New Pipes

[Mykk]

Hello Everyone,

I just finished wrapping up the new exhaust on my '04 Silverado. Here are a few shots from the job. The plan was to go from single 3" pipe to dual 3" pipe


Old pipes: 2.5" Y-pipe to single 3" & Flowmaster Super 40




I've been really happy with the sound of the Super 40 on anything I've put it on, from 4.3L v6's to BBC's and the single S40 was no different on my 357ci, it sounded good.

So, I will use two Flowmaster Super 40's on the new pipes.











After the Super 40's were welded up, there was an obvious baffle rattle from inside one of the mufflers. That rattle was noticeable with the engine running, but it did sound good.

A pair of Flowmaster Super 44's arrived in the same flowmaster order, and I figured they were worth of a shot.



They sounded awful! Idle was a hollow tin like sound, cruise sounded good, and hard acceleration was way too raspy like glasspacks, so off they went and two new Super 40's were welded back up.



Here's a video of all three exhaust & muffler combos.

YouTube - Chevy SBC: Single Flowmaster Super 40,...

Believe it or not, those little turndowns did have an affect on sound too. Idle sounded less poppy, but hard acceleration sounded more raspy...

Now, the reason for the bigger pipes: I had felt the single 3" was on the restrictive side for my engine. And it all started when I cut off the tailpipe/ extra pipe after muffler that was twisty bendy to run out the side thru the bed.

As soon as we fired up with the dual 3", my narrow band o2 gauge started reading a tad leaner. While driving with the bigger pipes, off the line torque remained the same untill 3000-4000rpm, were it felt I lost some low end, but anything 4000+rpm just opened a new world of power.

The engine now revs up to the 3200rpm stall of the converter faster, and I even had to pull a few degrees of timing out to keep from knocking a bit. that tells me the overlap of the cam & the combustion chamber must be acting more efficiently compared to the smaller pipes.

I am not thinking of adding an H-pipe in the system, if not for any reason than to help the 4000- torque and apparently H-pipes make the system sound even deeper...

Oh yes, BTW. This engine is not quite what you had expected for this era of truck.



.040" over 86-95 roller cam 350 block
Patriot 'Vortec' heads, 2.02'Int / 1.6"Exh valves 185cc Int runners
Vic Jr copy intake
Speed Demon VE 650cfm carb

Comp XR276HR-10 cam & 1.6 roller rockers
.535"Int / .544"Exh
224/230-110


Cheers ~Mykk

[combustion]

real nice work. i liked it better in the end. also watch out for them brakes.