During the recent SAE World Congress in Detroit Dr. Gary Smyth participated in a panel on new generation drivetrains beyond 2015. Dr. Smyth had some interesting things to say about the internal combustion engines and where they are going so AutoblogGreen arranged to talk to him afterwards. Dr. Smyth is the Director of Global Powertrain Research and Development at General Motors. This is the transcript to the interview in the latest AutoblogGreen podcast.

AutoblogGreen: I'm talking today with Gary Smith who is the Director of power-train systems research at General Motors. I saw Gary speak a couple of weeks ago on a panel at the SAE World Congress on next generation power trains and he said some interesting things so I wanted to follow up a little with some of those things with Gary. Gary, first of all, can you tell me a little about what your role is at General Motors.

Gary Smyth: Yes I'm actually responsible for all of the power-train research and development that's done globally within the corporation. We have the power-train organization and then we have research and development so all of the research is my responsibility.

ABG: One of the interesting things that popped up during your portion of the discussion on that panel is you mentioned two-stroke engines which back in the early to mid-1990s for a time seemed to be the next big thing. At the time I was very much into two-strokes and was following along with that whole technology, with what Orbital Engines was doing and all the various companies that were at least looking into two strokes. Can you talk a little bit about what happened with two-strokes and why they seemed to go away?


Gary's comments on two stroke engines, diesels, HCCI and more can be found after the jump

GS: Well I think Sam, really the advantage to the two-stroke was first of all the size of it. Certainly when you look at the power output from the two-stroke from a unit/mass perspective, it certainly is better than the four-stroke. But really the real benefit of the two-stroke was the fuel efficiency that you could get from it. That fuel efficiency came from the fact that you don't throttle the two-stroke engine which you do of course on conventional four-stroke engines. Since then we've done a lot of development in reducing that parasitic loss on the four-stroke. In fact most of the technology we're developing, active fuel management, direct injection, etc., is all going after the pumping loss, on reducing that pumping loss. So really in essence the four-stroke engine has come up to parity with the two-stroke on the fuel economy potential. And that was one of the biggest drivers for the two-strokes, so that's why you really didn't see it happening in production.

ABG: So I guess some of the technology that was being looked at that time on the two-strokes, with the direct injection and some of the other things has any of that helped with the development of some of the current four-stroke engines and is that being fed into current engine development?

GS: Absolutely. In fact I started at General Motors working on the two-strokes. In fact all of my research at University was on two-strokes. So I'm a strong supporter of them. I was also one of a small team who decided that it didn't make sense. But what we did do is we took the technology, we took the torque based control structure that we were using on two-strokes, we took the direct injection systems and we've applied those onto four-stroke engines and if you look today, in fact GM right now, I think by next year will have about 200,000 direct-injection engines on the market and we intend to do a lot more of that. So if you even look at advanced technology like HCCI a lot of that was based off of some of the enabling technologies you saw in two-strokes. And and that was primarily the direct-injection fueling system.

ABG: Since you mentioned HCCI, why don't we talk about that a little bit. I think probably most people that aren't following it directly may have never even heard of it since I don't think there is anything like that in production right now. Can you explain a little bit of what HCCI is and the benefits of it?

GS: Well, first of all it's a homogeneous charge compression ignition. So what it really is what I would call the next generation combustion process. So it's not a technology, it's really the process, it's the combustion process that we're developing and it really is, think of it as clean, efficient combustion. Like the two-stroke, the two-stroke by the way ran very lean and by the way we could run HCCI on the old two-strokes, we're not doing the same with the four-stroke where we are running the engine extremely lean and we're not using a spark plug, it's the whole combustion process is what we call kinetically controlled. It depends on the air fuel mixture in the cylinder. So, we're now controlling the combustion without a spark plug. We're running extremely lean and we need a number of enabling technologies to help us control the combustion. One is direct injection. The other is very wide-authority cam phasing. The other is very precise control. Another one is significant residuals or exhaust recirculation gases that we would take into the cylinder. So, much more complex from an engine perspective but allows us to really get the upper bound fuel economy potential of the four-stroke engine and do that with very low emissions.

ABG: And, what kind of fuel are you running in the HCCI engines, is that running with gasoline or with diesel fuel?

GS: Primarily gasoline but we're also looking at HCCI-type combustion on diesel engines as well. We call it PCCI but again all of these would come under what I would call low-temperature combustion. And what it's really doing is my running extremely lean you're driving down the temperature and if we drive down the temperature then we drive down the NOx generation. And that's the key whether it's diesel or gasoline. So you'll see this type of low temperature combustion on both diesel and gasoline but we're putting tremendous effort right now on the gasoline engines and it's our view that you know if you have to develop a special fuel for these technologies then you will not see them on wide-spread applications. So clearly we need to be able to use the fuels that are available today around the world so that again we can get this technology developed or these processes developed and get it out in volume. And get it out across the globe.

ABG: So you're using regular pump gasoline like we see today in the 87 to 90 octane range in the HCCI engines?

GS: Absolutely. And in fact you know the lower octane is actually better for the HCCI process.

ABG: Someone else during one of the sessions, it may have been the same session I saw you in, spoke on running HCCI engines on as low as 80 octane gasoline. Traditionally you wouldn't typically run a fuel like gasoline in a compression-ignition engine. Is it the lean combustion that allows you to get away with doing something like that on an engine like that?

GS: Well, it's the lean combustion, it's also very temperature controlled. So that is why we look at different strategies with our variable value train systems, we look at re-compression, we look at re-breathing, we have very complex injection strategies where we actually reformulate the fuel in the cylinder so we're doing a lot with these enabling technologies to allow us to develop the right type of mixture that is going to combust. And that is very dependent again on temperature, it's very dependent on the actual mixture that you have within the cylinder. So again, a number of key technologies are allowing us to do that. Cam phasing is one, and I would say very wide authority cam phasing, fast cam phasing, direct injection is another.

ABG: What kind of timeline are we looking at before we might see HCCI engines on the road in production?

GS: I think it's still still hard to say. And as you know I'll not give any precise projections on production timings. What I would say is that I actually believe that GM is probably one of the leaders here, there's a number of companies that are pushing very aggressively within HCCI. you know we're at a point where we're putting significant effort in both the research organization within the advanced engineering organization. This is truly a global program, by the way we're working in Europe, we're working in North America, but if you look today and if you were go round and ask automotive companies to let you drive HCCI vehicles I don't think you're going to see too many demonstrators out there today so we're at a point where everyone is heavily into developing the process. The key breakthroughs by the way is in the control of HCCI. It's very easy to make the engine run in this mode. But this is a light-load combustion mode. I have to go back to more traditional combustion with the heavier loads. And I have to be able to transition in and out of that and I've got to develop the control systems to do that. I would say to you that we have made significant progress there but as of today you will not see vehicles either in production or close to production, so while we're working aggressively there's still a lot of development that's required.

ABG: Okay. Back to diesels. Traditionally, diesels have not been very big in the U.S. market. They've been a lot more popular in the European market because of the much higher cost of fuel over there. GM announced a new a diesel V-6 at the Geneva motor show a couple of months ago. What sorts of things is GM doing with clean diesel technology, and are we going to see any of these do you think in the U.S. market any time soon?

GS: Well, diesel is very important to us first of all because you know if you look at our portfolio, GM globally makes everything from a 1.25 liter and 1.3 liter right up to our 6.6 liter Duramax which of course is very successful here. The real key is will diesels make it in the North American market? And a lot of people look at it like, well why don't we just use our diesels from Europe and bring them here, they seem to be very successful in Europe. The real challenge is meeting the emissions here in North America, because if you look at NOx emissions in North America and you look at our standard for Tier 2 of Bin 5 which is our '07 standard, it is one-quarter the standard of Europe today. So it's one fourth the standard. And so we have to meet that, actually usually with bigger vehicles or with bigger engines because we've bigger vehicles. So we have a major challenge which is how do we meet emissions here in North America that are the most stringent requirements in the world. Then also of course if you look at it from a standpoint of the cost of fuel, even though it has increased here, it is still relatively cheap versus what you will pay in Europe for fuel. So, we have announced, and we did announce that post-2009 we will be introducing a new V-8 engine here in North America. We have stated that we know how to meet and we will meet the emission requirements of all 50 states, so we'll meet Tier 2 Bin 5 emission requirements. And so we have said that we will be coming into the light-duty market. The real challenge is, and I think diesel will be important to us going forward, the real challenge is is how much penetration will you see with the diesel engines and the challenge is as we meet these emission requirements we're adding even more cost to a very costly engine. You have to remember that even in Europe today a diesel engine probably costs about twice the cost of a gasoline engine and then we're adding even more cost as we go with more sophisticated after-treatment systems. So while some people may say the challenge is emissions, the real challenge is is what is the cost of this propulsion system when you meet all of the requirements?

ABG: The V-8 that you mentioned is that going to be a successor to the Duramax for the truck applications or is that intended as a passenger car-type engine?

GS: Well I think, I think what we have stated there is obviously that engine will come into the light-duty market so it's clearly as a V-8 that's going to come into the larger vehicles, the trucks, the SUVs within the light-duty market, Today of course the Duramax is over 8,500 pounds. It's in the heavy-duty market. So clearly it's not a replacement, it's in addition to the Duramax.

ABG: The last area that I wanted to ask you about was camless engines. There's been a lot of talk from Seimens VDO in recent months about pushing their camless engine technology and Lotus Engineering first showed something more than a decade ago. Is this an area that General Motors is looking at as a potential technology to use and do you think it's something that can realistically be useful and go into production any time in the foreseeable future?

GS: Well I think first of all the one thing that we've got to do and the one thing that I talked about when we were at SAE was that we really have to go after upper bound fuel efficiency in our portfolio. We are laser-focused on that right now on making that happen. So now you start looking at what are the technologies that will allow you to get to that upper-bound efficiency. And part of that is adding complexity to the valve-train system and we are doing a lot of work looking at very complex valve train systems. We have a lot of course cam phasing was the first introduction of variable valve timing. Now you are seeing variable valve actuation, etc. And you're seeing everything from, again, cam phasing to two-step, to other mechanical systems that are fully flexible to electro-hydraulic systems to electromagnetic systems like you've seen with with Seimens. All of these are adding significant complexity and significant cost and what you need to understand is how much flexibility do we need. We certainly are doing significant development with fully flexible systems and in fact we have a program with the DOE and the Government where we are looking at electro-hydraulic valve train and systems. However what we need to understand is what will the requirements be of the valve train and system and how do we do that with the most cost-effective and durable solution and while we're investigating fully flexible systems we actually feel that we can probably meet all of the requirements that we're looking for with less than fully flexible systems such as two-step, with cam phasing, etc. So really the jury is still out on whether you need fully flexible systems but we do need a lot more authority with regard to valve timing and actuation.

ABG: Right.,and obviously a camless system, although it give you a great deal of flexibility there's also clearly some power requirements just in order to actuate all those valves at those kinds of speeds.

GS: Exactly. And as the engine speed goes up and the load goes up that power goes up as well.

ABG: You start to lose a lot of the benefit that you would potentially get from the flexibility.

GS: Absolutely. And really our goal is how do we get that fuel economy potential and how do we get it out there in the millions that the customer therefore can afford to purchase.

ABG: Is there anything else that you wanted to add to this?

GS: No, I think in general you know the one thing that I would say and that we talked about at SAE is I think this is the focus that we're on right now, on displacement of petroleum. And the one thing that I say to people is we need to be looking at very bold moves to make that happen. Because today, we're probably consuming 130 to 140 billion gallons of fuel in our vehicle fleet today, and we're looking at that increasing significantly in the future, and that's not acceptable. We have to look at how do we create more diversity, with regard to the fuel and how do we improve the efficiency of the vehicles that are using conventional fuel. So this is not just about developing technology, it's about displacing fuel and from my perspective it's therefore developing the technology fast but getting it out in volume products so that again you can actually displace fuel as opposed to niche applications. So clearly the challenge we have and what we're driving to right now is going about displacing fuel and efficiency of gasoline is extremely important to that, we need the right technologies and we need to get it out across the whole portfolio in volume. Diesels again can play a significant role because of their efficiency and then we also talked about what else do we need to do, alternate fuels, partial electrification of the vehicle with hybridization, etc. So there's a lot happening and all of it is focused around energy diversity, displacement of petroleum and ultimately that is driving us absolutely in the right direction from a CO2 perspective as well.

ABG: Well thank you very much, Gary, I appreciate you taking the time to talk to me today.

GS: Sam, it was my pleasure.


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