I finished installing an adapter on the OEM mufflers, and got it tested! The results were very good, but not quite as good as I hoped they would be. It looks like the OEM mufflers might make a few ft-lbs less than my 3" single. However, the torque curve has exactly the same shape, and it is super quiet. When I first started driving it, I thought it was actually making more power than any other mufflers, since the quiet just made it feel faster (does that make sense?). Without actually going back to the Dyno shop, which I may do, I won't really know for sure how much difference in power there is. I haven't been trying to do "standardized" street dyno pulls, so it's normal for the plots to vary a few ft-lbs from one set to the next. The only reason why I think they are making less power is because the AFR gets a bit richer as the RPMs climb compared to the 3" single.

Here are some pictures of the install.

 

Here is a plot showing the AFR's from 4 different muffler configurations with my mid-pipe. The upper red line is the 3" magnaflow single, green line is the Q300, blue line is the 1.75" magnaflow single, and the lower red line is OEM.

 

I fixed the rattle that was coming from inside my mid-pipe last night, and it made a significant difference in sound. It was just a symptom of my horrible welding...

I also repeated the recordings of the 3" Magnaflow single muffler that I have. It sounds really awesome, except for a bit of rasp at high RPMs that I believe are caused by the 7-8 significant holes I have in the pipe that connects the muffler to my mid-pipe. I will remove the muffler tonight, and patch the holes. In the meantime, here are the recordings. Note that there is some drone for small RPM range, but it isn't as bad as the Q300 with the OEM cat or HFC. Above 3500 RPMs, there's WAY less drone than the Q300.

Outside Accel
Outside Free Revs
Inside Full Throttle
Inside Cruise Throttle

 

Awesome work as usual! The gains from this thing are solid and like stated before w/o many significant header options for stock block/light mods i think that paying 1k for this instead of a header that may or may not give gains is fine by me.

Im personally impressed by the design and intrugied by the fact that moving it back makes such a big difference.

I will def look into one of thse once my ITBs are on and running. Thanks for all your work!

 

This is very impressive stuff. I have followed some of gernby's posts on the NA section and this man is a wizard who has been experimenting with the S2000 platform for a long while. I do agree if there was a muffler bolt-on option it might be more attractive to some, who would rather just sell their existing exhaust than cut into it. And $1200-1500 for a full exhaust isn't a lot if it adds significant NA hp and tq, reduces drone, and is emissions legal in 49 states. I mean, the ASM, J's etc. can cost more than $2000. A big for trying to bring new ideas to the S2000 platform!

Just curious from a total race view...how does it sound with no muffler at all?

 

Thanks guys!

I haven't ever run my mid-pipe without a muffler, but I did run it with a home-made 3" megaphone muffler once. It was uber loud, but everyone said it sounded good. It was very high pitched, like a sport bike, but it didn't drone. Honestly though, I don't think my mid-pipe would really belong on a "race car", since the benefits it provides aren't really needed in a race car (big gains in mid-range torque, reduced drone, reduced smell and emissions). If I wanted to have a race car that I also drove on the street, then I guess I would probably just have 2 muffler sections. One muffler section would be a quiet single or dual, then the other would be a race muffler or straight pipe section long enough to reach the back bumper.

 

Congrats for the new topic. I just saw it yesterday. I just have a couple of questions. Does anything in this equation change when we apply this to a bigger discplacement of more efficient engline? (ie. F24 or 2.2L with cams headwork etc.) Does this midpipe have any restriction in comparison to a 70mm or 76 headerback exhaust? (i.e in the high rev area with 5th gear) If the answer to both questions is no, then this is the part i ever dreamt of. To cut the long story short, is there any disadvantage using it performance-wise? Keep up the good work!

 

Awesome work Gernby. I'm really considering getting one of these instead of a header. I would love to do a back to back dyno on my current setup whenever I go get tuned by a better tuner, as I feel there is more in my current setup.

 

There will be some level of power that would make a larger diameter front pipe beneficial, but it should devinitely NOT be larger than the header collector. My mid-pipe effectively acts like a very long tube header. If I sold a 70mm front section, and it was mated to a 60mm header collector, you would lose a significant amount of the scavenging that the expansion chamber creates. To date, I haven't found an exhaust that makes more power than mine, even when that exhaust is cat-less. I've considered buying a Berk Single several times, just to do a dyno comparison. In the end, I couldn't justify the cost, especially since I had already tested a Berk-Like single.

 

I built another single muffler prototype last night, but won't be able to test it until tonight. It looks funny for a reason.