Twin Turbo 928 fixed and back out there terrorizing the streets!
#1696
Nordschleife Master
Thread Starter
This is what the infinity pipe will look like
It will be a challenge for future generations to fit a bigger exhaust under 928 that is structurally sound and that doesn't drum!
infinity pipe:
infinity pipe:
#1698
Nordschleife Master
Thread Starter
#1700
Nordschleife Master
Thread Starter
For the same reason that explains the whole project: Because I can. ;-)
More seriously, those cats together will flow enough for the pump gas tune, so there's not loss. They will also knock out 4-5 dB of noise over a broad frequency band. They will clean up the exhaust gasses.
Here's an estimate of how much a (generic) cat will quiet the exhaust:
Finally, it's just an option: they are v-band clamp attached and I can put in straight test pipes whenever downpipe pressure would otherwise get a bit higher than desired. Optimally exercised, options are valuable, right?
More seriously, those cats together will flow enough for the pump gas tune, so there's not loss. They will also knock out 4-5 dB of noise over a broad frequency band. They will clean up the exhaust gasses.
Here's an estimate of how much a (generic) cat will quiet the exhaust:
Finally, it's just an option: they are v-band clamp attached and I can put in straight test pipes whenever downpipe pressure would otherwise get a bit higher than desired. Optimally exercised, options are valuable, right?
Last edited by ptuomov; 10-04-2017 at 06:26 AM.
#1701
Nordschleife Master
Thread Starter
Is the infinity pipe a restriction?
On the infinity pipe area: For reference, ignoring the wall thickness, dual 3.5" pipe gas area of 19.2 sqin. The infinity pipe with 6" overall width and 1/2" segment taken out from both pipes will have an area of 17.6 sqin. It's only a 8-9% area reduction after the gas has already cooled somewhat and after the pulses have already combined. My judgment is that it's never going to be a bottleneck in a system that is dual 3.5" upstream of the infinity pipe. And most importantly, it fits.
#1702
Nordschleife Master
Thread Starter
Revenge of the nerds
These photos in a sense document the revenge of the nerds. High school geometry does work in real life! Savor the Wise Owl stamp that you got if you stayed awake and paid attention in the math class! ;-)
In any case, this is a one gentle and well flowing y-merge from the dual 3.5" cat outlets to the 6x3.5" infinity pipe:
The iPhone editor that rennlist uses sucks hairy *******, by the way.
In any case, this is a one gentle and well flowing y-merge from the dual 3.5" cat outlets to the 6x3.5" infinity pipe:
The iPhone editor that rennlist uses sucks hairy *******, by the way.
Last edited by ptuomov; 10-01-2017 at 06:54 PM.
#1705
Nordschleife Master
Thread Starter
#1707
Nordschleife Master
Thread Starter
#1709
Rennlist Member
My son agreed- not that big. Maybe a half pound lol.
#1710
Nordschleife Master
Thread Starter