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Discussion Starter #1
Hi All,

I've been racing my bbc powered Malibu for a couple years now with full street exhaust. When I built the exhaust, I tried to make it as efficient for a full system as I could. It consists of:

Dr. Gas X-pipe with 3 1/2" head pipes (same size as the header collectors) feeding into the X and the exit pipes out of the X are 3". The mufflers are super long 20" case Dynomax welded Ultraflow's. I then built full tail pipes over the axle and exit behind the tires. The tail pipes were made from 3" mandrel U bends that are tig welded together. I used larger radius bends to minimize any flow restriction. I also used collector rings in front of and behind the mufflers so any portion of the exhaust could be removed for servicing.

I tested with and without the tails and saw no on track performance difference. The total system weighs 70-75 lbs.

Just for my own curiousity, I ordered some parts to build a "race only" exhaust and still meet the race orgs rule regulations. Basically the rules state mufflers are required and the exit must be 3".

I am going to use two short sections of 3 1/2" pipe feeding into a small 3 1/2" Schoenfeld 8" long circle track/sprint car muffler (yes, 3 1/2" pipe diameter/4" body diameter/8" long). On the exit of the muffler I'll use a transition cone/reducer to drop to the required 3" exit where I'll attach a 3" turn down.

For weight reasons I'd like to keep this real short if possible.

I know open header guys run torque tubes approx 18" long and cut them to the burn mark on paint (old school method I guess). How long after the collector should I shoot to make the new muffler assemblies?

Should I simply make it as short as possible (I'm guessing 16" is the shortest possible with muffler, reducer & turn down), or do I need to shoot for a specific length for power/torque?

thanks for any input
Todd
 

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Discussion Starter #2
BTW, the engine combination is a mild normally aspirated 454 BBC making approx 650 hp. The car runs 10.20's @ 130 mph weighing 3580 lbs w/driver. The car is raced on s 275/60 drag radial DOT tire.
 

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Thanks Jim. I will use collector rings so I can switch between the street & race exhausts.

Anyone else with an opinion or experience with the length off the collector?

Parts are due in tomorrow and plan to get started in the evening.
 
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