March's billet aluminum pulley...
March's billet aluminum pulley system was used during the dyno sessions and was retained when the engine was installed in the GTO.
Take Two
Once the refurbished Barry Grant SixShooter was sent back to Barry Penfound, it was reinstalled, and the engine was sent to Michael's Racing Engines in Macedonia, Ohio, for a second attempt at testing. After multiple pulls and backup pulls (which include timing and jet changes), it was determined that the second was the best. The 21st Century Tri-Power laid down a corrected best of 507.6 hp at 5,700 rpm, with 528.3 lb-ft of torque at 4,400 rpm. Read on as we outline the performance of this impressive powerplant.
On The Dyno
Best Pull Tuning34-degrees total timingNo. 70 main jets, 6.5 power valve in center carb; No. 73 main jets, no power valves in front and rear carbs
| RPM | Corrected
Torque | Corrected
Horsepower |
| 2,900 | 490.2 | 270.7 |
| 3,000 | 488.7 | 279.2 |
| 3,100 | 488.3 | 288.2 |
| 3,200 | 487.9 | 297.3 |
| 3,300 | 489.5 | 307.6 |
| 3,400 | 491.1 | 317.9 |
| 3,500 | 498.9 | 332.4 |
| 3,600 | 504.0 | 345.5 |
| 3,700 | 510.1 | 359.4 |
| 3,800 | 512.8 | 371.0 |
| 3,900 | 518.3 | 384.9 |
| 4,000 | 520.4 | 396.3 |
| 4,100 | 523.0 | 408.3 |
| 4,200 | 527.1 | 421.5 |
| 4,300 | 528.2 | 432.5 |
| 4,400 | 528.3 | 442.6 |
| 4,500 | 527.8 | 452.2 |
| 4,600 | 526.9 | 461.5 |
| 4,700 | 525.5 | 470.3 |
| 4,800 | 523.0 | 478.0 |
| 4,900 | 519.1 | 484.3 |
| 5,000 | 515.6 | 490.9 |
| 5,100 | 511.2 | 496.4 |
| 5,200 | 503.2 | 498.8 |
| 5,300 | 497.7 | 502.2 |
| 5,400 | 490.2 | 504.0 |
| 5,500 | 481.7 | 504.4 |
| 5,600 | 475.3 | 506.8 |
| 5,700 | 467.7 | 507.6 |
| 5,800 | 456.7 | 504.4 |
| 5,900 | 448.3 | 503.6 |
| 6,000 | 434.7 | 496.6 |