1970 318 duster exhaust question???

[RustyRatRod]

Pretty simple, really. We all are familiar with the exhaust size/horse power chart. Use it.

 

[rumblefish360]

2-1/2 is good if you pump up that engine a little or a lot.
Flow master has a chart (or did) that had exhaust pipe sizing for dual and single exhaust systems based on HP level output. Of course this general sizing could go up or down on useage. Down 1 size for street, up 1 size for strip. Just like carbs. LOL

 

[alpha13]

I run 2 1/2 from my headers all the way out the back, and I think it performs very well.

With that said, I originally had 2 1/2 going back to the muffs with turn downs in front of the diff. Since i ran it all the way out the back, the performance difference is very noticeable, for the better..

See when my buddy and I talk about backpressure we know what we are talking about. But when the term backpressure was coined it was just an easy word to use. Now though everyone and their brother uses it and they have no idea what it actually means. So now when someone says backpressure they really are thinking backpressure. Now I'm sure everyone has had different experiences with different pipe size. I'm not about to try to argue about anything. I was just explaining the science behind velocity and volume and pipe diameter. There are different sufficient pipe sizes for different applications is all. I liked using two inch pipe because it's easy to fit and it creates good throttle response. Of course I'm still talking about a stock 318. Like I said before if I had 2.76 gears and and I was driving in town with a two barrel I would definitely be using 2 inch. Like I said I'm not trying to argue and I'm sure everyone has their own experience with different pipe sizes.

 

[91r/t]

Well, 2-1/4 isn't that big of a difference to 2-1/2 to make me have an exhaust shop try and duplicate the amazing quality of TTI 2-1/2. I guess I'll deal with any loss from the step up to get the quality of the system and hangers etc.... Also I am running the stock manifolds so there will be some restriction anyway and "backpressure" from that to make it not so crazy.