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I still have my inox Hirsch exhaust from my total los accident saab 9-5 i am gonna see to fit this exhaust underneath to have better flow.
 

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Anything is possible, but I would just make a custom exhaust. If you are doing the work yourself AND you are good at it, you might be able to save some money. Most professionals are not used to reusing used parts, so their fees will be higher than usual.


Also, 2.5" exhaust is good up to 350-400hp, you really do not need to up to 3" until you are making over 400hp.
 

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Keep in mind that the stock exhaust system includes a resonator that actually works to improve scavenging/flow. On these ECU vehicles a free-flowing exhaust might even degrade performance.
 

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For welding things its no problem foe me as long as its no aluminium.

And i have the complete exhaust including the resonator .
 

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Keep in mind that the stock exhaust system includes a resonator that actually works to improve scavenging/flow. On these ECU vehicles a free-flowing exhaust might even degrade performance.

i have the complete exhaust including the resonator . its completely inox and 3 inch .

I can't imagine giving your car less resistance for letting the exhaust fumes go out its gonna have less performance .

This comes from my totaled saab 9-5 with Bigger injectors and tuned ECU it had 280 Bhp.
 

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John, there is something to what Pico is talking about, just Google exhaust back pressure. The loses can be real at low/mid RPM range, at high RPM it will help but only if your current exhaust is at full capacity.


However, lack of back pressure “concerns” are exaggerated in four cycle engines… People like to pass it along because it is sounds counterintuitive. The reality is that it doesn’t really mater, it isn’t something that you are likely to notice by driving your car (without instrumental testing). And BTW, resonator is only one part of your exhaust system that contributes to total “back pressure”, it is just as important as the exhaust manifold, the catalytic converter and the muffler (actually, exhaust manifold is most important to exhaust scavenging effects ;)). You add (or remove) resonator if you want to change the tone (frequency) of the exhaust (it doesn’t have much effect on volume).


At the same time, you will not see much improvement, ether, unless your current exhaust is very restrictive. So you would be doing this mainly to “make it sound cool” ;). Just make it work with or without resonator and be ready add it later on if you do not like the sound.


BTW, in turbo engines there is no such thing as “good back pressure”, the more flowing exhaust you get, the better (to a point, where it stops helping, but it is never hurting you).
 

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Discussion Starter · #7 ·
John, there is something to what Pico is talking about, just Google exhaust back pressure. The loses can be real at low/mid RPM range, at high RPM it will help but only if your current exhaust is at full capacity.


However, lack of back pressure “concerns” are exaggerated in four cycle engines… People like to pass it along because it is sounds counterintuitive. The reality is that it doesn’t really mater, it isn’t something that you are likely to notice by driving your car (without instrumental testing). And BTW, resonator is only one part of your exhaust system that contributes to total “back pressure”, it is just as important as the exhaust manifold, the catalytic converter and the muffler (actually, exhaust manifold is most important to exhaust scavenging effects ;)). You add (or remove) resonator if you want to change the tone (frequency) of the exhaust (it doesn’t have much effect on volume).


At the same time, you will not see much improvement, ether, unless your current exhaust is very restrictive. So you would be doing this mainly to “make it sound cool” ;). Just make it work with or without resonator and be ready add it later on if you do not like the sound.


BTW, in turbo engines there is no such thing as “good back pressure”, the more flowing exhaust you get, the better (to a point, where it stops helping, but it is never hurting you).
Oké i understand then i won't bother changing it if it don't help getting moere BHP out of the engine . By the way my saab was indeed a turbo engine
 

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I can't imagine giving your car les resistance for letting the exaust fumes go out its gonna have less performance .
It is definitely counter-intuitive, especially for many of us Old School types, unless a person has a lot of experience with 2-strokes in which pulsed back pressure is very important. That said, I doubt you will do any harm by installing a big exhaust system on that little engine. Maybe the catalytic converter.

Let us know how it goes for you.
 

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Discussion Starter · #10 ·
3" way too big, should be more like 2 1/4"
Sho you right Sho you right (barry white) I know now i will not change the original exaust now :laugh


But i will stil close my EGR valve >:D
 

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Discussion Starter · #12 ·
Take a look at the intake trunking before the airbox. There are some gains to be made there.
Thats something that i am gonna do first so it get lager volume of cold air this with the closed egr valve will probably improve the responce of the engine.
 

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Sho you right Sho you right (barry white) I know now i will not change the original exaust now :laugh


But i will stil close my EGR valve >:D
Here's my exhaust setup, using the strange caldina side-entry muffler. the Caldina muffler has an electronic valve in it to open/close one of the dual exits, it's strange, but note that EVEN the 3S-GTE Turbo, has an electronic output on the ECU called BPC- and BPC+ (BACK PRESSURE COMPENSATION) These terminals send 12V to a flapper valve to open/close that butterfly valve, and help increase/decrease backpressure based on driving conditions or something, I've never narrowed down the function, but am planning on putting an LED on the dash of my Wife's Stock Caldina and seeing when it activates/deactivates for Info's sake.



Just something I've noted and thought I'd mention to throw some kindling on your fires. lol

 

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Great stuff, Rav4hunting! Did I hear a rev-limiter cutting in there?
.
 

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Wow, an electronically controlled muffler? I've never heard of such a thing!
 

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Wow, an electronically controlled muffler? I've never heard of such a thing!
Pretty cool, eh? Have you seen the professional 2-stroke racing boats that have a long muffler extension that is extended for acceleration and withdrawn for high-speed? Similar principle. Super effective.



Speaking of counter-intuitive exhausts, this is a 2-stroke V8.

 

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Wow, an electronically controlled muffler? I've never heard of such a thing!
I know right! I had neither heard of such a thing! It's there though, I actually had that cut out with a torch from the Caldina muffler I've put on my Rav4. but it is completely functional on my Wifes Caldina. It's very strange.
 

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Sounds like an inventive way to widen the torque band. My guess would be more restrictive at lower rpm to increase the exhaust velocity and assist scavenging then opening at higher rpm to prevent restriction once the exhaust volume increases. Toyota did something similar with intakes on some of the 4ag engines I believe. They added throttle plates to the intake runners to restrict the intake and increase the intake velocity to assist cylinder charge at low rpm then open at high rpm so as not to choke the engine. Of course now they can adjust the valve timing to perform this function.
 

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Sounds like an inventive way to widen the torque band. My guess would be more restrictive at lower rpm to increase the exhaust velocity and assist scavenging then opening at higher rpm to prevent restriction once the exhaust volume increases. Toyota did something similar with intakes on some of the 4ag engines I believe. They added throttle plates to the intake runners to restrict the intake and increase the intake velocity to assist cylinder charge at low rpm then open at high rpm so as not to choke the engine. Of course now they can adjust the valve timing to perform this function.
I do know that about the 4A-GE, which is pretty cool, no one doing engine swaps with the Gen4 3S-GTE are connecting this BPC- and BPC+ terminals, I have it disconnected on my Rav 4 and I have no check engine lights as a result. I do notice my Wife's Caldina Idles 'Meaner' than my Rav4, and I've narrowed this down to the "trumpeting" effect of the dual tips only having one port open during Idle. Perhaps this is to help get the engine temperature up quicker? My Rav4 now with it's 3s-GTE swap is very hard to warm up in the cold weather I've noticed.
 
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