3" exhaust
09-04-2006, 11:59 PM
#2
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i don't know that there are any dyno sheets available, but yes, big low end torque losses on an NA 968 with 3" - even too free flowing of a 2.5" causes problems - that one we have seen on the dyno - it's very noticable in the car too
if you get really crazy with the motor though, and were talking about a race car, you might pick up a small amount at 7k or so with a 3", and you wouldn't care about what's happening at 2.5k anyway
if you get really crazy with the motor though, and were talking about a race car, you might pick up a small amount at 7k or so with a 3", and you wouldn't care about what's happening at 2.5k anyway
09-05-2006, 11:46 PM
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no - i mean a system that flows too freely - components that would lead to such a thing would be a straight through muffler (as opposed to a reverse flow), or a cat that is too free flowing - we've played with a lot of different stuff, and it has been very illuminating - i've had 4 different systems on my car alone - i finally got one that works - it took 3 different mufflers, and 4 different cats to finally get the flow right - interestingly, i ended up with the largest cat of the 4
in street trim, this engine seems to be extremely finicky when it comes to back pressure, exhaust gas velocity, and flow - torque loss has been extremely common with almost all of the cat-back systems - the standard method of "opening it up" does not work on this engine
no cat-back system has thusfar published dyno proven gains - there is some improved throttle response to be had by a couple of them though - in a properly tuned system, there is also the potential to work in symphony with some other mods
on most of them, weight loss is also significant - tone can be dramatically improved too, which makes it more fun, though is frequently misleading when it comes to performance increase
feel free to email me - i would be happy to give you more details
in street trim, this engine seems to be extremely finicky when it comes to back pressure, exhaust gas velocity, and flow - torque loss has been extremely common with almost all of the cat-back systems - the standard method of "opening it up" does not work on this engine
no cat-back system has thusfar published dyno proven gains - there is some improved throttle response to be had by a couple of them though - in a properly tuned system, there is also the potential to work in symphony with some other mods
on most of them, weight loss is also significant - tone can be dramatically improved too, which makes it more fun, though is frequently misleading when it comes to performance increase
feel free to email me - i would be happy to give you more details
09-06-2006, 12:50 AM
#5
I am going to a 3" for future plans, but for the time being it will be on a chiped/intake/exhaust setup. I am flanging before and after the muffler so I can run a straight pipe, chambered, or straight through muffler for different things. Of course I will be on the chambered muffler for now but I plan on dyno'ing it. I also lost a significant amount of torque over stock with my mods, but I picked up top end. My car definantly has more grunt to 7000, where before it kind of kicked the bucket at about 6500ish. I find myself using the chip more than before when I would always shift at 6700-7000.
Our cars have very large ports, fast burning combustion chambers, and a relatively straight exhaust system to start with. When I pulled the head, it reminded me more of my built E30 M3 head that had been ported and polished, big valves etc...than a stock 3L NA head. I came to the conclusion that this engine could really be powerful with some beasty cams, good headers, larger MAF, larger injectors, and really good tuning. Based on other 3L engines, I think 270-280whp would be possible with big enough cams. We have already proven the engines RPM capability, so why not use it? The WebCams are only like 254, why not some 272/282's to open it up to 8000?
All hypothetical questions and answers!
Wes
Our cars have very large ports, fast burning combustion chambers, and a relatively straight exhaust system to start with. When I pulled the head, it reminded me more of my built E30 M3 head that had been ported and polished, big valves etc...than a stock 3L NA head. I came to the conclusion that this engine could really be powerful with some beasty cams, good headers, larger MAF, larger injectors, and really good tuning. Based on other 3L engines, I think 270-280whp would be possible with big enough cams. We have already proven the engines RPM capability, so why not use it? The WebCams are only like 254, why not some 272/282's to open it up to 8000?
All hypothetical questions and answers!
Wes