Since manifolds already suck at scavenging which is why headers are worth so much power on a stock small block chev replacing them with long tube headers should be your first consideration. Otherwise, forget replacing the pipes with anything larger than what bolts to the manifolds, it would be pointless.
You can never flow more than the largest restriction…and manifolds on the SBC are it. Duals are REALLY a dumb idea, since they add cost and complexity both in added components and for working around it for no benefit. Thanks for commenting. Hog head — Not to be catty, but I suggest remedial English. I have a stock 5. My goal is to freshen the engine in a year with better cam, intake, and all new bearings etc. I plan on retaining the TBI system all this to tow a camper.
Any ideas are greatly appreciated. Also, this 5. How fast can it run a quarter? Sounds like a cool project. Is there some mysterious acoustical or pulsing gas flow physics behind this? Stock hp is about , looking to squeeze about crank or about at the wheels. The stock setup has two cans out back but is effectively a single exhaust in the middle.
According to the flow chart, numbers, and max hp per 2. Assuming they are a guideline, are those HP numbers more or less determined as max crank or max wheel hp? I am planning to keep the resonator to keep the rasp from the V6 in check, I want a throatier-deeper sounding exhaust rather than loud-raspy and annoying. The end of this midpipe will merge back from a single to a dual again, where I currently have a unit installed from mandrel-bends. These units are top notch as the cuts are nice and clean, without obstructions that cause turbulence.
The other thing is to leave it all as a single 2. My gut is telling to do a single 2. Help me please, I need to make an educated decision. The difference between 2. If you have to go down to a 2. Since 2. I got a Peugeot GTI 1. I am upgrading the head to a model bigger valves that will put me at hp, on the same size stock pipes.
I also have a French downpipe that I want to install, which is know to make good horsepower on this car, but the rear end of this downpipe is 2. Should I mount 2. Renato — Normally, a 2. However, turbochargers change the rules a bit. Feel free to keep the 2. Hi Jason — Wow, I read through this entire thread. I commend you in being able to keep your cool while answering, technically, the same questions over and over.
A lot of my searching has been on mustang message boards and it appears to be many people simply repeating what they read on the internet, without attempting to apply reasoning, science, or hands on experience.
After visiting 6 exhaust shops in person, I was met with the same ignorance. And right on par with what I would expect, only 1 mustang owner inquired on this great write-up. With that said, I completely trust your advise. First of all, I inherited a v6 4. I just wonder… is it easier for these companies to package the 2.
Basically, if the car is a daily driver and has got a 4. Eli — First, thanks for the kind words. On to your question — if the chart suggests 1. Even Ford Racing offers a system this size, which makes me question their product line a bit. The good news is that these are all cat-back systems, and the most critical portion of the system is from the head to the end of the 2nd catalytic.
As long as that chunk of the system is dimensioned properly, things will mostly stay the same in regular street driving. Ah, you have beautifully confirmed my suspicions. Now I can stop searching the internet trying to find answers. I can also enjoy a nice sigh of relief. Reader note: My comment here is specifically in regards to upgrading a 4.
No racing or towing. Simply put I would gather that: A Choosing between dual 2. Apples to apples. No use going out of your way trying to locate 2. Low end torque loss minimal and still not felt by average driver, thus, not mentioned to you. I look at it like colour shades— Most people would say dark blue is dark blue. But a small margin of professionals interior designers, for instance would be able to pick and point out the different blue hues in a single colour spectrum.
To their clients.. Please, please, correct my response in a follow-up comment if I am wrong. I like what you wrote. I have a 8. I just want a free flowing exhaust thats all. It is not a restriction. Should I just go with a magnaflow or american offroad muffler? What is your take for an Explorer with 3.
It is hp stock with 2. I think about whp or close to at crank is possible which looks like 2. Thinking go 1 size up on a turbo. Still, there are a ton of after-market parts for these engines.
Pretty sure you can find an extra hp. That will make your Explorer a hell of a surprise for some unlucky Mustang or Camaro owner. The problem is in building something that is not too large. I have sourced the smallest merge collector I can find, a 1. Will these three primaries be too much flow and reduce my low end torque? Any advice or comments you have would be most helpful…. Sorry — no idea here. When you get to small displacements, it all hinges on the valve design…can you copy the OE exhaust?
What r your opinions on catback systems? I have an 08 silverado w 5. Only thing done is a live tune and I opened up the airbox so it can breath better.
Some have said theres no noticable difference in performance just good sound….. The closer to the engine you modify the exhaust, the more difference in performance it will make. That is, of course, IF the exhaust is problematic in stock form, and the changes made are beneficial, not negative.
Exhaust is a very complex science. Too much exhaust in terms of CFM the system can flow is as bad as too little, but for different reasons. Any modifications made to intake or exhaust airflow MUST be tuned into the PCM unless the system is using wideband O2 sensors…common narrowband o2 sensors cannot modify fuel delivery under heavy load, which is where airflow modifications are most critical to make sure fueling is right.
But can you noitice a difference in performance? I now realize that this is major overkill for this engine and my style of driving. Muffler has two outlets. Can I remove one side of system after the muffler , weld that muffler outlet shut and use the remaining side? What will this do to my fuel economy? Mike — It could help to weld one side shut.
The concern I have is about the part of the exhaust system before the last cat…is that original? This thread is amazing, Thank you for keeping it alive. I have a civic type R fn2 4 cyl, cc, dohc.. Bigger exhausts sacrifice low-end grunt, but they accomplish maximum throughput at high RPMs. The import tuner market by and large is cluttered with people who have bought into marketing hype, then use that hype to advise others on what is supposed to work best.
With an entire community that thinks there is something wrong with the OEM setups that can be cured with a few hundred dollar bolt on pieces here and there, with no analysis, dyno testing, and actual tuning, it is very easy to sell components that are questionable if not downright preposterous. There ARE good modified import cars out there, done by people that actually understand engines, but the majority of what we see is all about appearance, not function.
Quick question, is the table still accurate when translated to single pipe exhaust? I crunched the numbers and found that the cross-sectional area of the pipe would be roughly the same as two 2. I guess I figured there might be some crazy physics involved that would make a single pipe produce different numbers than half of what a dual pipe makes. Thanks for clearing that up! James — Thanks.
Have fun. I want the formulas for calculating the exhaust pipe of a two wheeler, it should contain formulas of diameter of pipe, back pressure, length, etc… We need this calculation for manufacturing a Go-Kart which has engine of a two wheeler…. I have a 74 dodge truck with a My mech wants to go easy old school and bring two pipes right back with individual muffler. Any thoughts? For anything other than looks or sounds or packaging constraints, which there is not on a truck , duals are pointless today when larger diameter pipe is easy and cheap enough to find.
For true dual exhaust set up, if I ran 1. Based on what I know about the stock 3. Hello, I have a first gen mazda 3 with the 2. Stock hp. I have vibrant headers installed which are a design. With the stock exhaust the headers showed a good increase in power, estimated 10 hp.
Would this replicate the scavenging effect the stock exhaust had? Thank you Jason. My best suggestion is to replace the stock system but keep the after-market muffler. Ian, does that vehicle use wideband O2 s?
If it does not, you may be feeling a lack of fuel lean under throttle if the exhaust helped. How far past the converter did they neck it down? Converter adds more heat to the exhaust, so if the necked down portion is immediately after the converter, it may have been a restriction that results in BETTER scavenging now, and a lean condition.
The piping necks down directly after the catalytic converter about a couple inches from 2. Mine is now 2. Whatever low end torque you lose is more than made up for by better flow at high RPMs, at least as far as time and trap speed are concerned. The testing I can find shows that long tubes make better power at the low end, but sacrifice some at the extreme upper RPM end of the same engine vs. I have a ford cobra 2, this car has been modified to have a 7. It currently has corvette side pipes with no mufflers, could it make more hp if i add mufflers?
Brent — It might, at least at WOT. Whatever size you want. Pick something that looks good, pick your favorite number, whatever. My advice is to install mandrel-bent tubing if at all possible, even if you have to order it online. Just makes so much sense. Where is the logic in this??? Whattya got Jason?
Mike — My first question: Is this exhaust setup developed for a specific head? As the exhaust cools and moves away from the engine, the size of the tube becomes less critical. Mostly, my advice is to find a set of headers that are designed for your specific head. I built an magnum for my 01 Ram. Its pushing between and HP. I want to get duals that go out the sides at the end of my cab. Would a 2. Straight through mufflers as well. Hi, i want to design a good exhaust muffler for my Ktm Duke Here is what I have.
New factory exhaust manifolds, new Walker cat assemblies, dual factory 2 inch exhaust. Currently running a 65mm throttle body, factory MAF. I just installed a gmpp ho and am adding headman headers to my dailey driver driver truck. I am using duel turbos as well. Considering the motor will be kept under rpm should i go with 2. Chad — With turbos, over-sized is better than under-sized. Sounds fun, btw. Please help me with exhaust diameter for my bike.. I have a cc engine with rev limit.
The bike put out N. What diameter size i need to [email protected]? This size work on the supercharged engine too? Thank You for the answear Gabor. Gabor — Sorry. Try the formulas, test, and see what happens. Bike engine design is different. I have a 2. I got the car 3rd hand and replaced both cats with new after market stock cats along with the 2 O2 sensors and a new stock muffler.
Or will I have to get a custom made header. If so how much less in diameter should it be than the precat inlet. My advice is to try and find a complete exhaust system headers and cat-back from one company, then model your system after that one. Hi, read a chunk of this. For all those wanting flow without noise, the walker quietflow mufflers are great. The steel ones are also cheap! It is in a truck and will bruised to pull a boat on occasion. It is mainly a weekend toy though.
The engine is a 71 block with the original pistons and rings still in it. It has a large cam probably too big and closed chamber heads. I have 3 vehicles and 2 of them I have done true dual exhaust and I would like to ask you some questions. This was a put together and I used what I could grab and I was thinking that I need 2. Should I do 2. See the table. But if not, look at the chart in the article.
I know the chart says that dual 2. All that has been done is pacesetter headers that run into dual cats and dual glasspacks which run on the outside of the frame and dump in front of the tires.
The hp and tq before were and and after were and I tend to believe results. I have upgrades that will push the power closer the the mark.
Often times, I see decreases in these lower RPM ranges with over-sized exhaust systems. Headers can often cause this problem too.
This is because exhaust gas velocity is better in smaller exhaust tubing at lower RPMs. Hello, what a great read with alot of helpful info. Test drove the car and its a no brainer for a 7 seater with lots of options thrown in. My only beef with the car is that it feels great off the line but I feel its lacking in the 50mphmph range especially when I want to overtake. Based on your chart, its it recommended that I go with a mandrel bent 2.
Also, from what I read from other sites, some seem to follow the mantra that bigger is always better for turbos as all the effective inertia is used ip by the turbo and getting the the exhaust out asap, allows the turbo to spool up earlier. Thanks for your patience.
Air intake and exhaust kits can also help, but engine tuners tend to have the greatest impact on diesels. Okay I have a question about my 96 bronco. Stock It currently runs a single 3 inch pipe from front to back with a flowmaster 40 series. I bought a 50 series 2 in 2 out 2. Still, a dual 2. The exhaust system is The car is around horses at rpm.
Do you think the exhaust is too small? Can it cause a noticeable lack of power and bad feeling of the engine? Our chart suggests 2. However, the loss of power after RPM may or may not be related to the exhaust system. Is the configuration of the manifold the same as it was when it left the factory, or is it different? Jason; Thanks for your reply. You are very clear and yes… something else looks wrong.
For one moment I thought the exhaust was part of the problem, but your explanation of a restricted exhaust symptoms make the things more clear. The exhaust is OEM for the original engine of the car with hp, but I upgraded the setup of the engine changing the whole intake of the car with 3 weber DCOE carbs. This is the same setup that came in the hot version of my car that delivered horses. The only thing I keeped original is the exhaust. When I made the transformation I thought that my exhaust was good to deal with horses but now….
At this moment, the muffler is a round XR1 borla 2. My expertise on non-US vehicles is quite limited. A slightly smaller size can really help with low-end torque, and they may have designed your system for streetability.
If not, you can work on them to try and get a change made. Thanks for the advice on emulating a well-known manufacturers sizing, that might be a good course of action. I had a flow master super 10 on my Silverado before. I have upgraded to a Silverado z My question is, how do I know what size is running on the stock exhaust as far as the in and out diameter.
I was building a engine exhaust based on my head flow cfm from a duratec 2. On the dyno it made a peaky rpm peak tq to hp at rpm and off cam was just bad. Thanks Jason! It has a 2. The chart says 2. I would consider single exhaust also.
Especially on a carbureted , which is probably not as impacted by all of this anyways. Hi — so your are rating by hp? I have a 3. Im considering adding a larger turbo — but not much bigger, Im hoping for around nm and hp — after exhaust, chipping — if need be a bigger turbo but most likely not.. Maybe they have something for your engine too.
I am converting my single exit exhaust into a dual exit. My sonata currently makes hp. My current single pipe is 2. Would it be ok to keep the pipe size 2. Should I go smaller when it splits? Can I go any bigger? Andrew — Look at the chart. Does your hp engine need a dual exhaust? HINT: the answer is no.
Mufflers are straight through. Reading through your comments again, that is what you suggested on the Nov 15 Comment. The longer length of tubing keeps gases flowing more uniformly, as the exhaust acts sort of like an insulator. Thanks anyway. Hello can u help me I Hav 2jzge vvti cc non turbo engine.. At rpm. Shane — The chart is a good place to start. Napa economy mufflers Have a good sound I wouldn't go any bigger than 2.
Stevie G , Dec 9, Joined: Mar 3, Posts: 14, Profile Page. Smittys are just glasspacks with a sheetmetal outer case that has Smitty stamped in it. I replaced mine with generic 12" glasspacks. The Smittys were too quiet for my taste. Joined: Mar 3, Posts: 9, Profile Page. I've had good luck with the "no-ends" glasspacks available at most muffler shops. Then all you have to do is weld some ends on them or weld them directly to the pipes.
I like to weld ends on and clamp them to the pipes so that you can take em apart later without getting out the cutting torch or Sawzall. If you're just looking for noise, that's one thing, but be aware that if you get a pair of muffs that turn out to have a good tone, about two weeks of steady driving will have it a little louder although it will have the same basic tone.
I like to run as long a glasspack as possible. It ain't the noise, it's the music It all depends on your application, as well as your preference. We also offer specialty manifolds like LS swap cast iron turbo applications and much more! You have a lot of choices when it comes to headers, we have made that quite clear. However, we are not trying to muddy the waters here, but instead help you realize that there are many options including primary tube size, short or long tube header length, coated or painted or bare!
Our exhaust header buyer's guide should be your first stop in configuring your hot rod's new exhaust system. The quick and easy way to choose what diameter pipe you will need from the headers to the mufflers is to go back to the old rule of thumb, that for every horsepower, 1 inch of total pipe diameter is needed across the system.
This, of course, is a rough estimate, and there are several complex mathematical formulas to help you discover the "perfect" size pipe to use for your hot rod project.
There are also several online calculators you can utilize, like this one. Simply input the horsepower figure of your engine, the number of exhaust pipes you are running to the rear of the car, and hit "calculate. Then you can shop our exhaust pipe kits and add the system you want to your cart. You can learn a bit more about exhaust pipe sizing with our exhaust pipe sizing toolbox guide on the subject too. Your choice of mufflers is as much about performance as sound. Engines are air pumps and the more air they can move, the more power they can make.
And, how do you improve the ability of an engine to help air leave the combustion chamber? Well, by adding bigger exhaust pipes. But despite what seems like simple logic, there is a limit to the bigger-is-better mentality.
Factory exhaust systems often create too much back-pressure, resulting in a high amount of exhaust gases in the chamber, which hurts power. But too little back-pressure can actually produce the same result, by slowing down the velocity of the gases. This is why you need to install the right size pipes to help find that sweet spot of flow. Well, two things are important to consider: power output and engine displacement.
Yes, they were big, but they barely produced enough power to get out of their own way! A modern F1 engine displaces only 1. Another thing to remember is that during the rise of emissions, a lot of good engines were choked down to make them more environmentally-friendly.
While this is true, the ability to produce the power to move the air out is still bad enough on the intake end to put a pretty short cap on the list of exhaust sizes. And you would have to work on that to see real gains. This does mean that power is a bigger player in the game than displacement, but both are still relevant.
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