Author Topic: 3" exhaust systems  (Read 2593 times)

william1

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3" exhaust systems
« on: April 01, 2010, 03:03:58 PM »
 i need to update the exhaust on my 69z, i have been looking at the magnaflow 3" SS  systems with the X pipe, but the more i look around the more confused i get, 2".5 or 3", stock look or not, etc, originality is not the main thing for this one, just a nice solid performance good sounding system, any help on this would be appreciated..

JohnZ

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Re: 3" exhaust systems
« Reply #1 on: April 01, 2010, 03:29:58 PM »
A 3" exhaust system (with all its fit and clearance issues) may be great for "bling" on cruise night, but it's a waste of money; exhaust gases cool VERY rapidly before they ever get to the mufflers, and their density and velocity go WAY down in a hurry. A street engine doesn't need a 3" exhaust system.
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hydromo

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Re: 3" exhaust systems
« Reply #2 on: April 03, 2010, 06:13:18 AM »
I have a ZZ427 crate engine headers built by Dan Lemons and a torque tech exhaust system 3 inch works great

77thor

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Re: 3" exhaust systems
« Reply #3 on: April 03, 2010, 06:31:28 PM »
3 inch pipes are only recommended for over 500 HP engines....
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hotrod68

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Re: 3" exhaust systems
« Reply #4 on: April 04, 2010, 04:26:43 AM »
I know if you uncork a 302 with headers you'll pick up 3-4 tenths at the drag strip, and that's significant. It's a balance of cam, compression, and exhaust gas velocity v/s backpressure. I have a 3" system on my car with a 406 and wouldn't dream of choking that engine with 2-1/2" pipes. But with either size pipes, the most important thing is the pipes being mandrel-bent. A 3" system with conventional bends is no better than a mandrel-bent 2-1/2" system from my experience. My 2 cents and good luck!
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LB68SS350

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Re: 3" exhaust systems
« Reply #5 on: April 04, 2010, 06:22:06 AM »
William -     I think a 2 1/2"  mandrel bent system on your Z would be the way to go. That's what I have on my '68 SS with a 355 (.030" over 350). It sounds great and makes really good power. I concur with JohnZ about losing exhaust velocity with a 3" system. That would KILL your torque, not to mention fitment problems. With the system I bought from Torque Tech, mandrel bent, 2 chamber Flowmasters, all 2 1/2", the car made 385 rear wheel horsepower and 448 rear wheel torque on the chassis dyno.     Larry

william1

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Re: 3" exhaust systems
« Reply #6 on: April 23, 2010, 01:35:14 PM »
went with the magnaflow 2 1/2" dual,,,  sounds great, the fit was no problem, and is solid,, will change a few things next time i have it off the floor, but over all, i'm happy with it, thanks for the info.......