Exhaust Pipe Size
- Thread starter LukeZ
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Engine masters basically dyno proved nothing is too big when it comes to exhaust or headers. Just that increases get smaller and smaller with bigger pipes. Personally if you plan to keep the 305, I'd run dual 2.5" If you plan to go with something bigger later, why not go 3"?
I went 2.5" on my car because I wanted a side exit exhaust and pypes only makes it in 2.5" (a very nice kit, and I am happy with the install, fit, and sound)... just wishing I had gone 3" not and payed the price for a custom exhaust.
I went 2.5" on my car because I wanted a side exit exhaust and pypes only makes it in 2.5" (a very nice kit, and I am happy with the install, fit, and sound)... just wishing I had gone 3" not and payed the price for a custom exhaust.
I bought the Holley / Hooker LS swap exhaust kit. 3" all the way back. Very nice fit and you can install it yourself.
I disagree, if the pipes are larger than they need to be the exhaust cools down too quickly and will slow the exhaust down. A 305 at 185 hp only has a little over 200 CFM so for duels it only needs a 1 5/8" pipe
pontiacgp is right in that too large a pipe will cool the exhaust and eliminate any beneficial scavenging effects you might see. It likely just doesn't matter that much though. I see guys trying to debate whether one size is better or not without using anything but anecdotes. I would say if you plan on upgrading at anytime, you will probably be alright with 2.5" or 3". While the 305 wont utilize the full capacity of either of them and you may lose some lower end torque, you likely wont notice. Most prefer the sound of a V8 with larger exhaust.
Thank you, pontiacgp and drogg. And Pontiacgp, do you have any sources or knowledge bases that you wouldnt mind sharing so I could so some reading, like how you reasoned that the necessary pipe diameter for a given engine size and how much gas its putting out in cfm is 1 5/8 pipe? Or are you just a physics master lol. You seem like you know your stuff brother
And on a side note. What setup im looking at right now, for many reasons such as cost, I am looking at shorty headers to a 3in Y pipe, through a Magnaflow cat, Flowmaster Super 10, and out a single pipe in front of the rear passenger tire (pipe is 3in all the way through. I would like to get the parts from Summit Racing and get a local exhaust shop to do the work and fit the pipes). Does this setup sound alright?
I'm a major psychotic but a master of nothing....there are plenty of links to help you out with the size an engine reguires
http://www.mk5cortinaestate.co.uk/calculator5.php
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