TurboXS introduces Garage Line Headers
03-05-2012, 12:27 PM
#83
FULLY SEMI AUTOMATIC
iTrader: (9)
will these blot up to any exhaust? iirc the turbo xs system needed modification to a flange when using a different mid pipe or cat back
03-05-2012, 08:05 PM
#89
Let me try to answer, I have the GL header in my basement, not yet installed. First, I've been able to find only one reference as to the size of the exhaust outlet from the "irons", in a ~2007 exchange between RotaryGod and TeamRX8: Ends = 47.6 mm x 27 mm, Center = 47.6 mm x 22 mm.
The stock manifold at the mating surface is Ends = 52.5 mm x 36.5 mm, Center = 52.5 mm x 23.5 mm. The stock manifold then very nicely and smoothly turns the rectangle into a circle with a ID pipe diameter of 43 mm.
Now the GL header flange is a bit more complicated, with the mating surface and the "pipe surface" being different, with a taper milled in between. GL mating surface: ends = 51 mm x 28 mm, Center = 51 mm x 28 mm. On the pipe side: Ends = 40 mm x 37 mm, Center = 39 mm x 25 mm. The pipe ID = 41 mm. The transition from GL flange exit to pipe is very abrupt.
How to make sense of this. If one ignores the rounded corners of the rectangle, one can track the area (in square mm) of the exhaust from exhaust runner to exhaust pipe. (non-mathematical use of < and >)
Stock Ends: 1285 < 1916 > 1452
GL Ends: 1285 < 1938 > 1480 > 1320
Stock Center: 1047 < 1233 < 1452
GL Center: 1047 < 1428 > 975 < 1320
Good, bad, ugly? The CW from the past (RotaryGod) and more recent (Eric Meyer) is that the exhaust system per se is hopelessly dominated by the siamesed center port and the 90 deg bends coming out of all ports. "Tuning" headers don't work as well as it does on other cars. RG argued that the pipes and flange exits should be smaller to keep flow velocity high. Is that "975" neck down a problem? Dunno.
I chose to modify center port somewhat however. I rounded sides of the pipe edge of the center GL header flange to reduce the abrupt change (23.5 to 41 mm) into the pipe. I did a similar thing to "smooth" that transition on the end ports as well. It took about 2 hours for the center port and .5 hr each for the end ports with a Dremel #8193 stone. I didn't change the size on the mating surfaces at all.
Is it the right thing to do? Haven't a clue. Blindly increasing the flange port size however, I think is unwise. I have a stock manifold installed that was enlarged all the way out to the gasket (Ends = 68 x 42 mm, Center = 68 x 38 mm) and am pretty convinced it's the cause of a rather large high-rpm deficit in hp measured on a dyno, as well as very black spark plugs. An uncertainty is the actual exhaust runner size as I was able to find only the one reference and haven't measured it myself.
The pipes are non-magnetic which means stainless. The port flange and triangular mating flange to the midpipe are, however, quite magnetic. Also (as you may be able to see in the pic), after washing the grinding dust out with water, the flange showed light rust. Some stainless will do that, like the kind used in most OEM exhausts.
Is the GL header worth $250? Most likely, if there are no fitment issues. One thing it lets me do that's not easily done with the OEM manifold is to add a bung for an EGT gauge. Racing? Try a TeamRX8 or Eric Meyer style system for $2000. Not in my budget though!
