The Power of 2.5- vs. 3-Inch Exhaust - Engine Masters Ep. 9

May 25, 2024

This time on Engine Masters presented by AMSOIL we're going to find out what happens when we try to put six hundred and twenty horse

power

through a two and a half

inch

muffler or a three

inch

muffler and you'll discover a really easy way. combo for over 600 horse

power

from a simple Chevy 454 but first you know I have to get this right done ok scientific analysis 3 inch muffler says ok not much difference let's get into the real science , here's the poor, innocent big-block Chevy that we're going to try to strangle with mufflers when this thing is running with open heads, it puts out six hundred and twenty horsepower and over five hundred and eighty pound-feet of torque with a curve that It looks like Scott Wyland's cardiogram, let me tell you how we're doing. it has pretty much a forged 454 bone base, the Wiseco pistons don't interpret the end of a quarter to 1 compression, the heads are edelbrock XT, what does that mean maybe X tra there is an oval port that has been CNC ported ?

They're actually pretty good. Up top we have an oval port matching the Edelbrock Performer RPM Holley nine hundred 50 CFM air gap intake alter XP carburetor and today we're going to shut off the

exhaust

via a two inch hook set up under the headers of the chassis, then there's the camshaft we have a solid roller on this thing if the Comp Cams it's at a one hundred and ten degree lobe separation angle and now we're going to put it on the dyno and find out what happens when you try to run all the power through a full two and a half inch

exhaust

system.

More Interesting Facts About,

the power of 2 5 vs 3 inch exhaust engine masters ep 9...

This seems ridiculous, but it is actually very good because we are going to imitate the exhaust system just as it could be on your car or crew cab, it may be because it is very long, but the difference between the two and a half and three and the muffler is not It's not just going to defeat them, it's going to be the tailpipe area of the entire system and that's why we've set it up this way and that's why we've included curves like the ones on the axis as a tailpipe bypass. , so this will give us a real world example of the difference between those two and a half inch Magnaflow and then a three inch, this time we have oil options, there is the AMSOIL z-rod 10 30 or the premium protection 10 40.

The z rod is more formulated for a performance type and they had a nicer option. for someone who's going to let an

engine

sit for a long time in a typical hot rod that might have 600 horsepower like this one, but we've been running the premium 10 40 guard on this big block and that's what we're going to use. This time bam I spilled it everywhere sounds of silence did you speed up the water pump? That's weird, that's the 600 horsepower solid roller motor, well yeah, we know this thing made almost six hundred and twenty horsepower the last time we ran it.

I've got the two and a half inch exhaust here, too much power, it kills, it's so quiet. I know, you like. How much horsepower do you give up to know exactly how much I'm really interested in? change the tune, will it run richer because they can't get air out of the

engine

? We don't have two meters so we'll figure out what you really want, that two and a half inch exhaust because an engine really likes back pressure and you really lose torque if the exhaust is too big oh yeah look that's already proven and it's a established fact.

I read on the Internet that you have become an Internet expert. I heard it's okay, we just took our engine that made. six hundred and twenty horsepower and we turned it into a 600 horsepower engine and we used to do what was 580 585 pound-feet, we turned it into 556 right now we're going to do the test with open heads with a 18 one inch header extension and no muffler of any kind, so here's the curve looking at the black line with two and a half inch mufflers and full exhaust. The redline is an open exhaust with an 18-inch header extension.

You can see that you are losing power everywhere, rather strangely. down here 3200 and under, but I will remind you that many people really like it, why drive my car anyway? If you go to 3500 rpm very quickly, especially if you have some kind of decent torque converter, the other thing that's low is the exhaust system, which is the longest exhaust system I've ever seen on hubs and bypasses and now look the used ones. the same fuel generates less power, so is it richer? This comparison is looking at the air fuel mixture here without mufflers and here with mufflers, so higher on the chart is leaner meaning less fuel and lower is richer meaning more fuel with the one who got rich. mufflers because it doesn't move as much air through the engine, I think it probably has to do with the active link signal from the carburetor.

I mean, the entire air track doesn't start or end at the intake manifold, it starts at the carburetor and ends at the tip. from the muffler, all of that is changing the resident wave, the reflected wave throughout the air system and so it's probably just a different signal than carbon, so what we're seeing here with the two inch exhaust system and a half is five hundred and fifty. -six pound-feet of torque, 600 horsepower, so now we're going to put in the three inches, hopefully we'll improve what it has to do a little bit. I bet that makes it stronger, right?

Think about it, so we can hear it work, it's depressing. We throw away 20 horsepower and how many pound feet and thirty you know when you're on the tram, those really short exhaust systems that are too loud, but just your head, so after thirty miles you still have to get out and beg someone else to drive. your car check your pulse no I'm afraid it's time to go what we just learned is that if you really hate horsepower and want to reduce torque the two and a half inch exhaust system is the perfect product for that, so now let's go up to the three inch and find out what happens, but first I want to make a couple of points: we are using the exact same model of magnaflow muffler for both tests and, more importantly, they have the same length and width in both cases because that really makes a difference now take a look at that shot of a two and a half inch system versus the three inch system it's a little obvious what's going to happen here isn't it when you were working on oil rigs that my crew chief would probably fire me for?

A double effort like this has to make it better, but if it doesn't, it will go a long way toward removing the grueling two and a half inches, throwing out all three right now looking to find or 620 horsepower again, we'll get there, no. I was pretty close. We wanted to put an O2 sensor in the exhaust. We can see if the air-fuel ratio changes with different exhaust sizes, but I didn't feel like soldering anything, so this is a clamp on the oxygen sensor band with a small gasket. so you can install without having to weld we used these Magnaflow stainless steel mufflers and these are good because check it straight out no obstructions no tubes no baffles just a drilled core and some gasket in there in fact I think one of The thing is that this test will be more dramatic if we use a bad muffler, these are pretty good, okay Dulcich, what I need you to do is run and calculate the total difference in pipe size for the total length of two and a half versus three. the cuban capacity, can you do that in cubic inches or cc?

What is 25 feet times three inches per foot squared? Yes, that's essentially as good as the open exhaust. Very impressive. Very close. Stronger. 570 pound-feet of torque. 640 horsepower. how flat is that crazy torque curve, boom, the three inch is better everywhere except down here below 3500 where I guess the motors just don't move enough air to really matter, I really care , but here it's load training, so call it open headers with it has an 18-inch extension, so now we're looking at a blue line indicating an open header with an 18-inch extension, black line, three-inch exhaust, line red, two and a half inch exhaust, it's interesting that way down here, 3200 and below.

When generating more torque with the exhaust system, we're thinking about a function of basically the extension length of the manifold before the airflow really starts to take over and then as soon as there's some demand for airflow, open the heads, the way to go, but look how close the three are. The inches that match up here never really come close, three inches is definitely the way to go once again. I think we proved the obvious in Engine Master. We do it so well. I know it's true. The three-inch exhaust makes more power than the two-and-a-half inches. exhaust what surprised me the most is that those three inch Magnaflows hardly kill any power and all I mean, I don't think it's enough to be noticeable in the seat of your pants, they may be obvious, but that one could be the ammunition. well you need to take the muffler guy when you say he wanted a three inch exhaust system he says you're crazy that's too big and you need the back pressure.

I know that happens to me so many times when you go to a muffler store, you know? The engine needs a little back pressure. I think we've disproved that at this point, with a two and a half inch system killing a lot of power compared to three and even open headers, that's true, zero back pressure, the other thing we did. -The camera is that we weighed both exhaust systems and that was a surprise to me and I, the three inch exhaust was only 10 pounds heavier than the two and a half inch exhaust and we had a big long exhaust system on this one. stuff.

I was expecting a lot more like, you know, twenty, twenty-five pounds. This part might surprise the audience. You know, how much that full three-inch exhaust system weighed, eighty-two pounds. That's a lot to carry. That could be a new argument to reject. I was surprised that at two and a half, at 72 pounds, I was expecting 40 or 50 pounds. I know you don't know the true facts until you measure it, weigh it, check it, test it on the dyno and find out, and that's it. exactly what we do here at Engine Masters presented by AMSOIL check back with us next time, but in the meantime, check out Motor Trend on demand dot com for gearbox videos 24 hours a day and be sure to visit us on social media at Instagram and Engine Masters on Facebook, hot rod Engine Masters return for more dyno violence in Engine Masters presented by AMSOIL.

Hey, guess what happens if you're on Motor Trend On Demand, dot com? You have access to Engine Masters 30 days before everyone else and there is an exclusive program there. with Dulcich and I, that's called roadkill garage now, here's a sneak peek at the next episode of Engine Masters live right now on Motor Trend On Demand. This is your camshaft for a female hydraulic roller lifter. This is your camshaft for a solid manly and violent. roller lifter and this time on the engine