Experienced Nissan tuner Litchfield is proud to announce the latest addition to its already impressive range of performance parts; a custom exhaust manifold that’s been specially designed to negate one of the biggest performance limitations present in the standard car, namely the combined exhaust turbine housing and manifold. The team at Litchfield has worked tirelessly to circumvent this major hurdle and the resulting log manifold allows customers to tune the GT-R’s phenomenal twin-turbo V6 to high output figures, while retaining driveability and reliability.
The fact that the OE Nissan manifold is a one piece design that incorporates the turbine housing means that fitting a larger, aftermarket turbo has traditionally been a challenge, with the only solution being to machine and weld each manifold assembly to allow the fitment of different turbo cores. Even this isn’t a complete fix though, as the range of suitable turbo assemblies is dictated by the size of the internal volute and the thickness of the turbine housing material itself.
These engineering challenges were of paramount concern when Litchfield set about devising a complete solution to the problem. Both log and equal length manifold designs were considered and evaluated at length, with the former eventually chosen for its low down torque and turbo spool characteristics, plus the fact that it promised to work better within the confines of the already tightly packaged GT-R engine bay.
Litchfield’s exhaustive design and development process was brought to bear on the new manifold, with the team drawing up and fabricating a pair of Inconel units to assess the basic nature of the design. Digital renderings were then used in conjunction with Computational Fluid Dynamics (CFD) analysis, allowing the firm’s engineers to see precisely where performance gains could be made and to highlight potential issues and restrictions present within the design. At the end of this intensive process they reached a manifold design that was an impressive 18% more efficient than the initial unit, with the most significant improvements in gas flow efficiency and turbo response being down to its unique conical design – for which Litchfield’s patent is currently pending. Seemingly minute adjustments have resulted in a gas flow that encourages cylinder scavenging and contributes to reduced turbine wheel response and lag, plus minimised restrictions to peak power further up the rev range.
Strength and reliability were considered to be the most important aspects to focus on when it came to the manifold’s construction, and the lengths to which Litchfield went to meet them are clear when the finished units are inspected. Formed from Ni-Resist D5S, a cast iron alloy able to withstand the rigors of extended heat cycles and extreme temperatures, the log manifold boasts impressive heat retention properties and will comfortably handle significant increases in power and pressure. Each unit is carefully CNC machined before being painstakingly hand finished by one of Litchfield’s engineers, a process which results in a finish that surpasses that of any OEM application.
The manifold kit also includes a number of other specialised components, most of which have been designed specifically for this application. A traditional gasket was swiftly rejected owing to the likelihood of it becoming a weak link in the turbo-manifold assembly, Litchfield instead opting for a combination of CNC 321 steel V-band clamps, unique in this application, and bespoke Wills Rings seals. Other fasteners contained in the kit include M10 Inconel bolts and Super Alloy K-Nut fixings with FEA (Finite Element Analysis) infinite cycle testing, while all fixings in the manifold package have been specified for Litchfield by a leading F1 engineer specialising in the technology of fasteners.
Litchfield’s latest manifold promises to open up a wealth of tuning options for owners of Nissan GT-Rs, and with a much wider variety of turbo units now able to be trialed and fitted, there’s every chance that power figures could well jump in the near future. The intensive development process needed to bring them to market means that they’re perfectly designed and will offer unparalleled levels of performance and reliability, thanks in no small part to the use of sophisticated development processes in their design and high end material in their construction.
For more details on this product – or to order, please visit http://www.litchfieldimports.co.uk/Nissan-GTR/nissan_gtr_manifold_design