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Little details make a huge difference in how an exhaust system will function.
Savage Diesel is pursuing reduced back pressure exhaust systems for VW TDI's in an effort to improve efficiency, improve performance and add longetivity to the turbo and other engine components. As critical as reducing backpressure is to achieving these goals, heat management and actual turbo exhaust side heat reduction is just as important.
A) A factory 2000 Jetta 1.9L ALH TDI ~2" diameter downpipe. Note the sharp approximately 1" radius 90* bend that is not conducive to good exhaust flow and low backpressure.
B) The Savage Diesel 1.9L ALH TDI downpipe design model 7C featuring a turbo exhaust outlet hole centered and matched exhaust flange that steps up to 2.25" for the first bend then stepping up to 2.5" in the return bend that meets a custom 2.5" ID 10" overall length flex section for maximum durability and resistance to metal fatigue and pipe cracking. A ball flange is being evaluated for installation at the flex output to provide a separating point between the downpipe and the catpipe section. Note: Additional advanced features are not shown
C) A sample 2.25" CNC mandrel bent pipe trimmed to length with reduction on flange end
D) A sample 2.25" CNC mandrel bent pipe, raw off the bender
E) Less than 5 minutes of CNC mandrel bender run to make this prototype pipe pile
A) An early prototype Savage Diesel exhaust flange featuring 43 mm ID pipe relocated to center of turbo exhaust hole as can be seen by a used OEM flange gasket attached to this flange by 3 bolts. Note: The 43mm section is about 1" long then it steps up to 2.25" pipe for the first turn
B) A VNT-15 with a new flange gasket to show that the turbo exhaust hole is smaller and not centered on the OEM flange gasket. This is actually a very horrible factory design because there is a large "pocket" of "dead space" formed behind this severe cliff face. That creates quite a bit of turbulence that acts as a restriction to exhaust flow. But worse than that, it provides a point where the exhaust flow expands and cools thereby heat soaking the turbo flange and in turn the turbo housing. The Savage Diesel design addresses this in a very effective way, by moving the expansion point away from the flange so that heat will be moved AWAY from the exhaust flange and heat soak the first bend instead where it will not be as detrimental to turbo life or efficiency.
Here we see a nominal exhaust outlet hole diameter of 41mm on the OEM VNT-15
The Savage Diesel downpipe design will meet the 41mm nominal VNT-15/17 exhaust outlet with a 43mm nominal ID centered on the VNT-15/17's exhaust hole for optimum flow and heat extraction from the turbo. 43mm was selected for the Savage Diesel pipe design to provide for any slight misalignment variances on install. A small step is better than a partially obstructed hole if there are any production differences in any of the components.
The OEM pipe meets the VNT-15 outlet off center with an inside diameter of almost 46mm. This dimension is actually closer to 43.5mm on the OEM PD downpipes which are much improved over the VE versions shown here.
Here we see the nominal ID of 2.25" mandrel bend .065" wall pipe at 53.5mm. Mandrel pipe is special no matter what grade of aluminized steel, stainless steel or aluminum is used in that it must be a smooth inside bore for the dies to pass through without jamming, galling, tearing or kinking the pipe. It is typically more expensive than seamed pipe used by crush benders.
Savage Diesel is available to supply TDI exhaust system builders with their own specific custom mandrel bent pipe needs in almost any grade of material needed. While the unwelded components for building the Savage Diesel downpipes will be available to any one in any quantity desired, custom bent pipes will require a minimum number of pieces per order. Savage Diesel will respect the proprietary nature of each customers pipe bend designs and will not sell one customers pipes to anyone else. Simply put, Savage Diesel will not compete with its own customers by reselling their designed products or exposing their products to being copied by others.
While it is expected that Savage Diesel will begin direct sales to customers of its products soon, it is the stated ultimate goal of Savage Diesel to eventually become a reseller supplier only.
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The production flange pattern proofs were tested today for the SDPP "Question Mark" Downpipe (SDPP QM DP) so named because of its general shape. The fitment was as perfect as expected and a small batch of prototypes were ordered as a last step in the pre-production design validation process. Actual road testing will finally begin within a month if all goes well. Waterjet cutting was chosen for its clean cuts and tight tolerance holding ability.
Here we see that the SDPP QM DP flange pattern proof perfectly fitting a grenaded VNT-15.
This version of the SDPP QM DP flange is affectionately known as the "Alien Head" (SDPP AH flange).
The OEM downpipe flange on the left and the SDPP AH flange on the right.
A used OEM gasket overlaying the SDPP AH flange as mounted on a blown-up VNT-15.
Note the SDPP AH flange hole is centered on the 15's exhaust outlet.
The OEM DP flange's two upper mounting nuts shown for clearance and proximity of pipe.
Here a standard Craftsman 12mm 6 point combination wrench is shown to display clearance on the
rear SDPP AH flange mounting stud and nut.
Here a standard Craftsman 12mm 6 point combination wrench is shown to display clearance on the
front SDPP AH flange mounting stud and nut.
A rough comparison of the SDPP QM DP top and OEM DP below it.
Note: The OEM pipe appears smaller than reality because of the camera angle. This was unintentional.
The OEM DP stinks bad enough without needing camera tricks to make it appear appear to be a poor performer.
View looking down, SD QM DP on left, OEM DP on right.
Note the backwards Question Mark shape of the SDPP QM DP that gives it its name.