Update by Tim Suddard to the
Shelby GT350 project car
Jun 20, 2012
We had quite the brain trust at the dyno with us: J.K. Jackson, Rennie Bryant and Ron Delvalle.
We kept switching jets until we got the air/fuel ratio correct.
A bit of tweaking on the power valve gave us great drivability.
In late April 2012 we got a chance to get back to the dyno. The last time we left the dyno we were running a bit rich still and peak power was at 360 horsepower and 371 lb-ft of torque. This time around, we were at Balanced Performance in the Atlanta suburb of Sugar Hill, Georgia. We love working with these guys. They have one of the nicest dyno shops we know of, as well as the mechanical expertise to help us get the most out of our cars. This time around, we had expert tuners JK Jackson of English Automotive, Rennie Bryant of Redline BMW and Ron Delvalle of Balanced Performance. If ever we were trying to perfect a tune, we couldn’t ask for a better brain trust in the room.
Every dyno is different. This is especially true if you travel 400 miles to different weather and a different altitude. Dynos are supposed to compensate, but the altitude in Altanta is different than it is in Central Florida.
Still, we started out with 350 hp and 337 lb.-ft. of torque. Down a little, but not too bad. To lean the Shelby out, we changed from a 78 to a 74 and then to a 72 secondary jet and horsepower went up to 375. Torque was a little lower than our best at 350 lb.-ft., but we were focusing on the air/fuel ratio and trying to get it perfect. These changes got us to an air/fuel ratio of 11.6:1 all through the rev range, until 5000 rpm where it dropped to an even safer 11.5:1.
From there we adjusted power valves to get tip-in and drivability perfect. We managed to really improve drivability, fuel mileage (although we haven’t tested rigorously for that) and performance. On our test drive afterwards, the car was noticeably faster. Unfortunately, boys will be boys, and our clutch started slipping after a burnout or two.
When we were putting this car together, the folks at Centerforce warned us that at nearly 400 hp at the wheels, we were at the upper limits of what a street clutch could handle. We were in a hurry and didn’t have time to wait and test their new dual-disc heavy duty clutch. Now the abuse has forced our hand; we’ll be installing it before long.
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