Is it worth a 3" pipe?

[borispeed]

I asked to the muffler shop guy if a 3" pipe that comes from the catalyc makes a difference. He said YES in V8's not in V6's. What I didn't ask is if it makes a difference having moods like cool air induction, air lid, and K&N filter (in the future I am planning to raise power with a low temp thermostat and program the computer with a power tuner). If you have a V-6 with a 3" pipe, what has been your experience?

[98Camaro3.8]

Definitely worth it. I would never go smaller than 3".

[shortdog273]

A 3" pipe didn't hurt my 1/4 times when I had my sixer.

[WickEdSix9838]

I ran quicker with my 3" exhaust than I did with my 2.5" exhaust with a cutout.

[mjparme]

You hear people say 3" is too big for our V6's all the time. But those people don't really know. The only way to really put to rest if 3" is too big is for someone to take their car, put a 2.5" system on it and then measure backpressure AND exhaust gas velocity through the RPM range, and then do the same thing with a 3" exhaust system. Then compare the results.

The guy that told you that has undoubtly never done this so he has no business telling you that 3" is too big.

An optimal exhaust system has near zero backpressure with high gas velocity (I have heard 300 ft/sec as the optimal velocity, but can't confirm/deny that number).

A bigger pipe causes gas velocity to slow down which may hurt gas velocity at low rpm's due to a relatively low amount of gases. Once you go up in RPM's gas volume increases rapidly and so gas velocity increases.

Does a 3" pipe give you lower gas velocity than a 2.5" pipe throughout the RPM range on our cars? And, does a 2.5" pipe give you near zero backpressure? No one knows. Until someone measures it no one will really have a definitive answer.

Just remember: Near zero back pressure with high gas velocity.

I would venture to say that a 3" system defintely gives you lower backpressure than 2.5", but the big question that no one has answered yet with real world measurments is, does the 3" system cause the gas velocity to drop below optimal levels throughout the RPM range.

Oh yeah, I have the 3" Rumbler and I ran faster at the track, although I also got gears and an LSD so it is hard to say what was caused by the exhaust and what was caused by the gears and LSD.

[ April 07, 2005, 05:15 PM: Message edited by: mjparme ]

[HAZ-Matt]

If the mods you list for the future are the only ones you will be doing, and if you consider identical catalytic converters and mufflers, 2.5" would probably be better for your application.

[borispeed]

Everyone of you have made more mods that the ones I have made, so problably your cars runs better for that. So it looks like the 3" pipe may gives a very little o no difference if I put it. Thanks all of you for your comments. Does anyone has more comments?

[99v6cam]

I've said this about 1 million times so I guess it won't hurt to say it again. With just a lid and loudmouth I ran 4 tenths faster than my stock time and I had a slower 60 foot time. 3" is teh awesome. I'm glad I get to enjoy it for a few more weeks before my parents make me get rid of it.

[mjparme]

Originally posted by borispeed:
Everyone of you have made more mods that the ones I have made, so problably your cars runs better for that. So it looks like the 3" pipe may gives a very little o no difference if I put it. Thanks all of you for your comments. Does anyone has more comments?

The amount of mods you have really shouldn't be the deciding factor. In a N/A motor the amount of exhaust gases coming out is determined by displacement and RPM's. The 3" pipe will probably be of benefit to you.

[98Silver6]

just go 3" no question about it

[HAZ-Matt]

Originally posted by mjparme:
The amount of mods you have really shouldn't be the deciding factor. In a N/A motor the amount of exhaust gases coming out is determined by displacement and RPM's. The 3" pipe will probably be of benefit to you.

And VE, which is determined by mods.

[grayman]

Full 3" system = good times.

Full 3" system is easier to install than trying to find a 3 x 2.5 (high flow) cat and a 2.5 (Mandrel Bent) S pipe to hook up to whatever 2.5 catback you get.

Full 3" system for about $400 plus some change and that includes a high flow 3x3 cat, mandrel bent S pipe, all the other sections as well as nice tail pipes, clamps, etc. Install it yourself in one day.

You (might...might I say...) notice just a hint of lag off the line (daily driving) with a Full 3" system. once you are past 1500 to 2000 rpms, though, you will feel an improvement in power/performance.

I had the HP3 power programmer prmium fuel power tune running before the supercharger. I did tests with the new 3" exhaust. Both improved performance, but the gain from the premium fuel power tune was greater with the 3" exhaust than without it.

A 2.5 V6 catback system (where you do not change the cat nor the s pipe) is the most affordable and
does give a little gain as well as a better sounding car. But you still have a bottle neck with the 2.25" cat and 2.25 inch S pipe.

Hope this helps. Good luck.