I'm building a rod with a 4.3 v6 motor. It should have about 270-290HP once im done building it. I just bought exhaust flanges and it's going to have 2" primary pipes for the headers. I want to run dual exhaust with an H pipe. What size tubing should I make the exhaust from. 2.25" or 2.5"? Thanks for your help.

Since a 4.3 is a 350 with 2 less cylinders, either size pipe will work fine. The crossover pipe should be 75% of the diameter chosen. Since I built the 4.3 in my truck and added proformance parts, I`m curious what combo your using.
However, 2 inch primary pipes are way too big, they don`t need to be any larger than 1 5/8, 2 inch primary`s will kill bottom end power.

Ditto what DV said.

I've never been crazy about duals on V-6's but there was an S-10 around here last year with a performance single exhaust that sounded really healthy.

so i guess i should reduce the primary tube diameter right out of the flages.

I have a set of s-10 headers in my 2.8L chevette witch is quite alot smaller than a 4.3. But headman used 1-1/2 primary's and a 2.5" collector so I just used 2.5 inch pipe all the way back, Here's a video of it with straight pipes http://videos.streetfire.net/video/...9500156e11b.htm

Here's another one with a 3.2Lstroker. The custom headers on this one are same diameters as the other one but this one has (custom)mufflers opposed straight's.
http://videos.streetfire.net/video/...87f00197eea.htm

Im very aware that 4.3L's sound nothing like 2.8L's being there 90* and 2.8L are 60* with a diffrent firing order.. but there still 6's... I figured it would give u an idea on what it might sound close to, may not be "AS" raspy as the 60*'s but its still there.. Dont use flowmaster 40's either ive heard bad stories about them on V6's

MICK!!!!!!!!!!!!!!!!!



How are you my brother vetter!

i have edelbrock tes headers and y-pipe, into a 3 1/2" exhaust, dynomax round muffler, and a dump. when i go throught the cruise shows, everyone stops and looks. they can't believe its a 4.3.

I'm having some bad ideas .........anyway to get a smallblock into a vette
Shane

Dont meen to get off topic but
There's a way to get a 565 bowtie block into a chevette
http://groups.msn.com/ChevetteCentr...hoto&PhotoID=90
That's my buddys that lives down the street from me 900hp on motor 1500 with juice.. short wheelbase drag cars are scary tho

and a SBC will fit with the only modifacation being to cut the heating duct a bit to fit the HEI and move the radiator to the front of the bracklet, of course you have to run an electric fan, and it wouoldnt be a bad idea to flip it over and weld some SUPPORT under it, otherwise you might get a bit of TWIST , but it can be done without much hassle.

Do you use s10 swap brackets or what?
Shane

you utilize your welding skills

THAT SOUNDS EVEN BETTER what about headers
Shane

block huggers is realy the only thing that would come CLOSE to fitting, and even then you would have to have someone who wanted to fool with it to make the pipes work. it takes alot of doing but these do work , how ever the short wheelbase can make for a "wild" ride, I know that from experience.