making a dual exhaust manifold-

[41/53dodges]

im working on currently designing a dual exhaust, and need to know whether i should connect all 6 cylinders and have 2 pipes running off of them or separate them into 1-3 and 3-6

also, if i started selling these, what would be a good asking price for them?

[Bob_Koch]

If it helps any stovebolt sells their cast iron ones for $340.

http://stoveboltengineco.com/index.php/catalog/store/#ecwid:category=412417&mode=product&product=1396124

[Dave72dt]

If a header style, definitely 1-3and 4-6. If you have something else in mind, seperating them would still give you the best pulse pattern and even tone. X or H pipe shoudn't be needed because of the natural rythym the inline 6 has, unlike the V8.

[41/53dodges]

i already designed a crude one using a program called "inventor" it would be built with plain stainless exhaust tubing, fishmouthed and welded together in sets.

originally, i was thinking i should use some more "aerodynamic" designs, but with this situation, i am thinking it might not really matter. what do you think?

[greg g]

take a look at member moose's website, he has been putting together welded tubing exhaust systems for a couple years, you might want to sent him a PM to talk about his process and designs.

[Dave72dt]

Tube diameter and tube length are important.

[Tony WestOZ]

Tube diameter and tube length are important.

Your not wrong there. Its a black art thats for sure.

When playing with the exhausts on 1 and 2 cylinder motorcycles I was racing 20 odd years ago it was suprising how much difference you can get from changing the diameter or the lenght of the pipe, even by a small amount.

One point with pipe diameter, going bigger is not always better. You can quickly drop bottom end power by going to larger a diameter.

[41/53dodges]

were these 2 or 4 strokes? 2 strokes are much more fickle with the exhaust system.

[Dave72dt]

The point where those pipes would turn blue used to be the length indicator.

[Tony WestOZ]

were these 2 or 4 strokes? 2 strokes are much more fickle with the exhaust system.

4 strokes 20 years ago, 2 strokes 30 years ago.

And your right 2 strokes are much more fickle.

[olddodgeguy]

There is a good explaination of exhaust sizes and length at: http://victorylibrary.com/mopar/header-tech-c.htm

As you will note this is for Mopar V8's but the basic formula can be used for most anything except for 2 stokes which is a whole different ball game. Have fun! Mike

[41/53dodges]

that basically just told me the engine should run 1.25" pipes. i somehow dont think thats right. maybe that size per cylinder...

[Dave72dt]

That would be for each individual cyl., not the actual tailpipe. Finding 1.25 pipe in mandrel bends may be something else again. 2" for the exhaust pipe should be plenty. Getting it too big promotes the tinny sound.

[41/53dodges]

That would be for each individual cyl., not the actual tailpipe. Finding 1.25 pipe in mandrel bends may be something else again. 2" for the exhaust pipe should be plenty. Getting it too big promotes the tinny sound.

2" OD was exactly what i was thinking to begin with. makes the fishmouthing tubes easy with the mills at school.