Test Pipe Vs Cat

[ExtremeJDK]

Originally Posted by Jordan

I'm just saying over and over again I've read that the gain with a test pipe is only a couple horsepower at most.

EXACTLY! Or how about even a LOSS of Horsepower over a quality High-Flow Cat?!

TEST PIPES ON STREET CARS ARE FOR WHITE-TRASH REDNECKS!

Seriously, the only advantage to a test-pipe over a quality High-Flow Cat is the cost. Grassroots Motorsports did a test this month with on a Miata with a number of different cats. Here are the dyno plots with #1 being the testpipe.



And look at the Emmission differences, especially the Hydracarbons and Carbon Monoxide. Even if you don't have emmission testing in your area, it's a Federal law and you can be heavily fined. Plus it's a pointless way to get the Tree-Huggin Hippies on the Car-Tuners azz. Don't give them an excuse!

[ExtremeJDK]

And ya know what? I bet even despite MANY MANY tests proving the VERY insignificant gain of a test-pipe over a modern Catalytic Converter ... someone will chime in with no proof or facts claiming that when they put on their Test-Pipe they all of a sudden "Smoked 'dem tires in 4th gear Yo!"

[jarnold]

Originally Posted by Jordan

I'm just saying over and over again I've read that the gain with a test pipe is only a couple horsepower at most. But then again, this may be because I've got a 1gen.

That data is on a 4 cylinder Miata. Not quite the same. Kinda interesting that the CO2 is less at 2500 than some with the cats.

If your 1st gen is a four banger it will not get as much of an increase. Extra Cylinders magnify mods like this. I can tell that with my old 97 Mustang GT Automatic it went from turning the tires maybe 30 ft at a launch to roasting them almost all the way through first gear. Unbelievable difference. Of course thay had 2 and some 3 cats on each bank. One other real world scenario which is almost identical to our cars. I had a Contour SE that I modded up. Chip, Found out that the 96 V6's were de-throttle (only getting a little more than half throttle) with a large wedge on the accelerator pedal, weird but true. I cut it down and it ran strong. Homemade K&N setup Cat back with 3" pipe a 3 "Flowmaster and mid car resinator deleted. I put on a High flow cat later. Could not tell any difference over the stock cat. Then the cat failed. The car would hardly run. I could not get a new one and need the car that day. My muffler shop welded me in a temporary pipe. It was a big increase in power. Way more than my cat back setup I did. I was tempted not to put a cat back on it was so much.(The SE would outrun an SVT after my mods) This is why when I read these claims I wonder if they are slanted so you will go spend 200.00 on one?

The bottom line is that cats are the biggest cork in the works and it jsut makes sense if you get rid of it you gain power. If you want to waist 400.00 + on stainless steel Borlas then go ahead and make it sound nice and gain 2hp. 100.00 with my setup and take the other 300.00 buy headers and a K&N CAI setup.

So back before we had cats we were all rednecks? LOL! For 130.00 less the Test pipe is the best bang for the buck. Extreme lives in Utah so his view of this is going to be biased. He also would probably vote for Al Gores Carbon Foot print hoax to get more tax dollars out of us.

[ExtremeJDK]

Originally Posted by jarnold

. Extreme lives in Utah so his view of this is going to be biased. He also would probably vote for Al Gores Carbon Foot print hoax to get more tax dollars out of us.

Actually I'm from Maryland. I'm in Utah now because I'm finishing my Bachelors in Automotive Technology, and there are very few Universities that offer a 4 year degree in CARS! WE've gone very in depth into emmissions and performance ... and of course a larger engine will see more power. My point is simply, a little 2.5L V6 will NOT see hardly ANY gain! It is NOT worth 1 HP for the harm done.

I love Hot-Rods ... I love raw powered 'redneck rides' ... but I HATE Ricers. And a Probe/MX6 with no CAT sounds about as bad as any Honda. I ran a test-pipe for a while too. Guilty. Glad I'm legal now though.


Someone post me a legitimate dyno-proven gain over a high-flow cat and I'll be satisfied.

[ExtremeJDK]

Originally Posted by jarnold

Kinda interesting that the CO2 is less at 2500 than some with the cats.

Also, CO2 is not considered a pollutant. HC, CO and NOx are. Combine every single source of man-made Co2 in the world and it accounts for less than 4% of the amount made by natural causes. (Volcanoes, Decomposition ..etc)

I realize I might have a pretty strong opinion .. border-line azz-hole ... I just can't stand seeing people remove the best emmission device on their car for no reason.

[jarnold]

OK I see your point. I guess the best comparo would be for me to put mine on and see what the real difference is. Seat O The Pants dyno? It is louder but with the stock mid resinator and the Dynomax with a resinated tip it is pretty smooth and not ricy. With the same setup and a Cat which a friend has on his it sounds really nice. Cuts the Db down allot. All I can say is that it was huge difference on the above mentioned cars I had before on the SOTP Dyno.

[blade_point2005]

If you gut your cat or straight pipe it, you r more than likely to lose power. engines need back pressure. i dont care about what my car does to the atmosphere, but i do care about possible loses in power. its just like disconnecting your EGR valve. ppl seem to think it gives you more power, when it actually does nothing but decrease your fuel mileage. hope that helps

[Tem]

Originally Posted by blade_point2005

If you gut your cat or straight pipe it, you r more than likely to lose power. engines need back pressure. i dont care about what my car does to the atmosphere, but i do care about possible loses in power. its just like disconnecting your EGR valve. ppl seem to think it gives you more power, when it actually does nothing but decrease your fuel mileage. hope that helps

there is still back preasssure with a test pipe

[Turk]

And what about a boosted 2.5L v6?

Most people who say that yer it went heaps harder with a test pipe often are going from a blocked 15 year old OEM cat to a test pipe. I felt that same "omgwtf it flies now" feeling when I went with my mangoflow universal hi flow cat. It felt like alot, because I came from a blocked cat.

Then again though in my case I think my magnoflow cat might be stuffing up from me running to rich, but with a boosted 6 you cant really help it as at 12.1afr's it is still plenty rich. Which is why im considering moving to a test pipe(or gutting the magnoflow) not for the extra power, but just for the fact that it is expensive(well mainly the effort of having to do it) to replace a cat every 3 months if it is going to keep getting stuffed.

[ExtremeJDK]

Originally Posted by Turk

And what about a boosted 2.5L v6?

Boosted? Then a Test-Pipe would be beneficial.
And yes ... running super rich conditions would also hurt your Catalytic Converter. You can still run a more pricey 'Metallic-Core' converter in place of the standard Ceramic core. They are designed for high-performance application that will see high exhaust temps and very rich fuel conditions.

[Turk]

Originally Posted by ExtremeJDK

Boosted? Then a Test-Pipe would be beneficial.
And yes ... running super rich conditions would also hurt your Catalytic Converter. You can still run a more pricey 'Metallic-Core' converter in place of the standard Ceramic core. They are designed for high-performance application that will see high exhaust temps and very rich fuel conditions.

Interesting

We dont get emmision testing here in NSW, but even if we did I would fail anyway with or without a cat. But the reason I would always stay with a cat is because it really does stink like [shizzle], and cops can tell straight away. Like someone mentioned, just because you dont have annual emmisions testing in your state, doesnt mean a cop cant pull you up and take you to the pit's to give the car a thorough look over and fine the [shizzle] out of you. They make cars with Cats for a reason, they would have to comply with NATIONAL regulations that come with federal fines. And everyone knows they sting more then state ones .

They have this tool that detect if a cat is not working correctly. Simple as shining a little laser dot on one side of the cat, then the other. So a hollowed out one will fail quickly.

[blade_point2005]

Originally Posted by Tem

there is still back preasssure with a test pipe

i kno, thats y i said "STRAIGHT pipe", not test pipe

[The_Evil_Demon]

were those oem cats or high flow cats? I'm not familar with the miata exhaust components. Straight pipe Resonator/ Glass Pack along with muffler High flow cat along with muffler

[Ryan]

Josh, I think the KL sounds pretty sexy with a testpipe. Watch from 0:58 to 1:45 for the TP sounds.
'94 MX6 LS at Miller Motorsports Park and an Autoc - Video

Of course, the rest of your exhaust must be well built, otherwise it will sound like crap, just like a previous exhaust I had on a car.

On the power issue, I have no dyno numbers. What my butt tells me is the TP looses torque below ~4500rpm. The throttle/engine response and feel is horrible from 3k-4500rpm. ~4500-6000 it feels pretty close to the stock cat. 6000+ there is a quite noticable increase in power. This I know because when I'm at the track, or even driving the car to the track, I commonly run the car to just shy of fuel cut, not realizing I was that high in the RPM band because I didn't feel the car loose power, where I feel the car start to really loose power just shy of 7k with the cat.

Somebody mentioned backpressure? It's not necessarily about back pressure as it is exhaust velocity. Often with the TP in place, the exhaust is just too large to maintain exhaust velocity at a given engine RPM. Thus as the exhaust makes it's way through the pipe, it looses velocity, stalls out, kills the scavenging effect, and can actually create MORE pressure in the exhaust system, which the engine then has to work to push out. Thus you LOOSE horsepower.

This explains why the engine feels more sluggish in the middle RPM's with the TP. The engine isn't moving enough air fast enough to produce a scavenging effect and keep exhaust velocity up. With the cat in place, it effectively reduces the pipe diameter enough to maintain exhaust velocity, thus I get more midrange torque and response

Ryan

[ExtremeJDK]

Originally Posted by Ryan

Josh, I think the KL sounds pretty sexy with a testpipe. Watch from 0:58 to 1:45 for the TP sounds.

C'Mon Ryan! Would you really drive Carmen around town sounding like that?! That is WAY to loud and annoying for anywhere other than Miller Track! And maybe Wendover!

Originally Posted by Ryan

On the power issue, I have no dyno numbers. What my butt tells me is the TP looses torque below ~4500rpm. The throttle/engine response and feel is horrible from 3k-4500rpm. ~4500-6000 it feels pretty close to the stock cat. 6000+ there is a quite noticable increase in power. This I know because when I'm at the track, or even driving the car to the track, I commonly run the car to just shy of fuel cut, not realizing I was that high in the RPM band because I didn't feel the car loose power, where I feel the car start to really loose power just shy of 7k with the cat.

But again ... you are comparing that to a STOCK OEM Cat! We have already determined and accepted the fact that an OEM Cat is a pretty big plug. What we are doing now is comparing a HIGH-FLOW CAT to a Test Pipe! I have a friend ... who drives an MX6 'just like' the one in that video ... who also lives in Utah ... who also has the name Ryan ... who is a certified Utah Emmissions inspector and should definately know the drawbacks of a Test-Pipe!

This topic has come up about 40 million times already and has been debated to death. It just comes down to ... are you willing to exponentially increase your emmissions for 1 HP and possibly that $2500 Federal fine?