The Stovebolt Site Forums The Shop Area General Truck Talk Tell me about dual exhaust

Dear experts,
If I have a 350 engine on my 1946 chevy truck and want true dual exhausts on it do I have to modify the engine. I had the pipes done on my 2001 truck, and they told me they did not reccomend true dual exhausts without engine modification, so reccomended is one manifold pipe connected to two pipes coming out the back for good sound and an increase in power of a small percentage. What say you?

I say find a different muffler shop. What engine modification are they talking about. Dual exhaust is the number one bolt-on power upgrade for a V-8 engine or most any engine. If you put a V-8 in your 46, I think that you'll find it easier to have duals made for it rather than trying to have some fancy bends done to make a single fit nice under your truck.
There's my opinion,
Scott

I agree, find a different muffler shop. Dual exhaust gives the exhaust system more flow which equals more power. One single pipe would create less flow which equals less power.
HSH

Somebody's blowing smoke up your exhaust. You can put duals on any engine, but there are limitations. The problem comes with too much pipe. The engine produces higher torque at low speed with some back-pressure on the exhaust side. If the pipe gets too big, you lose the bottom end torque, which is what gets your truck moving.

My recommendation on dual size is 2" for a stock or mild performance 350. Step up to 2-1/4" over 325 hp, and go up to 2-1/2" above 375 hp. I will admit that these numbers are on the conservative side, but they do take into account the fact that unless you are racing, you rarely have the engine at high enough rpm to need the extra capacity.

Sounds like someone is pulling your leg.Probably trying to sell you a 1 in 2 out muffler setup.You dont need any engine mods to install a dual system.Both of my trucks are equipped with headers and dual sytems,one with Flowmasters,the other with Magnaflows.

On your '01 they may be concerned with the O2 sensors and converters. The engine is designed for the exhaust system so any change to it could cause trouble for the computor. Is very hard for shops to change new equipment with out getting in to legal troubles with the feds. As for your older engine, 2" to 2 1/4" will work just fine. Stepping down to 2" tailpipe will keep the exhaust flowing faster, which will blow the water out faster and keep them from rotting out. The smaller pipe keeps the heat in the exhaust gas, which keeps it flowing faster. Larger more powerfull engines move more air which require more pipe to move it! Joe

My take on what they told you applies to the newer vehicle. The emission control rules in some states are such that muffler shops will not make modifications that will impact those rules and thus will only do mods from the cat converter back.
Their reply does not pertain to your 1946 truck. They will probably be very happy to set you up with a new system. It should consist of a cross over tube or X pipe between the two pipes and then two mufflers followed by rear exit tubes over the axle. I would not recommend side exits as the noise level is louder in the cab.
I have found a shop here that will do the plumbing for $200 while I supply the mufflers. With mufflers included the cost should be between $300 and $400.
The diameter should be either 2 1/4 or 2 1/2. I am going to run 2 1/4 on my 350 set up. Larger than 2 1/2 is not necessary.
If you are looking to increase the power in your 2001 then a computer chip or reprogrammer should be your first step.
Are you in Korea now? If so - stay warm.

ya i would think they were talking about all that emissions junk on my 78 chevy suburban it has the stock 350 no mods what so ever and i got a full brand new aluminized exhaust system from LMC truck (glasspacks included) it went from exhaust manifolds to tailpipes and its all 2 1/4" pipe put bout 12" long 2 1/4" to 3" tip on the end it rumbles real nice going down the interstate at 70 mph (3,000 rpm) its a 4 speed so that helps with raping it out but with the tips on the exhuast does not snap when you down shift
Nate

Go to a muffler shop.They can fix ya up.That 350 has to breath.Someone was pulling you chain.If you have Classic plates and O,I see Korea,I hope in the USA.Im from Pa,USA you don"t need emission after 1972.Let her rip

The trucks in ohio and i will be soon,but oldironchevy was right about the emissions thing because that is what they talked of.

You may be running into the kind of problem I frequently run into with my motorcycle. When you go to the shop the punks kids working there don't know jack about anything made before 1995!!!! Find yourself a shop with some grey beards in it!

boo