The Kenne Bell Foxbody 2.1L Supercharger Build
Finally, Back on the Road: Lessons Learned After a Winters Worth of Upgrades
After a long winter of work, a few unexpected hiccups, and a lot of patience, the car is finally back out on the road—and running better than it has in years.
Fixing the Electrical and Cooling Foundation
One of the first major hurdles to overcome was a faulty SVE alternator from Late Model Restoration. After diagnosing the issue, LMR came through and warrantied the original – which only had about 50 miles on it. The 200-amp SVE alternator upgrade has proven to be exactly what the car needed. Between dual electric fans, air ride system with dual Viair compressors, amps, subwoofers, and general electrical load, the previous 130-amp unit simply wasn’t cutting it. The new alternator handles everything without stress and offers some much needed peace of mind.
Cooling improvements followed. The Contour fans I had previously installed were not keeping up which led me to upgrade to dual 12” Spal electric fans to better manage the heat.
Vintage Air and Brake Upgrades: Big Wins
The Vintage Air Gen 5 HVAC system has been a standout success. Even in smoking hot weather, the cabin stays comfortably cool—sometimes almost too cool. Being able to drive with the windows up and AC blasting is a game-changer, especially after 25+ years of driving this car without AC sweating my a$$ off!! This car was a non – AC car from the factory.
The 03/04 Cobra brake upgrade was another major highlight. Aside from a single rear bad caliper right out of the box - that was quickly warrantied and replaced, braking performance has been excellent and confidence-inspiring. The look of the bigger brakes behind the 18” wheels is an extra bonus too!
The Kenne Bell Supercharger: Power With Compromises
The centerpiece of the build is the Kenne Bell twin-screw supercharger—and it’s been both thrilling and challenging.
Initial dyno testing revealed a major problem: the pulley setup was pushing boost levels toward a dangerous 17 psi on a stock bottom-end 302. That kind of boost would have ended badly. With limited parts on hand, the solution was an underdrive crank pulley, dropping boost down to a safer 6–7 psi. The result was a modest dyno result around the mid-300 horsepower range – which is still respectable, but underwhelming given the supporting mods like AFR 165 heads and a Comp XE266HR camshaft.
After some tuning struggles, including stalling and drivability issues, the tune was revisited. A Cobra-spec crank pulley was installed, placing boost in the 10–12 psi range. With additional data logging and tuning, the car finally came alive.
While there’s no updated dyno sheet yet, real-world driving suggests the car is now safely in the low-to-mid 400 horsepower range. In a 3000 lbs. Notchback on street tires, that power feels strong, responsive, and incredibly fun.
Heat: The Twin-Screw Trade-off
The biggest downside of the Kenne Bell supercharger is heat. Twin-screw blowers are very good at instantly making boost, however in the process of doing so, they generate an enormous amount of heat.
This particular 2.1L Flowzilla unit was purchased used and had at one point been intercooled, but sadly the previous owner removed the intercooling piping and sealed it off. That decision forced me to use a methanol injection kit to try and manage the intake air temps. While the methanol system appears to be doing its job, it’s widely acknowledged that intercooling would be the better long-term solution.
Heat management has improved significantly, and the car can now cruise comfortably with the AC on and the temps at a manageable level; but an intercooler - and possibly a better-vented hood - remain on the wish list and will possibly be considered down the road.
Would I Do It Again?
Absolutely!
The Kenne Bell blower delivers instant power, unmistakable sound, and endless smiles per gallon. That iconic supercharger whine alone makes the experience worth it. However, if I was starting from scratch, the build would begin with an intercooling solution before anything else.
Heat is the enemy, and managing it properly unlocks the true potential of this setup.
Comfort, Seats, and the Joy of Driving Again
Inside the car, the Recaro seats look great and feel fantastic once you’re in them, though their aggressive bolstering does make getting in and out a bit more involved. Still, the comfort and support are well worth it.
Most importantly, the car is running exceptionally well - arguably better than it ever has. After owning the car since 1997 and enduring too many years without AC, being able to cruise comfortably, enjoy the power, and simply drive the car again feels incredibly rewarding.
Between the blower and the AC, the smiles are constant - and after such a long journey, it’s finally time to just enjoy the ride.