Turblown Engineering Cast 347SS IWG EFR Turbo Manifold


These are now on back order as of 5/8/2024

Turblown Engineering's Cast EFR IWG Turbo Manifold now supersedes our older welded version . This manifold when combined with an EFR 76708374, 9174 or 9180 delivers the fastest boost response possible for each frame turbo. This combination will make your 13B 2 rotor feel like a 20B in the low end and mid range at higher boost pressures.

Cast 347SS
This manifold is cast from 347SS which is far superior to 304SS. Not only does 347SS last longer at elevated temperatures , there are no welds like those found in traditional turbo manifolds. When a welded turbo manifolds fails, they almost always break at or next to the welds. A broken turbo manifold even if it features a life-time warranty can be a serious hassle to remove and send back in for repair, especially if you miss a race because of it. We have weighed our cast manifolds vs our welded units and they actually weigh a few ounces less! Since these manifolds are investment cast, they are less than 1/2 the thickness of your traditional cast iron turbo manifolds, and therefore do not retain as much heat as cast iron manifolds. There are zero downsides to this casting process vs welding. 

Tapered Main Runner Inside Diameter

This manifold's inside diameter slowly tapers down as it reaches the T4 flange. This process is only possible with a cast manifold. A traditional welded manifold does not change inside diameter. This tapering process is identical to the volute of a turbine housing. By tapering down it increasing velocity, and speeds up the exhaust flow and increases boost response.

CNC machined flanges

All flanges are CNC machined to be perfectly flat. Most turbo manifolds are just belt sanded flat, which is not as accurate as CNC machining. 

Smoother transitions

Welded turbo manifolds require hours of hand porting with a die grinder, and sanding drums to contour the change in shape from a round tube to a square T4 flange. We have taken this step, just like the rest of the manifold, to an even higher level of quality. The investment casting process makes every transition seamless. Welded manifolds are made from short pieces of cast elbows. Every time there is a joint it is welded, there can be a slight disruption on the inside diameter if the pipe is not perfectly matched, or the weld penetrates all the way through. This disruption is eliminated with the casting process resulting in a better flowing turbo manifold. 


Only the 7670 & 8370 IWG turbo will fit the FC3S 13BT engine without modifications. 8374, 9174 and 9180 require 1/8" removal of the LIM flange where it meets the block on FC 13BT engines. We do not offer this service. S5 FC3S Waterpump housing will not clear 8374 or 9180 without modifications, or moving to s4 water pump housing( will swap onto S5 front cover will a little work). 

7670,8370, 8374, 8474, 9174, 9180 and 9280 will fit the 13BRE, or REW engines regardless of 2nd or 3rd gen chassis selection without modifications to the stock LIM. This system is RHD compatible for FD3S & FC3S chassis. 1st gen FB chassis fitment for engine swaps is same as above. 

This turbo manifold will fit the 13BREW JC Cosmo Chassis( all sizes). This turbo manifold will fit an REW swapped Rx8. The bigger B2 frame EFRs( 8374+) sometimes require slight trimming of the subframe mount near the compressor cover, depending on which subframe kit you have. Smaller 7670 models do not require any mods. 

TurboSource T4 turbo gasket is recommended. Standard stamped 304SS gaskets will require grinding on OEM 93-2002 Rx-7 lower intake manifold to clear 8374 and 9180 compressor cover. Slightly grinding is required to fit Xcessive Manufacturing 3rd gen lower intake manifold even with the Inconel Gasket sometimes. OEM FD3S airpump will clear EFR 7670 selection with no modifications. EFR 8374 & 9180 require slight grinding, and a custom tensioner bracket( see photos). 

Pictured waste-gate bracket adapter is required for all chassis models. OE BorgWarner unit will not work with turbo orientation. 

Studs are required for all IWG EFR turbochargers. Bolts physically cannot clear rear near turbine housing. 

Optional 3" mandrel bent downpipes are available for FD3S chassis. Will clear RHD models. Stock location 3" 2 bolt vibrant flanges. Requires 3/8" hardware to bolt to FD OEM cat( not the same exact flange, but it does work). 

This manifold comes standard with twin 1/8 NPT exhaust gas temperature or exhaust manifold backpressure ports( plugs included- require anti-seize and final tightening if plugs are to be used).

Turbo Hardware is NOT included. T4 flange thread pitch is M10 x 1.5

Additional information available on our blog post here.