combfilter

iTrader: (3)

well I am really really trying to figure out if I should go ahead and have resonator removed also while i am at it. I was looking over roro's and that is what he did. I really want performance, but removing the resonator scares me because I do not want a loud car. I myself don't think it would make it any louder, but again I know the least amount of this here. I just want to make sure to do this right the first time while i am at the shop.

Gernby you don't know if the resonator is straight thru do you. This would help answer GNN's question.

07txlex you going to be around tues, or wed? I am going to try to go dyno my car either wed, thrus, fri after work at that shop. Yea, I don't mess around. I have some money saved up for this stuff right now. roro told me that there is a shop in florida working on a turbo for the is. If this is true, then that might be my next purchase after this fiasco. I guess i would need to get fordged internals and crap. I am going to get more details from him. I want to at least have the 2nd fastest IS there is. I am also going to look into LMS and see about their supercharger. I have friends that are real good with cars that said that should be easy to put on. roro said he has removed it twice with no problems.

After that it's wheels. This is one thing I wish the north texas people would get together a meet or something. I want to see some 19's in person with the eibach kit.

lobuxracer

iTrader: (2)

Powerhouse Racing is also working on a turbo kit for the 350. I would imagine there are quite a few concerns working this.

You don't need forged internals, you already have them (except the pistons, and that's going to be a problem since the piston crown design is proprietary and the key to GDI working correctly.)

Removing the resonator will make the car louder without a doubt. So will removing the cats.

Hameed

Very interesting reading in this thread.

Not an apples to apples comparison (my car is not an IS) but it sheds some light on the some of the questions asked.

I have a 99 GS400 and went with a custom exhaust from the cats up front all the way to mufflers.

Here is my write up from April last year regarding it with some pics and a vid.

I dynoed the car, however I don't think the results were in any way accurate as the guy who did the dyno didn't really know what he was doing. I will dyno it again sometime in the future though to see what I gained from the setup.


I removed all the piping and all three resonators from the cats up front all the way to the L-tuned mufflers at the back. I replaced all of that with 2.25 inch mandrel bent pipes and a Magnaflow 2.25 inch stainless steel Tru-X pipe - (specifically this one http://www.autoanything.com/exhausts...A2672A0A0.aspx ).

Pros
The sound is just so awesome!! The outcome exceeded my wildest expectations. It is very loud on WOT ONLY. That alone is worth the price of admission. On start up, the exhaust does not have a very deep note to it, however when you drive off and accelerate very hard, the exhaust note is pure music to my ears!!! It sounds like a more sophisticated version of a V8 mustang, however deeper than than a mid engine exotic car like a Lambo or Ferrari.

When cruising at city speeds or the highway and the tranny has shifted into 5th, you can barely tell the difference compared to the L-tuned mufflers by themselves (my previous only exhaust mod). So for example when I come home my neighbours don't know I am coming home. I was very concerned that the exhaust would be loud ALL the time, but that is not the case at all.

The exhaust gases are now flowing more freely (bigger 2.25 inch pipes and no resonators) and the X-pipe also contributes to that effect by creating a vacuum when one bank of cylinders pushes air out thus causing the other bank of cylinders to move its air out faster. The car definitely feels peppier, however I will dyno the car so that I can see what HP gains this mod made. I know I have not done a baseline dyno, however I will just take an approximate and average base number that others have done and use that as my base. Yes that is not exact or scientific, however I can't just afford to dyno the car so many times.

The nasty drone at 2100 rpm with the L-tuned mufflers is completely gone!

Cons
Some minor drone on part throttle at slow speeds (less than 30 MPH). Very minor. Not even worth mentioning, but I just wanted to share that the exhaust is not perfect that's all.

Now onto the pics.

1. Stock Exhaust



2. Stock Exhaust removed



3. First in-process pic with the custom Y-pipe and Magnaflow X-pipe



4. Second in-process pic with the straight pipes after the X section


5. Last pic showing the complete system



6. Pic of the car on the hoist



Now onto the videos!
I would right-click on the links below and choose "Save As" and save the videos to your hard drive rather than trying to watch them as they stream as the first one is pretty big at 12 MB. I deliberately did not make it smaller just so that you appreciate the full effect better. Remember to turn up your speakers to full volume when listening.

When you watch the video, the start up does not sound that great in this video - the actual note of the exhaust is actually more deeper. I am not sure why the camcorder does not catch that. However on the second part of the video when accelerating away, it does a pretty good job of capturing the sound.

For those of you wondering how reckless I was doing this on my street - I did it very early in the morning when there was nobody around. I think the sound may have pissed off one or two people though. Oh well.

1. Start up, Drive away and Drive by
http://www.prudensconsulting.com/yah...00_Revving.wmv

2. Drive by
http://www.prudensconsulting.com/yah...00_DriveBy.wmv


For some reason I could not capture the "drive-by" sound effect very well. The car sounds much better than what I was able to capture here.

caymandive

iTrader: (2)

Hameed great write up and the photos are very helpful. I'm really curious to see what ends up being the best option for us IS350 owners for the best compromise of power and sound.

07Txlex

Hey troy read this dude's exhaust setup above.. I get off early on tuesdays and don't work wednesdays so I'm good, lets get together and go so we can once and for all figure this **** out.. I'll text u here in a bit

combfilter

iTrader: (3)

yea just read it. heheh great write up and his GS sounded seriously ****ing wicked.

i was going to dyno thurs, but heck i can do wed if you want to go. also you need to check out the springs. I love them even more now.

07Txlex

Sure man whenever is cool.. If you wanna do it on thursday that might work if it was afternoon or evening. Either way we'll meet up so u can get that coupon, I thought you were doing the exhaust sometime soon, is that going to be Saturday regardless of the magnaflows coming in or only if they do?

combfilter

iTrader: (3)

exhaust will be sat only if i get my magnaflows. I got the tracking number today, and it shows that it already was picked up from the place i ordered it from. The only caveat to that is that they only had 1 muffler in stock. Their system still let me order 2 so that usually means the other one drop ships from magnaflow. Heck the both might even drop ship from there. MLK might slow down the mail also. I am praying that they get here by friday, cuz I don't want to have to wait another week till i can go again. The place i am going to do this out is open m-f from 8-5 and sat 9-1. I have to get there right at 9 on sat to have them do it.

regardless I need to dyno my car first, so i will do that wed. I'll give you a shout.

Irishman06

I'd weigh in, cuz I'm familiar with basic exhaust theory, but I also know that there's still a fair bit of black magic involved in really making everything work, soo...

Where's Pimp350 when you need him? Dude, did your car come yet?

combfilter

iTrader: (3)

well put your 2cents in. We'd like to hear it.

do you happen to know if the stock resonator is straight thru?

Irishman06

The parts of basic exhaust theory I know are mostly related to how an engine functions and an acoustical/mechanical analog. Here goes nothing:

The most powerful exhaust, obviously, is the one that permits the exhaust gases to exit the engine with as little "fuss" as possible. To this extent, just like any super-high horsepower dragster you see, 6 straight exhaust pipes, one from each cylinder, will give you the freest flowing exhaust you can get. Using the length of these pipes (and your intake runners), you control the shape of your torque curve. The analog here is to a spring-mass-damper system, actually, or a similar acoustical resonator. Your intake and exhausts will be most efficient when they hit resonant frequencies with the engine RPM. (Engineers who aren't following me, or want math, go google "helmholtz resonances" or PM me and I'll find an SAE paper for you to buy)

Now, when it comes to merging exhaust pipes together, things get complicated. The acoustical resonance still plays a part, but its multi-tiered and I'm not even sure I understand it. Primary length is important, but that's header design. Overall length does matter, as well as muffler baffling, cats, x-pipes, etc. Basically you'd want to use an x-pipe to improve scavenging, if that's what you're going for (same principles, get the exhaust pulses balanced and flowing freely) and you'd want to design the other elements to be acoustically "aligned," if you will.

With respect to the stock resonator, if its truly a "resonator," its just a big empty chamber to cancel out some funky noise they found in testing, or to increase the effective "length" of the exhaust (resonator, like above? No way. This makes sense). But it could be a sort of "pre-muffler," which could be straight through or baffled.

Does this help?

Hameed

Thanks caymandive! I absolutely love it and hopefully you guys figure out an optimal setup for your 350's.


Thanks combfilter! In person it sounds even better!

Gernby

iTrader: (1)

It shouldn't be hard to determine if the resonator is straight through, or not. Just disconnect the muffler, and look into it.

Cornellian

LOL! Interesting thread!

From my experience, I’d say that it is better to have a negative pressure at the exhaust valve during the overlap period when both exhaust and intake valves are open. Exhaust system will usually resonate at a particular engine RPM and will use the pressure waves reflected by the ends of the pipes to modify the time history of the pressure at the exhaust valve.

If you couple two or more of the cylinders' exhaust primary pipes together than the interaction between the pulses created by each cylinder will modify the pressure characteristics at any given RPM. Normally when 2 or more cylinder's exhaust pipes are coupled, the firing order of the engine will become more significant. Also, the frequency of an exhaust pipe is set by its length from the engine exhaust to the tail-pipe.

It is basically the same principle as harmonics in physics. You’re looking for the “Right” tone to get best performance! It’s actually kind of difficult to have a “single” exhaust system that will give you power in all sorta RPM range because it depends GREATLY on the size (i.e. diameter and length) of the pipes. So, any given exhaust system will usually have a “sweet” spot at certain RPM range.

As for doing all this stuff! Well.........easier said than done if you don't have resources!!

Irishman06 I don't know where the heck my car is and don't know when I am going to get it .........

Irishman06

Those of you interested in in-depth reading on acoustical performance of intake, exhaust manifolds, pick up SAE Paper 2005-01-3803, Development and Validation of an Impedance Transform Model for High Speed Engines. He does most of his analysis on the intake side, but its somewhat useful in understanding what happens on the exhaust side as well.

Pimp -- sorry about your car not getting to KY quick enough, but that still doesn't mean you should be posting from work ...