[DeTomaso] Hall Headers

[Daniel C Jones]

> Dan Jones'Great 351C Dyno project recently tested a set of the bronze
> Port Stingers from MPG ( I believe that's right).

That is correct.

> IIRC, they were good for an honest 5-6 horsepower, but far, far less
> than 20 hp.

The peak HP difference was only 3 HP but the maximum difference was
14.6 HP at 4500 RPM.  Understand that peak numbers are not important.
It's the area under the curve between shift points that is important.
The Stinger inserts made a meaningful improvement across most of our
tested RPM range:

Port Plate Test
Same setup as pull number 10 with the unported iron 4V heads, Strip
Dominator HVH intake setup and Pantera headers.  The Pantera headers
come straight out from the cylinder head, whereas the Mustang Hooker
long tube headers turn downward more quickly.  In this case, the
exhaust port insert seems to help.

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 with the Pantera headers.

Without Stinger Exhaust Inserts
RPM     HP      Torque (ft-lb)
4000	278.7	362.9
4100	291.9	370.3
4200	294.8	369.3
4300	301.1	368.1
4400	308.9	369.0
4500	319.2	372.6
4600	331.7	378.5
4700	345.3	385.5
4800	356.9	390.1
4900	363.5	389.9
5000	372.8	390.4
5100	378.2	389.6
5200	382.4	386.5
5300	389.9	386.4
5400	396.7	385.9
5500	403.1	384.9
5600	407.6	382.3
5700	408.0	375.7
5800	405.9	367.4
5900	398.5	355.2
6000	395.4	346.2
6100	399.0	343.4
6200	404.4	343.6

With Stinger Exhaust Inserts
RPM     HP      Torque (ft-lb)
4000	278.7	366.3
4100	286.2	367.0
4200	297.4	372.0
4300	310.4	378.8
4400	322.4	384.7
4500	333.8	389.6
4600	343.4	392.2
4700	353.6	395.0
4800	365.5	399.6
4900	372.6	399.7
5000	376.0	395.1
5100	385.4	396.4
5200	388.9	393.2
5300	395.0	391.3
5400	404.5	393.0
5500	411.0	392.4
5600	410.4	385.1
5700	404.9	373.3
5800	406.1	367.6
5900	407.6	362.5
6000	402.5	352.7
6100	400.9	345.8

I've got all of this data plotted and need to host it somewhere
for all to see.  With the graphs, you can tell at a glance how
important the various changes are.

> ...if you are running 4V ..the exhaust ports should be dremeled
> on the top of the header so the escaping gasses won't crash
> into a wall.

Another area where the Hall headers have a problem is in the
the collector.  It necks down to a very small cross-sectional
area.  Cutting off the collector and welding on a better one
would likely yield a benefit, assuming the mufflers aren't
too restrictive.

If I were to design an under car Pantera header from scratch,
I'd probably do a step header with steps of perhaps 1 3/4",
1 7/8" and 2" though I'd likely sacrifice one of the steps to
get fit a decent length collector.  Might be worth some simulation
work to see how that would compare to the Euro GTS headers.
With a step header, the port plates might not be necessary.

Dan Jones