I Pipe power loss?

[Red94Camaro]

Someone told me that if I were to put an I pipe on my 94 3.4 A4, then I would lose pressure and lose hp too. Is this true? If not, how much would it cost?

[Camaro15]

well i've talked to a bunch of people on here and they said that if we would go 3" on our I pipes that we would loose pressure and could cause losses in power but they said that the 2.5" would be ideal which is the size i'm planning on getting.

[Dominic]

3" is a bit on the large side for a 3.4L - try 2.75 or 2.5, it should flow plenty freely for that engine.

[AZ3.8Camaro]

What about a 3.8? I don't understand why back pressure is so important, I have heard that without it, your exhaust cycle can be to easy for the motor and you can mechanically break it. I would think if the air is easy to push out, it would be better. But it you think of it, by the time you add a cat, an I pipe and a muffler with all the bends and everything, you should have some back pressure even if you have 3inch pipes.

[NBMA4V6]

its been said sooooo many times

i dont know about the 3.4 since i dont have one

THE 3.8 WILL NOT LOSE ANY SIGNIFICANT AMOUNT OF TORQUE WITH 3 INCH EXHAUST..THE GAINS WILL FAR OUT WEIGHT THE LOSES..I GOT THE 3 INCH AND I LOST NO, NONE, 0 TORQUE


Jeff W

[Blizzard96]

I plan on going with a 3" exhaust system in the next two months...if I lose some, so be it but I can always make it up...but I know the 3" would sound better.

[navyblue2000]

<blockquote>quote:</font><hr>Originally posted by NBMA4V6:
its been said sooooo many times

i dont know about the 3.4 since i dont have one

THE 3.8 WILL NOT LOSE ANY SIGNIFICANT AMOUNT OF TORQUE WITH 3 INCH EXHAUST..THE GAINS WILL FAR OUT WEIGHT THE LOSES..I GOT THE 3 INCH AND I LOST NO, NONE, 0 TORQUE


Jeff W<hr></blockquote>
boy, you're adamant in your points, aren't ye jeff? [img]tongue.gif[/img]
i have a Z28 i pipe, it's 2.75", so it'd be perfect 3" in fact...i'd might be willing to sell it for the right price, as i'm movin up to 3"

[nikkev]

You will be fine with a 3" on your 3.4.You don't lose torque at all,but it does move up the RPM band sometimes which may make it feel like you lost torque.Good luck.
Kevin
"former 3.4 owner"

[Guardsman]

The only thing I did was put the 2.5" WS6 tail pipes on my muffler. I lost a bit of bottom-end torque from that, but I gained on the middle and top ends. I think that a 3" pipe would be overkill on a 3.4 or a 3.8, 2.75" would really be pushing it. A 2.5" should be more than sufficient, unless you've just got the money to blow playing around with it. One thing that you have to keep in mind is that with your exhaust, it's a a balance of lowering the backpressure, but also keeping the velocity of the exhaust gases up. If you let the exhaust gasses slow down too much, they can actually hurt your power.
I read an article on it once in Super Chevy or one of those other magazines. Basically, it involves not only the exhaust gasses leaving, but the shock waves that they create, and how and when those shock waves travel through the exhaust system, including back up the exhaust. The exhaust has to be tuned for the best performance, and like anything else on the engine, if you throw the tuning out of wack, it affects the whole system.

[Steve Caroccia]

On the technical side of things, a bigger diameter pipe means a velocity loss and pressure drop loss. The power reduction is coming from the velocity loss. You have 6 cylinders working in sequence, the exhaust of one cyclinder draws a vaccuum to help draw the exhaust gas from the next cylinder. When you increase your pipe size, you lose some of the vaccuum.

:burnout

[AZ3.8Camaro]

Thanks steve thats what kind of explanation I was looking for. At least now I understand it. But the best approach is NBMA4V6's. He's tried it, tested it, and it works. Going 3inch!

[EDIT] By the same logic, wouldn't you want smaller intake pipes as well, how about smaller supercharger pipes? Smaller fuel lines? Why doesn't side exhaust work better then? everyone knows when you blow air by the side of a pipe, it creates a vacuum in it. Heres the way I see it. Where flow is involved, bigger is better. Take a small funnel, pour a cup of water in it, time it. Take a bigger funnel, less time huh? The exhaust stroke is designed to push the exhaust gas out, wouldn't that be force enough alone? Its like blowing through a garden hose compared to a dryer hose.

[ April 17, 2002: Message edited by: AZ3.8Camaro ]</p>

[NBMA4V6]

o yeah and as torque goes to prove i lost no torque and actually gained power from the exhaust

before i got the 3 inch i pipe and OA pipe i was cuttin consistant 2.1's and runnin high 14.9's..these numbers were very cery consistant..like 3 trips to the track and same results consistant..

i switched and got the 3 inch and now i cut 2.04's and run 14.8's that is also consistant as ive done this twice..

ive now ordered a high flow cat and parts to make a 3 inch S pipe so we will see how those help..

Jeff W

look at all the people with 3 inch exhaust..no one says man i wish i stil had the 2.25 inch exhaust that torque was great :rolleyes:

[AZ3.8Camaro]

I agree. Notice how with every mod. there's always someone saying "not a good idea" and some crazy science or fuzzy math.

[ItalianStallion1]

My experience is not an argument with someone else. It's a fact and it's my experience.

What I have is a 97 with SLP CAI, RK Sport headers, and 3 inches all the way back. That means from the y pipe there is an adaptor to go to the 3 inch cat and then three inches all the way back as one pipe, well three pipes slip fitted and welded to be exact. I had a flowmaster 80 series. The Flow was broken in, very very loud. I had to have my stereo on most of the time, specially the freeway, because of the resanence. At the start the car was a bit slower. At highway speeds of around 80 plus the car picked up.

Before I put the 3 inch I pipe on the car was very quick. I was able to chirp at the shift to second gear and I have an A4. I remember one time with my friend. It was real late and there was no one out so he asked me to show him what the car can do. We were at a stop sign and I took off across the street. The only thing is the street wasn't directly across. You had to slitly turn if you know what I mean. I had done things like this before and nothing happened. But, this time I almost lost control of the car. The wheels started to slide and I had to get off the gas or it would have been curtins. So I was very happy with the speed but I wasn't happy with the sound. So I went and got the 3 inch I pipe regardless of what people told me.


I switched mufflers and now I have a Borla. The Borla I have is not the adjustable cat back, it's the rear section. It's not broken in and the noise is not quite as loud but it seems to be getting louder after time. I've had it on for about two months. With the Borla the car as regained much of the lost power. It feels about the same as before. I think this setup is a good median through out the torque band.

The point of my story is that your setup of everything you have is going to determine if you have a loss of low end torque or not. Now if you don't plan to get headers then you probably aren't going to have to worry about loosing any low end. But if you are going to open up the whole exhaust then you might want to not get a 3 inch. My second point is that our car's are never going to sound like a V8. They're V6's and they'll always be V6's. That is something that I had to learn. I wasn't happy with the power loss. My car was all grunt and no bite. Now, there's grunt and bite. The Borla sounds awesome once I open it up and it's getting better all the time. It's not quite as loud at idle but it doesn't hurt my ears.

I think you should find out if there's anyone with your exact muffler and your exact setup that you're going for and ask them specifically about their experience and how they feel.