Catback Exhaust - Explained

What is a catback? How does a catback increase performance?
Catback Product Link - amzn.to/1TTRgZe
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Why should you get a catback exhaust kit? This video explains the benefits of a cat back exhausts, using a Yonaka Motorsports sourced cat back exhaust for Acura Integras.
Yonaka Motorsports - www.yonaka.com/
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[@The-Athenian]

Using the metric system in a video watched internationally. You're the real MVP.

[@saratj1]

Id be willing to wager that the overwhelming majority of the audience are more familiar with US customary units (had to look that up) and using a single system would have basically no effect on the channel. The US creates a disproportionate amount of the entertainment that the world watches and Im sure the world has adapted to watching content that caters to an american audience.

[@The-Athenian]

saratj1 If the percentage of countries using the imperial system was similar to the percentage of internet content created by the US, I would agree. I think ideally we should do as Wikipedia, and always try to use both. Even though the official IU is the metric system.

[@patricknintemann924]

it is good he uses the metric system too . i only know the metric system . when he would use another then i would have to calculate how much is that in the metric system . so , using both is easyer for all .

[@SayWhaaaaaaaaaaaaaaaaaaaaaaat]

MUCH more people uses metric, so... Also metric is better for videos and in measurment anyways no need decimals in many cases so integers are easier to remember

[@GoodmanDontLai]

For engineers, using the metric system is more often than not, an imperative.

[@matthewd6306]

Dogback exhaust usally performs better.

[@UCGhy34YYL0R3LirWIvhvxng]

+Matthew D But catback produces a more pleasant sound - your car will purr like a cat.

[@darinhumble4656]

+B0NEZ and arch up into the air

[@supernova4300]

Haha yea cats suck

[@supernova4300]

+Michael F yea coz ur mom taught her well.

[@galaxymode]

Catback exhaust for catalytic converters, Dogback exhaust for dogalytic converters.

[@thetek1742]

I feel like an online student watching your vids, good job man

[@scott185]

He's not saying it will increase the power to 225 hp. He was simply saying the bigger exhaust will allow enough airflow for an engine producing approximately 225 hp. So if you were to tune it then this exhaust will help airflow up to 225 hp.

[@flow5718]

That's a load of bull mate. How is changing just the catback part going to reduce bottleneck and increase airflow when you're still using the stock exhaust headers and catalytic converter and the pipe in between those two? Honestly, I think all a catback exhaust does (on its own without other exhaust manifold mods) is 'improve' the sound, and that's subjective.

[@daexion]

@@flow5718 Even with stock headers it's possible for the diameter of the catback piping to be a bottleneck and cause back pressure. If you don't have stock headers, then the next bottle neck would be the catback pipes. You are right on the sound of the exhaust itself being subjective, and increasing the potential amount of flow won't necessarily help if the engine is still stock as the video mentions.

[@flow5718]

@@daexion I don't have any links right now, but search for as many catback only mods with real dyno tests and you will see in most cases putting catback decreases the hp slightly. stock engines need a certain amount of backpressure.

[@stayfrostie2583]

@@flow5718 Do you even tune bro?

[@carsonho9338]

flow cat back is much longer travel than the header, it will help for sure when in high rev

[@Pwnsweet]

Forgot to take off his helmet when making the video...

[@luddakris5397]

LOLS...

[@ernestocayetano9495]

Lmfao dude made my night

[@wesleyrichardson2953]

lol

[@602katana]

hehehe

[@PavelIsp]

It adds +200HP

[@shmollyshmoo9133]

You taught me so much when I was in high school about 10 years back. I just now stumbled across your page again, the nostalgia. Thank you guy, you are one of my heroes who helped me (a female) get into cars when I had nobody to talk to about them. ❤

[@BanjoMasterPete]

One detail that was not mentioned was the possibility for better MPG. I personally did a larger cat-back exhaust on a similar car (2000 Ford Escort ZX2) and without any big modifications I had gained around 2 or 3 MPG. Then, once I had the muffler replaced with an even better flowing one, I had gained another 2 MPG. This was noted directly after only doing that replacement, as I keep track of my MPG at most fill-ups.

[@OrcaBoat3]

I have no modifications on my 3.7 5-cylinder engine. I installed a MBRP cat-back exhaust on the truck and I noticed a significant improvement in throttle response and acceleration.

[@georgereginald6084]

Wow this guy grew up on KZbin

[@takadekadaka2493]

Great video! Just my two cents (coming from what I learned as an HVAC engineer and applying it to cars): I think you should have mentioned the fact that there are a lot of reasons why even if the exhaust system past the catalytic converter is the ONLY limiting factor in your setup, there are a lot of factors that go into why you still don't get a power increase that is one to one with the proportional increase in the pipe's interior cross sectional area - you could get higher or lower depending on your set-up. I realize that you presented a simple concept to show that the flow rate would increase as a result of the increased diameter, but in doing so you held a lot of the other variables equal that play a big role in the system. But I think if you had talked about turbulent versus laminar flow (using the Reynold's number) and mass flow rate, it would have explained a lot more. Namely: - Laminar or turbulent flow through the pipe (High Reynolds number>4000 = turbulent,

[@jacobgold8857]

This guy gets sooo technical I love it

[@EngineeringExplained]

It makes for good conversation in interviews. That's initially why I started this.

[@flickerblip9044]

There is a lot more to performance exhaust systems (if done correctly) than just back pressure. A properly designed system will create a negative pressure wave in the headers to increase fuel scavenging on the intake stroke. while this is largely accomplished through proper header design, the rest of the system is key to proper header performance, including the amount of back pressure present. I know you know this, but it is not mentioned in the video at all. simply adding a cat back can actually result in less performance, unless the rest of the system is designed properly. Kevin Cameron has a great breakdown of exaust system engineering in The Sportbike Performance Handbook. Love your videos, BTW.

[@flickerblip9044]

forgot to add, the intake system design is also integral to the system. it is just an airpump in the end.

[@lliaolsen728]

+Brian Donegan I came to the realization that headers do most of the scavenging. You can get some benefit from the rest of the exhaust as well but the biggest and strongest "suction wave" or in your terms, "negative pressure wave" occurs when there is a large change in the diameter of the pipe. The length of the header determines when this wave will travel back, but not it's strength. This makes the collector or any large change in volume critical in providing a point at which there is a large change in volume from the primaries 4-1 or secondaries 4-2-1. The exhaust just efficiently removes the exhaust and really should be focused on flow. I have yet to have a car that could fit a muffler right after the collector to prove that the change in volume on a 4-2-1 right after the header would be beneficial because most 4 cylinder cars don't have space for a muffler there without ripping up the floor, or removing the engine and running it on a stand.

[@lliaolsen728]

+Llia Olsen If your info was taken from Motorcycles that have a much shorter exhaust run. You could really considered a muffler after the header as your first big change in volume.

[@nostylecaleb3106]

Brian Donegan what do you think about a magnaflow catback going on a mk4 2.0 vw golf? Its stock engine until i can get the money to work on it more.

[@peterk.2772]

Too Stancy I had a 2000 2.0 Golf 2 door. I had a Vibrant cat back exhaust and a KN washable panel filter put on the car. The midrange performance felt a little better. The change in performance was slight not dramatic. The exhaust tone was lower and louder. My advise is if you enjoy listening to the stereo while you drive don’t change the exhaust.

[@LucasJonasch98]

so many interesting videos, you're keeping me from my homework.

[@EngineeringExplained]

At least you're still learning. :)

[@Spartan0917]

Did you graduate

[@rupert6478]

Did you graduate

[@beebo979]

dude thank you... as an automotively oblivious person, this is the most I've ever understood out of any car tutorial video, your explanations are amazing and you're very concise, once again thank you

[@A_SEGA_Dremcast]

I have that very exhaust and I love it. My Integra's exhaust was aging and full of holes. The Yonaka catback was inexpensive compared to replacing the OEM piping. The car sounds as the speaker describes. It's relatively quiet when you drive normally, but does get deep and loud when you increases the RPMs. It cleans up nice and I've not had any issues with it. Is there a performance benefit? Maybe, but I haven't noticed a difference.

[@EngineeringExplained]

Well honestly all the bushings are probably shot, but what needs it the most is the rear trailing arm, and the tool for the fix is fairly expensive. Awesome that you've got the catback!

[@TheCryptoMiner]

The measurement you got was from 2 different spots in the system. You have to pull off stock one and measure it from the flange.

[@rickc1898]

I absolutely love these videos. Its great to be able to invest a quick 5 minutes or so in exchange for some solid, useful general mechanical knowledge. This guy is gonna make a great teacher one day

[@NoAffiliation]

These "explained" videos are very very helpful! Thank you for taking the time to make these!

[@mitsaras68]

"simple math" (points to something in Chinese)

[@davidvalle3068]

it is simple

[@jeezy4764]

Quick maths

[@ollie2244]

Pi Also pie, I love pie.

[@sampelonable]

I love this channel. This channel is going to change my life

[@EngineeringExplained]

Glad to hear it, thanks for watching!

[@T1000.Android]

Look at thr Mop on that head 😅

[@ErickMartinSucre]

Thanks for teaching regular guys like me about car stuff.

[@CC2755]

This man is extremely smart. It's a pleasure to watch these videos.

[@EngineeringExplained]

Indeed, I do need to install it some time!

[@NovahTheHero]

This guy had no idea that this video would get 2.2m views. Guarantee he had no clue. Good stuff bro

[@xorkatoss]

or you could just say: 1.Catalytic Converter = clears the gas so it's not harmful to enviroment (remove it you don't need it) 2. Resonator = keeps the flames from going out (remove it so your car can go boom boom) 3. Muffler = reduces the sound of your car (remove it for loudness) so yeah pretty much remove everything and use a straight pipe for eargasm :D

[@malcolmcarey6519]

This would be a bad setup for a daily driver tho, right? Your girl won't be impressed when you're driving down the highway and your car is too loud to have a conversation, keep the resonator & muffler. Also take care of the planet dammit, keep the cat

[@GhostOfAMachine]

I only removed the cat. Kept the resonator and muffler because drone noise on highway is fatiguing

[@Forde3654Eire]

I've got a few automotive engineering books I've borrowed from my university library for leisure reading... its great to see all the theoretical stuff I'm reading up in your videos :)

[@daniel.s.stefanov]

JESUS CHRIST, what happened to the comments in here? xD

[@crunchysoup406]

ikr lol

[@amangodara1772]

Since so many years your videos are just Timeless and phenomenal.

[@HondaGoPshh]

I have a 2001 Toyota 4Runner, i wanted a B'A performance throaty sound...I was curious and instead of buying an expensive exhaust system, i just took mine off past the 2 catalytic converters! Sounds amazing and my engine loves it!

[@joanwong5519]

your videos really explained the topic really well, because of you i'm getting more interested in cars and engineering, well done!

[@thatanimationboy]

How are you doing 5 years later?

[@EngineeringExplained]

Backpressure is simply referring to the pressure losses caused by a large quantity of air trying to squeeze through relatively small pipes. The larger the pipe, the less restriction it has, but simultaneously the lower the exhaust velocity. Optimum is a balance of the two.

[@LMF5000]

Fellow mechanical engineer here. I'd like to understand your reasoning behind your recommendation: Given that horsepower is proportional to exhaust mass flow rate, then by following your suggestion to tune engine until bhp/area ratio is the same as the stock system, this means that you are basically targeting to keep exhaust flow velocity the same as the stock system (mdot = rho*v*A => increasing mdot in proportion to A yields constant v) Is there a reason that you think this is the optimum operating point? Is it because you assume the rest of the exhaust system is tuned to work best at this particular flow velocity?

[@Titilomelirifa]

By what I heard he said you start to see a difference around that hp range.

[@aiyoo4517]

People fear ur comments that is why you have not been answered

[@WaffleShortage]

probably just relying on the assumption that the exhaust flow interaction with everything else was engineered well by the original engineering team at whichever car manufacturer. it's a good rule of thumb for the layman, but obviously some crazy custom shops and engineers who want to bore out cylinders and do all kinds of their own crazy tuning and dyno analysis might stray from this guidance. i think this is meant more for like, the average 'car enthusiast' who just wants to slap some parts on and not actually have to have a staff of like 5 guys working to redesign and rebuild his engine and do days or weeks of diagnostics and troubleshooting and such. is it absolutely a scientific and great rule? maybe not... but it's probably good enough for the consumer.

[@teresabarbu4991]

A mathematical explanation, very nice. Often people want exact numbers but don't take into consideration the MULTIPLE variables. Knowing where the exhausts limitations are by diameter will be very helpful thank you.

[@patusher77]

So if i had say 2250 hp, would I find significant gains from a 22.6" catback exhaust?

[@EngineeringExplained]

No, it's certainly not a linear relationship, and I've oversimplified it, but with 2250 hp you would certainly be restricted with a 2" exhaust.

[@JavTheRipper]

Straight pipes!

[@clipsedrag13]

pat I'm so happy you made this comment... I signed in and everything just to comment on how this was explained in the video. I'm not trying to criticize the poster because I'm sure he understands engine power and back pressure better than he explained in the video. What I'm trying to figure out is if he meant at around 260hp you start to notice the best gains from a 2.5" exhaust? For the most part 2.5-3" exhausts will take you up past a thousand whp before you just run straight headers on a 4 cyl.

[@abtwopoint0]

over a million subscribers? killing the game!

[@freakasis]

I am sorry that you had to add the "listen closely" thing to the video. People...

[@mullipolli]

7 years has done you well my friend :)

[@kingcrimson234]

You can't just say "oh it's 60% larger so it's good for 60% more horsepower". There is more airflow potential, but that's not really as important as you're making it out to be. If an engine needs to push more air out, it will just increase the flow rate through the pipe. Up to a certain point, this doesn't cause an issue. I upgraded a Mach 1 Mustang from 300 HP to 520 HP, I have 3" diameter exhaust piping. Going larger isn't going to help me much if at all. The original diameter was 2.5" and I increased the horsepower by about 73%. The speed of the air flowing through the exhaust just increases a bit. You won't really see any gains on a dyno by switching to say, 4" exhaust piping. In fact, you will probably lose some low end torque. Most of your videos are really good, but frankly there's some misinformation in this one.

[@nickdseidel]

I disagree with you, while your right that putting an exhaust system that is much too large will cause losses in low end torque, the extra back pressure caused by more exhaust gasses will have a negative effect as well. So if you ate going to significantly increase your horse power and keep your stock exhaust, you will deffinately not reach the full potential.

[@kingcrimson234]

Nick Seidel I was mainly talking about pipe size though, a stock exhaust system usually has very restrictive cats and mufflers. I was more referring to having high-flow cats and mufflers already and then changing the pipe size. It doesn't matter much unless you are doing some truly insane power upgrades. I should have been specific about that. In the video, he was suggesting that a 60% larger diameter pipe is good/ideal for 60% more horsepower when you really need nowhere close to that.

[@nickdseidel]

+kingcrimson234 Okay I deffinately see your point now, and you're right, if you're going to install high flow cats and mufflers you really don't need bigger pipe diameter.

[@kingcrimson234]

65PontiacTempest That's 100% true. Every build has its own sweet spot for pipe diameter. I went the forced induction route personally. (Procharger) A little bit bigger exhaust may make more power, but I'm pretty happy at my power level. Alright, I lied. I'd like some more but I'm nervous about my factory rods and pistons holding up if I increase the boost!

[@captaindeadpool1640]

+kingcrimson234 yea I agree and I think interpretation between us about this is the same I was thinking dam I can go from 140 hp to 225 hp with just a 60mm bigger exhaust ,

[@shakotanstyle7409]

You made this so much more simple than any forums I read on.

[@EngineeringExplained]

Yep, traded in the Integra for it. They ended up having to pay me, resale on Integras is killer...

[@EngineeringExplained]

I am indeed! Working on getting a garage so I can have some space for install videos - no promises on when I'm getting these done though haha.

[@25gwolfable]

it would be nice if you could at least six played everybody that by getting extra horsepower by putting a free-flowing exhaust you lose torque if you lose torque you lose fuel economy if you don't care about fuel economy that go ahead and free fluid will make the exhaust sound the way you want it but if you're worried about the fuel economy and you need the torque it's good ideal to give them an option all the pros and cons between free flow and standard exhaust thank you

[@dbow4life666]

This is the only video I’ve seen that correct and well explained.

[@EngineeringExplained]

Thanks for watching!

[@akdaus]

how about straight pipe?

[@misterawesome1234]

literally, a straight pipe.

[@skaargan]

Reasure i was hoping some explanation on the benefits and drawbacks of the system,

[@misterawesome1234]

U can google it, not hard to find some pages with decent information. From the top of my head, the lack of a muffler increases performance ever so slightly by increasing flow. Also makes look douche-y with the obnoxiously loud. Just don't do it please

[@NextSelection671]

mat arif leen My Nissan 240SX has a straight pipe exhaust. Header to Muffler was 1 pipe, almost no air restriction. Benefits? 1) Noticeable power gains Drawbacks? 1) Less engine response. 2) EXTREMELY LOUD! It's a track car so I don't care.

[@chadw8481]

it depends on what your putting the straight pipe on. even the diameter of the pipe would change what a straight pipe would do.

[@seekter-kafa]

i remember in the old days when petrol was full of lead and sulphur i had to change at least 3 complete ex. pipes during a car's lifespan, it would just crumble into dust all of a sudden... now i have 18 years old car with cat. converter and the pipe is still as good as new

[@Rhythmeister]

So why DO you guys across the pond call the exhaust manifold the header? What is the intake manifold known as, stateside?

[@EngineeringExplained]

+Liam O'Flaherty why do you call the trunk the boot, the hood the bonnet, etc etc. Different vernacular, just how the world works. We call it the intake manifold as well.

[@Rhythmeister]

Engineering Explained I'm wondering why one manifold is still called a manifold and one a header, it baffles me! Keep up the good work btw :)

[@Birdskyhigh]

Engineering Explained I have a question about the ford ecoboost motor. I just got a 2013 f150 with the ecoboost and the dealership says that straight piping it will cause the tubos to overspool because the backpressure isnt there anymore. Is this true? Do I need backpressure in a turbo motor?

[@markfrye9602]

Nathaniel Hylton yes u need some form of back pressure otherwise your turbo is running a lot harder then it needs

[@bodyrepairuk8783]

Long story short exhaust manifolds are cast iron, fairly heavy, have smaller tubes and they're not all equal in length, Headers are aftermarket which use individual steel tubes for each cylinder, are all equal in length and have wider tubes, both have advantages and disadvantages depending on whether you're after performance or longevity

[@EngineeringExplained]

They have fairly large pipes for each cylinder, and these are individual pipes for each cylinder. They're also much shorter than in a car, thus have much less losses.

[@JonCaveman]

Nice hat

[@tylerrobert9925]

I own a 2013 and honestly the axel back exhaust maybe only added 5 hp, but I love the rumble of the boxer so it's worth it, hopefully adding a downpipe soon

[@W1llDaBeest]

Why do you do area and not volume?

[@EngineeringExplained]

Area restricts mass flow (volume).

[@W1llDaBeest]

Okay. Thanks.

[@ultimate1576]

+keepthinkingPC Each car is different. Some cars have really restrictive factory exhausts while others have highly tuned, highly optimized exhausts. If your car has a restrictive exhaust, you will likely see gains with a cat-back alone. If your car has a very well tuned exhaust, you'll likely see better gains with upgrading intake/bolt-ons first.

[@devolutionrc8016]

cat back without resonator on my 94 320i shaved 1 second of the 0-100 kph time, I also removed the baffling from the air box.

[@devolutionrc8016]

ammendment it wasn't a cat back but high flow cat and cat back.

[@19anilam]

Dude, it's great that you try to be nice and respond to comments, but people are so ignorant that most of the time there's no point in doing it. I'm just waiting for a comment about how a bigger exhaust creates drag, or adds weight... Btw, love the channel, learned a lot! Cheers mate!

[@CreatorOfSwag]

wait, lower the sound? who would want that?

[@scottbrixey6284]

It's not really "lowering" the sound, just changing it. People want a low rumble from their exhaust. It's just changing the sound, which may sound like lowering, but it's really not...

[@djnekkon]

lower fre0/tone. thats what you want "deep"

[@OBARRVAGOS]

I'd rather have more flow than loud

[@Sanchara]

I LOVE how technical these videos are. I'm learning so much!

[@p3l1k44n1]

So kids, you're supposed to get a bigger exhaust AFTER you put your engine mods in. Bigger exhaust will decrease the power of your stock engine.

[@benjay2985]

+Jsp P5 Taunus unless it's a turbo Car Then the best is really No Exhaust and just about 3-4 inches coming out of Turbo Exhaust./..

[@willdog3]

Idk if that's true, I've heard you want some backpressure with most engines (idk about turbo though). But that could be wrong. I'd like to see a comparison video of a car with and without exhaust after the turbo to see what happens.

[@JobeMinacum]

Lol what?

[@dragonslayer1483]

how is that possible? isnt backpressure a myth?

[@willdog3]

Back pressure is not a myth. The argument is whether you need some or not. And Engine Masters tested different exhaust vs no exhaust and found that even 3 inch straight pipes are better than open headers. Now, you can definitely tune an engine to account for zero back pressure, but for most applications you will want exhaust anyways, and more back pressure can also reduce emissions and increase efficiency.

[@bambamyong]

Wow going back 8 years and watching this video. This is so wild

[@articledon4880]

Is he wearing a wig?

[@boostedkidproductions9719]

I thought the same thing😂😂

[@boostedkidproductions9719]

Nicolas A lmao

[@vinbinjil]

keep in mind that this is in 2013 haha

[@J.higashi]

My car has gotten a noticeable difference in gas mileage (for the better), as well as performance. It was an expensive process (sort of) but completely worth it. Btw I did a Hi-flow cat back resonator delete on an Audi. Not a fun job but sooo nice when you hear/feel the car for the first time (and every time from then on).

[@totszwai]

lol that's a catback for integra. know that shape by heart. XD

[@car_ventures]

yep you are spot on... resonator = tuned for reducing specific frequencies i.e if 500hz is very prominent at speed limit, then the resonator will work to tackle that frequency. The muffler applies a blanket reduction of db's across the whole frequency spectrum

[@jamesbarker6373]

This is old technology EVs are the future :) You guys will be like the steam engine people nowadays, yawn.

[@BigDette]

A Resonator is designed to "cancel out" highway speed tones to make your drive quieter while cruising. Doing this also remove some of the raspy noise found in high end revs. A muffler is designed to quite down the entire exhaust range, from idle to wide open throttle. Both can be removed and still pass emissions but if your town has a noise ordinance then you might want to keep them on.

[@kylemilford5968]

You should have mentioned, The best way to gain MPG, would be increasing engine power and efficiency, Which usually go hand in hand up to a certain point.. If you take a car with 100 hp, and 35 mpg that requires 35% throttle position to maintain 70 mph, turn that car around into 225 HP, you could expect anywhere from 25-35 mpg, and probably 25% throttle position to maintain 70 mph as long as your power range starts near your cruise speed... Which in that example you could actually be cruising using 34-35 mpg, where the first scenario would be cruising at 70 at about 30 mpg... Performance usually increases cruise MPG, which decreasing WOT MPG

[@EngineeringExplained]

Correct, as I mentioned in the video it depends mostly on the most restrictive point. It's a process which requires multiple steps to do it right.

[@EngineeringExplained]

Yes, I measured to make sure before making the video, but did fail to mention this.

[@EngineeringExplained]

It could be, perhaps. I'd look into some forums and see if you can find some dyno sheets, or from exhaust manufacturers. See if they have some data to back up any claims they may make.

[@EngineeringExplained]

I do, eventually. I will have videos for each install, and hopefully test videos outlining any benefits/changes.

[@Monkey_G5]

Thanks a lot for your videos, you are saving me so much money in learning what car mods actually do and how to use them.

[@EngineeringExplained]

Great question, and of course it depends on the current exhaust's restriction, and where the restriction lies. But if everything else is up to speed, for an engine like mine it may be good for about 10 hp, or maybe more if it was turbod.

[@GERntleMAN]

Many people would be surprised if they knew that many cars with +500HP only have exhausts with about 65mm diameter. And they perform quite well. There is so much more to this topic than just increasing the diameter and done.

[@EngineeringExplained]

Depending what you're going for, I'd say engine mods first. Depends on the make though, and so far I haven't done any dyno testing to see if there is a performance increase just on the stock engine.

[@M20AFKS]

try it please

[@toywolf89]

Definitely subscribing I've learned more I. The past 8 mins watching two vids then I have spending a week with my friends who are into card thank you sincerely

[@EngineeringExplained]

Haha, thanks for subscribing.

[@kzoomin]

tuned allmotor B20vtec with 421 header, catback exhaust ---> Toda header, complete 3inch mandrel bent piping, 3inch resonator & muffler. +19 whp, same wtq. dyno tested.

[@EngineeringExplained]

Yes, that was one of the points I was going to discuss, however since this is much larger, it appears that it would weigh more. The Yonaka was about 29 lbs I believe, I haven't weighed the stock one.

[@EngineeringExplained]

Mechanical, and you are correct. I've learned the vast majority on my own time.

[@EngineeringExplained]

For the most part, yes. Removing it may remove (very slightly) whatever restriction it may have caused.

[@mcintda]

But measuring the pipe isn't enough, unless we know everything else is upsized to scale.

[@cpittsau]

The internal diameter of the pipe itself can be a bit of a phurfy. All the pressure issues are introduced inside the muffler can itself. Use the vernier calipers to measure the internal pipe diameter of the OEM centre pipe rather than the OEM muffler tip (looks to be where you measured). Here's some examples of what you'll find inside typical mufflers that are designed to knock out sound pressure waves and resonant frequencies, significantly slowing gas flow rates and introducing significant turbulance. From my Subaru Legacy GT-B: corptech.no-ip.org/doodads/htdocs/cars/MY07Lib_mod_gutmuffler.asp and From prior Subaru WRX's: corptech.no-ip.org/doodads/htdocs/cars/MY05WRX_mod_gutmuffler.asp Btw, good series so far, make sure you keep up with the grounded analysis and physics based reviews. Try not to get sucked into the commercial colouring that will come with "free" parts and services.

[@Tain950]

I love this guys videos he makes things so easy to understand

[@user-xb7iz5pt7z]

Correct me if I’m wrong. What I know is changing the cat back exhaust, DOES NOT increase MAX horse power. It just allows your engine to perform differently form the stock ones. If your engine is 200 HP, you are not gonna get 250 HP just by replacing the exhaust. What it does is to let your engine reach the peak at different RPMS depending on the exhaust.

[@EngineeringExplained]

It would go under the assumption that the amount of exhaust created is relative to the amount of power created. Creating more power means more air and fuel burned. If you burn 60% more fuel, (at the same efficiency as stock) and have an increase of 60% power, your exhaust will have a 60% greater load. The relationship is unlikely to be perfectly linear, but I'd say it's a fair assumption. I hope to eventually have test videos illustrating the value better.

[@EngineeringExplained]

Everyone's at a different level, I'm just trying to help people learn. Some questions may sound a bit ridiculous (and some are) but if I were to be on a "boats - explained" channel I'd probably say plenty of things which would sound dumb to someone well informed on the basics. I do try and remove the trolls though haha

[@nezerac]

You always do pretty dern good vids man. I'm never disappointed. The issue is I get so distracted by your uploads that before I know it I've gone completely down the rabbit hole. lol. Good job. Very simple explanation that helped me understand the topic THAT much better and answered some questions I've had but never asked. Thanks!

[@mithellpath1071]

The most helpful part for me was the division to find the difference in the area of the diameter

[@EngineeringExplained]

Correct, it's oversimplified as the pressure losses though the pipe are not linear with diameter, nor speed.

[@EngineeringExplained]

Proper engineering, proper materials. It's that simple. Creation of vehicles through modeling, rather than iterations. The US is getting better, but you're correct, Honda/Toyota are pretty bulletproof companies.

[@meerkhan4404]

u can also have a stright pipe weld on with a muffler an u can wrap it to protect against rust that well also help 2an a half well do fine or 3 inch

[@Totally_B]

You should do a video on vibro-acoustic tuning of an exhaust (tuning the reflective and incident waves). This is where exhaust design gets interesting!

[@JustAnotherPersonHere]

Very interesting equation to determine the best mated hp for a specific inlet measurement. Thanks man, this is good stuff!

[@EngineeringExplained]

It's definitely oversimplified, but probably a decent starting point.

[@EngineeringExplained]

Yep, 140 at the fllywheel. I have a video on engine vs wheel for anyone unsure of the difference.

[@EngineeringExplained]

Not sure about the tones. Yes about the cat, though it's illegal in most states except for track use.

[@louisjamesreeves]

Thanks man your allways right there when i need the technical explanation@!

[@EngineeringExplained]

You can buy them on Yonaka's website, or from a dealer, or many online sources. They're not too pricey either.

[@123frederikt]

On a two cycle a proper exhaust system can increase the power output by around 50-60% since scavenging is more important on a two cycle. Either way I must have misheard, I guess I just got confused by the 225hp you wrote down on your whiteboard. Great video, great explanation in layman's terms!

[@EngineeringExplained]

I would certainly agree, if their reason is for increased performance. If they simply want a different look/sound, I'll allow them to make their own subjective decision on whether or not it's better. Like I said, I do hope to eventually get some tests on this.

[@stevedacey3587]

Larger exhaust systems have 2 basic drawbacks in terms of power with a stock motor, both involving exhaust gas flow velocity. A cat-back system that's significantly larger than the outlet diameter of the cat will only serve to slow the speed of the exhaust gases as they expand to fill the larger pipe. It's an example of Bernouli's principle, which also explains why water comes out of a hose faster when your thumb reduces the diameter of the opening. Also, the pulses of the slower after-cat exhaust aren't likely to be tuned to the pulses at the cat's outlet, causing power-robbing harmonics and further slowing overall exhaust gas velocity at the tailpipe. Even putting on large diameter headers can easily reduce power by reducing velocity which is needed to "scavenge" the last exhaust gases from the combustion chamber just after the piston passes TDC. Turbos, of course, change the equation in some ways.

[@Haloruler64]

You can definitely see improvements replacing exhaust on some cars. I know the performance Toyota 4A-GE 20V Blacktop came with an exhaust manifold that had a few bends that were incredibly restrictive, where just replacing the manifold showed great gains. So in cars with poor exhausts, it can show a bit of a difference. Not much though, because the engine isn't putting out much power anyway.

[@Blo0dredRidingHo0d]

For an na engine the black top 4age 20v is pretty good!

[@Haloruler64]

Blo0dredRidingHo0d Agreed, I love it. Wish I had one!

[@GreenJr6]

I've replace the Resonator and the Muffler on my 07 Civic for High Performance ones. I can feel a difference. I kept the stock Midpipe.

[@EngineeringExplained]

It vibrates that much huh? ;)

[@GreenJr6]

It Feels fine, I like it. Can any Horsepower gain happen with Just the Resonator and Muffler replaced? To me a little bit.

[@EngineeringExplained]

If the stock ones are restrictive, yes. Likely at higher RPMs.

[@GreenJr6]

Okay right I thought so.

[@tolikechicken]

In case he doesn't get to it, here is a simple explanation! Resonators basically resonate with the sound waves in order to quite them. It doesn't work at all frequencies of the exhaust though. Pretty much a tube in a tube separated by some sort of packing. A muffler gives the gases multiple "rooms" to expand to slow them down, lowering the noise. I only have a resonator on my bike and a "baffle" that is basically the exhaust tubing with holes. Can't tell much of a difference vs straight pipes.