Cylinder Head Development
Ford X.Flow alloy rally race head build and testing for customer.
This alloy head was fitted with 1.625" inlet valves and 1.375" exhaust valves, ported and flow bench tested on our Superflow 120 to verify flow volume and velocity. The graphs show the comparison between a standard iron x.flow head and our modified alloy item. This head is now capable of producing a in excess of 180hp on the 1840cc engine it was destined for with suitable camshaft. Intake ports are kept small to aid torque output which was in excess of 162ftlb. Head comes with bronze guides as standard and inserts suitable for unleaded fuels. However we do change these for turbo application to a Beryllium Copper alloy seat insert based material for better heat distribution.
Std. head castings are usually in stock.
Nissan Skyline GTR or GTS porous casting repair
If your GTR or GTS engine fills the expansion tank and radiator with oil then it is a sure thing that the cylinder head casting has gone porous.
This symptom is due to the oilways across the cylinder head going porous due to age. Rather than scrap the head, especially if it has been ported and had the bucket guides relieved for high lift cams and bronze guides fitted why not just have it repaired. We have reclaimed over 150 GTR and GTS heads for most of the top Skyline tuners in the country and a fair few in Europe. Turn around time is normally 3 days. We can also at the same time modify the water jacket to aid high rpm hot spots and pump cavitation if required at extra cost. All heads are returned pressure tested to 2bar at 90* water temp. To date all have passed 100%. The head can never fail again with this conversion so is a once in a lifetime repair.
This service is carried out on your cylinder head only.
Lotus Twincam 1558cc Stromberg cylinder head inlet port development.
The first step in order to achieve greater air flow on most engines is to develop the correct valve seat area shape. In this instance we have a Lotus
Twincam head which has had the basic 45* angle seat cut with a 30* top cut. All our valve seat and chamber profiling are carried out using
either with a Mira or Serdi machine.
We now have added a 75* cut inside the throat within 3mm of the i.d of the valve seat. This opens the throat to now start to blend into the port size
and shape. You can now see the affect by just adding this one extra cut.
Now we add a cut of 60* to finish the transition between what will end up our port and the valve seat. This again helps air flow around the valve.
A 90* plunge is now added at 1mm inside of our remaining 75* cut. This will be the last cut to blending valve seat into port. You can see now how
much extra throat area we have gained already without even touching the ports.
Now we need to blend the seat into the combustion chamber in order to finish the transition between port and combustion chamber. For this we
use a 45* cut but this is now on the outside of our 30* cut to give the effect of a funnel for the incoming air and fuel charge.
Now by hand our 90* plunge cut into the port is blended into the original material to finish the transition taking care to correctly radius the short
side or bottom of the port. No polishing is required in this instance as the rest of the head it totally standard. Polishing will gain no air flow it is the
shape that is critical.
This is a view of our finished modifications and you can see how much better the transition between port and combustion chamber now looks
compared with picture one.
Finished head with valves fitted. Detailed work can clearly be seen in the combustion chamber on both inlet and exhaust areas.
Now all that is left to do is check the head on our Superflow 120 flow bench to validate the work. This shows our head being set up for testing. The
flow bench told us that the flow above .065" all the way up to .425" increased by an average of 11cfm. That equates to a potential gain of 4.7hp per
cylinder or a total of nearly 19hp over the standard cylinder head casting.