for a stock 85 GT,

what are the stock pipe diameters travelling fom the cat out?
and is it convention to refer to ID or OD?

ie:

cat outlet diameter:
diameter of pipe to muffler:
muffler inlet pipe diameter:
what's the length of the stock muffler?:
muffler outlet pipe diameter:
exhaust pipe diametere to tips:

i thought it was 2", someone told me it's different 1.75"?

thanks for your help all!

Nick.

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1985 RED GT 2.8 V6, 99.5k KM!

'WHO REALLY NEEDS REARVIEW MIRRORS?,
JUST KEEP YOUR EYE ON WHAT YOU'RE GONNA PASS NEXT!!!'

It's 2" OD. I put the calipers on mine not too long ago. I have it off the car and in the garage.

Your local parts store or the Fiero store will confirm it.

quote Originally posted by OHNIKO: ie: cat outlet diameter: diameter of pipe to muffler: muffler inlet pipe diameter: what's the length of the stock muffler?: muffler outlet pipe diameter: exhaust pipe diametere to tips: i thought it was 2", someone told me it's different 1.75"?

Everything on your list is 2".

I don't know the length of the stock muffler.

To answer your other question, when talking about tubing (and we are when talking about exhaust) the dimension refers to OD. When talking about pipe the dimension refers to ID.

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Doug Chase
Chase Race
Custom roll cage and exhaust fabrication

quote Originally posted by Doug Chase: Everything on your list is 2". I don't know the length of the stock muffler. To answer your other question, when talking about tubing (and we are when talking about exhaust) the dimension refers to OD. When talking about pipe the dimension refers to ID.

It actually depends on what kind of pipe you're referring to. Plumbing pipe sizes don't correspond to any particular dimension on the pipe itself. Different schedules of pipe have different wall thicknesses in order to handle different pressure requirements. Since plumbing fittings depend on the OD of the pipe in order to go together, stronger pipes with thicker walls have reduced inside diameters but the same outside diameters. Most all structural pipe, or tubing, is called out as the outside diameter and wall thickness. Differing applications have different tolerance holds, that affects which diameter, inside or outside, is the important one for making that pipe or tube. That's why hydraulic cylinder tubes are held on the inside and usually called out as ID and wall thickness.

FWIW,

JazzMan

All stock V6 exhaust is 1 7/8" inside diameter

That is correct, but the tubing and fittings for exhaust work are sold based on the outside diameter, that way wall thickness is not relevant, at least as far as fitment goes.

JazzMan

excellent all, thank you!