Miata Mailing List: May 1997, Message #50
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From: 	hsue <hal109@Mcs.Net>

Subject: Re: exhaust diameters

Date: 	Thu, 1 May 1997 10:00:40 -0500



On Thu, 1 May 1997, Frank Mowry wrote:

> Could someone run down the definate list of cat-back diameters?  As I'll be

> turbo charging in the future, I want to find the largest diameter pipe from

> the cat back.  The exhaust's I'm interested in:

> 

I once measured the inner diameter of the exhaust pipe on my '94.

It was about 1.75 inches I.D. The Jackson catback measured about 

2.0 inches I.D. The outlet flange on the converter had an I.D. of 2.50

inches. I wonder what the manufacturers use as the driving decision

for the exhaust pipe diameter. Is it the extra costs to buy and

bend the bigger pipe, or is there a tradeoff between back-pressure

and low-end torque on non-turbo, non-SC cars? I suppose it's the

bean counters who decide.



Harry Sue

Chicagoland