Exhaust Question

[JDM RunX]

Hi all,

I went to my local muffler shop the other day and had a interesting conversation with one of the guys. I drove my car up the ramp and we discussed ways to improve the exhaust. He said that the stock system is very effective. In his opinion, all I need to do is remove the catalytic converter and add a different resonator and performance muffler. The overall cost would be around $350-$400 US. Is this the route your Muffler shops take when upgrading the Stivos? What power increase can I expect from such a modification?

Thanks.

[SILVABULLIT]

Hi all,

I went to my local muffler shop the other day and had a interesting conversation with one of the guys. I drove my car up the ramp and we discussed ways to improve the exhaust. He said that the stock system is very effective. In his opinion, all I need to do is remove the catalytic converter and add a different resonator and performance muffler. The overall cost would be around $350-$400 US. Is this the route your Muffler shops take when upgrading the Stivos? What power increase can I expect from such a modification?

Thanks.

←

Hey JDMRunX

replacing the cat,resonator and rear muffler won't give you too much of a gain at all. These cars are very sensitive to back pressure so putting a huge muffler on(eg cannon type muffler) may actually make the car go worse not to mention sound ordinary :o If the runx system is the same as the stivo then the standard cat is great and will flow ample gases without restriction due to its shape. CES have made a system from the cat back which uses the standard cat, increases pipe diameter and has a custom made resonator and rear muffler. This system is compliant with Australian noise regualtions,sounds great and has proven gains. On a standard car it gains 9kw at the wheels and on a car with TRD CAI and TRD headers it gained 6kw. It's all stainless steel construction and quality craftsmanship along with proven gains make it a must for those who want to improve the output of their car as well as increasing the torque that the engine produces. Those of us who have the system on their car are extremely happy with it and would recommend to all Sportivo/RunX/T-sport owners.

By the way the price of the system is AUD$960 with mild steel flanges and AUD$1060 with stainless flanges. This also includes the relevant gaskets and nuts and bolts.

If you want to know more then contact myself or Danthuyer.

Cheers SILVABULLIT :D

[CAP]

Yes, you shouldn't have to change the Cat. Don't go with the first outfit you speak to, do alot of research, like Silverbullet said, fit the wrong set up, and you actually go backwards with outputs. A loud system doesn't actually mean it's effective.

[JDM RunX]

Thanks for the info guys. I wonder how much it would cost to ship the CES system all the way out here. I've noticed from the pictures in you gallery that your muffler is on the right side of the car, The JDM RunX goes across and comes out on the left of the car. Does'nt this mean that the brackets may be different? Has anyone tried the TRD exhaust package? Heres a pic of mine.

[KoroLa883]

If u'r exhaust run across and comes out on the left hand side then there are many option for u to choose. There are: trd, c-one, fujitsubo and hks to choose from. They are properly designed mufflers, so u shouldn't have problem with gaining power.

[kcorro]

there like mentioned

Edited May 13, 2009 by kcorro

[georgec]

Thanks for the info guys. I wonder how much it would cost to ship the CES system all the way out here. I've noticed from the pictures in you gallery that your muffler is on the right side of the car, The JDM RunX  goes across and comes out on the left of the car. Does'nt this mean that the brackets may be different? Has anyone tried the TRD exhaust package? Heres a pic of mine.

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JDM RunX, that's a different rear to our Sportivo. Is yours a sedan? The area where your muffler is situated is where our spare wheel sits.

Cheers

gc

[georgec]

Hi all,

I went to my local muffler shop the other day and had a interesting conversation with one of the guys. I drove my car up the ramp and we discussed ways to improve the exhaust. He said that the stock system is very effective. In his opinion, all I need to do is remove the catalytic converter and add a different resonator and performance muffler. The overall cost would be around $350-$400 US. Is this the route your Muffler shops take when upgrading the Stivos? What power increase can I expect from such a modification?

Thanks.

←

After having a good look at the exhaust system on an Australian Spec Sportivo, I tend to agree with your exhaust shop. The exhaust tube diameter and bend radiuses are good for sustaining probably another 60 kW over standard power levels. The cat is similar in external construction to those found on AMG Mercs etc - and perhaps even with a high quality stainless steel monolith. That means that it should flow reasonably well and be quite durable (if the cat exit is smooth internally as an AMG cat). However, it is a source of significant restriction compared to the standard straight tube due to the internal mesh. Regardless, it is illegal to operate a vehicle here in Australia without a cat and the penalties are significant.

The only other place then is the muffler - and it looks fairly restrictive. I would be tempted to give that a go in order to improve performance. In fact I suspect that you would be better off leaving the standard tube diameter (and take advantage of the noise suppression qualities of standard diameter tube) rather than going larger - for little if any benefit in flow and working with a less restrictive muffler - where you will have better results and have a chance of obtaining good sound quality.

In other words, work on the areas that are restrictive and leave the free flowing parts alone.

Silvabullit touched on the issue of back pressure and its affect on engine performance. I doubt that this applies in this case because we are talking about exhaust enhancements well down stream of the individual exhaust headers and well after the cat. Primary header sizes have a great affect on engine performance because they have a great affect on the gas velocity and more importantly the timing from one exhaust pulse to the next as they merge in the exhaust. Traditionally (and this should certainly apply to Yamaha designed heads as used in the Sportivo), zero back pressure exhaust after the cat will result in the greatest improvement in engine power.

However, one can't achieve that if we wish to pass ADR28/01 stationary noise test which is based upon "SAE J1169 Measurement of Light Vehicle Exhaust Sound Level under Stationary Conditions". Engine RPM must be held steady at 75% of rated peak horsepower RPM (which is 5850 RPM for our Sportivos) and be under 90 dB when measured 0.5 m from the exhaust tip at an angle of 45 deg.

In my opinion, it is vital that we abide by ADR28/01 and I applaud Silvabullit for doing so. Here in Melbourne, if you run an exhaust that sounds anything but standard, it's only a matter of time before you will receive a letter in the mail from the EPA. If they feel like being a pain, they can demand that you present the vehicle for further investigation and then they go over it with a fine tooth comb.

Enough raving....

Cheers

gc

[CAP]

By the look of it - You've got the Japanese spec exhaust set up, so you're at an advantage to us because you'll have a much broader set of options.

[JDM RunX]

Ok Guys, first off I have no idea where to find resellers for those packages so if you could post some links that would be great.

As for whether or not my car is a sedan, yes it is. It looks exactly like your 4dr stivos. My car is officially called the Corolla RunX Aerotourer Z. I think.

The TRD package also claimes to add 6hp for about the same cost as the CES system but all the sites I've found with it are in Japanese. I'd really like to see what those other manufactures are offering. Come to think of it, I kinda like the idea of slowly building my own TRD Sport M version.

When it comes on to legal limits, that does'nt exist here in Jamaica. Once in a while the cops may give you a ticket for being too loud. They say it is a defective vehicle so there is a penalty for that, but thats so rare nobody is concerned. People here mod the hell out of their cars and the laws of the land does'nt affect us or look for us. So basically I have no limitations from the government.

I really want a set up that will get me to or pass my 126.77Kw at the wheels goal. I only need 4Kw to make it. :)

[MR22ZZ]

Hey JDM

Firstly do you think you could post a few pics of your car, it sounds pretty good, I'd like to have a look...

Secondly try using Babel Fish translation to look at the Japanese sites, they don't always give good english as it is direct word for word translation rather then a translation of a complete sentence so sometimes words are wrong or in the wrong order to what we are used to but give it a go.... http://babelfish.altavista.com/

Cheers

Dylan

[SILVABULLIT]

In response to george c regarding back pressure it's not just relative to headers, cats or mufflers. Pipe diameters do play a vital role in the movement of the expelled gas out of the system. I also think that the standard would be very restictive if you had a Stivo developing some 200kw or so as you stated. (141+ 60). When we developed the CES system the rear muffler does definately affect back pressure. We tried 2 different rear mufflers with the first having very little back pressure or restriction and the car was very gutless under lift but absolutely screamed at the top end. Made the car hard to drive. The muffler we have fitted on the system increased the mid range substantially and did very little to affect the top end at all.

The standard cat is not a restriction point - CES was amazed at the size and shape and said it would probably flow enough for an engine of some 3 litres in capacity. We stepped up the pipe diameter to match the resonator and rear muffler cause if you didn't you would have an uneven flow of gas in the pipe. It would flow fast in the pipe then into the resonator it would slow down to fill the expanse of the chamber then try to compress again back into the pipe etc etc. Matching the diameter of pipe helps to maintain a continual and consistent flow of gas as well as being able to flow a larger volume in a larger pipe. but as I said in testing back pressure is still a factor even at the rear muffler so it's not much use in putting a large diameter resonator and muffler on if you're not upgrading the pipe diameter as well. Just defeats the purpose. But the standard system compared to say a type r Integra is very good. Our pipe diameter is about 60mm and the Integra is about 45-50mm with the muffler's on the Stivo being less restrictive as well.

If you want an exhaust system that sounds great then you can't go past the CES system. I've heard Stivo's with cannons etc and they are very loud and I would imagine drony in the car as well.

I guess it all comes down to what you like ;)

[kcorro]

[site it is all there.

Edited May 13, 2009 by kcorro

[MEGAGTS4]

Yes but have you seen the pipe directly after the headers, it would have to be nearly three inch in diameter, this acts as an expansion chamber allowing the gases somewhere to go quickly before it has to pass through the system, reducing back pressure, also when the gases get pushed into the smaller pipe it incresses the exhaust gas velocity, they use the same principle on gas turbines, plus the standard 2 1/8 system is mandrel bent and has enough flow to handle 250 hp, as for back pressure even a pipe without bends or mufflers has "restriction" or " back pressure" just not nearly as much.

For instance a 3" pipe with a constant radius 90deg (mandrel) bend.

the 90 deg bend has approximately the same restriction as 9 feet of straight pipe.

Also the catalyst ceramic substrate would just about create enough back pressure on its own, and does the CES exhaust remove all the 2 1/8 pipe in the system or does the flanges join onto a 2 1/8 pipe, just curious... and yes i am an exhaust fitter. The CES system sounds like a great exhaust system though, as it performs and is quiet to a certain extent.

[SILVABULLIT]

Pipe directly off headers is dual wall and has another pipe inside with a divider down the middle which creates a 4-2-1 style header. 2 pipes feed into either side and at the end where the pipe has the elbow in it is basically where the divider finishes. CES system doesn't step down in pipe size at the flanges either. It's larger diameter pipe than the standard system and we have reduced some of the angle on the bend in the system at the rear of the tunnel to try make the gas flow the smoothest way possible. Only tight bend is where the system goes up and over the rear suspension as does the standard one. No other way around it apart from it hanging down under the suspension and that obviously being too low and making it illegal.

I agree with you megagts4 on restriction etc but someone was talking about just replacing the resonators and muffler with larger diameter units thinking that this would make a considerable difference. For noise maybe but to be make the most gain pipework could do with some work too. My car was the guinea pig for the CES system and I know how much the system has improved the overall performance of my Stivo.

PS. Could the first person to extract 250hp out of a Stivo let us know exactly what you did to get it and of course how broke you now are :P

[georgec]

Hi Silvabullit,

I get the feeling from the tone of your response that you may have thought I was not supportive of the approach taken by CES - which is not the case, but given the context of the title of this thread, seeking a low cost solution, I may seem a little abrupt in the following response.

There are many ways to skin a cat (as in a puss puss). It is the norm for the exhaust industry to produce a cat-back system that improves flow (reduces exhaust back pressure) and as CES have done, reduced the back pressure through the exhaust piping and muffler. Again, this is not unusual in the exhaust industry and a perfectly acceptable solution - that results in an improvement in engine power output.

As you stated, CES went to a good deal of effort to improve the flow (reduce back pressure) through the exhaust tubing only to have to run a restrictive muffler. It seems a waste to have to undo all that fine ducting work by adding more restriction somewhere else (muffler).

There's nothing magical or mystical about exhaust gas flow so far down stream of the headers and cat. It's all momentum based.

However, given the context of this thread, a less restrictive muffler on the standard exhaust can be matched to result in the exact same back pressure profile as a cat back system that employs a restrictive muffler. It's a matter of attacking the restrictive elements first. Now this may result in excessive noise - or perhaps not. I don't know, haven't tried it and probably never will on this car.

In a nutshell, you're after a target back pressure profile and you can free the flow up in a number of areas. At the end of the day, it's just a back pressure profile.

Regardless there are a couple of issues that require clarification.

1. The standard exhaust tubing (size, bends and total length) should be well capable of a couple of hundred kW - not that you'll ever see that from 1.8L naturally aspirated - unless you can make the power through even more outrageous revs (power is a function of RPM x torque). For example, if you could maintain the torque output at 10,000 RPM as is currently produced at 7800RPM, the engine would be making 180 kW. We actually do have a very good base exhaust system in our Sportivos.

2. Cat sizing is a function of the mass flow rate of gas, not engine capacity (though sized by capacity to make it easier for the exhaust industry). The cat size used on our Sportivos is appropriate for the application, though not that huge for the exhaust gas mass flow rate. The fact that the cat looks like a 3L cat is no doubt correct. There's 141 kW worth of exhaust gas that needs to pass through the cat substrate, not some fraction of that flow as found in other (lesser) 1.8 L engines. In fact, one could go further and say that the entire exhaust system looks like one for a 3L engine - only shorter :)

Also, I bet that if you probe the pressure drop across the cat, you'll find it substantial, particularly at high engine RPM. To say that the standard cat is not a restriction point is not correct, regardless of how CES's description was interpreted (because I doubt that they actually said that the cat was not a source of restriction on this engine).

If you want an exhaust system that sounds great then you can't go past the CES system. I've heard Stivo's with cannons etc and they are very loud and I would imagine drony in the car as well.

I guess it all comes down to what you like  ;)

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I'm with you here. I have no respect for loud exhausts on the roads and as a driver, can't stand exhaust drone. A pox on drone.

Cheers

gc

[MEGAGTS4]

4-2-1 eh well this configuration is suited best to help the mid range due to the scavenging effect, strange how they would use this as the 2zz-ge has most of its peak power in the upper rev range, i wonder what effect a set of tuned length headers would have on the peak power figure...

[JDM RunX]

Thanks for the link to the TOMS site. Its kind of wierd though, I don't see prices, ordering information or catback exhausts. What about links to those other manufactures mentioned?

[MR22ZZ]

4-2-1 eh well this configuration is suited best to help the mid range due to the scavenging effect, strange how they would use this as the 2zz-ge has most of its peak power in the upper rev range, i wonder what effect a set of tuned length headers would have on the peak power figure...

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I think this was done to improve all around drivability if the engine and attempt to minimise the torque hole between 5K and when lift kicks in, it's not always about top end...