exhaust mods?

[wilfongtsi]

has anybody done any crazy exhaust mods to get more power and mpg's? something like losing the muffler and reson. and maybe even the second cat? just got my insight a couple weeks ago, and really love it.

thanks
mark

[Rick Reece]

Try the link below. Have fun, Rick
http://www.cardomain.com/memberpage/350420/2

[dan]

And the related discussion:
Has anyone tried Claude Akley's Muffler Mod? http://www.insightcentral.net/forum/vie ... php?t=1285
If you have not found it already.

Hi Dan:

___Follow Rick’s link …

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:1qzzrdqh]Waynegerdes@earthlink.net[/email:1qzzrdqh]

[bigtrouble77]

I still plan on trying it... Now that it looks like i'm gonna keep my cvt (and not upgrade to a newer 5speed) I may see if my local mechanic will take it on.

[dan]

Hi xcel-

I had, and I did again follow Rick’s link to cakley’s excellent site. I am still fail to find a direct link back to the related discussion here...

[coolcat]

Originally Posted by dan

Hi xcel-

I had, and I did again follow Rick’s link to cakley’s excellent site. I am still fail to find a direct link back to the related discussion here...

He modified his exhaust system to basically bypass the muffler. I'd like to see pictures of what Mitch has done to his Insight. He's got a SuperTrapp muffler where the second cat originally was. He removed everything after the first cat and just put the muffler right up there in the middle of the car. I've been thinking that sounds like the way to go! I'm just a little worried about the heat and the possibility for exhaust gasses to get back into the car.

Later,

Matt

[dan]

Hi coolcat-

Everyone here is trying to be so helpful!
-Rick Reece helped out moutwilfongtsi with a very relevant link. (Response 1)
-I tried to supplement Rick’s assistance with another relevant (much related) link (response 2).
-xcel (I think) tried to help us all out by pointing out my redundancy. (Response 3)
-I attempted to clarify why I believe my posting was justified. My reference to “link”
referred to an internet link. (response5)
-I assume that you interpreted my use of the word “link” to mean “relevance” and are trying to help me understand. (Response 6) Your response was very polite and on topic.

Relevant posters: In an effort to keep this thread “on topic”, if you have comments directed to me not related to exhaust modifications, (automobile, not personal ) please send me a personal message. (I have tried to be very clear, but I have learned that things are not always as they seem, and that it is easy to inadvertently step on toes here.) I do not want to be responsible for going any further off topic

[BlueInsight1595]

Ok, have to respond here... I have seen too many get disillusioned by the "larger piping/less resistive exhaust is better."

The bigger the exhaust, the less backpressure and resistance there is. Resistance=bad and it is important to get rid of it as much as possible. Unfortunately, there is a downside to this. With a n/a engine, only one thing that pushes the exhaust gas out is the piston. The exhaust valve opens and the piston pushes out the fumes using some of the engine's energy.

When you have a smaller exhaust, backpressure is your biggest enemy. With a larger exhaust, you get rid of that resistance, however there is a problem... in your exhaust system, that piston gets a bit of assistance by a suction within the exhaust system.

You can best understand it by thinking about a straw with water. Something you probably remember from elementry school... imagine 2 glasses sitting on 2 different steps of a staircase. The glass that is higher up is full of water and the one on the lower step is empty. If you take a U-shaped straw and stick each end in each glass and you start the flow by sucking the water from the lower end, the water will continue to flow into the lower glass until the top one is empty. This is all done because a velosity has been created and gravity has chosen the direction of the flow. (If you still cannot imagine it, think about siphoning gas out of a fuel tank).

Back to the Insight, the exhaust system works in the same way, the flow of gases also has velocity within the pipes and therefore, there is a suction that literally pulls the exhaust gases out of the cylinders freeing up the engine of the old gases and taking some stress off the piston (and increasing efficiency). Now, a 1.0L can only create so much exhaust at a time (especially at low RPMs like the Insight runs), so if the exhaust is too big, the gases move slower (there is more space to fill) which means the velosity is slower and the suction is less (once again putting more stress on the piston). Also, if it is too big, there may even be some reverse flow going on within the pipes because there just isn't enough exhaust to fill up the pipe completely.

Take this into consideration when you think of doing mods of this nature to a n/a (normaly aspirated) engine. In the case of Willie's turbo Insight things are a bit different.

Just remember... it is hard to out-engineer the engineer (Honda). And for those wondering where I draw my knowledge from... I am an Aerospace Engineer with an emphasis in aerodynamics/flow. I am currently employed as a flow control systems design engineer.

If some of you have the need for speed... do what I did... invest in a weekend toy and leave the high-mileage Insight the way it is... engineered just right!

-Clayton

[redgiki]

Here's the link to Cakley talking about the improvement to his MPG through bypassing the muffler. Was a hot topic when I first joined the board