Modified Air Flow
Experience has taught us that in order for an engine to perform well it need to be able to 'breathe' properly. Performance may be enhanced by using port sizes that are matched to the needs of the engine. Add to this the smoother bore of a ported manifold or trumpet base and you can get a greater volume of air into the cylinder without compromising air speed. The results are greater power and also improved volumetric efficiency thereby increasing the power output of the engine without requiring a comparible increase in the fuelling needs. In basic terms a standard engine will probably produce 50BHP per litre capacity, with better induction and a few other 'trick' alterations it can be made to achieve 75 or in extreme circumstances even 100BHP per litre (although this is usually considered cost prohibitive).
Porting and Port Matching
Most of us have understood the benefits of porting on a cylinder head but the induction system is often overlooked. Although less dramatic than port shaping and chamber modifications on a cylinder head, the alteration of the inlet manifold and trumpet base on a standard fuel injected Rover V8 give excellent gains and at a relatively low cost.
The 45mm radiused trumpet base (shown above) has been matched to a 45mm ported inlet manifold and the manifold in turn has been port matched to the cylinder heads. The resultant unobstructed airflow from inlet to valve allows for the seamless passage of the air into the cylinder without sacrificing air speed and thereby increases performance. There are many factors which effect the airflow, it's speed and tumble characteristics and these are tested on a flowbench to insure positive results.
The standard plenum chamber fitted to most fuel injected Rover V8 engines is quite restrictive. The first level of upgrade is simply to open out the 'throat' of the plenum chamber and increase the size of the inlet 'butterfly'. This increase in the size of the throttle body gives an increased capacity for airflow as well as a 'crisper' throttle response. When combined with a full induction upgrade and the skill of an experienced engine tuner this can produce a marked improvement.
The introduction of the carbon plenum systems bring the science of induction technology to another level. Not only is the carbon pleasing to the eye, but allows for a reduction in heat transferrence from the engine to the induction charge and thereby increases performance. The twin throttle bodies on the plenum shown below offer a further improvement in throttle response and the increased overall size of the throttle body results in more available air for the engine. ACT Performance Products is responsible for the design and much development has been centred on the increased airflow and improvements in the flow characteristics of the air. These developments culminated in the tripple throttle body with increased volume in the collector (shown below,right). These Plenums are designed to fit on the standard TVR Griffith and Chimaera and therefore incorporate a collector which accepts the Lucas Airflow Meter.
If you have any questions about one of these conversions or would like us to further discuss the suitability to your vehicle and application then please call us or e-mail with your questions or comments.