Author Topic: Question for Bored and Stroked  (Read 1359 times)

Offline 83CHEVY

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Question for Bored and Stroked
« on: February 07, 2003, 11:16:00 AM »
Hey B&S, I noticed that you recommended dual 3" exhaust with a 383.  I was going to upgrade to headers and dual exhaust this summer and wanted to ask you if you thought the GM HT383 needed dual 3" or would 2 1/2" give me more torque?  The headers I have picked have 1 5/8" tubes and 3" collectors, so I would have to reduce to 2 1/2"  I picked this motor because of the torque curve and mild cam.  I want a little street performance, but I want to be able to tow most of all.  What do you think???


Offline oscarone

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Re: Question for Bored and Stroked
« Reply #1 on: February 08, 2003, 12:15:00 PM »
Here is my opinion.  The smaller (1-5/8)  are better for a truck.  You want your hp and torque at the lower rpm.  The smaller tube headers increase exhaust gas velocity and help to scavenge the cyl.s at the lower rpms.  If you build an engine to run at high rpm (racing...) than you would want the larger tubes.  Put in a balance pipe when you convert to duel exhaust.  It really helps improve torque.

Offline bored and stroked

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« Reply #2 on: February 10, 2003, 01:55:00 PM »
Funny you ask. My old 383 combo was almost EXACTLY what you have going.
It was a vortec headed, 325hp, 430lbs/ft 383. I had 1 5/8" into 3" collector full length headers with dual 2.5" exuast on it. Pretty dang close huh? :D

Yes I think 3" would be better for better overall tract times. But if this is a daily driver/towing motor then I think Id stay with 2.5"
The only problem I have with this exaust combo is the size is going in the wrong direction from collector to pipe. You want the oriffice the gas is coming out of to go into a bigger area. Same idea as step tube headers. They start small [like 1.5"] and go one step bigger [to 1 5/8"] so I would rather use 2.5" collectors into 3" tubes.

But with the above combo, and one dead cylender [dont ask, the cam lobe was flat for years before I knew and before I bought it] I could yank the earth off its axis. It was an absolute torque monster at low RPM's. I could start from a dead stop at 1000rpm no prob. I think you'll be very pleased with it.