Is a Cat Delete Worth It?

- Well. So the only original part left on the Miata's exhaust is the catalytic converter. Now catalytic converters are great for reducing unwanted emissions and burning off toxic pollutants coming out of the exhaust. And I can honestly accept that. But in the case of the Miata, I'm looking for unbridled horsepower. And the catalytic converter is kind of a restriction, isn't it? How much is it restricting my exhaust flow? That is what we are going to discover today. We are going to make a straight tube to replace the jack. Then we'll go back to the dyno to see how many horsepower that straight tube puts out.

We have a welder. (upbeat music) Thanks to Honeygain for sponsoring today's video. Honeygain is an application that will allow you to earn money just by sharing your Internet connection. No effort required. Simply install Honeygain on your Android, MacOS, Linux or Windows devices and you're done. Consider it the Airbnb for your internet, and with no personal data collection or device storage required, it's 100 percent secure. Honeygain uses your Internet connection to obtain various information from the web, such as flight prices or shoes. It's a way for sites with the best deals to compare prices from different regions, almost like the Google of web tracking for businesses.

And while they do it, you get paid simply for sharing your connection. Now don't expect to make millions, but it could cover your Netflix subscription every month. Nice. I just won 20 dollars. So, what are you waiting for? Sign up by clicking the link in the description below. And if you use the promo code 'donut', $5 will be added to your Honeygain account. Now back to the Money Pit. (soft music) This is what the inside of a catalytic converter looks like. It is basically a honeycomb pattern encoded in some rare earth metals like palladium, platinum and rhodium. So when hot exhaust gas is forced through the catalytic converter, many chemical reactions occur and the exhaust is basically cleaned.

A lot of harmful contaminants that would come out of the tailpipe are removed in the catalytic converter, and the only things that come out of the tailpipe are mostly harmless. So the goal today is to replace this catalytic converter with a straight tube or maybe you've heard it called a test tube before. The same thing. To do that, that means we're going to have to do that. So let's see what we're working with and make a plan of action. This is aluminum steel. This will be very easy to work with, easy to weld, maybe it will rust over time, especially these mild steel flanges.

But it will be relatively easy to make and these are also the cheapest materials we can get. So the first thing I'm going to do is try to calculate the angles of these flanges on the pipe in terms of degrees. We got 86.3. So basically we got about four degrees of angle from the vertical. Here we have 82.1, which is about eight degrees off vertical. And now we know that we're pointing eight degrees this way and about four degrees this direction. These are the zip ties I have. She is flat. She is made of mild steel and is cheap.

And it is for a two and a half inch tube, which is this one. Now you can see that there is a small gap. What that means is that you can do it like this. So I think we'll be able to get enough of an angle without doing too much. The trick will be to establish that angle before welding it. Alright. There were many ways to cut the exhaust pipes. The other week when we did the Nolan exhaust cutouts, we cut the exhaust pipes by hand. You can also use a reciprocating saw such as a jigsaw or cutting disc.

But to make good, repeatable cuts, what the doctor really ordered is a band saw. Now this one is pretty cheap, almost the cheapest there is. I think they cost about $275 today. Basically what I'm going to do is cut a little bit off the end, but at about an eight degree angle, let's start cutting. Well. So band saws like this usually have some type of tension control so you can adjust the tension and then you can step away from the cut while it's happening. So I already have your set. (bandsaw screeching) Okay. So we have our little wedge at about four and a half degrees this way and about seven degrees the other way.

Alright. So we're really close to our first attempt. Now I just need to measure the total length of this thing, cut it, and then do this again for the other flange. (bandsaw screeching) Okay. Our pipe is ready for welding. Now we need to prepare our flange for welding. And the only thing we have to do there is clean it. Every time you solder something, it is very important to clean the metal. So I'm going to clean the flange and clean the bottom of this tube a little bit. But I'm going to be careful with this because I don't want to remove too much of the aluminized coating because that's what keeps it from rusting.

Alright. So we are ready to attach this flange to this pipe. So welding itself is a huge money pit and a very deep rabbit hole. So let's start today. And today we're just going to focus on MIG welding, which again, in my opinion, is the easiest version of welding out there, anyone can do it. It's pretty simple. You just have to know some basics. That's what we'll cover today. The first thing we're going to do is tack weld this tube to this flange, which means we're just going to put some little bits of solder on to hold this together so we can test it on the car and make sure everything's okay. well before soldering completely on all sides.

Well. So the first thing we're going to do is turn on the switch on the back of the machine and then I'm going to turn on the gas. You might notice that I have two gas tanks back here. This is because this machine performs MIG and TIG welding that use different gases. This is my MIG tank. It is a mixture of 75% argon and 25% carbon dioxide. That is what is generally used for MIG welding. So I'm going to open it. And then we have this pressure regulator that measures the flow of gas to your machine. I have to set it to about 30 CFM or cubic feet per minute of gas.

As far as I know, that's standard stuff for MIG welding. And this machine is very easy to set up. It has an automatic configuration function. So you can select the thickness of the material you are working on and then it will calculate how much heat and how much wire speed you use. Now, on any MIG welder, those are really the two main settings: heat and wire speed. So I selected this material with a thickness of 18 gauge. These numbers don't necessarily matter. Most soldering irons will only have two knobs with random numbers. And it doesn't really matter.

What you need to find is simply the relationship between heat and wire speed. And it really depends on what you're working on, in terms of what type of metal it is and how thick it is. So those are the basics you have with me. Well. Now this is ready. Let's put our pipe in place. So the only thing we need to do besides using our torch is grind our workpiece. So obviously you can ground whatever you're working on, but especially if you're working on a nice soldering table like this, we can just ground the table. Next we'll set up our piping and then put some studs on it.

Let me find a welding helmet. (upbeat music) (soldering iron crackling) Okay. Well, she's added. Now. We can take this to the car and make sure everything is okay. Similarly, we had to trim the bottom of the pipe there because it would have stuck past the flange. We'll have to do the same here. You can go like this. (blade whirring) (upbeat music) Okay. So we have our test tube in place. We have our flange bolted to the rest of the exhaust and it looks like it will work great. So now I'm going to bring the welder here.

I'm going to put this zip tie in place. And then we're basically ready to completely solder. It's always a good idea to disconnect the battery from the car you're welding on. If you're really going to weld a car. Basically, when you are welding you are using a lot of electricity. And if any of that electricity gets into your electrical system, it can cause bad things. One of my friends when I was a kid broke the back window of a car because he left the battery connected. (soldering iron crackling) Okay. Now we have this fixed. It's time to get it out of the car and go solder it and talk about how to solder it.

So as this progresses, I'll solder in a sort of C pattern. Capital C, capital C all the way around. Now, since our flange is a much thicker material than the pipe itself, it will be able to withstand much more heat before burning. So what I'm going to do is basically spend most of my time on the flange, injecting heat into it. And then I get close to the pipe just for a minute, just for a second. That's the method. Now, the other thing that is important is how far away you are from the piece with your torch.

So you want to be about three eights of an inch and a half inch away from the surface of what you're welding with the torch and something like this, where we have this 90 degree joint that I'm going to be at. about 45 degrees in this direction. And then I'll be at a certain angle in this direction. If this makes sense. Now there are two ways to do it. You can guide the puddle where you are welding this way and drag your torch in front of it. Or you can push it towards where you are pushing the torch from behind.

It's kind of a personal preference. I do both. Depending on what I have to do, depending on what I'm working on. So once you understand how to hold your torch and all that, do some sort of test where you don't actually solder, but just confirm that you can actually do it, look like I'm punching, I'm having a bit of a problem there. Then I should have this on my shoulder. I probably should have done it from the beginning. But I didn't, and I wouldn't have done it if I hadn't made that dry pass. Then we will do like this.

And then we have a clear and pleasant path in every way. I'll probably do this in two or three different sections. That being said, let's do it. (upbeat music) (soldering iron crackling) Okay. So the first side of the test tube is all soldered and it doesn't look terrible if I do say so myself. I'll let it cool for a minute as is and then we'll turn it over and solder the other side. (soldering iron crackling) Okay. Then the test pipeline is completed. Now the only thing left to do is go to the dyno and test it and see how much horsepower we gain.

Come on. We're back with my friends at EF1 Motorsports to take advantage of some EF1 tuning testing time. So the original cat is in the car right now. So let's put the car on the dyno and do some surveys and see how much power we're generating as is. And then we'll do that and install our test tube for our straight tube. And then we'll do more surveys and see how much horsepower that straight tube left us with. (upbeat music) So it's three races with the cat in place. And our average power is 234 and a half horsepower and 215.6 pound-feet of torque.

So now let's go back to our test tube, do this again and see what the numbers give us. (upbeat music) Okay. So we're getting some interesting results and I'm going to try to explain what I think is happening here. We put the test tube in and lost the ability to control impulses, which caused some creep. Now, what we're seeing here is momentum. Now the dotted blue line is our run with the cat, and you can see that the momentum increases and the red stays pretty stable where we want it. But the magenta line is with the test tube.

And you can see it rises and starts to flatten out like we're controlling it, but as the RPMs go up and our exhaust flows so well with our new test tube that the internal waste gate of this turbo basically gets overwhelmed. And it's not able to release enough pressure to keep our momentum at the level we want. We are telling you to completely discard the impulse at that point. It doesn't matter. He's just pushing. Since we have such high RPMs and that little internal waste gate is just overwhelmed. So we're stuck in this. I mean, we're making like 260 horsepower out of the test tube because we can't keep the boosts at the level we want.

That's a great thing. I mean, we make like 30 horsepower, but apparently we're also at the limits of our waste gate setup and, as such, our turbo setup. So we could have changed the turbos in the not too distant future, if we want to change the way things are going. Well. So, with our momentum creep issues explained, I still want to try to do this test a little more apples to apples. So I just put the jack back on and now what we're going to do is try to match that boost to our tune so we're trying to put the same amount of boost through the jack on purpose.

Then at least we can see how muchPower we generate at those boost levels with the jack in place versus those boost levels with the test tube. Although testing boost levels is accidental, does it make sense? I hope so. (upbeat music) Very good. So we just ran the cat test again. And we're looking at our momentum map here again and you can see our original momentum line that we were chasing, that magenta line is in there somewhere, just buried by all these other momentum lines because we did a really good job of mimicking that momentum, that momentum we were having.

So once we did that and retested the cat, the numbers we came up with are as follows: We have 252.8 horsepower on average with the cat and 210.1 pound-feet of torque on average. Then, with the test tube, we achieved 257.7 average horsepower and 217.2 average pound-feet of torque. That means we got 4.9 horsepower and 7.1 pound-feet of torque out of the test tube. It's not bad at all. It's certainly not those 30 horsepower that we were seeing in difference. But given our momentum creep issues, I think this is a pretty valid test as far as testing goes. Well, we more or less did.

We made a test tube. That was great. We put it in the Miata and definitely gave it a lot more power. Now I'm not very happy with the way we did the power. I think we have some issues that we talked about. So I'll have to address those issues in the future. But for now we are producing 260 horsepower. So I have more work to do on the Miata. Now, if you also like working on things and you like the types of videos where we work on things, then you have to check out yesterday's bumper to bumper where Jeremiah drives over the 2000 horsepower Altima.

They talk about 3D printed body panels. They talk about how the hell it makes sense to basically remove the entire chassis and replace it all with tubes. And they will divulge a little secret. Which seat is the most fun for riding in a drift car? Hint, it's not the front seat. So go and look at that bumper to bumper. You will not regret. You only have to click here. Oh, and don't forget, we have an underground, the Donut underground. And one of the perks that ends tomorrow is that we'll send you a free sticker every three months, if you're a member.

But you must register tomorrow to take advantage of the free stickers. To learn more about Donut Underground, just click the Join button below and I'll see you on the subway. And with all that said, I'll see you next Wednesday. Don't forget to follow me on Instagram @Zachjobe and I'll see you cool cats in a week. Bye bye.