The DynoSim software allows us to test different cam profiles that are in the Comp Cams da
Desktop Dyno
After we figured out the compression ratio, it was time to figure out how much power we would be making. For this we used Comp Cams DynoSim software. The program is divided into six sections. The first section allowed us to select the engine size with overbore, and it provided the stroke and calculated the total displacement based on the engine make and model.
The next section had a list of common cylinder heads allowing us to enter the airflow data for each lift point and get the exact cylinder-head airflow into the dyno graph. This is where the Cylinder Head Database on CarCraft.com is helpful. A number of cylinder-head flow tests from the same flow bench are posted on the site to cut and paste. Also, AFR has flow data on its Web site just make sure the data is from the most recent version of the head.
We know we made you figure out your compression ratio the old-fashioned way, and you probably know that dyno software has a compression-ratio calculator built in. You still have to know the deck height and the cc's of the head to use it, and our math was within 0.004 of the calculator's, so we know it's right.
The next two sections are a little soft in our opinion, with a selection of intake designs such as "high-flow single plane," and so on. You can neither see nor control the math in this area. The exhaust section basically assumes you are using good headers.
The cam section is highly detailed and offers a great deal of control. You can go to the Comp Cams Web site and download a custom profile or type individual cam-timing specs into the Cam Manager. We tried three different cam grinds and posted the results in the Dyno Results sidebar. To verify the DynoSim's accuracy, we are going to run the same cams on the dyno at Westech Performance after the engine is built to tell if the software got it right.
Next month, in part two of this series, we are going to balance the rotating assembly and assemble the short-block.
*All three engine sims were run using the small-tube open exhaust and dual-plane standard floor options.
Dynosim Results
Cam 12-564-4 Hydraulic Flat Tappet
230/244 duration at 0.050
0.487/0.501 lift
113 LSA
| RPM | Horsepower | Torque |
| 1,000 | 69 | 362 |
| 1,500 | 119 | 418 |
| 2,000 | 173 | 455 |
| 2,500 | 220 | 462 |
| 3,000 | 264 | 462 |
| 3,500 | 323 | 484 |
| 4,000 | 371 | 488 |
| 4,500 | 412 | 481 |
| 5,000 | 440 | 462 |
| 5,500 | 457 | 436 |
| 6,000 | 460 | 403 |
| 6,500 | 449 | 363 |
Cam 12-433-8 Hydraulic Roller
236/242 duration at 0.050
0.520/0.540 lift
110 LSA
| RPM | Horsepower | Torque |
| 1,000 | 62 | 327 |
| 1,500 | 109 | 382 |
| 2,000 | 162 | 424 |
| 2,500 | 208 | 436 |
| 3,000 | 251 | 440 |
| 3,500 | 315 | 473 |
| 4,000 | 370 | 486 |
| 4,500 | 417 | 487 |
| 5,000 | 454 | 476 |
| 5,500 | 479 | 458 |
| 6,000 | 486 | 426 |
| 6,500 | 482 | 389 |
Cam 12-443-8 Hydraulic Roller
242/248 duration at 0.050
0.540/0.562 lift
110 LSA
| RPM | Horsepower | Torque |
| 1,000 | 58 | 303 |
| 1,500 | 105 | 368 |
| 2,000 | 154 | 406 |
| 2,500 | 198 | 417 |
| 3,000 | 240 | 420 |
| 3,500 | 305 | 457 |
| 4,000 | 361 | 474 |
| 4,500 | 412 | 481 |
| 5,000 | 448 | 471 |
| 5,500 | 473 | 452 |
| 6,000 | 487 | 426 |
| 6,500 | 485 | 392 |