View Single Post
RarlyL8 RarlyL8 is offline
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,256
Garage
I was in the middle of Beta testing the active exhaust when the ignition went on the fritz. Really stoked to get back to it and actually see the final product! I started this project 10 years ago and have been tinkering with it bit by bit all this time. The legal crap (patent applications) also take too much time. You would think an active exhaust for a 930 would be a simple thing, but once you get into it you see all these issues that must be overcome. You can't just slap a Y-tube on the turbo with a valve and a pipe on one side and a muffler on the other (yes I tried that first). The problem is (a) it's ugly as hell (b) the valve will burn up in short order close to the turbo and (c) the quiet side becomes too restrictive or loud due to packaging constraints. I wanted a muffler that looked like a conventional muffler. That meant some really tricky internals.
Another issue is failure mode. With 2 smaller pipes instead of one 3" pipe (like our Street/Hooligan/Outlaw Series) you will have some restriction on the muffled side. If the valve fails and all you have is the muffled side bad things can happen; the engine won't boost and the engine gets hot. I saw this first hand while going through a dozen different valves testing them to failure. The solution was finding a VERY durable stainless valve and having that valve be open as a default. The engine barks when you fire it up as the valve slams shut. Cool side effect!
The sounds this muffler makes and doesn't make are just beautiful. It is so quiet at idle and disappears like a new car at cruise. But when you boost it HOLY $HIT! It just SCREAMS! It's the best sound I have ever had in any car I have owned (I know, maybe you should own more types of cars). My 930 does have my tuned headers which add to it but with the Euro J-pipe it still sounded really good.
But that's not all.
You can modulate the valve. You learn quickly how to drive the car so that the valve stays shut all the time, or you can lug the engine and open the valve (self inflicted boost lag anyone?) so the turbo whistle can be heard loud and clear! Awesome!
I'm going to have my daughter film the car tomorrow afternoon and with luck we can post it.
__________________
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 04-01-2017, 07:50 PM
  Pelican Parts Technical Article Directory    Reply With Quote #674 (permalink)