Rally Exhaust?

[LandSpeed-DSM]

Thats almost impossible to say offhand Leon

Log Maf Hz with the stock exhaust on a few different 3rd gear WOT pulls. Then change exhaust setups without changing anything else, and Log a few more pulls in comparable conditions.

Do you have a pocket logger or any intentions on ECMLink?

V3 Lite or Full would be my first mod, honestly. After maintainence of course.

 

[Leonthefaded]

I will not be using ECMlink in my car. If it cant be said off hand then I suppose I am left only to judge it myself, if and when the time arises.

 

[LandSpeed-DSM]

At the very least you need to get a logger or ScanGauge/UltraGauge and a Wideband UEGO if you are going to be making VE mods.

 

[knochgoon24]

Just a little thing on exhaust temperature.

Before I wrapped my downpipe back to the cat, after a casual drive around town, my exhaust tip was usually still cool enough to touch. Now that I've wrapped it, the exhaust tip is hot enough to burn my leg through jeans. That much heat is lost in the early part of the exhaust.

Whether this has been a good or a bad thing for exhaust flow, I don't know, but I wrapped it to try and quiet the exhaust down, which it has to an extent.

 

[Leonthefaded]

At the very least you need to get a logger or ScanGauge/UltraGauge and a Wideband UEGO if you are going to be making VE mods.

I dont know exactly why I need to have a logger or scan gauge for an exhust system or my build. I've seen alot of high HP guys using these but in case it isnt known I'm not doing all of the stage 1 ugrade path.

 

[jtmcinder]

I dont know exactly why I need to have a logger or scan gauge for an exhust system or my build.

We will remind you of this some time down the road (as it were).

 

[PieEyedPiper]

This was the "theory" on exhaust gas that I was reading through when Glenn and I were having a discussion about something similar about a month back.


Reading this ^^^ makes sense picturing it in my head however, trying to figure out how a restriction in the back of the exhaust system doesn't hurt power out vexes me.

I don't blame you, at all.
I can recall a guy on the forums, before your time, who was having a hell of a time making power with his e316g with a 3" dp into 2.5" catback. I recall him claiming an increase of 2-3lbs/min on link when he switched to full 3".

However, that's no indication of whether or not a 2.5" into 3" would produce better or worse results.

 

[jtmcinder]

I've been reading up on this for the Evo and here's my summary:

Of course, a full 3" is best.

But, if there's going to be a section that is smaller (maybe for sound control), then it's better if the smaller section is towards the rear than towards the front.

Thus, when people follow the standard upgrade path and replace the cat-back first, and replace the downpipe and cat second, they see good gains both times which are often near equal. However, if they first replace the downpipe and cat, and later replace the cat-back, they see more gains in the first step, at least when it comes to low torque and respool (which is what I care about). Even more: if you compare two cars, one with a 3" cat-back and OE front section vs one with a 3" downpipe and cat and OE cat-back, the latter often has better low torque than the former.

These are wild generalizations that would, of course, depend on lots of variables, such as how much of the system is downpipe and cat vs how much is cat-back, how big was the OE piping, etc, etc, but the fact that there are counter-examples to the standard "wisdom" that the cat-back is the most important has been an eye-opener for me.

 

[LandSpeed-DSM]

I dont know exactly why I need to have a logger or scan gauge for an exhust system or my build. I've seen alot of high HP guys using these but in case it isnt known I'm not doing all of the stage 1 ugrade path.

Really? After all this time you have spent on the forum you don't know why? WTF

We will remind you of this some time down the road (as it were).

What he said^

I've been reading up on this for the Evo and here's my summary:

Of course, a full 3" is best.

But, if there's going to be a section that is smaller (maybe for sound control), then it's better if the smaller section is towards the rear than towards the front.

Thus, when people follow the standard upgrade path and replace the cat-back first, and replace the downpipe and cat second, they see good gains both times which are often near equal. However, if they first replace the downpipe and cat, and later replace the cat-back, they see more gains in the first step, at least when it comes to low torque and respool (which is what I care about). Even more: if you compare two cars, one with a 3" cat-back and OE front section vs one with a 3" downpipe and cat and OE cat-back, the latter often has better low torque than the former.

These are wild generalizations that would, of course, depend on lots of variables, such as how much of the system is downpipe and cat vs how much is cat-back, how big was the OE piping, etc, etc, but the fact that there are counter-examples to the standard "wisdom" that the cat-back is the most important has been an eye-opener for me.

That is "generally" true based on the numbers and theory, as well my real world experience. Bigger downpipe/test pipe will make for more significant gains, but you are still limited by whats plugging the end of the pipe as well as how long it is.

Where possible, I will recommend the largest feasible downpipe right off the turbo, and staying at least that size the whole way to the end of the tailpipe. It is worth it if you have the room.

 

[jtmcinder]

Next question on this:

Assuming (i.e., correct me if I'm wrong and ignore the rest) that it's downpipe velocity that is key to either or both of low torque and respool, does that mean that divorced downpipes (where the main outlet from the turbo and the wastegate outlet have separate pipes for some meaningful distance) are worth it on a system that is going to start big and possibly neck down later (for noise issues)?

If it isn't obvious, the goal here is a street-driven (quiet) autocross car.

 

[LandSpeed-DSM]

Yes that would be the route I would take, and you want a shallow angle of re-entry, <45*. Re-introduce the wastegate discharge to the main flow atleast 12-18" down stream.

Later is better in this case to an extent, obviously with diminishing returns.

 

[jtmcinder]

Thanks. That matches what I've seen and it matches the theory. To be clear (and please check my thinking), the reason for the shallow re-entry of the wastegate pipe to the main pipe is to avoid ruining the flow in the main pipe, both when the wastegate is open and when it is closed.

The mistake that a lot of exhaust-builders seem to be making (at least in the Evo X world and at least from the point of view of low torque and respool) is that they go to the hassle of making a divorced downpipe, but then have the wastegate pipe re-join after only 6". I know their excuse: that anything longer allows the two pipes to expand differently as they are heated, so the whole thing rips itself apart, but if all you care about is low torque and respool, then put a flex section on the wastegate pipe to deal with this, yes?

 

[LandSpeed-DSM]

Thanks. That matches what I've seen and it matches the theory. To be clear (and please check my thinking), the reason for the shallow re-entry of the wastegate pipe to the main pipe is to avoid ruining the flow in the main pipe, both when the wastegate is open and when it is closed.

The mistake that a lot of exhaust-builders seem to be making (at least in the Evo X world and at least from the point of view of low torque and respool) is that they go to the hassle of making a divorced downpipe, but then have the wastegate pipe re-join after only 6". I know their excuse: that anything longer allows the two pipes to expand differently as they are heated, so the whole thing rips itself apart, but if all you care about is low torque and respool, then put a flex section on the wastegate pipe to deal with this, yes?

Bingo! You see that alot with the Turbo Pro-Mod guys.

As far as the angle at which they join together, its all about keeping turbulence to a minimum. There will likely be a velocity/pressure differential no matter how you do it, but its the way they are brought back together that will have the most significant effect in how they mix back together.

Same thing for the pipe leading from the manifold to the wastegate, you'll find it much easier to control boost if the valvehat is facing incoming flow on a shallow angle instead of having it T'd off at a 90* angle.

When it comes to fluid flow, smoother is better.

 

[jtmcinder]

In my class, the OE turbo and boost-control system may not be touched, so it's the internal wastegate of a TD05H that I'm dealing with. But, get this: because the SCCA still hasn't gotten its act together on these scary, mystical "turbocharger" things, while the turbo control system in terms of the wastegate, BCS, and ECU must be stock, you can do anything you want from the moment the exhaust goes through the flapper, so you can toss the O2-sensor housing, go with a divorced downpipe, and run a restrictive pipe on the wastegate outlet and get whatever boost you want that way.

 

[LandSpeed-DSM]

Haha a bit of an oversight, I suppose.

"Exhaust gasses go in, withcraft happens... and then you go faster."

 

[Ghost_92TSi]

Hands down, Thermal R&D is the best looking bolt on exhaust and sounds great!

x2. Only exhaust I have ever wanted. I love mine to death. I chopped out the tip and made it a full 3 inches and have a mil spec cat.

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[Leonthefaded]

Really? After all this time you have spent on the forum you don't know why? WTF



What he said^



That is "generally" true based on the numbers and theory, as well my real world experience. Bigger downpipe/test pipe will make for more significant gains, but you are still limited by whats plugging the end of the pipe as well as how long it is.

Where possible, I will recommend the largest feasible downpipe right off the turbo, and staying at least that size the whole way to the end of the tailpipe. It is worth it if you have the room.

I know that most of you use link, a lot of you use widebands, and some of you use sfacs, but I don't know one thing about tunning. I considered a wideband but I saw no need for the basic bolt on upgrades I have planned. Even in the upgrade path under the tech section in the stage one upgrades for the HP range I'm going for there's nothing about tunning. And drivetrain mods seem optional.

So for a simple exhaust systen why do I need any tunning? Please help me understand.

 

[LandSpeed-DSM]

You are changing VE, with the potential to move much more air.

Problem here is complex. You want that UEGO because in Open Loop.. the ECU is referencing the stock timing and fuel tables which are based on the stock airflow curves.

You will be moving more air than would otherwise be possible in various parts of the map, and have a good chance of running lean.

Additionally, if there are complicating factors like an old clogged fuel filter and degraded wiring back to the fuel pump you might push a system that was on the edge of too lean and too much timing completely over with disastrous effects.

Even if you consider that an extreme example, its one of several all-to-realistic scenarious you could be putting yourself into.

At the very least you want a Wideband UEGO, fuel pump rewire and an OBD2 pocket logger. I would go so far as to say an AFC as well.

That is why so many of us, myself included will tell you, a Wideband and ECMLink should be your first mods after maintainence.

So you can diagnose problems before they put you out of commision, and they let you retune when you do add modifications. You don't really know what you're affecting till you have real data and you should not be modifying blind anyways.

Take whatever preconceptions of cars, modifying, maintainence and tuning.. and forget them. I mean that with all due respect. They are clearly doing you no good and you need to listen to what people are trying to tell you.

We are here to help, and this advice is free. But it feels like you really dont want to hear it, yet keep askling questions.

 

[Leonthefaded]

You are changing VE, with the potential to move much more air.

Problem here is complex. You want that UEGO because in Open Loop.. the ECU is referencing the stock timing and fuel tables which are based on the stock airflow curves.

You will be moving more air than would otherwise be possible in various parts of the map, and have a good chance of running lean.

Additionally, if there are complicating factors like an old clogged fuel filter and degraded wiring back to the fuel pump you might push a system that was on the edge of too lean and too much timing completely over with disastrous effects.

Even if you consider that an extreme example, its one of several all-to-realistic scenarious you could be putting yourself into.

At the very least you want a Wideband UEGO, fuel pump rewire and an OBD2 pocket logger. I would go so far as to say an AFC as well.

That is why so many of us, myself included will tell you, a Wideband and ECMLink should be your first mods after maintainence.

So you can diagnose problems before they put you out of commision, and they let you retune when you do add modifications. You don't really know what you're affecting till you have real data and you should not be modifying blind anyways.

Take whatever preconceptions of cars, modifying, maintainence and tuning.. and forget them. I mean that with all due respect. They are clearly doing you no good and you need to listen to what people are trying to tell you.

We are here to help, and this advice is free. But it feels like you really dont want to hear it, yet keep askling questions.

How come this information isnt reflecting what is presented in the Stage 1 Upgrade Path for the 2G 46g3T? I have alot of questions because this is the first I've heard of tuning being so strongly suggested for "Simple" bolt-on parts. I apologize if my mechanical knowledge isnt where alot of the more experianced enthusiats are in the arena of tuning, but its not. I have never really shown much interest in ECU tuning, or data logging, and I wouldnt even know what to do with it. For the past 7 years I thought bolts on where simply that.

Now I did however have the knowledge and common sense to know that when you start moving into bigger modifications such as larger turbochargers, injectors, fuel pumps, internal modifications outside of the range of the OEM specifications. You would then require ECU tuning, A/F logging, Advanced engine management and various other tuning components.

one of my previous questions wasnt answered regarding a precooling pipe section used before and after the catalytic converter. Would this help cool the exhaust air whil at the same time helping it expand? Because I'm trying to folow what some of you are talking about and alot of what your saying is over my head. My understanding thus far is that expansion of the exhaust air is good.

 

[jb2zero0six5]

1990 Eagle Talon TSI AWD Tsudo 3" exhaust - YouTube

Full 3" exhaust.. "High-flow" cat section, 2 resonators and the "fart-can" Muffler, Ebay Tsudo system. Hasn't rusted, stainless steel. I also have a tubular 3" O2 housing, didn't have my FP race manifold on yet.

 

[Leonthefaded]

1990 Eagle Talon TSI AWD Tsudo 3" exhaust - YouTube

Full 3" exhaust.. "High-flow" cat section, 2 resonators and the "fart-can" Muffler, Ebay Tsudo system. Hasn't rusted, stainless steel. I also have a tubular 3" O2 housing, didn't have my FP race manifold on yet.

That is very nice, Its very close to what I'm looking for, I think thought to get to that tone or even closer I would have to swithc manifolds and have alot more similarities to your system

 

[LandSpeed-DSM]

How come this information isnt reflecting what is presented in the Stage 1 Upgrade Path for the 2G 46g3T? I have alot of questions because this is the first I've heard of tuning being so strongly suggested for "Simple" bolt-on parts. I apologize if my mechanical knowledge isnt where alot of the more experianced enthusiats are in the arena of tuning, but its not. I have never really shown much interest in ECU tuning, or data logging, and I wouldnt even know what to do with it. For the past 7 years I thought bolts on where simply that.

Now I did however have the knowledge and common sense to know that when you start moving into bigger modifications such as larger turbochargers, injectors, fuel pumps, internal modifications outside of the range of the OEM specifications. You would then require ECU tuning, A/F logging, Advanced engine management and various other tuning components.

one of my previous questions wasnt answered regarding a precooling pipe section used before and after the catalytic converter. Would this help cool the exhaust air whil at the same time helping it expand? Because I'm trying to folow what some of you are talking about and alot of what your saying is over my head. My understanding thus far is that expansion of the exhaust air is good.

Please take this in the least offense manner possible, as I see patterns here that are problematic and lead us to threads like these:

A.) You don't really seem to know how to perform actual research, or were not taught how to search properly in school. So that not may not be entirely fair to blame on you.

B.) Your question was answered, by me. Fluids/Materials DO NOT EXPAND when they cool. The exact opposite. They contract and become more dense.

C.) I also explained why those finned pipe sections are literally worthless.

Don't blame the forum or an upgrade path tailored to the lowest common denominator for your research ability's shortcomings. Take some personal responsibility for the things you do and say.

I wouldn't be so bold as to call what you have knowledge or common sense. You have suppositions and theories.. which is a start, I guess. Whether or not they are based on reality and sound principles is another matter.

Again, let me stress this is not intended as an insult or an attack, this is simply empirical observation and my being honest. I dont sugar coat well. I am not a PR guy, and I am not here to BS you.

We as a group, I feel safe in saying, are more than happy to work with you and answer questions if you bring them from a position of trying to gain an understanding of the subject and not pre-loading your statements, which you are prone to doing.

 

[jb2zero0six5]

I have the FP race manifold now, and the tone is just incredible. The "bigger" 7cm TD05H housing, FP manifold, and recirculated O2 housing really gave it that low growl I love so much. It's never, ever raspy and boosting is pretty loud. I love it.

 

[Leonthefaded]

I have the FP race manifold now, and the tone is just incredible. The "bigger" 7cm TD05H housing, FP manifold, and recirculated O2 housing really gave it that low growl I love so much. It's never, ever raspy and boosting is pretty loud. I love it.

I thought about getting the FP manifold myself then decided to stick with my stock manifold, but now I'll give it a second thought.

How much did it cost you to peice your system all together? I know I'm in hawaii so my prices will differ quite a bit but I'm pretty good as guessing by how much by now. Do you have any sound clips of your car at WOT?

And some photos of where your resonators are located in your setup would be appreciated as well.

 

[LandSpeed-DSM]

Don't PM me, Leon. You apparently don't know what trolls are either, so your accusation is somewhat amusing.

Trolls dont take the time to answer your questions.

Half the reason I am responding to this thread is because I don't want others to read misinformation and repost it elsewhere. Or atleast when they do search and this thread comes up they find legitimate answers from the half dozen or so folks who chimed in here to help you.

You may not like my posted observations of your habits, but this is a public forum and it is not really an attack or insult if what it describes is true. Like I said we, myself included. are happy to help you, but you need to help us help you.

Not all the answers you get are going to be the ones you want, but that doesnt make them less valid.

Maybe just maybe, and I hate to ring my own bell as thats really not my style, but there are few better examples of this.. if one of the wisemen is taking my advice on an exhaust system he intends to use in a multi-purpose street and competition application, its because he is an educated and knowledgable individual can see that I know what I am talking about and can back it up with both theory and experience.

Try and take in some of what I said in my last post, it is not meant as an attack. It is to help you in the long run.