Turblown Engineering begins production casting T4 Twinscroll External Wastegate Fd3S Rx7 turbo manifold

Turblown Engineering is currently developing the Ultimate FD3S T4 EWG ( external waste-gate) Turbo Manifold. This Investment cast 347SS tapered T4 Twinscroll FD3S turbo manifold will soon supersede our proven welded version. Our welded version is proven to over 700rwhp, and hold boost pressure as low as 6 psi on road raced Rx7s.

How is the new cast version different from highly copied welded version?

Turblown Cast FD3S EWG Turbo Manifold

Turblown Cast 347SS FD3S Rx7 Single Turbo Manifold

347SS vs 304SS
Tapered Main Runner Inside Diameter
1/8 NPT EGT or EMBP bungs standard, not optional
Every Flange is CNC Machined
Larger Inside Diameter Entrance Bore
Smoother transitions


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.

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. Typically CNC flanges are 2x as flat as properly belt sanded flanges. The wastegate flanges typically leak slightly on a welded manifold, even if the face is belt sanded flat. The outside vband flange, and inner wastegate seat dimensions do not stay true because of the welding process.

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 is usually 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.

Design and Fitment

This manifold has Proper Waste-Gate Placement for Proper Boost Control. Does your current turbo manifold over-boost from poor wastegate placement? If so this unit is guaranteed to never boost creep! The entrances to the waste-gate runners are in the direct flow, and tear-dropped. The waste-gate runners are very short to disrupt the flow as little as possible. These manifolds are flanged for twin TurboSmart Comp40 waste-gates. Tial MVS units will also work.

This manifold fits both LHD, RHD, Stock LIM, Xcessive LIM, and most Vmount Inter-Cooler Systems. It will accommodate any size down-pipe up to 4″. It also clears the Pineapple Racing Idler Pulley( Except for GT42, or S472/475- we recommend our EWP kit here) Air pump, Air Pump Bracket, and EGR require removal. Heat Core Hardline Requires relocation or replacement with flexible line. Fits most popular turbo sizes like Garrett, GT35R, GT40R, GT42R(T4) Precision 6262,6265,6266,6765,6766,7175( H cover only for 7175), Borg Warner( standard airwerks and SXE) S360, S362, S366, S472, S475, EFR EWG 7670, 8374 and 9180.

Group Buy Pre order information can be found here.

T4cast

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