Test Pipe?? Worth Buying???

[pkgto66]

I wanted to know if the test pipe would sound ok or be ok to put on my car. I have a 1997 Eclipse Gs with Apexi World Sport 2.5 it sound nice but i wanted to know if the test pipe will make it raspy and if anyone has a test pipe. I Dont want a bad sound? is it illegal to have on in missouri??
[email protected]
Aim-pkgto66
THANX
PATRICK

 

[weith1111]

Test pipes are most definitely not emissions legal. Your exhaust will be noticeably louder, not anymore so than going from a stock exhaust to aftermarket, it will make your car audible from indoors though, if it's not already. I can hear my car from the other side of the house when it's idling in the driveway.

It does add a little power, by removing a HUGE restriction in the exhaust path. Some claim as much as 20 hp. I'd say that's more like 15 virtual hp by the sound increase, and 5 hp of real power.

It shouldn't change the note of the sound, just the volume. The muffler should still make your exhaust sound like it always has.

 

[DiamondStarM]

On a NT car you will want to maintain some backpressure for the low end, if your catback system is mostly a straight through design then you might want to keep the cat besides the fact that it will make it ungodly loud and raspy. Maybe a high flow cat is best of both worlds for you.

 

[weith1111]

On a NT car you will want to maintain some backpressure for the low end, if your catback system is mostly a straight through design then you might want to keep the cat besides the fact that it will make it ungodly loud and raspy. Maybe a high flow cat is best of both worlds for you.

Good call. Didn't see this was in the NT forum. A lot of research has gone into backpressure on NA motors, and everyone tends to agree a restriction like a cat or muffler a few feet from the header(s) is where it needs to be. I'd agree with keeping a cat. Maybe doing a highflow, but cats are so expensive I don't know if the benefit would outweigh the cost. And now I have to take back my comment about the sound, I don't know if it would sound like crap or not. Turbos sound nice

 

[BigRand]

If your taking on the cat on an NT, be sure you have a resinator before your actual muffler, Your stock cat is a huge restriction that should be removed, but if its replaced with a test pipe, you need to make sure there is something else in line. That offers a little bit of restriction to help control the exhuast note that is about to come rumbling out of your engine.

If it were me I would get rid of the cat and replace it with a highflow 2.5" one instead. But always rememeber miami (money is a major issue) and that it might be a lil more costly then you think.

Another thing that you might want to decide, is if your going to end up going turbo or not, because if your not, and you don't have headers already, a test pipe won't net you the benifit that buying a set of headers would. I can't tell from your profile, but I'll have to assume that you don't have them. I would get those first then worry about the testpipe issue after that. Unless your going turbo eventually well then you should be worrying about headers or a testpipe right about now.


I think I'm done confusing ya.

 

[dr1665]

On a NT car you will want to maintain some backpressure for the low end,

Negative. Backpressure is NEVER wanted on ANY car. It's all about gas velocity.

Removing a functioning catalytic convertor on any car is FEDERALLY illegal, so even if you live in a state where there are no emissions requirements/testing, it's not allowed. This doesn't mean you can't get away with it.

You will see minor gains with a test pipe. Not what you would find with a turbo car, as turbos force air through the motor (an air pump by all definitions), but gains none the less.

The exhaust note will become raspy. There is no way around this. Even I, with a 33" long glasspack for a test pipe, get rasp all the time above 3500rpm, whether the engine is warmed up or not.

If you're looking to buy a test pipe, pick up one of those high flow "cats" on eBay. They are not cats at all, but they will bolt right up. Just be ready to do the installation by yourself, as most muffler shops will not do this for you due to the legal rammifications of messing with a good cat.

 

[weith1111]

Negative. Backpressure is NEVER wanted on ANY car. It's all about gas velocity.

I jumped on the bandwagon too quick. Backpressure isn't good. What I was poorly attempting to refer to was creating an effect that increases exhaust velocity, almost a vacuum, by proper size and placement of a muffler, resonator or something else shortly after the motor.

None of my SBC buddies want to talk right now, so I can't get the specifics, but I recall the research showing that, say, a 3" diameter straight flow exhaust with a muffler on the end, flows poorer than the same setup with the muffler placed much further up, up where a cat would be.

This is a reason why side exhaust kits aren't just for show...sometimes. They have short piping from the headers to a muffler or resonator, creating the effect I mentioned, and then any piping after that is pretty much pointless, so they just dump it ASAP, either out the muffler and down to the ground, or to short pipes out the side. I recall the research going so far as to prove it was better than running open headers, but that could have been someone BS'ing.

I'd assume, but could be wrong, that this would all function the same way on a 4 cylinder.

 

[DiamondStarM]

He is already running a 2.5" catback system which is what many turbo dsms are running so if we are talking about exhaust gas velocity then isnt he already overkill with the pipe size? I would imagine a 2.25" pipe would be better for a nt engine of that size. ...Just thinking out loud, mind you I havent been inclined to put exhaust on any of my NT's

 

[weith1111]

He is already running a 2.5" catback system which is what many turbo dsms are running so if we are talking about exhaust gas velocity then isnt he already overkill with the pipe size? I would imagine a 2.25" pipe would be better for a nt engine of that size. ...Just thinking out loud, mind you I havent been inclined to put exhaust on any of my NT's

You are on the right track, as exhaust isn't quite as simple as pipe size unfortunately. Most people think bigger is better, but what they don't know, is, depending on the application, 4" piping may actually perform worse than a 2" pipe, and certainly not flow twice as good. Without knowing his specifics, and really without getting his car on a dyno and trying a 2, 2.25 and 2.5" setup, no one could really say what would be best. And variables like cat, hiflow cat, no cat, and muffler choice only complicate things.

Now, since we are talking about a sub 200hp 4banger, not a $100,000 race car, I'd say do whatever the heck you want cause it ain't gonna make that much of a difference. Do what you like and what's affordable.

Be good to mother earth and keep the cat on. This way you can have a conversation in your car without shouting, too. If my car were driven more than 4000 miles a year I'd consider putting a cat on too, the only reason I'm catless is because the car has developed into more of a project than transportation, and I like it noisy and dirty.

 

[dr1665]

I jumped on the bandwagon too quick. Backpressure isn't good. What I was poorly attempting to refer to was creating an effect that increases exhaust velocity, almost a vacuum, by proper size and placement of a muffler, resonator or something else shortly after the motor.

Rock on. This is accurate.

I think the reason you would want some form of exhaust as opposed to an open header would be better scavenging of the cylinders. With an open header, the pulses would be gone in short order. With a little length of properly-sized piping after the header, there is time for more scavenging - more exhaust in the pipe means more "pull" and therefore, better flow. (? Theory here.)

 

[DiamondStarM]

http://www.dsmtuners.com/forums/showthread.php?t=213461&highlight=nt+backpressure

...isnt this exactly what I said, even recomending a high flow cat?

Having a wide open exhaust with large piping on a NA car works for the touring cars since they are mostly in the upper rpm range. Yes you will have more horsepower when you are in the upper rpm range but you will sacrafice the low end. The original poster is asking if he should remove his cat not if he should have someone research and test the perfect size and length of pipe as well as muffler placement. He isnt getting a perfectly tuned exhaust so it would benefit him to keep some form of cat.

 

[XMasta19]

sorry many of us don't venture out of our safe-haven here in the n/t forum

 

[l6u9k6e9]

Dont do it unless you plan on going turbo!, I have a tsudo n1 exhaust that sounded great untill i put in a hi flow cat,,, then it was rasp city, i was embarrased to rev the car up. The only thing that kept me going was that beautifull 16g collecting dust and waiting for supporting mods. Also i probably did gain power uptop but i could not feel it AT ALL. I COULD however feel the torque that i lost. I damn near had to drop the clutch at about 2k everytime i wanted to get moving. Not worth it, illegal, sounds shitty, need i say more? Put it towards an afx under drive pulley if your not going turbo.

 

[cb3016]

Go with a 2.5" High flow, magna flow makes a 50 state legal one, you will get a deeper more rumble like a mustang sound. Although I have never bought anything just because it sounded cool...Seriously i would but on an exaust that played circus music if it ment good horse power and torque.