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

this time on engine masters presented by AMSOIL we're gonna find out what happens when we try and cram six hundred and twenty horsepower through a two and a half inch muffler or a three-inch muffler and you're gonna find out a really easy combo for 600 plus horsepower from a simple 454 Chevy but first you know I have to do this right ready ok scientific analysis 3 inch muffler says ok not much difference let's get into the real science here is the poor innocent big block Chevy that we are gonna attempt to strangle with mufflers when this thing is running with open headers it makes six hundred and twenty horsepower and five hundred and eighty plus pound-feet of torque with a curve that looks like scott wyland cardiogram let me tell you how we're doing it it has pretty much a bone stock forged 454 bottom in doesn't Wiseco pistons interpret ending a quarter to 1 compression the cylinder heads are edelbrock XT what does that mean maybe X tra there are oval port that's been CNC ported they're actually pretty good up top we've got a matching oval port Edelbrock Performer RPM air gap intake Holley nine hundred and 50 CFM alter XP carburetor and we're going to be shutting the exhaust gases through a set up two inch hooker under chassis headers today then there's the camshaft we have a solid roller in this thing if the Comp Cams XR 284 are got two hundred and forty eight degrees and duration at 50 on the intake low the exhaust is 254 the lift is 654 and 661 and it's on a hundred and ten degrees lobe separation angle and now we're gonna roll it into the dyno and find out what happens when you try and shove all about power through a complete two and a half inch exhaust system this looks ridiculous but it's actually really good because we're going to mimic exhaust system just like it might be in your car or crew cab dually it may be because this really long but the difference between the two and a half and three and muffler isn't just gonna beat them up well it's gonna be the area of the exhaust tubing in the whole system and that's why we've set it up this way and why we've included bends like the over the axle like a tailpipe turnout so this is gonna give us a real world example the difference between that two and a half inch Magnaflow and later on a three inch this time we have oil options there's the AMSOIL z-rod 10 30 or the premium protection 10 40 the z rod is more formulated for a performance kind of guy that they had kind of a nicer option for someone who's gonna let an engine sit for a long time sort of in a typical hot rod that might have 600 horsepower like this but we've been running the premium protection 10 40 in this big block and that's what we're gonna go with this time bam I spilled it everywhere sounds of silence did you rev up the water pump that's weird that's the 600 horsepower solid roller motor well it was yeah we know this thing made nearly six hundred and twenty horsepower the last time we ran it now we've got the two and a half inch exhaust on here too much power it kills it is so quiet I know you like that how much horsepower you give up about to find out exactly how much the thing I'm interested in actually is how its gonna change the tune up is it gonna run richer because they can't get air out of the motor we've got no two meter so we'll find out you know what you really want that two and a half inch exhaust because an engine really likes back pressure and and really you lose torque if the exhaust is too big oh yeah yeah watch that's already proven and a established fact I read on the internet you've becoming an internet expert I've heard ok we just took our engine that made six hundred and twenty horsepower and turned it into a 600 horsepower engine and we've used to make what was it 580 585 pound feet we turned that into 556 right now we're gonna pull up the test with it on open headers with an 18 inch collector extension and no muffler whatsoever wow so here's the curve looking at the black line with two and a half inch mufflers and full exhaust the red line is open exhaust with an 18 inch collector extension you can see you're losing power everywhere strangely enough down here 3200 and below but I'll remind you a lot of people like lots why drive my car anyway this is all at wide open throttle not necessarily indicative of what you're doing on the street at part throttle because if you're on it you're going through 3500 rpm really quickly especially if you have any kind of decent torque converter the other thing that all low is the exhaust system thats the longest exhaust system I've ever seen over the axles and turnouts and now look at used the same fuel making less power so is it richer this comparison is looking at the air fuel mixture here with no mufflers and here is with mufflers so higher on the chart is leaner meaning less fuel and lower is richer meaning more fuel it did get richer with the mufflers because it's not moving as much air through the engine I think it's probably has to do with the link awake signal the carburetor I mean that whole air track doesn't start or end of the intake manifold it starts carburetor and ends at the tip of the muffler all that is changing the resident wave the reflected wave throughout the whole air system and so probably just a different signal to the carbon so what we're looking at here with the two and a half inch exhaust system its five hundred and fifty-six pound-feet of torque 600 horsepower so now we're gonna go put on the three inch hopefully improve that little bit it's got to it has to I bet it makes it louder right think so then we can hear it run it is depressing we threw away 20 horsepower and how many pound feet thirty you know when your out in the street car those really really short exhaust systems that are way too loud but just your head so after thirty miles yet to get out and beg for someone else to drive your car check your pulse no I'm afraid its time to go what we just learned is that if you really hate horsepower and want to kill torque the two and a half inch exhaust system is the perfect product for that so now we're gonna step up to the three incher and find out what happens but i wanna make a couple points first we're using the exact same model of magnaflow muffler for both of these tests and importantly they are the same length and width in both cases because that really makes a difference now have a look at that shot of a two and a half inch system versus the three-inch system kinda obvious what's going to happen here isn't it when I was working on oil rigs my my crew boss would probably fire for double wrenching like this this has to make it better right but if it doesn't it's gonna help a lot take off the two and a half inch exhausting throwing the three on 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 the different exhaust sizes but I didn't feel like welding anything so this is a clamp on oxygen sensor band with a little gasket so you can install without having to weld were using these Magnaflow stainless steel mufflers and these are good because check it out there straight all the way through no obstructions no chambers no baffles just a perforated core and some packing in there in fact I think one of the things is this test will be more dramatic if we used to bad muffler these are pretty good ok Dulcich what I need you to do is run out there and calculate the total different in pipe size for the full length of two and a half versus three the cuban capacity right can you do that do that in cubic inches or cc's whats 25 feet times three inches times pie r squared yeah thats it essentially as good as open exhaust very impressive very close its way louder 570 pound feet of torque 640 horsepower and look how flat that crazy torque curve is boom the three-inch is better everywhere except for down here below 3500 where the I'm guessing the engines just not moving enough air to really matter really care but here it's freight training so call it open headers with it 18 inch extension on it so now we're looking at a blue line that indicates an open header with an 18 inch extension blackline three inch exhaust red-lined two and a half inch exhaust it interesting that way down here 3200 and below that we making more torque with exhaust system on it we're thinking a function of basically the collector extension length before airflow actually starts to take over and then as soon as there's some demand for air flow open headers the way to go but look how close the three inchers matching it up here never really close the three inch is definitely the way to go once again I think we proved the obvious on engine master we do it so well I know it's true three inch exhaust enough makes more power than two and a half inch exhaust the thing that surprised me the most is that those Magnaflow three inchers almost didn't kill power and all I mean I don't think enough that would be noticeable by the seat of your pants they may be obvious but that might be the ammo well you need to take your muffler guy when you say I wanted three inch exhaust system he says your crazy thats way too big and you need the back pressure I know thats happen to me so many times you get a muffler shop are ya you know your engine needs a little bit of back pressure I think we disproved that right now at two and a half inch system killing a bunch of power compared to three and even the open headers for that matter that's true zero back pressure the other thing that we did off-camera is that we weighed both the exhaust systems and that was a surprise to me and me to the three inch exhaust only weighed 10 pounds more than the two and a half inch exhaust and we had a big hanging long exhaust system on this thing I was expecting a whole bunch more like you know twenty twenty-five pounds this part might surprise the audience you know how much that complete three inch exhaust system weighed eighty two pounds thats a lot to be lugging around that might be a new argument for turn downs I was surprised that the two and a half as at 72 pounds I was expecting 40 or 50 pounds I know you don't know true facts till you do the measurement you weigh it you check it you dyno test it and you find out and that's exactly what we do here on engine masters presented by AMSOIL come back to us next time but meanwhile check out Motor Trend on demand dot com for gearhead video 24 hours a day and make sure to check us out on social media on Instagram its Engine Masters on Facebook it's hot rod engine masters come back for more dyno violence on engine masters presented by AMSOIL hey guess what if you're on motor trend on demand dot com you get access to engine masters 30 days before anybody else and there's an exclusive show on there with Dulcich and myself that's called roadkill garage now here's a sneak peek at the next episode of engine masters that the live right now on motor trend on demand this is your camshaft for a girly hydraulic roller lifter this is your camshaft for a manly and violent solid roller lifter and this time on engine masters presented by AMSOIL here gonna help you decide which one is right for you check out this engine masters now at Motor Trend on demand scientific analysis not much different ok two and a half of 2013 ready no real difference

Channel: MotorTrend Channel

Views: 5,078,240

Keywords: Engine masters, EngineMasters, Engine masters challenge, Episode 9, Video, Show, Motor trend, Motortrend, Hot rod, Hot rod engine masters, Exhaust, 2-1/2 versus 3 inch exhaust, 2.5 versus 3 inch exhaust, 3 inch mufflers, Exhaust power, Dyno test, Power test, Review, Magnaflow, Big block Chevy, 454 Chevy, 600 hp, 600 horsepower, Power combo, Westech, Steve Brule, Steve Dulcich, David Freiburger

Id: _PVXvHkr-Vs

Length: 14min 33sec (873 seconds)

Published: Mon May 16 2016

Reddit Comments

[u/[deleted]]

I just know some kid is going to watch this and justify putting a fart can on his civic

FOR THOSE REAL HP GAINS

[u/[deleted]]

For "most people" running a car with 250 -300 HP, would the difference be as explicit?

[u/[deleted]]

I know most car guys aren't interested in calculus, but I really wish they would actually compute the area under the curve and compare those values. You can see the difference in peak power is real, however small, but what was the effect on the whole power band? Is it the same percentage as the differences in peak?

It'd be nice to have a number other than peak power to point to that explains how much power the engine really makes throughout the rev range.

[u/BrandonNeider]

For someone who currently has a cam,heads,long tubes 6.1 Hemi connecting to the stock exhaust. Maybe I should consider changing that exhaust and give up the sleeper sound if I'm looking at a bit more HP for not much money

[u/event_horizon_]

That video was wayyy longer than it needed it to be.

[u/Slimy_Shart_Socket]

Anyone read the comment section? Next Roadkill is Friday according to David Freiburger! !

[u/[deleted]]

If you have a street car with mild mods, (350-500 horsepower or so) then the performance difference between 2.5'' vs. 3'' exhaust will be extremely negligible at best, and not worth the extra $$. You don't need 3'' exhaust unless you're making some power, and even at that you still don't "need" a 3'' exhaust.

[u/Rguy]

Would have liked to have seen them do a 4", maybe find out at what point bigger is too big.

[u/AutoBach]

I'm really disappointed that the "engine masters" didn't take time to correct the A/F ratio on the 2.5" exhaust setup. I think we would have seen a reduced spread if the AFR was even close to similar. In one spot the AFR is 12.25 for the mufflers and 13.25 for the open system and that can make a huge difference in output. Also, I would have liked to see what both systems would have done with an appropriately placed x pipe.