2 inch exhaust big enough for a 305 V8 engine ?

Question

I just got a new muffler and tailpipe installed on my 85 Caprice with a 305 engine 4-barrel carb. The pipe looks smaller than the one that was on before. At first I thought everything was fine, but now I think the performance might be a little slower.

Am I imagining things? The end of the tailpipe is 2 inches in outer diameter, and the pipe is kinked down a bit when it goes over the axle. The intermediate pipe going into the muffler looks like it's about 3 inches diameter.

Is the 2 inch pipe standard? If it is smaller than standard, will it affect performance ?

Thanks

"Doc" · Accepted Answer

How big in diameter is the crossover pipe (from manifolds to catalytic)?Doc

MasterBlaster · Answer

"Lecher9000" wroteIt shouldn't. My 302 T-Bird starts as 2" and finishes as 1 7/8".I would think that increasing the velocity of the exhaust gasses (by slightlyreducing the pipe diameter), beyond that caused by the normal expansion, would help "squirt" the exhaust cloud away from the car. And as Martha would say... "That's a good thing".If you're worried, there should be a ricer shop nearby where youcan get a nice chrome 8" diameter tip.  :)

Steve · Answer

2" OD is VERY small for a single-exhaust v8, IMO. Now I'm not a believer in monster 3-inch dual exhausts being needed on anything smaller than a 426 Hemi, but 2" single is a soda straw. It could be hampering performance. 2.5" should be adequate for a smogger 305, but not 2". Remember that cross section goes up in proportion to the radius squared.

Lecher9000 · Answer

Awkward to measure it there, but looks like slightly larger than 2 inches, asin 2 and 1/8 inch OD.

Lecher9000 · Answer

Thanks for the Walker gif.  It shows the tailpipe as being 2  1/4 inch, just asI thought.  Also shows the in and the out on the muffler being 2  1/2 inch.

"Doc" · Answer

Sounds about right to me.  A common mistake people make is to put monsterexhaust on small displacement engines (such as the 305), which reallyhampers off-idle torque.Doc

2 inch exhaust big enough for a 305 V8 engine ?

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