Why dual exhuast vs. single?

[docflower]

I have a stock 72 c20 with a 350. The stock exhaust needs to be replaced to due to age and wear. I was thinking to put dual exhaust on to let it breath better, but my mechanic says not to do it. The truck is a daily driver 108K orig miles on it. Ramhorn exhaust manifold and quadrajet carb.

What are peoples thoughts (aside from cost) regarding putting dual exhaust on my truck? Aside from a bit of HP increase (which I dont really need) what changes would be seen? I have read from other threads there is also a consideration of having too little back pressure, would that be a problem?

Cheers!

[68gmsee]

Cool factor? I also like the sound of duals vs. single exhaust.

If you are trying to squeeze every ounce of h.p. it might help but in my case, a daily driver, I didn't notice any change and my mpg stayed the same.

[Wrenchbender Ret]

Dual exhaust is the best single thing you can do for a v-8 engine. It breaths easier giving more power, better gas mileage & cooler running exhaust manifolds & ex. valves.

[special-K]

For me it's religion and it's been every V8 I've owned. I no longer can explain for I have lost sight with the origin of my ways.

I'd like to answer that with two questions. One...what was the reason you mechanic gave you not to do it? Opinions are like trucks. Everyone has one. The second question is why V8? Why put 1/2 the engine's cylinders on one side and 1/2 on the other? I use a simple formula,one pipe for each cylinder bank. Why take one from one side to squeeze into the same pipe as the other side? The manufacturer did it to maximize profit. Why do all hot rods have dual exhaust? Ok,I'm asking way more that two now. Anyone who said dual exhaust doesn't give enough back pressure is too cheap to buy two pipes and using that as an excuse,because it's surely not true about back pressure.

[406 Q-ship]

Originally Posted by docflower

I have a stock 72 c20 with a 350. The stock exhaust needs to be replaced to due to age and wear. I was thinking to put dual exhaust on to let it breath better, but my mechanic says not to do it. The truck is a daily driver 108K orig miles on it. Ramhorn exhaust manifold and quadrajet carb.

What are peoples thoughts (aside from cost) regarding putting dual exhaust on my truck? Aside from a bit of HP increase (which I dont really need) what changes would be seen? I have read from other threads there is also a consideration of having too little back pressure, would that be a problem?

Cheers!

Why does your mechanic think that single is better? Cause there is plenty of evidence to say he is wrong. Put a clean 2 1/4 dual system with an H-pipe and a quality set of mufflers, you will not regret it.

[docflower]

Originally Posted by 406 Q-ship

Why does your mechanic think that single is better? Cause there is plenty of evidence to say he is wrong. Put a clean 2 1/4 dual system with an H-pipe and a quality set of mufflers, you will not regret it.

My mechanic is like 70 or something and is firm in his beliefs (so i take everything he says with a grain of salt). He says its a waste of money for a daily driver. If it was a hot rod maybe then it would make more sense. He said the mfr made them with one pipe for the best performance of the stock motor. I can see his point, but I also know mfrs do like to cut costs as well.

What type of system would you recommend? Seems like the dual exhausts Ive seen are Xtype.

[406 Q-ship]

X-pipe is slightly better (bigger gain a high performance engines) but an H-pipe will work very well on a stocker. I used a Heartbeat system on my 1974 truck and it fit pretty well (did have to do a bit of changing) with a pair of Hemi Turbos from Walker. Nice and quiet but no h-pipe (got lazy). Find out what a muffler shop will charge to make up a dual system fofr your truck.

That old man is clueless, what would he say about the daul exhaust option that all the V8 cars and trucks could have. Kind of kills his facts all to heck.

[docflower]

Originally Posted by Wrenchbender Ret

Dual exhaust is the best single thing you can do for a v-8 engine. It breaths easier giving more power, better gas mileage & cooler running exhaust manifolds & ex. valves.

This seems logical. I want to keep the ramhorn exhaust, and dual seems to be the popular choice... for obvious reasons.

What about exhaust location? In front of wheel, behind wheel, straight out the back... Pros/Cons to locations?

So no arguments for keeping the single exhaust then???

[406 Q-ship]

Go over the axle and at least behind the rear wheels, after a long drive your ears will thank you.

[Wrenchbender Ret]

I believe in the Ram-Horns. Definitly exit behind the axle. I like the cool factor under the rear bumper, except panels or Burbs. Then behind the rear wheel. I dont see much advantage to X or H myself but I'm older then your mechanic so a lot of these guys know more about that.

[special-K]

Originally Posted by docflower

He says its a waste of money for a daily driver. If it was a hot rod maybe then it would make more sense.

Put duals on it and it'll be a hot rod...DOH!!

[bollybib]

If you ever need to remove the oil pan (like I just did the other day) you won't have to mess with removing the crossover pipe. I like duals. I can't imagine a V8 without.

[robzilla]

i changed out my single exhaust out to a dual setup, without x or h pipe. had the exhaust come straight out back. couldn't come out the side due to the trailing arms.



haven't noticed improvement in mpg, and the sound isn't much louder than the rusted out single muffler

[Ackattack]

When my 69 got shipped to me, the shipping company ripped the old exhaust off. I got a quote from an exhaust shop for duals w/ 40 series flowmasters for a total of $800 or so!!!

I ended up getting this kit:http://www.summitracing.com/parts/HOK-16621HKR/


I put some cherry bomb turbo mufflers on it. I got lazy and dumped them before the axle, but the sound is not real loud.The total cost was less than $300 and I didn't have to hassle with taking it somewhere.

[70STOVEBOLT]

The only argument I would have is if you were going with headers. With a lot of miles like that on the engine, it could make the engine start burning oil if you were to install headers.
I have experienced this at least twice with a high mileage engine. With manifolds I have never seen it. Anyone have an idea as to why this would be?

[Fitz]

Originally Posted by docflower

My mechanic is like 70 or something and is firm in his beliefs (so i take everything he says with a grain of salt). He says its a waste of money for a daily driver. If it was a hot rod maybe then it would make more sense. He said the mfr made them with one pipe for the best performance of the stock motor. I can see his point, but I also know mfrs do like to cut costs as well.

What type of system would you recommend? Seems like the dual exhausts Ive seen are Xtype.

Well, Doc your mechanic is right. Duals on your setup will add maybe 8 hp, cost twice what a single system would and if you think you can tell the difference the extra power gives I have a bridge in Brooklyn to sell you.

Now, all that said, I run headers, dual exhausts with an "X" pipe and it sounds great! so, it's a choice; style vs practicality, but the performance difference will not be noticeable with a stock motor.

[57larry]

run duals. they sound better, 2 pipes coming out the rear looks better and duals are better for your engine. run center dump manifolds 2 1/2 inch type. the keep the heat away from the starter unlike headers

[SCOTI]

Originally Posted by Fitz

Well, Doc your mechanic is right. Duals on your setup will add maybe 8 hp, cost twice what a single system would and if you think you can tell the difference the extra power gives I have a bridge in Brooklyn to sell you.Now, all that said, I run headers, dual exhausts with an "X" pipe and it sounds great! so, it's a choice; style vs practicality, but the performance difference will not be noticeable with a stock motor.

Exactly. I bet your mechanic is not 'clueless' as some would suggest; I'd say he's practical. Manufacturers did single exhaust because it was 'good enough' to get the job done w/o spending anything more than necessary to maximize their profit margin to continue manfacturing.

That being said, on a stock set-up there won't be much improvement & it probably isn't cost effective upgrading to duals. The slight improvements w/a properly sized system (whether its a new larger/better routed single or true duals) is better seat of the pants performance (feels stronger/more responsive) and/or efficiency (mpg's).

Like others stated.... dual tail-pipes do look better to most enthusiasts.

[Beelzeburb]

My exhaust guy suggested running a single 3" system on my Suburban, but I requested a dual 2.5" system instead. It was simply what I wanted. It wasn't until I got home that I did the maths.

Dual 2.5” exhaust = 9.8 in2
Single 3” exhaust = 7.1 in2

I also later learned that the 1988 pickup my engine came from actually had 2.5" dual exhaust from the factory.

[68gmsee]

Originally Posted by 70STOVEBOLT

The only argument I would have is if you were going with headers. With a lot of miles like that on the engine, it could make the engine start burning oil if you were to install headers.
I have experienced this at least twice with a high mileage engine. With manifolds I have never seen it. Anyone have an idea as to why this would be?

Scavenging comes to mind. Could be the suction created in tuned headers. But just guessing here since I'm not a physicist.

[slomotion]

I like duals, I like the sound, and it gets burned (no pun intended) into every hot rodders heart that duals are the way to go. I've had duals and headers on most of my hot rods and trucks, but like someone said earlier, they cost roughly twice as much as a single set up, and the performance difference on a DD may or may not justify the expense. I don't think Detroit's main reason for a single pipe was all profit margin. They've got some pretty savvy engineers on the payrole. What I was told a long time ago was Detroit was actually looking out for us. A single pipe is slower to rot out from acids and moisture because they tend to run hotter and all the bad stuff gets burned out, or dried out. Another reason is the exhaust pulse from one cylinder helps pull the next pulse through causing a scavenging effect. It's all above my understanding, but even serious header builders use this principle when they design a header by making the tubes a certain length so that the exhaust impulses don't collide at the collector.
There, you have it...JMHO

[PanelDeland]

I like the way duals sound run out the back.I also like quiet but throaty mufflers.The best advice is to listen to a few rides with duals.Find one you like and ask about it.If you plan on engine upgrades then that is the first step.If you don't it still sounds cool.I've almost always had duals until I started driving V6 and inlines and have even decided to convert to duals on a v6 when I need new ehuast.

[special-K]

Personally,I think an 8hp increase makes it worthwhile. It's definitely noticeable and I have no need for a bridge . The way I look at it,dual exhaust is the first thing I do...get what gases are made out a little better and gain a little power,as well as give a sound that makes me like to drive the vehicle. Then,anything else I might do for power in the future will be of more benefit with better flow of gases. It's all about flow and you need to open up the outlet before you open up the inlet.
As far as noise level goes,dual vs single has nothing to do with it. That's all about the muffler(s).
What do pretty wheels & paint jobs or chrome air cleaners & valve covers do for performance? We do what we do because we love our trucks. We buy little Japanese econo-boxes because it's practical.

[Andy4639]

I drive my truck everyday just about. In fact just got back home. I have duals in it but as stated a single will work just as good if sized properly. Cool factor is duals though.
A street engine you may tell a differance in the way it runs but over all it's a street truck D/D. Most want MPG out of them not performance on a D/D.
I know I do. My truck isn't a race truck it's a D/D so MPG is more important to me than 8hp is.

That being said I like my system but a single would be fine.
In the end it's yor truck build it the way you want it. Oh, almost forgot I like the rams over headers.