Reply to "1970 Boss 351"

> DeTomaso claimed the exhaust system upped the horsepower to 330.

DeTomaso claimed it but the dyno says otherwise. The stock mufflers
lost 50 HP and the Pantera tubing log manifolds (they are noy headers)
are no better than the cast iron exhaust manifolds.

> I expect the stock Cleveland exhaust manifolds are super restrictive
> compared to the stock Pantera headers.

Not the case. Both are quite restrictive.

Torker intake with HVH spacer. Runs nearly identical to with the
4 hole 1 inch. 1 3/4" Hooker long tube headers.

RPM HP Torque (ft-lb)
4200 318.8 397.5
4300 325.0 397.7
4400 331.6 395.9
4500 339.4 396.1
4600 349.9 399.2
4700 360.6 402.9
4800 368.0 402.8
4900 372.4 399.5
5000 378.0 397.0
5100 388.6 399.7
5200 397.1 401.1
5300 401.3 398.2
5400 404.9 393.8
5500 409.9 390.9
5600 412.1 386.7
5700 407.9 375.8
5800 401.4 363.8
5900 398.9 355.1
6000 401.3 351.2
6100 407.0 350.2

Repeat of the Torker intake manifold test but with the 1 3/4" diameter long
tube headers and Magnaflow mufflers replaced by the OEM 351C-4V cast iron
exhaust manifolds and a short elbow of pipe (no mufflers). At peak, the
engine was down nearly 30 HP and at 4200 RPM, it was down a whopping
59 HP and over 70 ft-lbs of torque! The engine also sounded rather odd
and the increased back pressure upset the idle quality noticeably. Combine
this test with the muffler test and it's easy to see you can throw away a
bunch of HP on a 351C with a poor exhaust.

RPM HP Torque (ft-lb)
4200 259.7 324.9
4300 274.3 334.7
4400 284.8 340.1
4500 294.8 344.0
4600 305.4 348.7
4700 315.1 352.2
4800 330.1 360.6
4900 343.2 368.8
5000 345.5 363.1
5100 354.0 364.2
5200 364.8 368.7
5300 368.6 365.4
5400 377.5 367.0
5500 382.5 365.5
5600 383.0 359.2
5700 384.7 354.4
5800 383.8 347.0
5900 376.6 335.6
6000 369.3 323.2
6100 380.5 328.4

Dan Jones