Reply to "1970 Boss 351"

> Thanks Dan. But I don’t understand your numbers.

The numbers shown are a comparison of headers to exhaust manifolds.

> Did you compare the stock headers to the stock manifolds?

We decided to skip testing the stock Pantera exhaust manifolds.
Given their dimensions and construction we didn't think they
would be much different from the Ford cast iron exhaust manifolds.
Perhaps we should test them for completeness' sake. BTW, they are
not headers as they have no collector. Rather, they are log type
manifolds like the Ford cast iron exhaust manifolds.

Some of the exhaust tests are summarized below.

Dan Jones

351 C Test 12 HVH 1 inch Spacer, CHI 3V heads, Hooker 1 3/4" long
tube headers and Magnaflow mufflers

RPM HP Torque (ft-lb)
3200 222.0 359.8
3300 222.4 354.8
3400 230.3 356.0
3500 240.0 360.3
3600 249.9 364.9
3700 262.0 371.8
3800 277.0 382.4
3900 293.2 394.4
4000 302.8 397.8
4100 315.7 404.3
4200 329.8 412.1
4300 341.1 416.5
4400 349.7 417.9
4500 357.7 417.5
4600 369.2 421.2
4700 377.5 422.1
4800 386.2 422.4
4900 394.5 422.9
5000 401.7 422.1
5100 411.6 423.7
5200 420.5 424.8
5300 428.3 424.6
5400 436.2 423.4
5500 434.2 415.1
5600 431.2 404.6
5700 430.8 396.8
5800 432.4 391.9
5900 433.2 385.7
6000 435.6 381.5
6100 435.1 374.4

We next tried a set of large tube Econo Altered drag headers which have
2 1/8" primaries of around 40 inches length and long 4" diameter collectors.
These were run without mufflers. Our mild street 351C was just not enough
engine to make use of these headers. They lost a whole bunch of torque and
didn't catch up until 6000 RPM. We then tried a set of Pantera 4-into-1
headers (Hedman style with 2V port openings). These have rather short
primaries (between 19" and 24") of 1 3/4" diameter and a tiny collector with
2 1/4" outlet. They lost maybe 15 ft-lbs but closed the gap some as RPM went
up. Overall, I don't think they worked as well on this engine as the Euro
GTS style Pantera headers had on the 408C. Those headers have a 2" primary
with similar short primaries but have a tri-y type collector. It would be
interesting to experiment with a better collector on the Hedman headers to
see what sort of improvement can be made. The stock Pantera ANSA mufflers
were just plain terrible. Just as the Euro GTS mufflers had on the 408C,
the stock Pantera mufflers lost 50 ft-lbs and 50 HP to the 1 3/4" long
tube Hookers with 3" Magnaflows.

351 C Test 13 Dragster Headers
Same as earlier with HVH spacer on CHI single plane intake except now running
a set of dragster open headers with no mufflers. Louder but not really better
and worse through the midrange costing around 20 ft-lbs at 4500rpm. 2 1/8"
primary with a 4 inch collector approx 12 inches long. Primary length is 40
inches.

RPM HP Torque (ft-lb)
3200 212.8 350.2
3300 216.4 344.4
3400 220.9 341.1
3500 225.3 338.2
3600 231.0 336.9
3700 239.6 340.3
3800 251.7 347.9
3900 267.9 360.4
4000 283.8 372.5
4100 297.7 381.3
4200 311.1 389.1
4300 321.4 392.7
4400 330.6 394.2
4500 339.2 396.0
4600 350.3 400.1
4700 362.4 404.6
4800 372.0 407.3
4900 380.8 408.3
5000 389.2 408.7
5100 399.5 411.5
5200 409.8 414.0
5300 417.9 414.1
5400 427.6 415.5
5500 430.3 411.1
5600 431.7 404.3
5700 425.3 392.6
5800 426.4 385.9
5900 434.5 386.3
6000 436.9 383.1
6100 431.3 371.3


351 C Test 14 Pantera Headers No Mufflers
Repeat with Pantera headers but no mufflers. Far from ideal exhaust
system. Area under the curve is reduced more than the peaks might
indiciate (compared to long tubes).

RPM HP Torque (ft-lb)
3200 219.8 355.6
3300 221.2 355.7
3400 229.5 354.7
3500 237.1 355.7
3600 244.8 357.1
3700 252.8 358.9
3800 260.8 360.4
3900 267.4 360.3
4000 274.5 360.6
4100 283.2 362.9
4200 292.5 365.7
4300 303.8 370.8
4400 316.7 377.9
4500 327.1 381.9
4600 335.9 383.9
4700 348.8 389.8
4800 366.3 400.4
4900 375.8 403.0
5000 383.5 402.8
5100 388.9 403.5
5200 402.4 407.3
5300 402.3 398.8
5400 410.8 399.2
5500 421.6 401.9
5600 422.3 396.1
5700 421.6 388.7
5800 417.7 378.5
5900 417.5 371.7
6000 419.7 367.3
6100 424.2 364.8


351 C Test 15 Pantera Headers and Exhaust System
Running with the Pantera headers and exhaust system and mufflers.
Terrible torque and horsepower down about 50 ft-lbs and 50 HP.

RPM HP Torque (ft-lb)
3200 187.1 306.5
3300 190.4 305.9
3400 203.0 313.2
3500 217.1 325.4
3600 238.1 344.3
3700 247.8 351.5
3800 257.9 356.0
3900 264.3 357.2
4000 271.8 357.6
4100 284.6 362.9
4200 292.4 365.4
4300 296.6 364.2
4400 305.8 364.6
4500 316.8 369.3
4600 326.2 372.2
4700 330.9 369.1
4800 331.2 363.4
4900 333.5 357.7
5000 341.1 358.2
5100 350.3 360.8
5200 361.2 365.0
5300 376.0 371.2
5400 380.2 370.3
5500 377.8 361.8
5600 373.5 349.9
5700 375.4 345.2
5800 377.1 341.8
5900 380.7 338.6
6000 383.8 335.9
6100 380.8 327.9

********************************************************************************
Torker with 1 inch 4 hole spacer
Unported iron 4V heads, Torker intake manifold with 4 hole 1 inch spacer. Carburetor would not fit on this intake without spacer so this is the
baseline for this piece. Going to try HVH spacer next.

RPM HP Torque (ft-lb)
4000 312.9 409.3
4100 316.6 406.5
4200 324.3 404.7
4300 332.7 407.4
4400 346.3 410.7
4500 349.2 408.1
4600 354.1 404.4
4700 362.8 405.1
4800 371.3 406.4
4900 375.1 402.2
5000 380.3 399.3
5100 387.9 399.1
5200 394.1 398.1
5300 395.3 391.9
5400 398.6 387.7
5500 401.6 383.4
5600 403.3 378.3
5700 400.8 369.4
5800 401.7 363.7
5900 401.1 357.2
6000 403.1 352.5

Torker intake with HVH spacer.
Runs nearly identical to with the 4 hole 1 inch.
A little better power but a bit worse torque.

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

Baseline with Pantera Headers
Baseline for tonight's testing using Pantera exhaust system. Running with the
4V heads, Torker intake , HVH carb spacer, 950HP carb, 38 degrees total timing,
Euro GTS "tri-y" headers (actually 4-into-1 with a tri-y collector, 2" OD
primaries, 2.25" collector) and Euro-GTS mufflers (small lunchbox size muffler
with dual resonators (per side). Reasonable numbers to about 5500 rpm where
power falls off. Down 38 HP to long tubes and Magnaflows.

RPM HP Torque (ft-lb)
3500 208.6 313.2
3600 212.7 310.7
3700 219.9 312.3
3800 230.4 318.0
3900 239.0 322.2
4000 251.5 330.1
4100 267.2 341.8
4200 282.9 353.7
4300 286.5 350.2
4400 296.2 353.2
4500 306.7 358.1
4600 319.3 364.5
4700 325.4 363.8
4800 334.1 365.3
4900 343.4 367.8
5000 345.7 363.5
5100 348.3 358.6
5200 354.0 357.5
5300 360.2 356.9
5400 365.7 355.6
5500 370.7 354.2
5600 371.6 348.4
5700 369.5 340.6
5800 364.8 330.4
5900 360.9 321.2
6000 356.6 312.2
6100 353.1 304.4

Pantera Headers Test 2
Modified mufflers on the GTS headers.
Same as Test 1 with Mike Drew's modified GTS mufflers. The GTS muffler
baffles were removed and replaced by a Y-pipe. The pipe was perforated
and muffler body packed with steel wool. Mufflers sounded better
(slightly more whistle to the tone) and peak power was up 13 HP with
torque was up around 10 ft-lbs over a fairly wide RPM range so this was
a meaningful modification but still leaves a lot of power on the table. Interestingly, the Euro GTS headers plus modified mufflers makes around
the same power as our previous test with OEM cast iron 4V manifolds
without mufflers.

RPM HP Torque (ft-lb)
3500 215.5 321.1
3600 219.8 322.9
3700 226.0 320.6
3800 231.9 320.7
3900 241.4 325.3
4000 254.1 333.6
4100 268.9 344.2
4200 283.6 354.3
4300 295.3 360.5
4400 305.1 364.1
4500 314.8 367.3
4600 322.7 368.6
4700 334.8 374.2
4800 344.5 376.7
4900 350.8 376.3
5000 353.2 371.1
5100 357.3 367.7
5200 364.4 368.7
5300 364.2 361.1
5400 370.9 360.5
5500 381.7 364.0
5600 384.5 360.5
5700 380.6 350.9
5800 374.9 339.7
5900 369.8 329.2
6000 366.7 320.8
6100 369.5 317.6

Pantera Header Test 3
Running with the Pantera header and the Magna Flows clamped
to the header via a 3 inch by 12 pipe. Same as Test 1 but
with 3" inlet/outlet Magnaflow mufflers clamped to the Pantera
Euro GTS headers via a 3" diameter by 12" long pipe. Good solid
power gain over baseline and modified exhaust system.

RPM HP Torque (ft-lb)
3500 223.1 333.8
3600 226.5 330.8
3700 230.9 328.0
3800 240.6 332.5
3900 252.0 339.4
4000 264.7 347.6
4100 278.9 357.3
4200 295.1 368.8
4300 314.0 382.5
4400 324.8 387.9
4500 330.1 385.8
4600 339.4 387.3
4700 352.4 393.2
4800 363.9 398.3
4900 369.2 395.9
5000 374.3 393.3
5100 378.8 390.2
5200 383.8 387.8
5300 391.1 387.6
5400 400.1 389.0
5500 407.0 388.0
5600 405.0 380.4
5700 402.2 370.4
5800 400.2 362.4
5900 400.4 356.2
6000 399.1 349.7
6100 399.2 344.8