Car Craft Magazine Homepage Car Craft
Facebook Click here to find out more!

Headers Comparison - Pipes for Power

Not All Headers Are Created Equal

Photography by

If you look at the average power curve numbers, you can see that the larger headers actually made slightly less average power. That's because the horsepower gain at the top did not completely make up for the torque loss at the bottom of the curve. So what's the bottom line here? If this engine is going into a light car with a manual trans and a deep rear gear, or at least an automatic with a stall speed of no less than 3,600 rpm, the larger headers might be a slight advantage. The important point here is that a 131/44-inch header is probably the answer, since it would improve the low-speed power while not sacrificing nearly as much horsepower at the top end.

Another point worth mentioning is that what we're seeing here with these two primary-pipe-diameter power curves is not really as much about power loss or gains as it is about moving the curve around where the engine makes its best power. Had we tested a set of 131/44-inch headers, we're confident we would have witnessed an average power increase over the other two primary pipe diameters. This merely reinforces the idea that engines operate best when outfitted with the right set of parts that complement the rest of the engine package.

Test 7: A 406ci small-block Chevy outfitted with a set of Dart Pro 1 heads, a healthy mechanical-roller camshaft, a set of Hedman 151/48-inch-diameter primary-pipe four-into-one headers, and a 211/42-inch exhaust using a pair of Borla XR-1 mufflers.

Test 8: The same engine outfitted with a set of Hedman 171/48-inch-diameter primary-pipe four-into-one headers with the same Borla exhaust system.

Test 7 Test 8 Difference
RPM TQ HP TQ HP HP TQ
2,600 432 214 385 191 -47 -23
2,800 433 231 390 208 -43 -23
3,000 429 245 411 235 -18 -12
3,200 433 264 440 268 + 7 +4
3,400 443 287 455 294 +12 +7
3,600 454 311 460 315 + 6 +4
3,800 464 335 456 330 -8 -5
4,000 464 353 444 338 -20 -15
4,200 466 372 436 348 -30 -24
4,400 469 393 436 365 -33 -28
4,600 470 412 451 395 -19 -17
4,800 474 433 462 422 -12 -11
5,000 472 450 461 439 -11 -11
5,200 467 463 461 457 -6 -6
5,400 457 470 457 470 0 0
5,600 447 476 449 478 +2 +2
5,800 438 484 445 492 +7 +8
6,000 429 490 437 499 +8 +9
6,200 417 493 434 513 +17 +20
6,400 402 490 418 515 +16 +25
6,600 385 484 405 510 +20 +26
Average Difference -7 hp -3 lb-ft
SOURCES
Doug Thorley Headers/Jardine Hedman Hedders
16410 Manning Way
Cerritos
CA  90701
310-921-0404
www.hedman.com
Doug's Headers
909-788-4878
www.dougsheaders.com
Hooker Headers (A Division of Holley)
N/A
8-00/-Hol-ley1
holley.com
DynoMax Performance Exhaust
500 N. Field Dr.
Lake Forest
IL  60045
8-47/-482-5000
www.dynomax.com
JBA Headers
7149 Mission Gorge Rd.Suite D
San Diego
CA  92120
800-830-3377
www.jbaheaders.com
Flowtech (A Division of Holley)
Bowling Green
KY
N/A
N/A
Stahl Headers
www.stahlheaders.com
Headers by Ed
P.O. Box 7494
Minneapolis
MN  55407
Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!

*Please enter your username

*Please enter your password

*Please enter your comments
Comments:
Not Registered?Signup Here
(1024 character limit)
Car Craft