My car has had the ETS 3.5" exhaust on it since I switched to the 3586 almost 12k miles ago. The car has always made great power and sounded good but as you can expect with 3.5" pipe and a 4" aeroturbine it drones on the highway at 70mph or so. The easy fix was putting a 4" silencer in the car for highway use, but this is really inconvenient when I find something I want to rev on. All setup though the car made its best power with this setup at 38psi, 794/561.

I must be getting old because I decided to use a 12909 Magnaflow offset in center out 3.5" muffler. I can have a conversation in the car on the highway and when it was on gas I still made 648whp at 29psi. I switched back to E85 to do some testing and a "check up" to see where the car was at. At 26psi on ethanol it will normally do 650-660whp. It was down to 645 which isnt too bad, so I turned it up to 32psi. At 32psi instead of 746 it was now making 713. I doublechecked the tune vs my old logs too make sure everything was happy and then turned it up to 37. Where it had done 790-794 it was now down to 739.

It will be getting one of our new boost dumps on it to see if I can get the best of both worlds. From what I can tell it really seems that the muffler is good to 650whp but after that it definitely starts to taper down. The car should be getting a 3794 in the future so it will be interesting to see what this exhaust does as far as power reduction with and without the dump.

Here is the video-

http://www.youtube.com/watch?v=k2-dA6rEBsc

Dyno sheet (before and after) -



High boost-

 

More midrange??

Im about to go down this path. I'm currently runnign a Trust Ti-R, but I think Im going to go to a custom 3" exhaust with twin resonators and a Large oval rear muffler..

 

i see loss all over... the only reason the other one looks like its spooling quicker is because of the AFR.. ones lean and ones overly rich.. makes a huge difference in spoolup..

just changing muffler tho making that much loss is rather scary.. choose your exhaust systems wisely.

 

It was a little cold out which can help with spool as well. There are a few mods for more low end between the 2 as well. More MIVEC range, playing with the Tru-boost, and the AFR of course.

Aaron

 

tscompusa, what chart are you looking at that shows losses every where?

The new muffler is showing almost 500 RPM faster spool and massive gains on the spool area.

Can you post the corrected charts?

 

the high boost.

the blue line vs the red line.

blue line shows quicker spool and loss uptop

red line shows laggier spool and way more power uptop.

if you understand a turbo system requires no backpressure, the blue line makes no sense.. why would it have quicker spool if it was choking topend? that means its more restrictive.. so why would it spool quicker? it wouldnt

the afr and his mivec changes did that.. and as he said the cold weather. cold weather did it cause it leaned it out more to his advantage also & more density in air.

the 26psi one is pretty good though, if its significantly quieter i would deal with that little loss.. but i dont think aaron wants to run his car at 650whp forever when its a 800whp car

 

The plots could easily be explained by a decent change in temperature.

Colder IATs can easily spool a turbo MUCH quicker. If that's the case, then it probably is down even more HP on a corrected chart.

 

well if both tunes are optimized for say ones 20F weather and ones 100F.. if they are both optimized for the temp changes you can get the same spool in hot and cold weather.. fmic will work more efficiently in colder weather tho of course.

 

Yeah spool as I said before is a combo of things but lower IAT is definitely the primary. 10* of more MIVEC range and more timing down low isnt hurting things either.

As White pointed out, I am not going to run at 650whp (I am not now) often. Normally I run 32psi on the street so I am at (now) 713ish for a daily. With the exhaust altered it should be back up to 746 or so.

Aaron

 

That much of a power difference on high boost is pretty ridiculous...ps your car sounds like a beast on the dyno...

 

When it gets the boost dump it will be even better

 

the fmic is HUGE.

 

just found this thread... nm my email. very hard to imagine a straight thru muffler losing power to a (4") baffled muffler. i know it would be a pita, but would be great to see a back-to-back.

 

I was just going to link you, but I see you already found it. I posted it up on our face book last night in hopes you would see it. This is the test I was talking about.

This was the Aero Turbine vs the Magnaflow right?

Michael

 

Good talking to you yesterday. Funny thing is that I had sent JB an email about 5 min before I stumbled across this thread.