnuson 2300 intercooled supercharger to the bright red Alternative Auto G8. The Magnuson’s have already made a great name for themselves in other LS based platforms with their beautifully packaged intercooled blower kits.
The Nitrous system on our G8 was great (and was left on in addition to the blower, except toned down), but we wanted to try to make more jam then the NOS without the cost and time to fill the bottle regularly.
The normal Magy kit for the standard G8 would have been the 1900 unit, but because of potential future upgrades and the obvious demand for more power as time went by, we instead went with the 2300 Magnuson for this car. We also upped the boost from the typical default psi of about 7-8, up to 10-11psi for the stock L76 G8 small block V-8 engine. At this level we were able to get just a touch under 490rwhp with just headers, and our unique exhaust that we developed and installed on this car. This combo unfortunately never beat our best ET when the car had just NOS and a VaraRam AirBox. Which was 12.0’s. The reason for this was the blower produced more punch off idle and caused greater traction problems for the G8 for the first 60 feet. At this time in mid 2010 their were no drag radials available for the stock 19in rims that we had widened. Also the NOS system was left on the car and used in addition to the blower. The NOS system was reduced to a 75 shot and the originally installed progressive controller needed much more tweaking to keep the NOS from coming on to hard from a dead dig, furthering the traction problems. And the shot of NOS combined with boost was not harmful to the motor because we were still using the MSD timing twister to pull more ignition timing whenever the NOS was triggered on top of the boost. The NOS bumped power up to 550 at the wheels.
Later in the summer of 2010 we then installed an Alcohol injection system with a very neatly and cleverly mounted 3 gallon reservoir in the trunk where the spare tire would normally go. With the Alky kit installed, we then bumped the boost to 12psi on still the stock non forged motor. This brought our Rear Wheel numbers up to 515hp, and the NOS brought it up to 575rwhp. As great as these number sound… once again in the late 2010 season the G8 never ran any decent number in the quarter mile do to major traction problems on the 19” rims with the BFG 295/35 tires we had.
For the 2011 season we decided to preemptively forge the short block with some good pistons, connecting rods and retained the stock crank and block. We did not stroke or do anything exotic here in any way, just good forged pistons and rods, minimal head work, and the only major change is we went with a very mild custom camshaft from Crower (to get away from the D.O.D. profile) that has only a slight hint of rumping at an idle. We did not want to go to crazy with the cam selection because we did not want to induce any drivability problems in this sedan, and mostly because we retained the relatively tight stock TQ convertor because of the low end TQ and grunt that the Magnuson produces.
With the now forged internals we decided that we could be more aggressive with the boost and the tuning as well. So the boost got bumped to 13psi and even the NOS system got a slight bump in jetting too. All of this ended up with some final numbers in the 550rwhp on boost alone and 620+rwhp when hit with the small NOS shot. This is still with 93 octane and the Alky kit doing its job. The power could have been much more we feel, but it is held back by the predominantly 2 & 1/4in. exhaust system. Not 2.5” or bigger like most might do.
Besides the forged motor and bigger camshaft our supercharged G8 ended up with during the 2011 season, the next best thing/miracle to happen was; Mickey Thompson released a new drag radial in 2011 that was a direct fit onto our already widened stock 19in G8 wheels. The new 305/35/19” MT tire fit perfect on the 19 X 10” widened production wheel, and fixed some serious traction problems that we experienced with our G8 as soon as the NOS and other things began to happen on this car when it was nearly new a couple years back.
To date for 2011 in very warm weather this G8 has run a best of 11.50’s at 118mph on boost alone, and 11.0’s at nearly 125.00mph with the NOS enabled on top of the boost at WOT. We feel that these numbers could have been much better given some sub 80degree weather, but sadly we didn’t get an opportunity to best these numbers in the fall of 2011.