So engineers really do know what they're doing after all...

any time you can make your engine breathe easier, whether its inhaling or exhaling, its good for engine power.

I'm looking forward to the Integra project videos so much. Keep up the great work!

Think of an exhaust system as a multiplier. (Example, not actual stats) Exhaust = 2% Exhaust + Intake = 5% Exhaust + Intake + Tune = 10% An exhaust alone will do nearly nothing by itself, same for an intake, but both of them together multiply each others performance. Every engine will have different results along with different stock parts to work with depending on model. If you want to greatly increase horsepower, your best bet is to research the best Exhaust + Intake + Tune combo for your engine. Currently im looking for a combo that will bring a 300hp 05'-09' Mustang GT to around

I'd like to see this after installing a header

Man, I really love your videos, but I wish you would also make a "long story short" version of all of them.

I love what you are doing man. Keep it up. I would love to see readings like this for lightweight Crankshaft pulley or Lightweight flywheel. There is so much talk about these things on the forums we really do not know what to believe.

Great job on consistent test procedures. I would encourage you to upgrade/ replace posi, clutch/pressure plate, and CV joints. One of the first things to go is going to be the clutch, posi ( if it has one), or CV joints... Only a slight upgrade on these parts ( stage 1 or 2 ) will make a vast improvement and make the car more consistent when testing parts and make ready for more power in the future.

Perfect example of how "easy performance" mods don't work no matter how much companies will tout "10 hp gain or whatever"(unless the system being modified is super restrictive, or they tested on a best case sinerio a.k.a modded vehicle). It's all down to how effective the engine is at moving air, because an engine is really a fancy air pump. I expect to see the same result when you get around to a CAI. Assuming no cams or FI are done before hand. Definitely going to use this methodology when I get a catback and a SC under-drive pulley for my Mini, to see what the difference is between all the combinations. Good video, can't wait to see more!

a couple of days ago i was sitting on the toilet and something came in my mind about weight reduction. there is one factor you never talked about and i don't remember anyone mentioning it: tyre pressure. less weight equals less stress on the tyres, they don't deform that much and thus create less rolling resistance, which affects acceleration. okay, anyhow, i admit that calculating the tyre pressure versus deforming is nearly impossible, but i'd say that a little less air in the tyres (around 0.05 - 0.1 bar) could have done the job, and meant one less factor to worry about. (anyway, lower and higher tyre pressure and their effects on acceleration might be another subject of testing...)

This is awesome, I basically have the same exact car(same color even) and I really like how meticulous you are and how well you explain what you're doing and explaining the results of your testing. I am also in the process of modifying my car(slowly but surely) and I had the same exact exhaust system on my list to purchase next and I really like how it turned out on your car. The sound it puts off is exactly what I was looking for and now I know exactly how it will help/hurt the car. Oh yea and now I know what problems I can expect when installing it as well. Maybe install a simple short ram or even cold air intake to help let that new exhaust show its potential and test the acceleration again and I'm sure you will see more significant gains from stock. Good work man.

I installed a cat back because I wanted my truck to be louder. Any HP gain is welcome.

@Engineering Explained I dont know if someone else mentioned that before but it is an importand note. The percentage of power increase is not the right one. As you modify the engine more by the time to get a better horsepower output than the stock 140hp,a part of the power gain will be exhaust gain,as the exhaust's inner diameter will be more relevant and suitable for the engine's power output. Correct me if Im wrong,we are here to learn! :)

I LOVE your acceleration tests :D.. well all tests in general... well all videos about your Integra. more please. I will finish all the rest of them by the end of the day...

Excellent. Showing you dont need fancy dynos to baseline and track improvements.

If it's not too much to ask is it possible to make a video to see how much acceleration is affected due to octane rating or different brands of gasoline. For example shell versus mobile 1 or Costco versus Sam's Club. -thanks Noro

These testing videos are awesome. Keep up the great work.

Pick up some 4:2:1 headers and some cams next. then get yourself a stand alone ECU and get some ITB's. after you get to where you have a good gain and drive it for a while, rebuild the motor with a higher compression ratio. You'll have to run a higher octane gas and you'll have to tune the ECU to do so but if you're making it a race car anyway it shouldn't be an issue. After that, depending on your application you can run a dry shot of NO2 into the throttle bodies and have one seriously fast car!

This is a performance exhaust on a vtec engine, surely it makes more sense to test a range that is relevant to the performance - ie when the thing is actually on cam, as this is what the exhaust should be designed to do....

This is a fast reasoning, so it can well be a wrong one. Its possible that one could measure the acceleration difference while applying multiple gears in one run, and at the same time, discarding the inconstant time of manual gear changes. We find the nº of frames that it takes to go from aKPH to bKPH in 1st gear. Then, in 2nd gear, we find the nº of frames that it takes to go from (bKPH - 5) to cKPH. Then in 3rd, from (cKPH - 5) to dKPH. In 4th, from (dKPH - 5) to eKPH. (The '5' is just there to produce a 'grey area' in between gears, so that there arent any discrepancies, thus a higher value could be used) We add the nº of frames in all gears (while ignoring the nº of frames in the "grey" 5 KPH of every gear) and we can calculate the acceleration time. This would be a test where all gear changes are seamless, therefore the acceleration time would be non-representative. But i think it could give us a representative % difference from one exhaust pipe to the other. Im not 100% though.

I like the methodical approach you are taking with this.

I suggest to get a baseline run at your local track, then do your upgrades and test it again to see if any time difference ;)

depends, if the factory one is restrictive and depends how big the factory log manifold is yes +5hp maybe factory vs aftermarket. 20 year old factory vs aftermarket up to +20hp depends how blocked old mufflers and cat are. u need extractors

On low RPM there will not be enough exhaust moving trough the pipes to give a significant airflow resistance. Testing 5k to 7k in 3rd gear would be easier and more relevant. When you add a turbo, testing low revs will be relevant.

no they don't, stickers do

It would be awesome if we could see the difference in a 1/4 mile test.

Would adding a catback to a car with CVT potentially be more effective or less effective than adding one with other transmissions? The cvt's RPM's tend to stay higher longer so does that mean the exhaust would be working better for a longer period of time?

you should do an ECU remap for your next video! will be interesting to see what hp gains you could get from your now better flow exhaust system and a remap!

If you can next do a comparison to straight pipe vs cat back. Now it can be straight pipe with cat, without cat, also with resonator and without. because there is a lot of aruments that going straight pipe will make you lose power. Even though you are making it eaiser for your engine to breath

The most restrictive area is in the header design on the B18. So it's expected that a catback won't shine unless you get a header matched up to it.

from the definition of "catback", even without doing cat delete, you can still have performance gains by having bigger exhaust pipe . Another advantage would be it will sound better 👍

Do an update on your sti!

So works better at higher rpms..... cant wait to put cat back on my 99 vtec prelude!! BWAAAAHHHHHH

I have installed the cutback on my toyota corolla GLI 2015 with 2000 cc and after some tests I found that the acceleration increased but fuel consumption also increased. This happens when I run the car in gear 2 thanks for your video

From various videos I've seen regarding exhausts and air intake systems, it seems like just adding a more free flowing panel filter and just replacing the stock muffler with a better flowing one will have the same effect has the latter while saving a ton of money. If a vehicle already has say 2.25 inch piping or better depending on the power it makes, then one would assume that it is designed for that diameter of piping and just making the flow better will give you a couple horse power while giving you a nicer sound and maybe a couple mpgs of you drive moderately. Would you consider this accurate?

Exhaust is going to bring more noise and MPG over anything. It is fun to lay into tye throttle and hear the tone...I just installed a Jpipe, test pipe (3rd cat delete), catback-magnaflow mufflers. I noticed A LOT more throttle responce and I couldnt stop smiling 😄.

Great experiment! Always worth watching your tests! Congrats !

The categorical RPM range falls to that low area because even standard cars have a bitching moment with the shifting between 20-40. Make that amount 35 and up and this improves significantly. Like you say, it makes sense and that catback exhaust could feel versa another. May look into this further to gather a tad more..

I just want you to test the effects on MPG this is much more widely debated than performance gains.

Thanks for sharing this knowledge acquired by testing / experiencing things on your own ! Great work done here ! Keep going on make us those videos :) I'd also like to thank you for ealier videos (**everything you need to know about cars** explained !) it helped me a lot in my restoration project of my 94 1g dsm ! If i can you help by any way I can, let me know (FYI I'm an experienced IT developer ;))

Hey, I imagine this has been mentioned already, noticed that your vehicle was not up to temperature when you were doing these tests on the 0-40 2nd gear tests from Catback 1 - Catback 2 there is a noticeable difference on where your temperature gauge is pointed. I could also then assume that the tyres were not at temperature and therefore you were not getting a consistent grip on all three tests & the engine was not at peak operating levels. Although I doubt the difference would be high it is important to have a fair scientific test, or at least highlight what makes a test unfair.

since the back pressure air and fumes exist faster a flow more freely i belive straight pipes "in some cases can" give you more power

bro, all these years and I had no clue you were tuner!

Love this series man. Keep it up.

so 2% sounds kind of small for something that would cost say $1000 or however much. would you say its worth the money or are there more cost effective things that could be done instead?

Hey, that was a great video and a good systematic way of evaluating the acceleration benefits of practically any modification. I know this would be very loud but have you done any tests WITHOUT the catback exhaust, and which would actually answer the question you pose in the title ;-) ?

In Short- more high end power. For the Integra with a B18B like Him and I, you don't have a lot of top end. Where you'd definitely notice is around 5k in 4th gear.

Simple answer is yes if you have modded for a bigger intake. if you have not, then dont bother.

The increased piping size throws of the balance and shift your torque band to higher RPM. That's one of the reasons your not getting a increase in power.

I suggest 40-70 mph in 4° or 5° gear.

Edit: You noticed this too! I just was a bit hasty I guess. :D Just a quick thought: we are measuring pretty small differences, and you're times appear to be limited to 1/30th of a second (i.e. limited to the frame rate of the filming camera). With fractions of seconds mattering in this test I would only go with the averages, not bests. Just because those could be at least partially swayed by the frame rate at which you are measuring. And when the differences are 1-3% (1/100 to 3/100) and you can only get 1/30th per second accuracy, might that influence the results a bit?

Project integra vids are totes my fav.

Subscribed for the integra have an 97 LS myself

You should've done a test with some added weight since the catback system is lighter than the stock one. So you could've just tested if the pipe alone makes a difference (increase or decrease the power).

Find an open quiet road... and try 4th gear pulls from ~2000rpm to rpm limiter or slightly lower... Like a dyno... but in real road conditions... That way you will have tested all (low,medium,high rpms)... on around 1:1 gear ratio...

This is one vehicle. Obviously cat backs vary vehicle to vehicle and engine to engine. It all depends on hose restrictive the stock exhaust is compared to the cat back. I’ve put cat back exhausts on some vehicles and felt and measured zero change, and some are night and day difference. Usually smaller engines don’t have much restriction stock due to less exhaust output and larger engines tend to respond better. Unless of course it’s a more modeler performance model from the factory with an optimum exhaust system and tune.

Enjoying this project, keep it up!

I think you really should get the car into the dyno. With the video we know that in acceleration, the values are not that different. But how much would that represent in HP? And them it would come the question, is it worth to spend $$ to "earn some HPs" and have almost the same performance? Just and engineer to engineer tip. Keep doing your excelent work!

Yet another awesome vid!

Catback on a turbo is far more effective use of $$ than catback on NA engine. Also one brand may suck, each should be dynoed

Can't wait for the next Project Integra vid. Do you already know what the next upgrade and test will be?

For better accuracy you could do your tests up a steep hill. It would be nice if you could performed the test to the rev limiter too.

LONG TUBE HEADERS, THEN CATBACK,cast iron manifold with catback haha

Taching it out to redline is going to reveal the biggest performance gains over stock. Go further!

Well your Integra's Catback sounds MUCH better than the guys on my campus, that's for sure.

love your videos, please do video if removing cats increases hp with proof

thanks a lot sir you answered all of my questions you're a master mechanic!

You should do all these tests again with a turbocharged engine

Engineering Explained You should install Poly engine mounts, I'd like to see how this effects acceleration. It would also be nice to understand the effects from a Engineering perspective. Since this is just a project car I'd say go for full racing engine mounts. If not, fast road mounts may be better for daily drivability. However, considering you're doing all these tests from 0mph and counting from 20mph, I can't imagine the engine mounts would make much of an improvement to acceleration, as apposed to slamming on the gas, as this is where i believe the engine mounts reduce the amount of throw of the engine, allowing the engine to put the power down quicker. Maybe I answered my own question, so maybe it won't effect acceleration using variables used in this test, maybe device another test where for e.g. you test acceleration using WOT only from 3000rpm.

Should change your tires to semi slicks next

I wish someone would just simply do a before and after dyno on it like a video I made on my channel for a supercharger.

Love your videos man

i have always been taught to NOT lug the motor. Keep the RPM's up until you are cruising. If you're losing speed due to a steep hill make the car downshift. In this case you shouldn't be in the 3rd gear going 20mph lol

Some systems will respond much differently than others, bmws for instance are very difficult to improve upon, where a dodge truck might benefit much more...

A dyno would be nice just so you can see the curves and see what the hp and torque is at different points. Like are you losing low end power to gain it higher in the rpm (answer is probably yes). However timed runs are much better for showing real world performance. It isn't uncommon for a car that make more hp on a dyno to lose to a car that makes less hp.

Think of the performance exhaust as a gateway to add more without restriction, you'll never get what you fully want without getting rid of that stock. (04 g35 with invidia exhaust + Invidia pipes + tuned) more to come. Went from 265-330hp. Btw I had a bad aftermarket exhaust before installations.

awesome video. very informative, thx an keep em coming.

What exhaust cat back was used? What type of system did it use manage sound? Little secret they them, the ones with the secrets don't tell is that harmonics are used on the more expensive exhaust that's why they cost more. The other cheaper ones use deflection, or a material to dampen to the sound.

So basically the higher amount of exhaust coming out of the engine, the more need of a less restricted exhaust. Seems like common sense.

Hi nice video as always! Was this cat back test without the weight or did u put the weight back? How did it compare against the weight reduction test? I reckon those figures would be more precise on how the catback exhaust improves performance. Thanks!

I guess the bigger diameter of the exhaust is to blame for the lower performance in low revs, but the performance is all about higher revs, isn't it? (well horsepower at least, but I'm pretty sure the catback exhaust gives more torque too)

a cat back will only free up mid - high rpm driving becoz of the flow low will suffer unless you get long tube headers in conjunction with a high flow cat or no cat at all also improving top end

Great video. I have been telling people for years that all that Hi Performance stuff is nice but only if your'e driving fast. The same goes for Cold Air intakes. They can cost from $200-$300 dollars for a plastic pipe and and hi-flow filter with power gains at 4,000rpm. I rarley get my truck to rev that high so I stick to the factory intake and save my money. It's my daly driver not a race car.

Car should be wicked once it's complete!

Cat back turbo and non turbo is like comparing apples and oranges

How did you choose a cat-back system for an automobile that spins 4,000 rpm traveling at 80mph on an interstate? Did you make a [ Loud droning at sustain speed vs performance gain comparison ] when choosing the components?

I would have liked to see this test done once again swapping back to stock to verify that there weren't any environmental factors at play. The percentage difference isn't perceivable and many factors could affect performance on a given day. Like is the intake temperature gauge heat soaked or not. Weather or not the temperature was colder? (colder air more power, more drag from tires and air) Was there any cross wind?... the list could go on forever.... anything less than 10% is pretty much erroneous data that is meaningless. The only practical way to test performance is on a dyno in a temperature controlled room.

You're an example of why I failed algebra in high school.

Super cool video!

Good points dude

this guy is a real g

Any updates on the Acura? I recommend braking down the engine an explaining what role the major components play. And boring put the engine or even swapping piston rods and pistons for lighter ones.

Can you explain why removing cat sometimes you will end loosing top speed on stock cars, Why some exhaust systems are better for acceleration and others are better for top speed? because theoretically if a car accelerates better it should do more speed, but that´s not the case

Cool video man

Needs a header. The catback offers such minimal improvement with better flow and weight savings...

what about turbo back exhaust? what is best with a turbo engine? any suggested products to give the best results?

I was thinking about the whiteboard in the background. How about filling it in "in sync" with the video. Like after the first pull with stock and catback, the bord would have that info filled in, but no more.. The way you do it now made me see the results long before you told me about it.. Just a personal opinion.. But it would be more "exciting" for me anyway ;) Great job btw, Whats the next thing you will change?

Seems more about looking cool with bigger exhausts. Unless your doing timing tests. The results are barely noticeable. Unless the default setup is shot or pretty poor letting gas fumes and air out. Then the difference will be much bigger. 4% increase tops in most cases. Who really cares I guess whatever floats your boat? Good video thanks for comparisons.

Please do a video for DiY TFT screen /dash for speed and other engine parameters

i think maybe just maybe the catback shifted the torque curve higher