JB400 Camshaft

Many people will recommend turbo and N/A cams for blown applications. Whilst these cams will certainly be an improvement over the stock cam, they are less than optimal in a blown application and will not maximise the use of available charge, resulting in lower dynamic compression ratio, which results in lower cylinder pressures and in turn less power.

Turbo cams are generally split duration with larger lift on the inlet to help overcome the high back-pressure ratio. This back-pressure comes from having the exhaust drive the turbine and causes the exhaust port pressure to be higher than the inlet pressure. On a blown engine there is no turbine to drive and so the inlet port pressure is higher, basically the opposite to a turbo. This means that turbo cams are not really a good fit for a blown application as the valve dynamics are incorrect.

Likewise N/A cams have narrow lobe separation angle resulting in a lot of overlap (the portion of the cycle where both inlet and outlet valves are open at the same time). In an N/A engine this overlap assists with cylinder scavenging where the exiting exhaust gasses help draw in the intake charge. Unfortunately having both inlet and outlet valves open at the same time on any forced induction setup results in the pressurised intake charge simply being pushed straight out of the exhaust port. Boost will not start to build in the cylinder until the exhaust port is closed.

We found that there was nothing available specifically for blown applications and so this is why we developed our own range of blower cams. Our cams will work on all blown installation, not just ours. All of our cams are custom ground for us by Engle, so you know you are getting a quality product.