Wider Exhaust E-350, Thoughts?

[JeffMoss1]

I've got a 1990 E-350 7.3L IDI.

The other day I took a 4" muffler off a Fire Truck and grabbed some extra 3" pipe lying around the yard.

I want to have the two pipes coming off the manifolds merge into a 3" pipe and then open up to the 4" muffler and follow that with 4" pipe to the back. The factory exhaust is 2.5" right now.

This will be a good test of my welding skills.

Anyone have any good info about what this'll do to the performance/efficency? I've heard a lot of opinions but nothing concrete...i've decided to just try it.

Some people say it will screw things up, others say it'll be awesome, i don't know what to believe. I'm going to clock my MPG and i'm also going to floor it and time myself going up a hill, then do it again after i switch it to see what changes...power or efficiency or both.

Lets see if you guys can beat all the BS i've heard from my engineering friends.

~Jeff

 

[Agnem]

Putting a bigger exhaust on is always an improvement. Your EGT's would be the real way to measure any changes.

 

[JeffMoss1]

How do I do that, just put a thermocouple at the end of the tail pipe?

I think EGT is exhaust temperature right?

And what am I looking for to see power or efficency changes?

~Jeff

 

[tuke]

I just installed a dynomax system on my 92 f250, which is pretty much what your describing. Sounds great. Does seem to have a little more get up and go. I'm still waiting to see if there is any improvement in mpg's. I was getting a little over 17 prior to installing. Its tough though every time I come to a stop and take off I want to matt the pedal . heres a few of pics, 1st one is after Y pipe to muffler, 2nd is Y pipe, lastly is Tail pipe

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[JeffMoss1]

Those pictures look really nice. How much did that all cost? Unfortunately mine won't look as shiny seeing as i'm scrounging around the junk yard, but that's the idea.

I'll take some photos of the fire truck system once it's done...if i'm not too embarassed of my welds.

~Jeff

 

[tuke]

Cost $330 got it from rockauto.com