One of the Pantera guys, Orville Burg, came up from Texas to drop an engine off
for Dave and helped us with another day of dyno testing the unported iron 4V
closed chamber heads. Our starting configuration was where we left off last
time: Edelbrock Torker intake with Pantera GTS headers and Magnaflow mufflers.
The engine was allowed to warm and then we made a baseline pull to use for
atmospheric condition corrections. Corrected numbers were close to our
previous pull, so we began our testing. Note that all of the numbers below
are 4 to 5% conservative compared to the calibrated EMC dynos. In previous
posts where I was quoting peak numbers only, I posted both the raw data
(corrected for atmospheric data) and also the data adjusted for the 5%
conservatism.

Baseline 10/17/09
Running 35 degrees timing with Pantera GTS headers and Magnaflow mufflers.
Torker intake, HVH spacer and 950HP. Cool clear weather today with very
high barometer and moderate humidity.

RPM Hp Torque
(HP) (ft-lb)
4100 283.7 361.3
4200 288.9 361.4
4300 297.4 363.3
4400 306.2 365.7
4500 315.6 368.4
4600 325.3 371.4
4700 335.4 374.5
4800 346.6 378.4
4900 351.9 377.8
5000 355.5 373.4
5100 360 370.9
5200 363.4 367
5300 368.8 365.5
5400 374.2 364
5500 378.9 361.9
5600 379.7 355.8
5700 381.7 351.9
5800 378.7 342.8
5900 373.4 332.8
6000 370.4 324.1
6100 373.2 320.5


Factory 4V Iron Intake
Holley 950HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Same as baseline except for running factory 4V iron square bore intake manifold
and 4 hole 1 inch spacer. The OEM intake required a spacer for throttle
clearance so was tested only with 1" spacers. Not a really good pull but
engine had time to cool. Going to try one more time but seems to be down
about 30HP from our baseline with the single plane Torker.

RPM Hp Torque
(HP) (ft-lb)
4000 273.9 356.1
4100 279.8 361.1
4200 276.3 345.9
4300 279.2 341
4400 285.6 340.8
4500 294.2 343.3
4600 304.5 347.6
4700 316.1 352.8
4800 326.1 356.3
4900 324.6 346.4
5000 328 344.6
5100 332.6 342.7
5200 335.5 339
5300 340.9 337.7
5400 351.1 340.8
5500 353.9 338.5
5600 349.2 327.7
5700 346.8 319.6
5800 349.8 316.4
5900 353.9 316.1


Factory Iron Test 2 - Same as 1st
Same as previous run. Engine seems to be somewhat rougher and more difficult
to load properly. 12.5 AFR. Going to try an HVH spacer on next pull to see
if it smooths it out somewhat.

RPM Hp Torque
(HP) (ft-lb)
4000 283.8 369.6
4100 282.7 361.8
4200 279.5 349.8
4300 283.5 346.3
4400 289.4 345.5
4700 313.8 350.4
4800 323.5 353.7
4900 334.7 358.1
5000 342.3 360.1
5100 344.5 354.9
5200 347.2 350.6
5300 350.7 347.5
5400 349.1 339.7
5500 348.3 332.4
5600 345.9 324.6
5700 351.2 324.5
5800 332 301

Factory Iron with HVH Spacer
OEM square bore intake, Pantera GTS headers and Magnaflow mufflers.
Much better with the semi open spacer under carburetor. Most likely due to the
amount of camshaft overlap and the interaction it has with the dual plane type
intake. It will be very interesting to see if this trend continues with the
other larger dual planes.

RPM Hp Torque
(HP) (ft-lb)
4000 278.9 362.6
4100 285 365.7
4200 288.2 360.5
4300 296.6 362.2
4400 304.1 362.9
4500 310.9 363
4600 318.7 364.1
4700 326.1 364.5
4800 335.4 366.4
4900 341.9 366.8
5000 345.4 363
5100 350.5 360.7
5200 355.8 359.4
5300 360.4 356.9
5400 362.3 352.6
5500 362.7 346.3
5600 364.9 341.8
5700 362.7 334.8
5800 356.9 323.3
5900 358.3 318.8
6000 363.1 317.9
6100 355.4 305.9


Performer with 4 Hole 1 Inch Spacer
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Note: Intake is actually the earlier F-351 4V version but appears identical to
the current Performer. The Perfomrer required a spacer for throttle clearance
so was tested only with 1" spacers. Baseline for Edelbrock Performer intake
with 4 hole 1 inch spacer which was needed to allow clearance for fuel log.
Good solid pull and for whatever reason the engine didn't seem to mind the 1
inch 4 hole on this dual plane. Going to try the HVH spacer next.

RPM Hp Torque
(HP) (ft-lb)
4100 285.7 365.8
4200 288.8 361.5
4300 298 363.8
4400 304.5 363.6
4500 309.1 361.1
4600 315.7 360.5
4700 325 362.8
4800 333.3 365.2
4900 337.7 361.9
5000 341.1 358
5100 344.8 355.2
5200 350.3 353.5
5300 352 349.4
5400 354.9 345.2
5500 359.5 343.1
5600 363.1 340.1
5700 363.2 335.3
5800 356.8 323.1
5900 354.2 314.9
6000 345.7 302.8
6100 352.9 303.2


Performer with HVH Spacer
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
HVH was also better on the Edelbrock Performer but not as drastic as with the
factory iron piece. Performner is better than factory intake or so it seems
on this engine.

RPM Hp Torque
(HP) (ft-lb)
4100 293.4 373
4200 295.9 371.5
4300 307.1 376
4400 309.1 369.3
4500 314.9 367.7
4600 323 368.9
4700 332.7 371.6
4800 343.9 375.9
4900 353.6 378.6
5000 353.4 371.5
5100 357.4 368
5200 360.2 364.2
5300 359.7 356.7
5400 362.5 352.5
5500 366.8 350
5600 369.8 346.5
5700 371.8 342.4
5800 371.5 336.5
5900 372.5 331.6
6000 364.2 318.9
6100 365.9 315.3


Performer RPM Air Gap 2V
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Baseline for Performer RPM airgap intake. Like many of the intakes designed
for 2V heads, the RPM Air Gap will fit either 2V or 4V heads. Running with
no spacer. Going to try the 4 hole 1 inch and HVH spacers next. Good solid
pull with good numbers.

RPM Hp Torque
(HP) (ft-lb)
4000 297.5 386.4
4100 297 382.7
4200 305.4 380.9
4300 313.4 383.5
4400 319.8 381.8
4500 328.4 383
4600 334 381.6
4700 338.9 378.7
4800 345.4 377.8
4900 352.4 377.7
5000 358.3 376.3
5100 363.6 374.4
5200 368.3 371.8
5300 371.7 368.8
5400 374.2 363.9
5500 379.1 361.9
5600 377.8 354.4
5700 375.8 346.3
5800 373.9 338.7
5900 374.5 333.4
6000 377.7 330.4
6100 375.5 323.2


Performer RPM Air Gap with HVH
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
HVH spacer seems to run about in the middle of the bare intake or 4 hole 1
inch. Good all around performance making over 380HP and torque.

RPM Hp Torque
(HP) (ft-lb)
4100 295.3 381.7
4200 299.8 375.3
4300 308.6 376.9
4400 321 382.8
4500 333 388.5
4600 337.3 385.3
4700 343 383.1
4800 349.8 382.7
4900 355.8 381.3
5000 359.2 377.6
5100 363.1 373.9
5200 370 373.4
5300 374.2 371.3
5400 376.5 366.1
5500 381 363.3
5600 380.1 357.1
5700 372.2 343
5800 370.2 335.1
5900 367.6 327.3
6000 365.8 320.2
6100 368.5 317


Performer RPM Air Gap with 4 hole 1 Inch
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Good pull and engine picked up about 5 horsepower and about 10lbs/ft with 4
hole. A good swap and about the best all around combo for these heads etc.

RPM Hp Torque
(HP) (ft-lb)
4000 298 389.8
4100 301.5 387.1
4200 308.9 385.4
4300 316.9 388
4400 329.8 391.1
4500 332.6 388.7
4600 337.2 385.1
4700 345.5 385.8
4800 353.6 387
4900 357.2 383
5000 362.2 380.3
5100 369.4 380.1
5200 375.3 379.1
5300 376.5 373.2
5400 379.6 369.2
5500 382.5 365.1
5600 384.1 360.3
5700 381.7 351.8
5800 382.6 346.4
5900 382 340.2
6000 383.9 335.7


Holley Strip Dominator with HVH Run 10
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
For the 10th pull of the day we switched back to the Holley Strip Dominator
and HVH spacer which was the best combination tested on the unported iron
heads previously. We found it to be virtually identical to our previous
numbers making about 390 HP with the Pantera headers.

RPM Hp Torque
(HP) (ft-lb)
4000 265.4 345.6
4100 278 352.7
4200 280.8 351.7
4300 286.8 350.6
4400 294.2 351.4
4500 304 354.9
4600 315.9 360.5
4700 328.9 367.1
4800 339.9 371.5
4900 346.2 371.3
5000 355 371.8
5100 360.2 371
5200 364.2 368.1
5300 371.3 368
5400 377.8 367.5
5500 383.9 366.6
5600 388.2 364.1
5700 388.6 357.8
5800 386.6 349.9
5900 379.5 338.3
6000 376.6 329.7
6100 380 327
6200 385.1 327.2

The Strip Dominator made more peak HP than the Edelbrock RPM Air Gap but
the Air Gap was close (within 5 HP) and made much better torque for most of
the RPM range. For instance, at 4000 RPM, the RPM Air Gap made 44 ft-lbs
more torque than the Strip Dominator. The cam used in this test is pretty
much tailor made for the RPM Air Gap. On a larger displacement engine like
a 408C stroker of a higher RPM and the Strip Dominator would likely be the
better choice. It will be interesting to see how the RPM Air Gap compares
to the Blue Thunder 4V dual plane (in both ported and unported form). It
might also be worthwhile to test one of the 2V single plane intakes on the
4V heads.

For this round of testing, we planned on finishing off the standard 4V intake
manifolds, keeping the more exotic 4V induction (Webers, Autolite In-Lines,
Bud Moore Ram Box) for testing on the ported iron 4V heads. Unfortunately, we
didn't get to test all the intakes we had planned on. The Blue Thunder high
rise 4V dual plane did not clear the large cap MSD distributor. Dave's going
to switch to a smaller cap and run that test later. Also, the accelerator pump
on the ThermoQuad carb was dead so we did not run the Offenhauser Dual Port
spread bore intake. Dave's going to make a spacer so we can run the Holley
950HP carb but we'll also run a test with either the ThermoQuad or a QuadraJet.
The Ford D1ZX Dominator single plane has a bore spacing pattern that is
different from the standard Holley Dominator carb pattern and will also require
a spacer. In addition, I forget to bring the Offenhauser Equa Flow 360 split
plenum intake. I'll bring it next time. The CHI 3V single plane intake needs
the dowel pins to be removed from the heads before it will fit. We'll do that
on the next 4V heads we test.

We test fit both a Roush A331 and an Edelbrock D351 (both intakes designed for
Ford Motorsport C302 heads) but neither intake would slip down far enough to
seal properly on the 4V heads. The A331 was a new-in-box intake while the
D351 had been milled. It's not immediately apparent why they did not slip
into place. We'll need to mock the high port heads up on a spare block to see
if the intakes require any milling. We also need to check the Bud Moore Ram
Box for distributor clearance (and also the Webers, Autolite In-Lines and IR
EFI).

Kirk Evans had also sent along a set of Parker Funnelweb intake port stuffers
that we were going to test but the owner of the Funnelweb intake needs his
intake back so we won't get the chance to test them.

Air-fuel ratios were a bit on the rich side (11.9 to 12.3:1) range but were
fairly consistent between the intakes so we didn't try any carb fine tuning.

With the intake testing finished for the day, we moved on to some exhaust
testing. First we tested the MPG Head Servive "Stinger" exhaust port stuffers.
These are the individually flanged brass inserts with the a tongue that sticks
into the 4V exhaust port floor, reducing the exhaust port volume. They bolt
between the header and the head. Feedback from some of the Mustang drag racers
suggested they might not do anything positive. However, one of the Pantera
guys had drag race tested them on an engine similar to ours and found they made
some additional power. Pantera headers differ from most 351C headers in that
they have several inches of straight pipe at the exhaust port exit, before
turning. Many Mustang 351C headers turn sharply down at the port exit which
might not work with the inserts, so my expectations were the inserts would make
a minor improvement with the Pantera headers but not the Hooker Mustang headers.
Surprisingly, the exhaust port stuffers worked on both the Pantera headers and
the Hooker long tubes to the tune of approximately 5 HP and 10 ft-lbs.

Port Plate Test
Same setup as pull number 10 with the Strip Dominator HVH intake setup and
Pantera header. The Pantera header comes straight out from the cylinder head
whereas the Mustang Hooker header turns downward more quickly. In this case,
the port plate/tounge seems to help in the next test we'll try it with the
Mustang headers and see if there's a difference for better or worse.

RPM Hp Torque
(HP) (ft-lb)
4000 265.4 348.9
4100 272.6 349.5
4200 283.2 354.3
4300 295.6 360.8
4400 307 366.4
4500 317.9 371
4600 327 373.5
4700 336.8 376.2
4800 348.1 380.6
4900 354.9 380.7
5000 358.1 376.3
5100 367 377.5
5200 370.4 374.5
5300 376.2 372.7
5400 385.2 374.3
5500 391.4 373.7
5600 390.9 366.8
5700 385.6 355.5
5800 386.8 350.1
5900 388.2 345.2
6000 383.3 335.9
6100 381.8 329.3

Hooker Competion Mustang long tube headers
These were also slightly better with the port plates. Seems to be about
5 HP and about 10lbs/ft better than without with both of our test headers.
These headers or the Pantera design seem to not be terribly bad about a sharp
quick turn down when leaving the cylinder head as some headers can be on the
Big Block Ford engine.

RPM Hp Torque
(HP) (ft-lb)
4000 281.6 365.6
4100 281 361
4200 286.1 358
4300 294.7 360.1
4400 304.7 363.7
4500 316.5 369.2
4600 329.7 376.1
4700 343.1 383.1
4800 349.8 384.1
4900 355.1 381.3
5000 357.9 376.2
5100 363.2 373.9
5200 371.3 374.7
5300 382.1 378.9
5400 387.5 376.9
5500 392.3 374.3
5600 392.1 367.9
5700 387.7 357.5
5800 384.7 348.4
5900 384.8 342.4
6000 378.7 331.7
6100 384.3 330.7

I have a set of Tubular Automotive headers for swapping a 351C into a '65-'66
Mustang that would be a good test of the sharp turn down theory (they have to
turn very sharply to clear the narrow 1st generation Mustang shock towers) but
they require me to pull the engine on my '66 fastback.

We still had a little time left, so we decided to see if the Pantera 180
headers would fit the dyno. To my surprise, they fit just fine after moving
the coil from off the top of the bellhousing. They worked about as well as
the Pantera GTS headers without the port plates.

180 degree headers without mufflers, no port plates and no real difference in
power. Running Strip Dominator intake with HVH spacer and 950HP.

RPM Hp Torque
(HP) (ft-lb)
4100 264.1 339.3
4200 273.7 341.7
4300 285.2 348.2
4400 300.1 357.9
4500 315.2 367.5
4600 321.1 367
4700 328.5 367.7
4800 342 373.6
4900 348.6 374.2
5000 353 371
5100 361.9 372.3
5200 369.6 374.2
5300 371.2 367.8
5400 378.5 368.3
5500 381.6 364.6
5600 384.4 360.2
5700 386.7 356.2
5800 380.2 344.5
5900 376.4 334.9
6000 374.1 327.2
6100 382.2 328.9

Running the 180's with Super Trap mufflers. Down a little torque but
about the same HP. Certainly not better than the more standard Pantera
header on this engine.

RPM Hp Torque
(HP) (ft-lb)
4100 249.9 320.7
4200 258.8 324.2
4300 272.4 332.8
4400 286.7 342.2
4500 302.4 352.7
4600 319.5 364.6
4700 333.9 375
4800 340.7 373.2
4900 345.9 370.9
5000 349.1 366.5
5100 355.4 365.3
5200 361.9 366.5
5300 365.2 362
5400 371.3 361
5500 381.7 363.6
5600 382.6 359.3
5700 379.8 350
5800 375.8 340.5
5900 373.1 332
6000 373.7 326.8
6100 378.3 326.6

Note the 180's used for this test have a very small collector that
is angled and would not permit testing the Magnaflow mufflers.
A better collector design might improve these headers. We did not
test the 180's with the port stuffers as we were unsure they would
fit with them.

Given the positive results of the exhaust testing, I'm going to check the
Magnaflow catalog to see if I can find a set of single inlet, dual outlet
mufflers that will fit within the Pantera body work and still preserve the
quad tail pipe look. If I find something suitable, we'll test it with a
couple of diameters of appropriate length intermediate pipe.

Dan Jones

Very interesting. What kind of cam was used in the test?

> Very interesting. What kind of cam was used in the test?

The camshaft is from Reed Cams in Georgia and is a custom hydraulic roller,
specifically part number 535-TM280HR-284HR-107A, and is ground on a standard
base circle steel core. In picking the cam specs, we were after a street
performance grind that would have a horsepower peak near 6000 RPM with a best
shift point of 6500 RPM, a wide mid-range torque band and some idle rump-rump.
We also wanted a cam that would work well with all the heads to be tested
which range from open chamber 2V iron to Ford Motorsport aluminum high ports
to CHI 3V's. We chose a hydraulic roller to avoid the lobe and lifter wear
problems associated with the low ZDDP content associated with current
automotive oils. Also, I'm a lazy street guy and setting lash on a solid
cam is a bit of a chore in a Pantera. The cam specs are:

228/232 degrees @ 0.050" lift (280/284 @ 0.006"), 0.588"/0.588" lift,
107 LSA, 68 degrees overlap, installed in the engine on a 104 intake
centerline.

The 68 degrees of overlap should put us in the right ballpark for a
street performance cam in an engine of 351 cubic inches, considering
our relatively large intake valves. I picked the lobe separation angle
using David Vizard's cam selection guidelines. Theoretically, for this
combination of bore, stroke, intake valve diameter, compression ratio
and overlap, this LSA should give us the best area under the HP curve
(not necessarily the best peak HP). For our valve diameters, Vizard's
guidelines suggest very large lift (between 0.615" to 0.766") with the
caveat that lift be limited to whatever is consistent with the longevity
goals. Since our goal was a street engine, we went with a relatively
modest lift of 0.588".

Dan Jones

Dan: Thank you for taking the lead and dedicating the time, effort and energy to testing so many induction variables. This round alone was super valuable for me, and I am sure as you test more, equally valuables to others on this forum and any other proud 351c owners.
All in all, it sounds like the widely available and cost effective Air Gap RPM 2v intake with standard 4 hole spacer was a pretty good setup for the 4v heads. Good to know, as I am currently running, and old performer (but with a 4 hole spacer) I may consider investing in an upgrade!
Cheers JC71

I also want to THANK YOU!!!!! for your time and energy to enlighten us with very useful and practical information. I am extremely curious/interested in the "Blue Thunder" manifold as that is the manifold I plan on using, once again THANK YOU SO MUCH!!!.....Mark.