The intake manifold of a Holden V8 Supercar is an essential component and effective tuning tool with regards to the performance of the cars on race day. Extensive studies have been undertaken on the tuning of intake manifolds and systems previously, but each engine has different characteristics and the intake manifold under scrutiny and investigation is a custom engineered piece for this specific application. Excellent engine performance requires the simultaneous combination of good combustion and good engine breathing. Whilst good combustion depends only in part on the characteristics of the flow within the combustion chamber, good engine breathing is strongly affected by the unsteady flow in the intake manifold.
This thesis report aims to comprehensively investigate the theories associated with the specific components of the intake manifold and using experimental tests to gain greater understanding of the flow characteristics of the intake manifold and assist in optimising the intake manifold to suit a new intake port profile. The main objective of any work on racing engines, especially in the V8 Supercar category, is to improve engine performance, more specifically power and torque, whilst maintaining fuel efficiency or slightly improving wherever possible. The added difficulty of V8 Supercars is that stringent rules and specifications have been set in place which needs to be worked within. The data received through this thesis project will assist in future developments of the intake manifold, especially in regards to the new designs for the Car of the Future in the 2013 racing season. Intake manifold tuning is most effective for engine performance when it is matched with a suited tuned exhaust manifold, though the exhaust will not be investigated here.
Testing was undertaken using a professional flowbench to evaluate issues such as the flow implications of various bellmouths, throttle butterfly operating directions and to compare the new porting profile to its predecessor. Empirical evaluations using industry experts' methods to compare the current intake manifold to data collected from a large array of different engines to provide a comparison along with methodologies to evaluate current flow conditions within the manifold and intake port. Engine simulation software and engine dynamometer testing was also utilised to provide an array of testing mediums
Bellmouth testing demonstrated that the elliptical profile bellmouth is the most effective in regards to volumetric flow rate out of the 3 profiles tested. CCW throttle operation performed 4.5% more effectively than CW for half throttle and this trend was consistent for ¼ and ¾ throttle over a range of valve lift heights. The new porting profile is capable of higher flow rates at medium lift values, but suffers at higher lift values compared to the old port. Dynamometer testing demonstrates that the switch of porting profiles is beneficial with significant power and torque increases over 5600RPM until the limit at 7500RPM.
Though various testing and evaluation methods have been utilised, there is nothing as definitive as dynamometer and track testing to confirm and design changes or improvements. Therefore for the intake manifold on the Holden V8 Supercar engines, developed and assembled by KRE Race Engines to be optimized to its full potential, a combination of testing, empirical evaluation, theoretical computation and computer aided software is necessary to provide a race winning combination.