I contacted kingmotorsport about the Omni Power Stainless Steel Test Pipe and they told me that the fit is perfect. It's $89 bucks.

 

Unfortunately, it's no use for a street car without an O2 Sim or a programmable ECU to disable the secondary O2 sensor.

 

i will have a surprise for all in a few days.

 

You could always try a mechanical fix, something like this...

http://www.scoobymods.com/forums/sho...9053#post19053

 

I can vouch for this...
I had to do this mod because my high flow cat kept throwing codes.
Zero CEL (P0420) O2 sensor codes ever since!

 

I'm sure there are other ways to accomplish the result, but they are generally not the most elegant method. Much like adding check valves to the MAP sensor so the ECU doesn't detect boost for a FI setup.

 

Could you explain how you did it? What size fittings, pipe lengths, etc.

Fo' sheezy. I've been fiddling with an electronic O2 sensor sim that I built myself when I put my cat together, just in case. Mine is just a pulse generator though, so it doesn't send the ECU a true synthesized sine wave like a functional wideband O2 sensor does. I suspect this is why my ECU throws a code when I use it. Do you know if anybody makes a synthesized O2 sensor sim that produces a "true" waveform that Honda ECUs seem to demand?

 

You might want to contact the creator of the ECG O2 Sim as he is an electronics wiz and an Internet friend of mine. I assisted with the data collection stage with an OBD2 scanner to monitor the secondary O2 sensor output from a Honda. We collected data during cold start-up, idle, as well as the various rpm points. He then programmed it to the processor within the O2 Sim to mimic the various conditions, unlike a simple resistor the only provides one value.

Here are some descriptions of the Sim.

 

I went down to AutoZone and looked in their "Help!" section for 18mm Spark Plug Non Foulers (part number 42002 or 42009), then I bored out one of the Spark Pug Non Foulers with a Dremel (use a drill bit that is able to cut aluminum/metal) until the O2 sensor was able to fit. Then I just screwed the O2 sensor into the bored Spark Plug Non Fouler and then screwed the untouched Spark Plug Non Fouler on top of the bored out Spark Plug Non Fouler, then I just screwed the assembled O2 sensor finger tight into exhaust O2 sensor bung and tightened it using a O2 sensor socket.

 

alright, but the flange pictured is definetely not our rear flange:

http://www.kingmotorsports.com/product.asp?product=462

which part number did KMS say would fit?

 

Holy crap, that's exactly what I was thinking of. Thanks for the link.

drkangel348 - thanks for the info.

 

You'll need something like this

 

Alright, so how much would a shop charge me to do the welding? Where can I get that flange?

 

Alright, I'm resurrecting this thread because I have some questions.

So this particular mod eliminates the cat after the header correct? The one cat that some members have basically converted into a high-flow cat (drkangel348, JTso).

There is also a cat on the header as well right?

My question is would eliminating either cat be better? Would eliminating both cats produce better gains? Or would you just lose low end torque (for high-end HP) due to lack of backpressure?

Since I am technologically inept, thanks in advance to the board members who can help me answer this question.

 

the TSX is a single-cat vehicle.

You will loose low end TQ
You should gain in the high end

 

Losing power due to decreased backpressure is a complete myth. The less restrictions in the exhaust, the better power you will make across the band.

 

So there is no cat as part of the header huh? So in aftermarket header applications, the mesh-looking area is just the flex pipe?

 

Since you definitely know a LOT more than I do, I trust you on this. BTW rmpage, do you know if anyone has tried this? I wouldn't mind giving it a try if it can yield a wider power band. With Hondata still cracking the '05 ECU, I'm interested in all sorts of alternatives at the moment.

 

If that is the case then how do you explain the lost power on JTso's post-tanabe/high flow cat dyno? Granted the loss is in the extreme low end, but I bet that a test pipe with move the intersection of the two lines higher into the rev band with little increase on the high end as compared to the high flow cat.

The K-series' EGR system relies on 5th stroke induction to operate correctly, by reducing / eliminating backpressure you're greatly reducing the operation of that system.

 

Yeah, that's just the flex pipe - it's straight through.

 

There's no EGR valve on the TSX...

 

Rightish, but there is still a EGR system built into the head

 

There's an EGR plate on top of the intake manifold but it's not connected to the cylinder head. There's simply no port on the head for the connection. If you removed the intake manifold and injector base plate, you will only see the intake ports plus the coolant passage.

Intake manifold



Injector base plate



Intake ports

 

so what is the channel above the intake ports that has oil residue in it? I was under the impression that all K24s except the CRX's flavor had an EGR system. I guess I'm mistaken, I stand corrected.

Either way it's quite obvious that you did loose power in the low end with your exhaust and cat. I finished building a test pipe last weekend and I'll be putting it on later this week. I moved my car out to california (I'm now in the bay area) from Colorado so I'm going to rebaseline to compensate to the drastic elevation change then dyno with the test pipe on. I'll post the dynos when it's all said and done.

 

Jonnerd,

Looking forward to your dynos. I am looking to doing this mod as well and want to find out what sort of difference it makes.

 

That can't be because of a loss of backpressure. Perhaps it was the sizing of the piping used, or the internal construction of the cat itself creating more turbulence and lowering exhaust gas velocity.

There is one location where backpressure does some good in the exhaust system and that is in the primary runners of the header. A properly-sized primary runner will allow an outgoing exhaust pulse to bounce off the first junction and head back toward the closed exhaust valve, then bounce off the valve again, speeding back toward the junction, in the right direction, as the exhaust valve is opening for the next exhaust stroke. As the pulse speeds away back down the primary runner, it creates a rarefaction (low pressure zone) behind it, which in effect "sucks" the next pulse of exhaust gas out of the cylinder, and if there is valve overlap it actually aids in pulling the new intake charge into the cylinder. This is why a properly designed header makes so much power (ceramic coatings help too, as they trap heat in the header and the higher temperatures also raise gas velocity). The benefit of increased flow is there too, but it's only part of the story. This is also why street headers have shorter primaries, because they resonate at a lower RPM when exhaust pulses are moving slower, whereas race headers resonate at a higher RPM where exhaust pulses are moving faster. A header's resonant range is where it produces the greatest power increase. Intake manifolds do the same thing with the intake valves, which is why the Euro-R header's long runners lack the low-end torque of the K24's short, fat runners.

After the header, the sole objective of an exhaust system is to get rid of the exhaust gases. The faster and easier it can do this, the better. What is important in the rest of the exhaust system is to maintain a high gas velocity. The faster each of the pulses shooting out of the header can move down the pipe (with each pulse dragging the next one along behind it in the rarefaction), the more performance you'll get. Pulses leave the downpipe at a certain size. Ideally the exhaust system should be sized to match them. Too small and the pulses compress in the exhaust pipe, which lowers gas velocity and increases backpressure in the header, leading to ineffective scavenging of the combustion chamber. Too big and the pulses can't fill the pipe, so they bounce around and into each other, lowering exhaust gas velocity and thus increased backpressure in the header.

This is where the "engines need backpressure" myth comes from. Common sense dictates that the bigger a pipe you use, the less backpressure there will be. This would only be true of exhaust gas flowed continuously, like from a turbine engine, not in pulses as piston engines produce. So if you slap a three inch exhaust on your K24, you'll end up with a very slow-moving exhaust stream, and a loss in power. Most of the time people see "bigger exhaust = power loss" and immediately jump to the conclusion that "bigger exhaust = reduced backpressure" when in fact the cause is something else entirely. Sometimes you see guys running just a header with an open downpipe at the drag strip or on the dyno. Along with making a ton of noise and possibly burning something up under the car, there is no better exhaust system in the world than a well-made header with an open downpipe.

Here are a few articles I found discussing this phenomenon:

http://www.miata.net/garage/KnowYourCar/S4_Back.html
http://www.uucmotorwerks.com/html_pr...torquemyth.htm
http://www.team-integra.net/sections...p?ArticleID=47

 

Wow! Thanks for the education post rmpage. So from your experience/analysis, do you think that the test-pipe would be a worthwile mod? I am planning on getting a set of DC Header(s) installed soon and wanted to couple it with the test pipe.

 

Thans rmpage. I was about to resort to my old archived articles, but you've hit the naill on the head 100%.

 

^^ I still have those things saved right here, actually.

Haha, I wouldn't claim to have so much of that, just the theory that goes into these things.

I'd expect a test pipe to produce a good amount of gains, since ANY cat is very restrictive compared to a tube of metal, but realistically I have no idea by how much. I mean, the K24 flows something like 300CFM or so at redline, so if you've got a high flow spun body 200 cell cat on there, which only starts to become restrictive at 400CFM (I made this up as an example) then it may be only a hair more restrictive to that volume of exhaust gas than a test pipe would, so you wouldn't notice much of a difference.

There are probably some people here who have far more real-world experience than I do who can offer something more substantive.

 

Well, I'll just have to do this mod and let you guys know off of my butt dyno hehe.

 

wow, awesome explanation.

That's the 5th stroke induction thing I was talking about I did not think about / know that it was only in the header though. Thanks!

I'll let everyone know about the test pipe dynos soon

 

Jonnerd, where did you get your test pipe, King Motor Sports? Did you have to do some welding to get it to fit, or did it fit right out of the box?

Thanks!

 

No, I made mine. I cut the proprietary flange off of my stock headers, ordered the rear cat flange, and welded the pipe together with a shielded (TIG) welder.

 

Speaking of which, it would be pretty cool if we could get a group buy of proprietary flanges going from somebody with the capacity to mass-produce a bunch. I'd buy at least two.

 

Are you talking about these?



I think that if KMS doesn't sell the particular part for our cars, I too will have to have my shop custom fabricate this part for me.

 

Those are slightly different than ours - they are for the RSX.