We have developed a true high performance 308 Holden Cylinder
Head suitable for fast street strip type application. Suitable
for unleaded fuels these heads are original castings that have
been extensively modified as follows:
These heads have gone through hundreds of hours of flow bench
and dyno time and flow more air than B Casting L34 and late model
VN on high port castings.
- All heads are chemically cleaned and magnaflux crack tested
- 16 new Bronze Guide Liners are fitted
- Hardened ex seats are fitted
- Larger inlet valves are fitted
- Ports are modified to suit
- Chambers are modified and polished
- Valves are new tuffrided steal ex with new Manley Race
Master stainless inlet valves assembled with new seals and
high performance springs.
Priced at NZ$$1595.00 + GST Complete.
All of these kits are designed to run stock rocker gear, although
rollers can be used up to 1.6 ratio.
More HP gains can be had as the heads flow enough air support
about 420 HP but in most cases, it will effect bottom end power.
Our aim is to produce ultra responsive street / strip kits using
mostly stock parts. Flow figures are available, all our dyno
testing was on the same stock short block at 9.6 - 1 compression
ratio with stock carb and manifold. We found the stock carb
and manifold to be a very good combination, we also found some
pretty horrible results using some after market manifolds.
The dyno tests shown are only a few from well over 120 actual
tests performed. A point worth mentioning is our test engine
for the stock heads and camshafts was also 9.5 - 1 compression
ratio. From our experience most stock engines are more in the
area of 8, 8.5 - 1 compression ratio. If this was the case the
gains we got would be a lot greater but for our own test reference
we want to know the exact gains, extra airflow and camshaft
would make. All testing was done on our own fully computerised
Dynamic Test Systems Dyno and corrected back to SAE standard
figures. Testing was done on automatic sweep test mode.