AutoRacing Technik CL9 Project Teaser *Updated With Sound Clip On Post 1*

[EUR003act]

oh, this is also my 2cents...

system 1: (twin mufflers)
each muffler is say 80db, and flows 300CFM
thats a total of 600CFM flow...

system 2: (single muffler)
sound level of 90db, flows 500CFM...
total of 500CFM flow...

System two is quieter, and flows more...

(these numbers are made up, i have no idea what an exhaust flows at, im just trying to show the difference)

[Chris_F]

what about if you ran custom headers that went 4 -> 2 and then kept twin piping down to two seperate canons

lol

IMO twin exhaust is only for sound level and looks...

lol, then you'd loose power...

oh, this is also my 2cents...

system 1: (twin mufflers)
each muffler is say 80db, and flows 300CFM
thats a total of 600CFM flow...

system 2: (single muffler)
sound level of 90db, flows 500CFM...
total of 500CFM flow...

System two is quieter, and flows more...

(these numbers are made up, i have no idea what an exhaust flows at, im just trying to show the difference)

Do you mean system 1 is quieter and flows more?

But that's the problem. You can't just add up the individual flow of each muffler and say one flows better than the other. It's more complex than that. How about the increased turbulance created by the y-join? The reduction in velocity of exhaust gases caused by splitting the exhaust gasses and forcing them to twist and bend through the extra piping and the extra muffler?

Also, faster traveling exhaust gases will create a scavenging effect that pulls subsequent exhaust pulses through the exhaust.

My main point though: if there was a true performance benift to a dual outlet exhaust on a 4 cylinder car (not talking about noise reduction or looks) why don't all of the tuners who are obsessed with extracting every last HP out of the k-series go with a dual outlet design?

By the way, I'm not saying that a dual outlet exhaust can't flow just aswell as a single (depending on the design). I'm saying that a single outlet exhaust is all that's needed regardless of the power figure you are chasing. It's also more straight forward to design a single outlet exhaust that will give you the flow you need for your setup.

[aaronng]

what about if you ran custom headers that went 4 -> 2 and then kept twin piping down to two seperate canons

Then your Euro would sound like it had a 2-cylinder engine. Hahaha.... Try it!

[integral90]

But that's the problem. You can't just add up the individual flow of each muffler and say one flows better than the other. It's more complex than that. How about the increased turbulance created by the y-join? The reduction in velocity of exhaust gases caused by splitting the exhaust gasses and forcing them to twist and bend through the extra piping and the extra muffler?

Also, faster traveling exhaust gases will create a scavenging effect that pulls subsequent exhaust pulses through the exhaust.

My main point though: if there was a true performance benift to a dual outlet exhaust on a 4 cylinder car (not talking about noise reduction or looks) why don't all of the tuners who are obsessed with extracting every last HP out of the k-series go with a dual outlet design?

By the way, I'm not saying that a dual outlet exhaust can't flow just aswell as a single (depending on the design). I'm saying that a single outlet exhaust is all that's needed regardless of the power figure you are chasing. It's also more straight forward to design a single outlet exhaust that will give you the flow you need for your setup.

Ultimately up until the split a single and dual outlet catback run the exact same course and you're right when you say the main problem is in the split but you'd assume a good aftermarket exhaust would have a good-quality split that won't disrupt flow that much. But a single outlet exhaust still has to bend in the same place at roughly the same angle as one of the dual's. What's the say it's impossible for the gas to flow as well if it splits before the corner as if it just stayed all together around it?

Not saying you're right or wrong but just looking at it from another perspective

[Chris_F]

Ultimately up until the split a single and dual outlet catback run the exact same course and you're right when you say the main problem is in the split but you'd assume a good aftermarket exhaust would have a good-quality split that won't disrupt flow that much. But a single outlet exhaust still has to bend in the same place at roughly the same angle as one of the dual's. What's the say it's impossible for the gas to flow as well if it splits before the corner as if it just stayed all together around it?

Not saying you're right or wrong but just looking at it from another perspective

Well if the gas splits after the Y wouldn't the energy/velocity of the gass travelling through the pipe is also split into two. It then has to travel through twice as many bends and mufflers before it exits the system. It adds complexity and that hinders flow for sure.

A well designed dual outlet should be able to flow very well, I'm just saying a single outlet exhaust shouldn't be a restriction by the simple fact that it is single outlet. (from the research I've done there should be no performance benifit of going to a dual exhaust if both systems are well designed)

[EUR003act]

lol, then you'd loose power...



Do you mean system 1 is quieter and flows more?

But that's the problem. You can't just add up the individual flow of each muffler and say one flows better than the other. It's more complex than that. How about the increased turbulance created by the y-join? The reduction in velocity of exhaust gases caused by splitting the exhaust gasses and forcing them to twist and bend through the extra piping and the extra muffler?

Also, faster traveling exhaust gases will create a scavenging effect that pulls subsequent exhaust pulses through the exhaust.

My main point though: if there was a true performance benift to a dual outlet exhaust on a 4 cylinder car (not talking about noise reduction or looks) why don't all of the tuners who are obsessed with extracting every last HP out of the k-series go with a dual outlet design?

By the way, I'm not saying that a dual outlet exhaust can't flow just aswell as a single (depending on the design). I'm saying that a single outlet exhaust is all that's needed regardless of the power figure you are chasing. It's also more straight forward to design a single outlet exhaust that will give you the flow you need for your setup.

Well if the gas splits after the Y wouldn't the energy/velocity of the gass travelling through the pipe is also split into two. It then has to travel through twice as many bends and mufflers before it exits the system. It adds complexity and that hinders flow for sure.

A well designed dual outlet should be able to flow very well, I'm just saying a single outlet exhaust shouldn't be a restriction by the simple fact that it is single outlet. (from the research I've done there should be no performance benifit of going to a dual exhaust if both systems are well designed)

nah i was just saying that up until a certain point, a dual system can flow more than a single... where that point is i dont know, and its going to vary greatly depending on the quality and design of each system... i was merely trying to point out that two quiet/restrictive mufflers can flow better than a single loud/free flowing muffler...

and yes it will get more complicated with pipe diameter and tuned lenghts and bends/joins etc. but unless someone needs maximum power, and can handle the noise, a straight thru 3" system prob isnt the best for street lol

[integral90]

Well if the gas splits after the Y wouldn't the energy/velocity of the gass travelling through the pipe is also split into two. It then has to travel through twice as many bends and mufflers before it exits the system. It adds complexity and that hinders flow for sure.

A well designed dual outlet should be able to flow very well, I'm just saying a single outlet exhaust shouldn't be a restriction by the simple fact that it is single outlet. (from the research I've done there should be no performance benifit of going to a dual exhaust if both systems are well designed)

But isn't the piping after the split thinner than before it? That could be tuned to keep the same velocity and back pressure as before the split but with the benefit of being able to run through 2 less restrictive mufflers than 1 huge one?

I just think the flow of single/dual outlet (if both are done properly) would be so similar it's pointless trying to argue which one is superior. From a performance aspect, rationally the single would have to have flow better (if they used the same exit mufflers) but the dual would look better and be more driveable and it's likely it would make almost identical power.

Overall, is this AutoRacing Technik CL9 a race car or a modified street car?

[Chris_F]

nah i was just saying that up until a certain point, a dual system can flow more than a single... where that point is i dont know, and its going to vary greatly depending on the quality and design of each system... i was merely trying to point out that two quiet/restrictive mufflers can flow better than a single loud/free flowing muffler...

and yes it will get more complicated with pipe diameter and tuned lenghts and bends/joins etc. but unless someone needs maximum power, and can handle the noise, a straight thru 3" system prob isnt the best for street lol

I see what you're saying. I guess at the end of the day, dual outlet or single outlet doesn't determine the flow but the type of mufflers your using and the piping diameter does. Maybe if you do a flow vs. noise comparison a dual outlet will come out on top. That would be a really interesting test! When it comes to exhaust gass velocity and scavenging the dual outlet will always be at a disadvantage.

You do get the weight savings with a single outlet exhaust though. My old J's racing exhaust was 17kg lighter than stock (that's like having a carbon fiber bonnet, carbon fiber boot lid, lightweight battery and lightweight race seat in the car lol).

That's true, a straight through 3" really isn't ideal for the street. 3" piping with dual outlet mufflers might be the best solution for a street driven euro if you're worried about noise. All the TSX race cars in the states use 3" single outlet systems aswell and I guess they'd be noisey haha.

But isn't the piping after the split thinner than before it? That could be tuned to keep the same velocity and back pressure as before the split but with the benefit of being able to run through 2 less restrictive mufflers than 1 huge one?

I just think the flow of single/dual outlet (if both are done properly) would be so similar it's pointless trying to argue which one is superior. From a performance aspect, rationally the single would have to have flow better (if they used the same exit mufflers) but the dual would look better and be more driveable and it's likely it would make almost identical power.

Overall, is this AutoRacing Technik CL9 a race car or a modified street car?

Yea usually the piping after the split is thinner but that doesn't neccesarily mean your going to maintain exhaust gas velocity, the energy is still being split into two at the Y join. With a good equal length header you're merging the exhaust pulses together achieve a high exhaust gas velocity (ultimately aiding flow and giving a scavenging affect). It's hard to see a benifit in splitting the merged exhaust gases after they have already been merged like this. You're just making the same amount of energy travel around more bends and go through more mufflers.

It's true though, in a real world scenario the two designs may flow similarly and it might not make much difference at all. I don't think a well designed dual outlet will hurt performance too much I just don't think it'll provide a performance benift (only a noise reduction benifit). If you're talking sound level vs. performance and don't care about weight... it might be a different story

[Kason]

revive much

so RBC will lose mid torque but gain in top end?

what about if it is tuned with emanage ultimate?

[integral90]

revive much

so RBC will lose mid torque but gain in top end?

what about if it is tuned with emanage ultimate?

RBC will lose you power everywhere except probably the last 500rpm.

Emanage is still only piggyback, it's limited and can't advance cam timing which the RBC really needs to be good.

With full intake, TB, ,exhaust and RBC I think I'm only just matching a stock Euro for torque up until about 5000rpm

[tony1234]

RBC will lose you power everywhere except probably the last 500rpm.

Emanage is still only piggyback, it's limited and can't advance cam timing which the RBC really needs to be good.

With full intake, TB, ,exhaust and RBC I think I'm only just matching a stock Euro for torque up until about 5000rpm

So conclusion.RBC=waste of time and money unless your car is highly modified,I,H,E,cams etc.

[integral90]

So conclusion.RBC=waste of time and money unless your car is highly modified,I,H,E,cams etc.

Agreed, +higher redline