Drag Illustrated Issue 151, December 2019 | Page 65

the next logical area of development would be
the combustion chamber.
Surprisingly, Frankenstein’s all-new, more ef-
ficient P-48 combustion chamber was always
designed to be smaller. That would allow more
in the way of head tuning and design. They did
something called “shallowing the valves,” where
they changed their positions in the newly config-
ured combustion chamber. Sitting in Moldstar
90 seats, the intake and exhaust valves are also
at new angles for better airflow characteristics
as well as flame front efficiency. The titanium
valves line up at 19 degrees for intakes and 22
degrees for exhaust valves; both specs are legal for
NHRA and all other series. The spark plug holes
were relocated to complement the more efficient
combustion chamber. All these changes were
systematically aligned to give the best possible
results when working together.
The new design allowed the combus-
tion chamber, typically 100cc or more for
existing heads, to be reduced to 88-89cc.
That, in turn, allowed the benefit of tak-
ing off a whopping 22 grams of weight
off each piston. Losing 22 grams times
eight – especially in the domes of the pis-
tons – equals a lighter rotating assembly
by 176 grams. That, in turn, created some
new capabilities the Hemi is not nor-
mally known for. Frankenstein-headed
Hemis could now rev faster and higher,
taking advantage of those raised runners
and smaller, more efficient combustion
chambers. All the changes were starting
to work together as they intended.
But all heads have a traditional area
of great concern: the valve train. So,
that assembly was also extensively re-
engineered. Half-inch pushrods were
initially used but still showed signs
of bending and flexing. They went to
9/16-inch with minimal intrusion into
the ports. They also used proprietary
Reid Rockers for ultra-high rpm stabil-
ity. Offset lifters were also used to aid
in correcting the valvetrain geometry.
This was more than just buying rockers
and lifters off the shelf. Working with
Darrell Reid, development was driven
in parallel on the valvetrain and heads.
The two companies researched every
December 2019
valvetrain failure they had seen in their careers
and designed past them.
After months of designing the head/rocker
combination, they built prototypes for Spintron
testing. Using digital models and real-world test-
ing, they worked together to create a system that
should be stable to 13-14,000-plus rpms. The
entire package was designed to give customers
a higher peak and average horsepower at the
wheels than any other head on the market. That
would translate to more MPH and lower ETs in
each application. The new package provides an
extremely stable valvetrain, which also efficiently
improves the induction and exhaust dynamics
to make big power at higher rpms. Two comple-
menting intakes were designed with the same
dedication and that is a story for another time.
Frankenstein didn’t stop with just better per-
formance. A good race piece needs to be user
friendly for serviceability, too. One feature they
designed in were O-rings on every mating surface
of the head including exhaust, head bolts and
spark plug tubes, making life easier trackside.
Another feature is solid billet aluminum spark
plug tubes, durable for as many times as Hemis
typically use them. They didn’t stop there. Valve
covers are not often thought of as integral head
components, but there was room for improve-
ment. Cast versions can crack, so the P-48 Billet
versions were engineered to be lightweight, strong
and durable. Quick and easy T-handle valve cover
fasteners round out the benefits.
The results were nothing short of incredible
– an amazing 300-400-plus more horsepower
to the wheels during early conservative testing.
Flow numbers were 600 cfm with 2.500” intake
valves and 480 cfm with 2” exhaust
valves. Testing and tuning are ongoing.
At the track, every single customer, from
Mike Janis to Jeff Sitton and the Pesz-
Jones Racing teams, had to take away
timing and add fuel to their tuneups
compared to the Hemi heads they were
using before. This clearly indicates P-48
heads offer much higher efficiency rates.
Frankenstein has also seen their
heads working on rough 4.550” bore
sizes and that bigger bore takes advan-
tage of better breathing. It unshrouds
the valves and helps the heads breathe
better. Frankenstein recommends using
the biggest bore with whatever the en-
gine builder, block manufacturer, tuner
and car owner are comfortable with.
There’s more than one valve size
available. Outlaw-style heads offer
2.500” intake, 2.000” exhaust with an
89-91cc chamber. NHRA is slightly
smaller with 2.400” intake, 1.900” ex-
haust with an 83cc chamber.
So, what’s up with that P-48 name?
The first-ever Hemi head created was
for an inverted V12 built by Chrysler for
the successful P-47 Thunderbolt fighter
plane in World War II. As this is the
next, clean paper design of that head
since those 1940s, Frankenstein’s P-48
heads are the next generation of highfly-
ers using Hemi power. -JOHN CAROLLO
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