rhussjr said:
Mike, Any updates on the downpipe status?
I finally got the new DP plotted... it was probably around $500 in scrapped pipes to get there... add 1* of bend here, subtract .5* there...
Next is the shrinkage calculation... most common stainless mandrel bends will "open up" or "straighten out" a small percentage of the bend angle when heat cycled. This becomes more significant when the bend angle is longer, like 90* and beyond... like the first bend leaving the turbo, where the hottest point is.
The Version 1.0 pipes lost about 3/16" across the face of the turbo flange over time. This makes them harder to remove and reinstall after the initial installation. It also places some stress on the flex if the front hanger bracket is used. But the super long flex sections I used seem to be handling it well. But that is still less than ideal. It may be a significant factor in why the early TT DP's were prone to cracking failures and it may explain why some aftermarket DP's begin to clang and bang as time goes on.
I am developing a multi-faceted strategy to deal with this issue.
First I am working to determine how many extra degrees to add to the new DP first bend to compensate for the "shrinkage" so that when the DP finds its final shape, it is dead-on my intended centerline.
Secondly I am investigating various heating methods to pre-shrink the first bends so that the DP's won't move very much after they are installed.
Thirdly I am developing a two-piece front hanger bracket that bolts together on adjustable slots. Ideally you would install the DP and snug the front hanger down where it fits the pipe and the OEM rubber pads the best. Then after a couple of weeks of driving one would loosen the front hanger bracket and readjust it as needed for the best fit. Then perhaps recheck and adjust as needed at the next oil change.
The pipes will still last a long time if they are installed once and forgotten about. But to make the flex outlive the car with the optional cat, it would be ideal to check and adjust a couple of times. But for sure, removal and reinstallation will be much easier with an adjustable front hanger bracket.
I plan to offer a 304ss 2.25" DP that is a plug and play replacement for the OEM DP for ALH VE's and BEW PD's. It will be modular and will use the small Magnaflow 54105D cat as the cat option. It will be a low cost DP, perhaps the lowest cost. It will use a 2.25" ANSA sourced flex pipe just like Version 1.0 used. It would probably pass any CARB certification test if I had the money to have it tested.
I will also offer a 304ss 2.5"DP version with an 8" long Vibrant Brand Flex section which will use the large Magnaflow 93006D cat as an option intended for use with my complete 304ss 2.5" system. I am looking at offering the Aero Exhaust 2525XL muffler with this system:
http://www.aeroexhaust.com/car_muffler_2525xl.html The combination of the cat and that muffler with built in resonator *should* yield a high performance low restriction system that is near OEM silent. This package will be up there in price with most of the other choices that shock you with their cost, but it spares nothing for quality.
I may offer an aluminized steel version of the 2.5" cat-back designed for use with something like the $18 Summit brand chambered aluminzed muffler for like real cheap.
And I may figure out a way to mate the 304ss 2.25" low cost DP to the low cost aluminized cat-back. That *might* allow for a complete system with a cat for less than $500.
I doubt I will have any pipes ready for sale by KROUT's GTG April 4th. Tommy who was doing my TIG welding is unavailable. So I am looking for another TIG welder. And I need to get all the hanger brackets worked out and into production.
