Nissan RB26/25/20 DET(T) Twin Scroll Turbo Manifold
The Full-Race RB20/25/26 Twinscroll Turbo Manifold designed for instant spool and tremendous top end power. Applying twin scroll divided-pulse technology with long, robotically welded thickwall runners, this manifold will offer increased turbine efficiency, allowing the turbo to spool up fast and hold on throughout the powerband. Runner geometry is adjusted accordingly for the known tendency of RB engines to run slightly leaner towards cyl #6. The Full-Race twinscroll RB manifold can fit any size T4 frame turbo from S200SX, S300SX, EFR series, GT35R, GT40R, GT42R and GT45R. *GT45 requires 5″ inlet compressor housing, 6″ will not fit! Turbos this large may require a hood scoop and are not usually recommended on the RB.
^Pictured with EFR 8374 internal-WG .92 a/r and A/C in an R34 GT-R
^Pictured with EFR 8374 internal-WG .92 a/r in Full-Race’s R14 (S14 w/ AWD conversion)
This is the only single turbo RB manifold designed for the RB26 S13/S14 swap (RWD or AWD)
Key design features:
- Constructed from thick wall stainless steel.
- TIG welded for ultimate strength and reliability.
- True merge collector creates a turbulent free area for the exhaust gasses to enter the turbine housing in even pulses at high velocities.
- Flanged for (2) Tial 44mm wastegates only.
- All mating surfaces machined flat for a leak free seal.
Optional Coated Manifolds
Full-Race’s 704whp R14 (stock bottom end RB26) with Twinscroll RB turbo manifold + EFR 8374 and catalytic converter on the UMS tuning dyno during Modified Magazine tuner shootout:
- A/C compatible ONLY with the R33 and R34 A/C compressor and lines (shorter in length and proper connections. Will not work with the longer R32 A/C compressor:
About Twin Scroll: Twin scroll turbo system design addresses many of the shortcomings of single scroll turbo systems by separating those cylinders whose exhaust gas pulses interfere with each other. Similar in concept to pairing cylinders on race headers for N/A engines, twin scroll design pairs cylinders to one side of the turbine inlet so that the kinetic energy from the exhaust gases is recovered more efficiently by the turbine. For example, if a four-cylinder engine’s firing sequence is 1-3-4-2, cylinder 1 is ending its expansion stroke and opening its exhaust valves while cylinder 2 still has its exhaust valves open (while in its overlap period, where both the intake and exhaust valves are partially open at the same time). In a single scroll AKA undivided manifold, the exhaust gas pressure pulse from cylinder 1 is therefore going to interfere with cylinder 2’s ability to expel its exhaust gases, rather than delivering it undisturbed to the turbo’s turbine the way a twin scroll system allows.
The result of the superior scavenging effect from a twin-scroll design is better pressure distribution in the exhaust ports and more efficient delivery of exhaust gas energy to the turbocharger’s turbine. This in turn allows greater valve overlap, resulting in an improved quality and quantity of the air charge entering each cylinder. In fact, with more valve overlap, the scavenging effect of the exhaust flow can literally draw more air in on the intake side while drawing out the last of the low-pressure exhaust gases, helping pack each cylinder with a denser and purer air charge. As we all know, a denser and purer air charge means stronger combustion and more power… but the benefits of twin-scroll design don’t end there. With its greater volumetric efficiency and stronger scavenging effect, higher ignition delay can be used, which helps keep peak combustion temperature in the cylinders down. Since cooler cylinder temperatures and lower exhaust gas temperatures allows for a leaner air/fuel ratio, twin scroll turbo design has been shown to increase turbine efficiency by 7-8 percent (faster spool, quicker response) and result in fuel efficiency improvements as high as 5 percent. It is wise to size the turbine housing A/R larger than the single scroll turbine A/R typically used!