Does a Catless Downpipe Make More Power Than a Catted Downpipe? Audi B9 S4
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- Опубліковано 19 лют 2023
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When you're making nearly 600hp in an Audi B9 S4, do you need a catless downpipe to make sure you are getting every last drop of performance? In this video I did a back to back comparison of a catless downpipe vs a catted downpipe while using a TTE810 running Integrated Engineering Stage 3+ 93 octane software. The results were TRULY unexpected! Enjoy!
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Seeing as so many of you are telling me to "Re-tune it for more power", I thought I'd pin a comment reminding you all that wasn't at all the point of this video. The point was to prove to all of those saying that if I ran a catless downpipe on my current setup that I'd make more horsepower with just a simple hardware change. As I have proven, that isn't the case.
To respond specifically to the "re-tune the car" comments. I use an Off The Shelf or "canned tune" from Integrated Engineering. They still currently hold the record for the quickest and fastest B9 S4 in the world, and I am second to them. There will be no re-tuning. They have optimized their tune for all of the hardware on their vehicle and that contains the same IE high flow performance catted downpipe I use.
If someone wanted to custom tune their car to see if it would make more horsepower with a catless downpipe at this power level, I'm sure you could squeeze out a few more ponies. But as I've shown with a stock turbo on E65 and now with a TTE810 on 93, the downpipe on a B9 S4 flows extremely well whether it be the OEM cat with a stock turbo or the high flow cat from IE with a hybrid turbo. Don't also forget the fact the pipe itself is HUGE! lol. I hope that clears up some of the questions and comments that are being made about the results of this testing.
Got it. The key being “current setup” and the fact is most people don’t do tweak the tune, they just bolt on parts. Thanks for doing this.
@GIZZMOTORSPORTS ya, this platform consists mainly of OTS tuning and bolt on parts. Very few have gone custom, and the ones that have, haven't shown very good results to date other than being dyno queens.
This annoys the crap out of most of us. Down here in the states we all run ethanol and high power not 93.
(on other platforms not b9 s4 specifically)
@S4Meow you have to keep in mind there are a lot of places in the States that don't necessarily have easy access to ethanol, and because of that, they are running pump gas tunes only.
Even i the catless was 2-3hp ahead, i dont want my vehicle to smell like crap. Thanks for the real original content, not just internet hearsay 👍
You're welcome
Yeah I put catless on my 435i it smelled so bad I went back to stock
Hats off to you man for doing the work most guys want to know before trying it for themselves to find out. It’s a lot of work and time spent for those videos 👏🏻
I appreciate that. Thank you very much.
Complete BS video. Cattless is always more superior. More power, more torque and less EGT
@PKperformanceEU 😂😂😂😂Clearly you skipped the entire part of the video that proved that you're wrong in this case, LMAO
Just removing the cat and getting back-back dyno runs isn't telling the whole story. Without seeing logs and wgdc, we don't know if the turbo is working easier or harder to make that boost. Back-pressure in a turbo car is bad, period. Anyone that says otherwise doesn't know what they are talking about. The problem is that when people modify their exhaust by adding diameter size or removing the cat, they "could have" actually increased the back-pressure. It all depends on things such as exhaust scavenging, exhaust velocity, pressure differentials, turbulent flows, restrictions, etc... My point is that if your turbo is working harder, you have added a restriction in creating a more turbulent flow for your exhaust by removing the honeycomb, which has in turn lowered your exhaust velocity and increased your backpressure. Maybe this is true. However, if your turbo is working easier, then you have reduced the backpressure, and you possibly need to tune for this, which will make more power and torque. Simply removing the cat and getting dyno runs serves as a good PSA to people who just think pulling out a cat will help, but without knowing what's actually going on w/ your whole system, simply saying "leaving the cat on is better" is not a true statement and should be taken with a grain of salt.
I read your first comment before you deleted it so it gave me a chance to read through all my logs previous to responding to this comment. Let me help fill in the rest of the story for you. The max WGDC I saw on the first set of 3 runs with the catted downpipe was 65.3%. The max WGDC I saw on the second set of 3 runs with the catless downpipe was 63.8%. Meaning there was a miniscule 1.5% difference. The turbo was working almost identically to make the same or an itsy bitsy less power than it did with the catted downpipe.
With that said, this video was made to quiet all of the people that had literally no idea what they were talking about, assuming that if you simply run a catless setup at this power level or anything below on this platform, it was guaranteed to make power with nothing other than a hardware change which I have proven is absolutely incorrect.
Yes, I agree with you 100% bro If you’re going to do a catless downpipe, you have to get a downpipe that is designed to be careless. Just a hollowed out previously chatted catted downpipe is not the same as a catless downpipe that is designed to be catless , because in such previously catted down pipes that’s been hollowed out. Now you have a big expanded chamber that’s going to cause turbulence in the airflow ,a catless don’t pipe that is designed to be such would have a very smooth transition from the turbo out to the exhaust where turbulence is minimized , and will offer much better airflow, which will intern make more power with all else equal .
I agree that the Power loss is from lack of scavenging and not from absence of back pressure. Back pressure sucks!
@stevenchin1143 I have a f90 that's tuned 93 oct w stock turbos, dinan x pipe w/ oem axle back. I switched from catless and catted back and forth 3 times. I was able to feel a difference especially in the low end. The catted primary dp had better torque compared to the catless dp. And yes the dp wasn't a hollowed out oem cat. It runs the correct piping designed for catless.
Thanks man, been running the Uni DP to pass emissions here with success. I very much appreciate all the time and effort you put into your research and production.
You're very welcome. Please keep in mind that this testing only pertains to the B9 chassis with the EA839 motor. I can't say that the test results will be the same on an RS3 or TTRS with a DAZA motor. Very different engine layout that has vastly different dimensions and shapes to their downpipes.
So awesome! Thanks for all you do for the community.
You're very welcome!
Catted vs catless is the same as 87oct vs 93oct. You'll typically see much of nothing when running a tune optimized for the former, but the latter allows you to tune for more power. More knock resistance allows you to push tuning further safely, and more exhaust flow is less resistance for the turbo to compress air.
Not even close
I see your point but aren't pretty much all stage 3 ots maps optimized for catless downpipes? If an ots tune is designed for use with a catless or high flow cat, as one would assume here, and the catted performs better I'd say that's a clear indicator that the catted downpipe works better in this application. As adam stated though if you're running e70 and 100+ more hp you might need the less restrictive option but at his current power levels on 93 the catted seems to be more than sufficient for the amount of exhaust flow created
Love it when assumptions and speculation is disproven. Thanks for putting in the work to show the actual results.
You bet! Thanks for watching.
Good content man! Got my first audi and now i'm hooked and your videos are great
Thanks for watching and for your support!
I installed the vrsf catless downpipe on my 435i tuned it to stage 2. Talk about performance gain. Went from 300hp to 360hp. So fun to drive. But be aware when you get the catless dp the smell is pretty strong at least for my car. I see a lot of UA-camrs down play it but the smell is strong. And if your state does emissions testing you're obviously going to fail. So if it's your daily and you put a catless dp you'll run into some issues. Just something to think about. I think I will save up and get a high flow catted dp in the future. But going back to stock dp and flashing it back to stage 1
Wow, that was surprising results. Thank you Adam!
Glad you liked it! Thanks for watching!
Thanks Adam! Great comparison backed by data
My pleasure!
so glad you're doing this video and putting the facts out there.
Thanks for watching
Bro I’m so hooked on your videos so impressed!! Can’t wait to get a b9 keep up the great content new subscriber ✌🏼😎
Thank you very much for the support!
Adam doing the dirty work for all of us! Now, I wonder if the outcome would change if IE had tuned for a catless DP. Regardless, you gave us the hard proof to quiet all of the internet "mechanics" lol
I'm doubtful of that, but I'm not sure I'll ever know
Pretty sure you need a tune for a catless DP
@@alloush5995 Not if the tune I was running was already designed to utilize any additional flow it may gain.
@@VancityAudi does this apply to other turbo German cars or just b9 s4
The need more back pressure and this catted dp to make more power ?
@Ali I can only speak to what I've tested. The owner of Racing Greed said they have seen less torque out of a car running a catless downpipe vs a catted downpipe in the past though.
I love all of the data and testing! I've never thought the catted would make more power lol. Thank you again for an amazing video!
You're very welcome!
Sandbagging.
@@aRYANz88 🤣
@@aRYANz88 lol
Thanks for this, I always assumed this just from running both but seeing it in your test makes me happy I went with a high flow cat on my 8Y RS3.
This testing only pertains to the B9 S4 chassis. The RS3 has a very different exhaust system with a much smaller downpipe, different size & style of turbo, and so on.
@@VancityAudi Thats why I upgraded it.
Really enjoyed your video!
Thanks for watching!
great stuff as always with this channel, i was about to buy a downpipe for my b9 s4
Thank you for watching
Wow, back to back comparisons, that is hard to find, at least on cat vs catted dp, well done! Tells us a lot. I feel better about my catted dp now. Wonder if the de-cat flowed more air, could the tune be changed to take advantage of that and make more power? Just asking. Looks like the bee-hive cat is very well designed. Guess a hi-flow catted is all we really need, unless we're trying to make 800+ hp.
I'm honestly not sure that changing the tune would do anything. It appears like the downpipe is so large that you have more than enough flow as it is.
Great video! Well done
Thanks!
Excellent Video Adam
Thank you
Man b/c of you I will be buying a S4, thanks for all these videos!
Glad you're enjoying them. These B9's are awesome!
You won’t regret it. I have an S5 Sportback and it’s so much fun to drive
I bought a used chinese catless downpipe for $350 and it fit great, quality was great, and sound is awesome. I didn't buy it for "more power" just wanted something cheap to get me to St2 power (and we don't have emissions where I live).
Glad to see a catted downpipe making more power though, something I would've never thought could happen.
Where did you buy it from idk where to buy used parts
A cheap Chinese cat? Fuck that! They can fragment and grenade your engine… 😮
I thought the same post install of my catless down/test pipes. This confirms my suspicions. Smh. Now I’m wondering if the location of the cats closer vs further away from the headers will produce a change in the performance of the catted setup.
Hi bud. Love watching you videos. This isn't quite compairing apples with apples. The tune is setup for having a sport cat. You require a different tune. I've done similar test to afew cars. Changing something as minor as a resonator causes issues with map. And a new map is required. Love to see this test done with a map to suit decat vs sports cat.
This is comparing apples to apples. Nothing changed except for the downpipe. If the gain in flow provided additional benefits, we would have seen it. Just like when I tested a high flow performance catted downpipe at a stock turbo E65 power level... it made no additional horsepower because the flow was already there from the factory: ua-cam.com/video/2OowJ99-SEM/v-deo.html
The downpipes on these cars are freakin' huge allowing way more flow than your average car's downpipe does.
The other thing too is that on turbocharged platforms, the turbo itself is providing the majority of exhaust backpressure. Changing to a catless downpipe should result in a negligible difference in performance
@@VancityAudi its not really apples to apples here. the car is already optimized for the catted downpipe while it is not optimized for the catless. if it does get tuned for the catless it will take advantage of all the extra airflow (if there is any) and make more power. maybe run both cars on the stock tune from the factory and compare the power between the stock downpipe, high flow catted downpipe, and decatted downpipe.
@@zoob4371 That testing has already been performed by the tuner. On a stock tune the change in downpipe made zero change in power.
Wow. Great work 🙏
Thank you
it would be interesting to see the boost curves on the graph throughout the dyno run. Not only the peak boost.
I'm hoping to share something like that in some upcoming videos.
Great video . video with info and puncture
Thank you
Excellent video. It has already been proven in the musclecar world that going catless doesn't usually have a huge impact on power; plenty of effect on sound, though....
Thank you very much
I'm not convinced I deleted my catyst converter on my cadillac cts and trailblazer ls I did a before and after and I gained horsepower and more sound that honeycomb in the catyst converter is a restriction that lowers performance worked for me I can't complain.
Please read my pinned comment
Adam, you’ve proved me wrong and now have me reconsidering. I wonder if the difference would be even greater on E70 with even a bigger loss in power?
Catted is better than catless? Interesting. Keep it up! For science🙌🏻
I say you test it on your SQ5! Reference my video in your video and compare!
@@VancityAudi Sounds like I’ll have to do another dyno day with you. 😉
@@Need4Built you should test it with catted downpipe, who knows maybe you will hit those 9's :)
@@porscheturbo_911 worth a shot right? 💪🏼
I always wondered this, I love a quiet ride,
I enjoy my daily to be quiet as well, but have a nice tone.
@Vancity Audi nice tone is a must! I currently drive an 2016 s3 but I haven't found a good exhaust, I have been contemplating selling my s3 and my tacoma to buy a RS3
@Hector Palomar DO IT! I owned a Stage 2 S3 and it's impossible to make them sound good, lol. An RS3 is game changing!
Great video, thank you!!!
Thank you and you're welcome!
I'm not sold on this, boost and timing the same on all runs? If you did a re-tune the catless should make more power. Having said that, I ran cats on my 416ci for all the day to day driving reasons you mentioned.
Yes, boost and timing were as close as one would expect on 6 runs all done within 90 min of each other. As for re-tuning it, that wasn't at all the point of the video. I'll post a pinned comment to answer everyone commenting to re-tune it for more power.
Yessss! Thank you Adam!
You're very welcome!
@@VancityAudi very informative video and extremely interesting results!
@@rubberskilla2991 thanks for watching!
Wow I really thought catless would have produced more hp. This was totally an episode of myth busters!
Great work Adam
If only I could make Mythbusters money doing this!!!
@@VancityAudi 💸💸
Great comparison, thanks very much! I would assume that these results are due to OTS firmware, guess results could be different on a custom tune. Nonetheless, Very interesting results!
If someone went in after the fact and changed the tune while running a catless downpipe, I'm sure something, even if minimal, could be gained.
Cool video. What CEL spec is that high flow cat?
performancebyie.com/collections/exhaust-systems/products/ie-performance-downpipe-b9-s4-s5-3-0t
This is an interesting test. I run a highflow catted dp myself but windering if there is a difference between a gutted cat and just a straight through pipe same diameter as the rest of the exhaust. Instead of having that larger chamber from the gutted cat.
I'm extremely doubtful there is any difference at all due to the sheer size of the downpipe.
Could it be possible to ECU has not learned quick enough to adapted with that extra flow?
We did 3 runs. 2 back to back. Then we cooled down the car for 10 minutes and did a 3rd. Plenty of time for the ECU to adapt.
I’d love to c more rs3 stuff like this.
Coil packs
3.5 intake vs 4
Etc
When my RS3 has a finally finished tune, I have a few comparison videos coming up this Spring.
Is this to do with exhaust scavenging? I remember i had a gsxr600 and it had a exhaust valve that was partially closed at certian times which actually increased torque down low and would fully open up at wide open throttle
That I'm not sure of, sorry.
Thank you.
You're very welcome
Cool, good to know thanks dude
You're welcome.
Have you considered doing WMI on this platform ? I’ve seen it done on an s5 and it made 480whp with 93oct and snow performance WMI
No, I have no plans of running WMI. When I need to make power, I simply switch to E70.
good work !
Thanks!
I love this, huge effort to bring this together. I wanted to share a thought on the why. I don't believe the backpressure suggestion that they gave, engines make more power when they have less of a pumping loss and they gain power from things like exhaust and headers because of pulse tuning. With that said, the gain with the cat is likely because catless is like having a huge resonator where the exhaust flow cavitates before collecting into the smaller pipe. The cat is likely acting as a foil or flow guide that doesn't allow the exhaust to collide and cavitate. Very cool setup and results thanks for sharing this!
Thank you for sharing your thoughts in a respectful and scientific way!
Thank you 👍
You're welcome
How different does the TTE810 feel from the TTE710? Also can you pleeeeease do a reaction video to the 810? Been waiting so long to see that
From my butt feeling the TTE810 feels a tiny bit laggier than the TTE710. Besides that, they are very similar. I haven't done any 1/4 mile comparisons to feel the difference but I suspect that up top I will feel it pull harder with the 810. I'm hoping to do a reaction video this Spring once it warms up and dries out.
I love these videos, but you don’t need back pressure. You need exhaust velocity. The shape of the catalyst probably also functions to smooth out the airflow. Having the big empty catalyst chamber is probably creating a lot of turbulence compared to a straight pipe. Fluid dynamics are very tough to predict, but I doubt the difference is due to back pressure.
That is a good point.
Thanks Adam.
However I do feel the gutted IE ex catted downpipe is just too big, hence the loss in power.
I have the Unitronic catted downpipe on my RS3 and also a catless downpipe in the similar shape. The only difference is the decatted version has a smaller diameter than the Unitronic catted one where the GESi cat is housed.
Theoretically I suspect a catted downpipe has to be made bigger to help with the flow. And the decatted one doesn't have to be so big as it flows freely. Actually just my assumption.
I do believe you though. Stock turbo and even hybrids I doubt will make serious power gains with catless. The guys at IE and Uni did their homework and the catted downpipes flow just as well as decatted.
Here is how I see your situation (seeing as I also own an RS3.) That Unitronic downpipe was specifically made the way it was to be able to pass emissions. That's why they used such a large catalytic converter to allow more air flow. They more than likely had to use a slightly larger cat to be able to handle the necessary flow and still pass emissions for those that have to worry about that.
For the B9 S4 platform all of the downpipes on the market right now are the same massive size. To my knowledge none of them were built to be able to pass emissions. They were built to allow for optimal flow while running a hybrid turbo, all while playing within the EPA guidelines. You'll notice that all of the performance catted downpipes sold are all sold as ONLY FOR OFFROAD USE*. I don't think it has to do with being too big. I think it has to do with the fact none of the OTS tunes available on the market were designed for use with a catless downpipe and don't take advantage of any potential power gains. Just my opinion on the matter!
In the video you said that the catless gives you some drone, and my understanding is that with HF cat you don't have it, is your exhaust otherwise stock?
This is my exhaust: ua-cam.com/video/Za0F30VPHlM/v-deo.html
Any way you can post the AFR of those runs? Including boost and timing?
Sadly, I won't be posting that data for all to see. I don't find that fair to IE. I've always suggested that anyone that wants to run their software to see what it does should purchase it for themselves. Here is what I did share in the other comments though: The max WGDC I saw on the first set of 3 runs with the catted downpipe was 65.3%. The max WGDC I saw on the second set of 3 runs with the catless downpipe was 63.8%. Meaning there was a miniscule 1.5% difference. The turbo was working almost identically to make the same or an itsy bitsy less power than it did with the catted downpipe.
A couple of observations. 1. Contrary to what the shop said about back pressure after the turbine being necessary for generating favorable engine torque, that statement contradicts the operating principles of a turbocharged engine. Power developed by a turbine improves with an increase in the expansion ratio across the turbine, which would result from reducing the backpressure in the exhaust, not increasing it. 2. You mention comparing the maximum values, which indicates other measurements were made with each DP that were different from the maximum, therefore there was run-to-run variance in the engine output. Since you have variance while holding the DP constant other input factors are changing which are causing the output to change. There are other variables affecting the output which prevents concluding confidently that the DP was the factor that produced the engine output changes. 3. In one of the replies below you mention that for the catless runs the oil had cooled to as low, or lower, than when you had begun. Oil viscosity increases as the temperature decreases, which would increase drivetrain losses, reducing the power measurement at the wheels during the second series of pulls. That may not have been the case, but it shouldn't be ruled out as a contributing factor if it wasn't investigated as a possibility.
1. I'll take your word on it that you know what you're talking about. The shop owner has seen this exact same thing happen to multiple cars where the car lost torque when they switched it to a catless downpipe, when they made no changes to the calibration.
2. Nothing changed except for the downpipe. What variables are you speaking of? Anything we could affect like oil temps we made sure they were nearly identical to the 1st round of testing so the results were as accurate as we could possibly get them.
3. The ambient temps and the operating temps were virtually identical for both before and after the testing. We confirmed this already in the comments below.
4. I'm not a scientist, an engineer or a mechanic. I did the best I could to do before and after testing on the same day, with the same tune, with the same software, on the same dyno, just with a different downpipe. To me and probably 95% of people out there, this is evidence enough that on this tune, a catless downpipe makes no additional power.
@@VancityAudi 1. Lacking information on those other cases I will assume what the shop owner saw was due to poor experimental procedures. If they operate like the half dozen different locations I've dyno'd at the shop personnel are not concerned with the design and analysis of the experiment they are conducting. 2/3. Variables like the engine oil viscosity, transmission fluid viscosity, differential fluid viscosity, tire pressure, securing strap force, coolant temperatures, ambient air temperatures, pre-turbo intake air temperatures, engine intake air temperature, the oxygen content of the air (affected by the exhaust), measurement equipment, and procedures during recording the information. Those are some possibilities that may or may not have affected the outcome, and there may be other variables. There are also variables that you might not be able to control, in which case how you take the measurements could be modified and the number of samples increased so the output can be analyzed using techniques that account for the variability. 4. I understand, I'm just offering observations. I think stating the conclusion has been proven is overstating what the information supports.
In addition to the outcome not correlating with the effect that increasing the expansion ratio has on the turbocharger operation, you noted that the wastegate duty cycle decreased slightly with the catless downpipe, but also the torque and power dropped. This is another result that is inconsistent with how the system operates.
Pretty good bro, I figured u would loose Hp. I've owned motorcycles for years now and when u remove the factory exhaust u loose back pressure for full performance., hats off Adam.
Thanks for watching.
Good work Adam!! I think the majority of people at these power levels just go catless because the risk of damaging a cat so close to the turbo from heat is still there but awesome to know that flow that good! I wonder what a stock Cat would do as far as flow hmmm
At a stock turbo level there is no power gain when running a high flow performance catted downpipe. I've already tested that: ua-cam.com/video/2OowJ99-SEM/v-deo.html
With a hybrid turbo I believe they claim they are good for like 50hp or something over a stock downpipe.
Just curious - was that an aftermarket or factory down pipe that was de-cat'd? Either way, very unexpected considering that just an intake + inlet, was worth 10 whp on a much lower state of tune.
It's almost like I answer this question in the video 😉
It’s the exact same downpipe as the catted on just gutted
@@VancityAudi D'oh! Missed it somehow. Totally understanding putting a cat back on to cut down on exhaust smell. The smell of non-cat exhaust is a nice nostalgia reminder of how things used to be, but it's actually very very stinky.
I figured that would be the results. I did that to m
y modified all 1le
I am decatting my 3.0 b6 AVK NA engine with the JHM 3.0 tune anybody out there have a similar set up for the 3.0?
I'm slightly curious if a downpipe that was made catless to start with, would fair any better? Although, I'm not shocked at those results based on my personal experience. Kinda like an open filter intake, it's more about sound than performance.
It wouldn't. By removing the cat from the downpipe it is literally the same thing that you buy from CTS Turbo as a catless downpipe for this engine.
For the second part of your comment for people that are buying the closed intake filter systems like the carbon fiber ones or even the basic it's not really horrible for daily use. Go talk to people that actually track the cars and everything they are not running closed systems and if they are they actually could drill holes in the Box because it's so restrictive.
Hey man, I'm curious, what symptoms did you have with your IE downpipe failing? My b9 sputters sometimes when I get on the gas. I know an exhaust leak or fuel components can cause this. No CEL either... Any insight? Cheers!
Zero signs other than a visual inspection showing it was failing.
If your car is still sputtering I may be able to help.
Just copped a b9 s4 yesterday…. Same color and year… got the warranty tho… but this is tempting
What's a "warranty"? 🤔
Even if you were to tune for the catless downpipe, I believe you would still see a drop in torque, especially in the low rpm range where the turbo is trying to build boost. Maybe you net more power in the higher rpm range, but it will probably be a trade off. Maybe it's worth exploring in another video, but it'll probably cost you a "catless tune" to do it! Great stuff out there! Keep up the awesome work!
Thanks!
That should not be the case. When the exhaust flow is initially increasing the rotation rate of the turbine it will be working to overcome inertia. Lower pressure after the turbine increases the expansion ratio across the turbine which will allow it to develop more power to overcome that inertia, so the compressor would be increasing the mass flow rate into the engine sooner, which should lead to the torque increasing for a given engine rpm.
@@mygolfmk7209 It's almost like this testing proves that your theory is inaccurate?
@@VancityAudi My theory is restating the principles of how a turbocharger operates. I think that concluding this experiment disproves the scientific principles of turbochargers is premature.
@MyGolfMk7 your theory is just a theory. I've already proven that by just changing to a catless downpipe on this platform & not changing any other variable (like a tune), it doesn't make any additional power. I've proven this by doing real world testing. Want to prove me wrong? Do your own testing by controlling all of the variables as much as I did. Then feel free to state your results all you like. Until you've done so, all you have is a theory. Peace.
The tune for the waste gate would need adjustment. Its probably hitting a cut. The less back pressure the better on a turbo. And yes this has been proven time and time agian on many many dyno's. Im not sayin your results are wrong but there are more things at play. With less backpressure the turbo spools quicker and will be more efficient. For that reason the tune will be different not to mention lower EGT's.
It wasn't at all. The difference between WGDC's was 65.3% vs 63.8%. Very, very minimal difference.
Very happy with my IE catted dp and I am ok even if it was down a couple hp for the other benefits!
Good thing it wasn't!
how about a high flow 200 down pipe vs stock down pipe like 800?
If you watch the video, I tell you that it's a high flow catted downpipe.
Yet another great video, which makes sense.
Until someone is trying to squeeze as much power out of their engine as possible, where any little airflow restriction can make a difference, todays fairly high flowing cats aren't going to be much of a restriction. It would be interesting to see a true catless downpipe comparison on this platform, since generally DPs made without cats v ones that have been gutted are generally slightly smaller in diameter and a little more streamlined.
On my last 01 sti my gutted stock downpipe made slightly less average hp/tq than my aftermarket catless, but you look at a subaru too hard and it looses power so.....lol
When you compare an available catless downpipe from CTS vs the gutted IE one I tested, you can see they are virtually identical. Im willing to bet money the results would be the same.
@@VancityAudi Being that they're basically the same size I would bet you're 100% correct there. I can't say i've looked at many down pipes for that platform to see if there is much size variation between any of the catted vs catless.
@@isaacdentremont6946 I think they are exactly the same size, haha
This man is a hero - men lie, women lie, numbers don’t!
Lol, I couldn't have said it any better myself!
Whats the Sound differences? And hows the smell catless?
Watch the video and not only do I show the sounds catted vs catless, I also discuss the smell.
To make a proper way You suppose to do a remap after catless DP because is change a flowing of exhaust fumes. So to make right 😊 comparison needs to be remapping after swap
Please read my pinned comment. Thank you
do you have smell with the catted? ty !!!
Very, very little smell.
What if IE made a tune specifically for the Catless downpipe. Would that change anything? I have the Catless DP and can’t get over the sounds to go catted.
They would never do that, so it's not an option sadly.
It would. This didn't prove much because freeing up the exhaust requires tuning for it. Power loss is likely due to the tune tailored specifically for a catted exhaust.
Faster spool in rpm where it isn't commanded = wastegate opens and power loss.
Catless also benefits from having lower EGT = lower cylinder temps = less ring expansion = less cracked ringlands.
Older n/a EFI cars would show increases in power with just long tubes added and no tune because they would be running a little more lean.
Add long tubes to a new n/a car not tuned for them and they will also show a power loss as modern ecus will add fuel.
@@thatoneguy401k Please read my pinned comment.
@@thatoneguy401khow do you feel about the back pressure you needed to get the gases out which is lacking will decrease your horse power?
Do you think you lost power due to the fact that after market DP are smaller diameter which you change the pressure? Would have loved it if you tested the after market DP like the redstar catless.
The after-market downpipe is the same diameter as the OEM downpipe.
I just read your comment again. You clearly didn't watch the video, seeing as I tested an aftermarket downpipe vs another aftermarket downpipe, lol
Does removing the cataluzer can damage ur engine
No. If they did, companies wouldn't make them.
Couldn’t you counteract the back pressure issue by using an aftermarket catless downpipe that isn’t bulged out where the catalytic converter would normally be? Because I know that some of them will just have the downpipe with the same diameter throughout instead of having that large bulge where the cat would normally be
Sadly, I'm not following your logic. By making the downpipe smaller right off the back side of the turbo, you would lessen back pressure? In my mind that would make more back pressure by limiting the flow with a smaller diameter pipe.
The portion of the downpipe where the cat is located is the exact same size as the turbo itself. It doesn't bulge out at all.
@@VancityAudi My logic is that having a smaller tube for the exhaust gasses to go through restricts the amount of gas that is able to consistently go through due to the friction caused by the gasses being squeezed through a tighter space, so due to this, the pressure inside increases causing the exhaust gasses to get forced out faster. It’s the same principle that explains why giant straight pipes hurt performance, when there’s a larger opening, the exhaust gasses can linger for a bit longer due to there not being enough pressure to push the gasses out of the exhaust, which subsequently hurts a vehicle’s performance. I was thinking something similar was going on with the gutted downpipe, because there’s a big bulge where the cat used to be, there isn’t enough pressure building up because the exhaust gasses may be lingering in that area a bit too long.
@Colton Ellis interesting concept. One would think that if that were the case, the performance aftermarket catless downpipes sold would be smaller and they're not. Come to think of it, no catless downpipe on any of my previously owned or currently owned Audi's are smaller in size, then the OEM catted downpipes. I would assume that there's a reason for that.
Hey Adam. I'd like to say more about even if you see catless gains more power on other platforms, most of the times it is just the back pressure change made turbos overspin a lil bit to run more boost and the current ECU is OKAY with the extra turbo spin. Slaping the cats on and run the exactly SAME boost curve as catless with SAME timing and SAME afr then you'll have the exacly SAME power output. It's pathetic how kids learnt car stuff on tiktok running their mouth around assuming mordern cars' fancy torque based ecus work like their shitbox civics, or how powergain from mods is same as their shitbox VQs.
Was it tuned for the De-Cat before the dyno run ? A De-Cat makes a huge difference on old school motors anyway :)
I was running the same exact tune for the before and after comparison which was made for the high flow catted downpipe. The tune was designed to optimize and make as much power as flow will allow. If flow increased it should have made the same or more power.
Tuner told me only go Catless if you have a bigger turbo than stock if not power is negligible
Depends on the platform and setup.
@@VancityAudi sorry! I should have clarified it’s for the B58 platform M40i I was told unless you get a bigger turbo and to get high flow or Catless but with stock turbo stay with the stock cat
My theory on this is it's kinda like a gun. The inside of a barrel has a spiral shape which in turn creates more power and energy for the bullet. Most honeycombs inside of cats are also spiraled giving the air more energy coming out. It's just physics. If you can induct air and spin it like a tornado it'll have great force than just pushing air
That could be the case if the cat was in a spiral shape. It isn't. It appears to be just straight through.
@VancityAudi also could be like a venturi effect. When the airflow hits an object it'll speed up
Did you change the files to a catless tune?
As I mentioned in the video multiple times. Same tune, same fuel, same day, within roughly an hour of each other before and after.
@@VancityAudi sorry for asking I did see that, but I guess my point is that in modern cars tunes can be different for different hardware. I see though that IE doesn’t offer a catless tune anyway (I imagine covering their assess from the epa). Good work on covering the options available
@@Turbokrankenwagon Thank you for watching.
Glad you are going back with the high flow cat in the car. Doing that experiment proving that you actually lose power/torque and also introducing more droning in the car should just about put an end to some of this keyboard mechanic nonsense that's polluting the internet
I wish that was the case, but if you read through the comments, there are still the know it all's out there that think they know better and still don't believe what I just proved.
you should of done with the E70 file
Feel free to do that yourself
@@VancityAudi thats what your here for
@Matias Gonzalez I did something that appealed to a larger amount of users. If you'd like to test the E70 file out with and without a cat, and share your findings online, I'm sure people would appreciate your efforts.
@@MatiasGonzalez1 Really? Why don't you pony up the cash to do all this testing?
The hole is very big that why ,the exhaust getting out just like that, now need a bigger turbo and all will be good
I’d love to see this done with an RSthree for differences . I believe just sound changes
At the power level I'm now at on my RS3, I will not be running a catted downpipe.
@@VancityAudi power level? So on a rs3 u believe it would have a difference?
@Jeff N absolutely. I should be near 900hp this year in the RS3. Hopefully pushing 40lbs, if not more of boost. My B9 makes just over 700hp and I haven't tested this catted vs catless downpipe theory at that power level.
@@VancityAudi gotcha makes sense! Ty my rs3 will be lucky to c 600wheel lol
@@MrNamesjeff17291 600whp is still a freakin' beast!
Id be ok with loosing the tiny but of HP for the sounds the TTE makes haha
Outside the car, it certainly did sound rowdy!
Did you tune between car and catless?
I covered every step of the process in the video
@@VancityAudi I must have miss that part. Interesting video, I would have thought going catless would perform better.
@razelllamanzares5368 many people did! That's why I thought I'd test it out for myself on this platform.
You took a design that was engineered to work with a cat and removed the cat, you could try to do one where you're using a DP that was designed without a cat? Red Star makes a catless DP.
It won't make any difference at all. The sizing is the exact same.
Was this with stage 3 still?
It's almost like I answer this question within the first minute of the video
Best mods if you only wanna spend 4-5 k ???? I already did a awesome touring exhaust though and rs grille and exterior looks beautiful 🤩
Everything in this video: ua-cam.com/video/dQf0t2_2rCw/v-deo.html
Peoples minds are blown! 😅
😮
Love your video-test! It will better if you used another dp(catless). You destroyed the catted dp. No good for the flow. Tuners recommended tune if you have catted and move to catless.
Please read my pinned comment.
@@VancityAudi my objection is that you used the same dp.
@@MrGeorgePont That wasn't the same downpipe.
@@VancityAudi I’m mean that the second dp was the same dp catted but you removed the inside. Wasn’t catless dp. You make it.
@@MrGeorgePont If you look at the catless downpipe sold by CTS Turbo, the downpipes are virtually identical to what I tested with. If you think the minuscule amount of ridges on the inside of the downpipe are going to make a lick of a difference in the amount of power the car makes I think you are mistaken. I'm so confident in the fact that if someone paid for another downpipe and the dyno session to do the testing between the gutted downpipe and the CTS Turbo catless downpipe, I would absolutely make another video on it to prove I'm right.
tune it to it..
That's also why you dont want to go too big diameter for an exhaust on a car with a turbo, you need backpressure.
No, that is incorrect
Seems like it should be retuned for the catless setup.
As I mentioned in the video, IE doesn't offer a tune for a catless setup. Seeing as they are still the world's quickest B9 in the 1/4 mile with the catted setup, I think it would be pointless of them to do so.
@@VancityAudi Maybe so for their business model, but for all others watching with different platforms and tuning capabilities, it would make sense to do this test with both scenarios optimally tuned.
@gbass7328 as I mentioned in my pinned comment and throughout the video. This testing wasn't done for different platforms or different tuning capabilities. It was simply done to prove to the internet trolls that my setup works just fine, and that installing a catless downpipe would do nothing for me in terms of power on my setup.
Yes, you have to re tune the car to compare
Honestly I'm running catless and res delete, just be prepared too smell gas fumes is all I'm saying .
I’m a certified UA-cam mechanic and I still say catless>catted 🤓
🤣
Your video title is a bit misleading. Should have been catless Vs high flow catted, which I think a lot of people agree are very close in terms of performance. Unlike the stock high cel restrictive cats.
Not sure how my title is misleading AT ALL, lol. It references EXACTLY what I tested. I even mention the type of vehicle.
@@VancityAudi I'm just saying most people will be looking to understand if a downpipe will give them more performance than their stock catted pipe, which is usually NOT a high performance/flow downpipe. Which is why I was saying it would've been better if you mentioned "high flow" catted vs catless.