ROUSH CleanTech Propane Expert Compares Propane to Diesel

ROUSH CleanTech, Compares a New Blue Bird Propane-Powered School Bus to a New Model Diesel Bus

https://player.vimeo.com/video/469886310

In this webinar, ROUSH CleanTech compares a new Blue Bird propane school bus to a new diesel. Adam Wilkum and Ryan Zic with ROUSH CleanTech look at power, performance, sound quality, and maintenance. Blue Bird is the leader in alternative fuels school buses, offering power options including all-electric, propane, CNG, and gas. Blue Bird does offer traditional diesel; however, the company is focused on fueling innovations to power the school’s transportation future. Since 1927, Blue Bird has built a solid reputation for superior quality and a dedication to safety.

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Roush CleanTech Transcript

Ryan:

Hi, I’m Ryan

Adam:  

and I’m Adam

Ryan:

We’re with ROUSH CleanTech. And today, we’re onsite to look at a new propane-powered Blue Bird school bus and compare it to a new diesel-powered school bus. There are a few things that we want to look at that are important to fleet and drivers alike. And we want to measure those and share our results with you. Adam, would you explain a little bit more about what you’re going to test?

Adam:

So, what I have here is a professional decibel meter. What we’re going to do is we’re going to take three readings. We’re going to take a decibel reading at acceleration, full acceleration. We’re going to take a decimal reading at idle. And then we’re also going to take a decimal reading here in the loading zone, where the students spend a lot of their time. We’re also going to go out and check some important performance characteristics.

Ryan:

So, we have a GPS device that we’ll use on both vehicles. That’ll download information to an app. That’s going to share those critical thresholds for us. So we’re going to focus today on zero to 30 and also zero to 60. And see what kind of acceleration times these two vehicles put down. We also want to look at another thing that’s important to fleets, which is maintenance and upkeep. So how are we going to do that at them? So what we’re going to do is we’re going to take both of these buses inside a shop. We’re going to put them up on a lift. What we’re going to do is we’re going to take a deep dive and look at all the emissions components that are under these buses. What we’re also going to do is take a look at a few preventative maintenance items just to see how the diesel stacks up to the propane. Awesome. Well, if you’re ready, let’s go pull these up on the rack. All right, let’s get started.

We’re underneath a new Blue Bird school bus powered by propane and a ROUSH CleanTech engine. Today. We’re going to look at the emission system that’s on this bus and how it differs from a modern-day diesel school bus. So if we start with where the exhaust leaves the engine through the exhaust manifolds up here, you’ll actually see where it comes down. This Y pipe and it has two upstream O2 sensors. So those are coupled with one downstream OTU sensor, which is located here on the catalytic converter. But this is the bulk of your entire emission system, this passive catalyst, which actually allows all of those emissions constituents to be cleaned up before it leaves the tailpipe of the school bus pass. This, it’s going to go through a connection pipe. That’s going to go to your muffler. And that’s the entirety of your exhaust system on a propane ROUSH powered school bus.

This is coupled together with an evaporative emissions canister, which is located here. And the purpose of this device is to capture the fuel from the fuel rails. Once the engine is shut down. So all of the fuel that’s at the engine fuel rail is going to come back and be captured in this evaporative emissions canister. And then later on, whether it be a day or weeks later when the vehicle started back up, this canister is going to be vacuum back out by the engine and sealed up again. So that can repeat the cycle again and again, but that’s the entirety of our emission system under this, that coupled with the ROUSH CleanTech calibration and engine certification makes the simple emission system possible on this school bus.

Ryan:

Okay, now we’re underneath a modern diesel school bus, and we’re going to show you the comparison of the emission systems and the complexity that we have associated with a diesel versus what we had on the propane school bus. So starting with where the exhaust leaves the engine and actually comes through the turbo downpipe, it’s going to follow this path and its first stop is going to be right over here at the DPF that stands for diesel particulate filter. So if you remember the black suit that used to come out of diesel tailpipes, that has to be caught today by modern-day emission standards. So the first stop will be at this DPF canister where it’s going to capture all of that set before it leaves the tailpipe. It’s going to follow that path through the canister, come out of this exit pipe. And then it’s going to go through a diesel exhaust fluid injector system.

So, this module and this doser are actually going to take diesel exhaust fluid from the tank that we’re going to look at in a little bit. And it’s going to inject this into this stream so that it can then go through the second canister, which is a selective catalyst reduction canister. That’s where you’re going to have the chemical reaction to reduce the amount of Knox that’s in the emissions before it leaves the tailpipe of the bus. After it leaves this, it’s got to head out and go through a muffler and through a tailpipe through the back of the bus. So before we go back there and look at that, we’ll look at the diesel exhaust fluid tank. So this is filled with usually 10 to 15 gallons of diesel exhaust fluid, which is a concentration that helps with the catalyst reduction to reduce the knocks out of the system. There’s a lot that goes on with this system. Everything from quality sensors to dosing levels, sump pumps, and injection system to allow this entire active system to work together, to get to the tailpipe emissions standards that we have today.

Adam:

Hi, this is Adam with ROUSH Cleantech. We find ourselves under a new Blue Bird propane-powered school bus with the ROUSH engine and fuel system. What I want to highlight underneath the bus right now is the simplicity of the preventive maintenance related to oil changes. What we have here is a $4 off the shelf spin-on filter and an oil pan that holds seven-fourths of oil. As you can see compared to modern-day diesel, this is about as simple as it gets. So we just got done looking at the Rouse engine with the inexpensive spin-on oil filter and seven quarts of oil. What we have here is a modern-day diesel engine, where we have a large filter that holds three quarts of oil spin on fuel water separator and a large oil pan that holds 18 quarts of oil.

So, one of the most important areas outside the bus for noise levels is the loading zone. That’s where the students spend a significant amount of their time outside the diesel bus. So you could see the decibels are about 76. So, we’re going to now compare that to the next to the Blue Bird propane-powered glass. So now we’re here next to the Blue Bird propane-powered school boss. We’re going to take another decibel reading and see how it compares to the diesel-powered bus. So we’re in about 62 decibels on the propane-powered bus over 10 decibels, lower. That’s quite a bit of difference.

Ryan:

So now we’re going to go out and do a test drive in the propane-powered Blue Bird vision. We’ve got our draggy GPS device hooked up. We’re ready to take some measurements of acceleration. And we’re also going to grab some sound measurements as well. So decibel in our cabin also by the driver’s area in a few different. So we can compare them to the diesel buses that we test later. So now we’re going to use our decibel meter to take a measurement of what kind of sound we have in the driver’s area when the bus is idle with nothing else on. So I’m going to hand this to Ken and he can give us a reading up there, right where he is.

So, it looks like about 53 or so when I’m not talking so really quiet driver’s area with this vehicle in drive at idle with everything else off. Thanks again. So now we’re cruising and the propane Blue Bird school bus and at highway speeds at about 55 miles an hour, we’re running at about 2000 RPM. So really comfortable is very quiet in the cabin while we’re doing that extremely smooth. And we also took some acceleration tests which will compare against the diesel bus here on that same exact route that we’re doing with the propane bus. Okay. So now we’ve got the entire team loaded into a newer diesel bus. We’re going to go out and do the same route that we did with the propane bus, take some of the same measurements acceleration. And we also want to know, have we had any changes in the cabin decibels and how much noise the drivers hearing while they’re operating the vehicle.

So, we’re going to go out and check out those routes, repeat them. And then we’ll show you the side by side comparison of how we finished today. And we’re at a standing idle with nothing on trying to find out what our driver’s area decibel reading is. So when we take a pause here, read about 60 and a half decibels. And if we compare that to the propane bus, that was at about 53 and a half decibels, a lot of people ask us to propane, have the power and torque that they’re used to with their diesel is because they need that throttle response to get out into traffic, get a full load across the road quickly. So we’re going to take a zero to 30 and zero to measurement. And for reference, the propane did the zero to 30 on this route at this exact same spot at 7.21. And it did zero to 60 at 25.88. So now we’re going to get out there. We’re going to try it with the diesel bus and we’re going to see what the comparison is.

All right, zero to 30 was hit at 10.9 seconds versus 7.21. And the propane trucking along with the 60, trying to get up to highway speed. There we go, bingo at 60 and that’s 39.79 seconds. I think there’s a lot of information out there and misinformation that diesels have a lot more power and that it causes them to be able to accelerate faster. And I think what we’ve found is that with more horsepower on the propane and the way that we have the transmission and the driveline set up is that it’s actually not the case that the propane is considerably quicker in a lot of ways, especially where it matters that snappiness off the line to get moving. I really think that the probate outshine and we saw it here in the numbers, you know, jumping up considerably three seconds plus on zero to 30. And then about 15, 14, 15 seconds, we’re talking about zero to 60. So I think drivers will really like that. You couple that with how quiet they are and it’s a better driving experience altogether.

So, we’ve had a lot of fun today with these two buses, we’ve had a new diesel bus and a new Blue Bird propane bus, and we got to put them through a lot of different comparisons. The first one we want to talk about and some of the results we have, or the decibel readings that we took.

Adam:

Yeah. The results were pretty surprising. So, at idle, we were seven decibels quieter with the Blue Bird propane-powered bus over the diesel bus at wide-open throttle. Surprisingly the propane bus was a little bit higher decibel reading. And we think that is because of the higher horsepower of the propane engine, the higher RPM of the propane engine made it a little bit louder. Really, I think the most shocking result, for me, was the bus was 14 decibels quieter in the loading zone. So where the students are getting on and off the bus at the beginning and the end of the day, 14 decibels is really a significant number.

Ryan:

And that’s really a critical communication zone. Cause that’s where a driver’s talking to students that are getting on and getting off that bus. Right.

Adam:

That’s what I thought. So how the emission system look.

Ryan:

So, we lifted the two buses up and we really got a great view of what the mechanics and maintenance people have to deal with regularly. So we looked at the propane bus and really it’s a simple passive emission system outside of a catalytic converter and a handful of O two sensors. It’s a very basic system and the longevity of it should be supported right along with it. And to go a little bit further with that simple emission system, we’re also meeting a low level of Knox with that emission system and no extra hardware by comparison. When we lifted up the diesel bus, there was a lot of componentry and stuff outside of the diesel engine that you’re going to have to look at and work on for the entire life cycle of that bus, whether we’re talking about the diesel emission filter or fluid, the diesel particulate filter the SCR system, all those dosing controls and the sensors that we saw in that system that go along with it, it’s got to be a considerable service item with a lot of costs associated with it.

What did we see Adam though on the maintenance side?

Adam:

So, we didn’t spend a whole lot of time looking at maintenance and honestly, it’s because, with the propane bus, there really isn’t that much to maintain a, we took a look at the oil, filter, the oil pan with the amount of oil that you have to put in the bus. The propane bus really shines in that department, you know, with the one filter in the, in the small amount of oil that goes in that thing. So as far as maintenance goes really not a whole lot to talk about on the diesel side you do have a couple, you know, an extra filter to moral oil. So yeah, a little bit more too, to maintain on the diesel side.

Ryan:

Well, we also went out and got these buses out on the road because we wanted to know if the old adage of a diesel bus has more power really held true.

So, we used our GPS device and we measured both these vehicles on the exact same route. And we checked out the zero to 30 and zero to 60 acceleration times. And what we found was that not only did the propane do better, it did considerably better on the zero to 30, we saw almost a full four seconds. It was about three seconds and change acceleration per improvement over the diesel, that same route on zero to 60, almost 14 seconds faster. So even though that diesel has more torque than the propane bus, what we found out is that the rubber just doesn’t meet the road and the propane bus outperforms in both categories. So what do you think really overall we learned today, Adam? Well, I think you can draw some pretty good conclusions. You know, really everybody’s pretty much in conclusion that propane buses can save you money.

Adam:

They’re better for the environment where we really get a lot of back and forth with fleet owners. Are you sacrifice anything propane buses, maybe they’re harder to work on. You need specialized tools. I think what we really found today is it’s just not true. You can find the best of both worlds. I think he could. And, and the fact that it’s a lot quieter and a better experience for the children riding the bus. I think you can’t really discount that as well.

Ryan:

Yeah. I think as riding on both buses today as a driver and a rider, I think my experience was better both on the propane bus quieter. We could talk easily amongst each other, and we had better throttle response to get out into the high-speed traffic.

Adam:

Right. And I don’t know about you, but if I was working on a bus that does emission systems, we took a look at it. I mean, I know which one I would choose, so, absolutely. Yeah.

Ryan:

So, thanks for joining us today, and looking at our comparison between these two bucks to learn more about ROUSH CleanTech please visit us at www.roushcleantech.com.

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