By Chirag Asaravala
Is the 2V Worthy?
When Ford debuted the 260 HP 4.6L 2V in the '99 Mustang GT
it was the highest horsepower levels ever offered in the pony
car since Detroit began reporting real engine horsepower.
Yet the terrible power to weight ratio due to the 600 extra
pounds carried by the new body style left enthusiasts longing
for the 5.0L glory era of EFI Fords. Achieving 300 horsepower
to the wheels with a 5.0L has been a simple matter of bolting
on one of many cookie-cutter combinations of aftermarket heads,
cam, and intake manifold. After all the 5.0L crowd benefited
from decades of preexisting aftermarket product development
for Ford's small block
The motor in this article will go into Project
01 'cus we spun a rod bearing in the stock motor last
pushrod engine family. The overhead cam guys had no such
lineage. What limited speed parts that were available for
mod motors were expensive and included a degree of difficulty
beyond the capabilities of most garage enthusiasts.
Fortunately things have changed over the past several years.
Thanks to a host of aftermarket companies and engine builders
dedicated to climbing the steep learning curve of the mod
motor, that crowd now has its own set of high-power recipes.
Companies such as Comp Cams have developed a nice lineup of
overhead cams and upgraded springs. And while we don't yet
have a true aftermarket modular cylinder head we have several
companies offering CNC ported versions of the stock castings.
Other products are quickly emerging too; a couple companies
are finishing development of an aftermarket intake manifold.
Fidanza Engineering has produced adjustable cam gears which
open up the realm of degreeing and dialing in the powerband.
So the question that has to be asked is whether or not the
4.6L 2V, despite it's 21 fewer cubes, is now capable of achieving
the 300-plus rear-wheel power levels from bolt-on modifications?
Moreover, can the average 400-piece Craftsman tool set owning
weekend enthusiast overcome the mod-motor modification fears
and perform a head an cam swap himself? We think so. In this
article we've teamed up with HCI Motorsports to show you how
to install a set of Patriot Heads and Comp Cams in your 2V
motor. In the next issue we'll drop the motor in our 2001
Mustang GT and reveal the dyno results.
CNC Ported Cylinder Heads
If you want to improve upon the flow of the PI heads you
have to port the stockers. (PI means "Power-Improved"
referring to the revised casting introduced by Ford in 1999.
The PI heads are a significant improvement over the '96-'98
castings.) While hand porting is possible for the highly-skilled,
it is undoubted more cost effective to purchase a set of CNC
ported PI heads from Patriot
Performance. They offer three stages of their 5-axis CNC
porting program. Patriot's Gunnar Bowlin tells us, "We
no longer mention the Stage 1 as it is priced so close to
the Stage II and on any level motor the Stage II is a good
fit." The Stage III head is only recommended when the
bore is oversized at least 0.020" as the larger valve
will otherwise be shrouded. Of course the Stage III also means
high-rpm power band and/or power adder is a prerequisite.
Patriot's heads feature larger valves, new springs and best
of all do not require sending in a core. The Stage II's sell
for $1295 outright and that is what we selected.
The intake port on the Patriot stage II head measured
1.700" wide by 2.050" tall (we measured at the
center horizontal and vertical axis' of the port. Note
that the port is opened up to the stock gasket dimensions.
On the Stage III head the increased flow is a result of
a larger valve and hand blending in the bowl area.
The stock intake port on our PI (performance improved)
head measured 1.510" wide by 1.870" tall, significantly
smaller than the intake gasket.
The Patriot Stage II heads feature exhaust ports opened
up .080" over stock to 1.420" diameter. The
result is a 30% improvement in flow.
The stock exhaust port diameter is 1.350".
Patriot upgrades the valves to 1.78" x 1.45"
(45.2mm x 36.8mm). The swirl dams in the combustion chamber
are ground down and the chamber is polished. This brings
the chamber volume up slightly to 46cc from 42cc stock.
This will reduce compression ratio by less than half a
The stock valve sizes are 1.75" x 1.42" (44.5mm
x 36mm). The cupped valves make up for the volume consumed
by the swirl dam above the intake valve and the raised
pad between the two valves adjacent the spark plug hole.
Both are factory attempts to promote combustion mixture
and reduce emissions. The swirl dam however shrouds the
intake valve significantly and is removed by Patriot and
other CNC porting companies.
|4.6L 2V PI Cylinder Head Flow
Patriot Performance Stage II vs. Stock
*Flowed with 3.55" diameter