Garrett GT3071R Twin Scroll Turbo

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Garrett GT3071R Twin Scroll Turbocharger

This is the latest from the Garrett GT series line of high tech ball bearing turbochargers. This is capable of spooling much earlier than the standard GT30R. Ideal for lightly built motors looking to get excellent power with exceptional spool, and road race applications.

Compressor Specifications:
  • 56 trim GT37 71mm compressor wheel with a max flow rate of 53 lb/min
  • 0.50 AR compressor housing available in 4.0 in. or 2.75 in. inlet
  • Good to 480 whp.
Turbine Specifications:
  • 84 trim 60mm GT series turbine wheel
  • .78 A/R turbine housing
  • Steel ball bearing center section.

.78 AR T3 twin scroll turbine housing.
1.06 AR T4 twin scroll turbine housing.
For High Power/High Flow Twin Scroll 30R applications, Full-Race recommends:
  • Cut down the bolts that attach the straps/CHRA to the turbine housing. The 12 point chra bolts that come with the turbo are extra long and the threads protrude into the volute, creating a small restriction. By cutting down the bolts and removing any extra threads, flow increases since the bolt head is not blocking it
  • Hand port out the inside of the housing -- there is a lot of material here and flow can be improved through porting
  • Extrude hone the volute -- this is recommended by Garrett engineers, since the extrude hone process will reach part of the housing that a grinder can not
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 engineís 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 2ís ability to expel its exhaust gases, rather than delivering it undisturbed to the turboís 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 turbochargerís 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 donít 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!

For additional information and/or related questions, feel free to contact us.
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