New LT1 for 2014 Corvette
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Great article(s), thanks !
The second article doesn't mention cylinder deactivation.
The second article doesn't mention cylinder deactivation.
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Funny I didn't notice the inconsistency in the articles regarding the cylinder deactivation. I am curious now to see which is true..
I was about to say, "Why are they redesigning the LS series engines already?". And then I remembered that the original LS1 is almost 20 years old by now.
Im not impressed with it. Im sure it is a great engine, like all of the LS family, but to me this was a double, not a home run.
am I wrong in comparing to the Coyote engine and not being too impressed?
Not at all, I was thinking the same thing.
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
Originally Posted By: JasonC
Not at all, I was thinking the same thing.
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
The new Coyote is far from a world beater. Sweet motor, but way too much complexity and too new to judge its 'greatness'. Let's get it 20 years down the road and see if it enjoys the reputation of the LS series of motors.
Perhaps you'd be more impressed with an LS7? Maybe an LSx?
Not at all, I was thinking the same thing.
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
The new Coyote is far from a world beater. Sweet motor, but way too much complexity and too new to judge its 'greatness'. Let's get it 20 years down the road and see if it enjoys the reputation of the LS series of motors.
Perhaps you'd be more impressed with an LS7? Maybe an LSx?
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
Yes. It depends on what aspect of engine performance you want to use for comparison. A 4-valve engine will always make more specific power than a 2-valve engine, but that's about where the advantages end. An OHV engine will be dimensionally smaller in height and width, lighter, more efficient, and have a lower CG than a DOHC engine due to lower parts count and fewer pieces rubbing together. The OHV engine will be cheaper to manufacture also because of lower parts count. And in the case of the new LT1, because of fewer holes in the combustion chamber, GM has more ability to optimize chamber shape, injector placement, and nozzle spray geometry than a 4-valve engine would allow.
am I wrong in comparing to the Coyote engine and not being too impressed?
Yes. It depends on what aspect of engine performance you want to use for comparison. A 4-valve engine will always make more specific power than a 2-valve engine, but that's about where the advantages end. An OHV engine will be dimensionally smaller in height and width, lighter, more efficient, and have a lower CG than a DOHC engine due to lower parts count and fewer pieces rubbing together. The OHV engine will be cheaper to manufacture also because of lower parts count. And in the case of the new LT1, because of fewer holes in the combustion chamber, GM has more ability to optimize chamber shape, injector placement, and nozzle spray geometry than a 4-valve engine would allow.
Originally Posted By: SteveSRT8
Originally Posted By: JasonC
Not at all, I was thinking the same thing.
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
Perhaps you'd be more impressed with an LS7? Maybe an LSx?
It does make you wonder what's going to happen to the LS7, now that the LT1 is within 10% of its peak power and has equivalent torque. Seems like GM has to put direct injection on it to make at least a 75 HP advantage over the LT1.
Originally Posted By: JasonC
Not at all, I was thinking the same thing.
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
Perhaps you'd be more impressed with an LS7? Maybe an LSx?
It does make you wonder what's going to happen to the LS7, now that the LT1 is within 10% of its peak power and has equivalent torque. Seems like GM has to put direct injection on it to make at least a 75 HP advantage over the LT1.
OVERKILL
$100 Site Donor 2021
Originally Posted By: A_Harman
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
Yes. It depends on what aspect of engine performance you want to use for comparison. A 4-valve engine will always make more specific power than a 2-valve engine, but that's about where the advantages end. An OHV engine will be dimensionally smaller in height and width, lighter, more efficient, and have a lower CG than a DOHC engine due to lower parts count and fewer pieces rubbing together. The OHV engine will be cheaper to manufacture also because of lower parts count. And in the case of the new LT1, because of fewer holes in the combustion chamber, GM has more ability to optimize chamber shape, injector placement, and nozzle spray geometry than a 4-valve engine would allow.
A couple of points:
1. Efficiency factors in power output, not just fuel consumption. In this case, Coyote wins, and this goes against your 2nd sentence which stated that a 4-valve engine will always make more specific power than a 2-valve engine. For if that is the case, then the 4-valve engine will always be more efficient.
2. I will give you height and width. Weight? Completely depends on what the engines are made of as well as their components.
3. The Pent-roof design (4-valve and many 2-valve engines) is about as good as it gets regarding chamber design. The only design that was potentially better for maximum power output was the hemispherical chamber, but it gave up low RPM performance and offered poor combustion characteristics (read: it burned dirty) when engine speed was low enough that the swirl effect was not promoted.
I don't think that GM having the "ability to optimize chamber shape" here is really a benefit, especially if it appears to do nothing to increase power output, which, at this point in the game, we have nothing showing us that it does. Certainly at 450HP for a 6.2L "ground breaking" pushrod engine vs 444HP for a 5.0L DOHC engine that is now a few years old, it doesn't demonstrate this characteristic.
I think the big advantage here is that it (the pushrod architecture) is compact and easy to manufacture. And likely this is why GM continues to use it.
This engine makes approximately the same HP/L as the LS7, which was very impressive when that engine debuted. This is not the same achievement nor does it deserve the same same level of recognition that the LS7 garnered for that very reason.
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
Yes. It depends on what aspect of engine performance you want to use for comparison. A 4-valve engine will always make more specific power than a 2-valve engine, but that's about where the advantages end. An OHV engine will be dimensionally smaller in height and width, lighter, more efficient, and have a lower CG than a DOHC engine due to lower parts count and fewer pieces rubbing together. The OHV engine will be cheaper to manufacture also because of lower parts count. And in the case of the new LT1, because of fewer holes in the combustion chamber, GM has more ability to optimize chamber shape, injector placement, and nozzle spray geometry than a 4-valve engine would allow.
A couple of points:
1. Efficiency factors in power output, not just fuel consumption. In this case, Coyote wins, and this goes against your 2nd sentence which stated that a 4-valve engine will always make more specific power than a 2-valve engine. For if that is the case, then the 4-valve engine will always be more efficient.
2. I will give you height and width. Weight? Completely depends on what the engines are made of as well as their components.
3. The Pent-roof design (4-valve and many 2-valve engines) is about as good as it gets regarding chamber design. The only design that was potentially better for maximum power output was the hemispherical chamber, but it gave up low RPM performance and offered poor combustion characteristics (read: it burned dirty) when engine speed was low enough that the swirl effect was not promoted.
I don't think that GM having the "ability to optimize chamber shape" here is really a benefit, especially if it appears to do nothing to increase power output, which, at this point in the game, we have nothing showing us that it does. Certainly at 450HP for a 6.2L "ground breaking" pushrod engine vs 444HP for a 5.0L DOHC engine that is now a few years old, it doesn't demonstrate this characteristic.
I think the big advantage here is that it (the pushrod architecture) is compact and easy to manufacture. And likely this is why GM continues to use it.
This engine makes approximately the same HP/L as the LS7, which was very impressive when that engine debuted. This is not the same achievement nor does it deserve the same same level of recognition that the LS7 garnered for that very reason.
It should also be noted that if there is a real driver present the Vettes I see at the strip consistently beat the new Coyotes on street tires.
OVERKILL
$100 Site Donor 2021
Originally Posted By: SteveSRT8
It should also be noted that if there is a real driver present the Vettes I see at the strip consistently beat the new Coyotes on street tires.
Given the weight difference between the cars, is this surprising?
It should also be noted that if there is a real driver present the Vettes I see at the strip consistently beat the new Coyotes on street tires.
Given the weight difference between the cars, is this surprising?
Nope, not to me. But it is to the many rabid Coyote fans there!
Remember I focus on trap speeds, not ET's.
Remember I focus on trap speeds, not ET's.
Originally Posted By: OVERK1LL
Originally Posted By: A_Harman
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
Yes. It depends on what aspect of engine performance you want to use for comparison. A 4-valve engine will always make more specific power than a 2-valve engine, but that's about where the advantages end. An OHV engine will be dimensionally smaller in height and width, lighter, more efficient, and have a lower CG than a DOHC engine due to lower parts count and fewer pieces rubbing together. The OHV engine will be cheaper to manufacture also because of lower parts count. And in the case of the new LT1, because of fewer holes in the combustion chamber, GM has more ability to optimize chamber shape, injector placement, and nozzle spray geometry than a 4-valve engine would allow.
A couple of points:
1. Efficiency factors in power output, not just fuel consumption. In this case, Coyote wins, and this goes against your 2nd sentence which stated that a 4-valve engine will always make more specific power than a 2-valve engine. For if that is the case, then the 4-valve engine will always be more efficient.
2. I will give you height and width. Weight? Completely depends on what the engines are made of as well as their components.
3. The Pent-roof design (4-valve and many 2-valve engines) is about as good as it gets regarding chamber design. The only design that was potentially better for maximum power output was the hemispherical chamber, but it gave up low RPM performance and offered poor combustion characteristics (read: it burned dirty) when engine speed was low enough that the swirl effect was not promoted.
I don't think that GM having the "ability to optimize chamber shape" here is really a benefit, especially if it appears to do nothing to increase power output, which, at this point in the game, we have nothing showing us that it does. Certainly at 450HP for a 6.2L "ground breaking" pushrod engine vs 444HP for a 5.0L DOHC engine that is now a few years old, it doesn't demonstrate this characteristic.
I think the big advantage here is that it (the pushrod architecture) is compact and easy to manufacture. And likely this is why GM continues to use it.
This engine makes approximately the same HP/L as the LS7, which was very impressive when that engine debuted. This is not the same achievement nor does it deserve the same same level of recognition that the LS7 garnered for that very reason.
1. When I say efficiency, I mean brake thermal efficiency and BSFC, measures which include the effect of engine friction. When I say specific output, I mean HP/cubic inch. It's all clear to me.
2. Oh come on, we both know that the LT1 and Coyote both have aluminum blocks and heads and plastic intake manifolds.
3. 4-valve pent-roof and classic 2-valve Hemi combustion chambers lead to port designs and valve sizes that are best at flowing air at high engine speeds, so they are good for specific output. But they inherently have lower swirl than 2-valve wedge or bathtub chambers, and require compromises in intake port design to generate tumble to make a fast-burn combustion chamber. In the case of the modern Hemi, Chrysler has gone to dual-spark and squish pads at the sides of the chamber to generate air motion to speed up the burn. The space inside a 4-valve chamber is so dominated by the valves that there is not much ability to place an injector without getting into cylinder wall or intake valve wetting problems. At this point, it becomes necessary to limit valve sizes to put in the injector, then specific output begins to suffer.
4. GM having the ability to optimize chamber shape is the major reason they pursued the redesign, judging by the amount of resources they put into optimizing the combustion system. Do you mean to say that they wasted their time? Remember, they have to improve CAFE if they want to sell cars, and DI is one major piece of the puzzle. Obviously, putting DI on the Corvette is only the start. The technology will spread to the rest of their OHV engines, especially trucks.
My point is that specific power output is only one aspect to look at when judging the "goodness" of an engine. You seem to only consider specific output.
Originally Posted By: A_Harman
Originally Posted By: Chrisfromalbany
am I wrong in comparing to the Coyote engine and not being too impressed?
Yes. It depends on what aspect of engine performance you want to use for comparison. A 4-valve engine will always make more specific power than a 2-valve engine, but that's about where the advantages end. An OHV engine will be dimensionally smaller in height and width, lighter, more efficient, and have a lower CG than a DOHC engine due to lower parts count and fewer pieces rubbing together. The OHV engine will be cheaper to manufacture also because of lower parts count. And in the case of the new LT1, because of fewer holes in the combustion chamber, GM has more ability to optimize chamber shape, injector placement, and nozzle spray geometry than a 4-valve engine would allow.
A couple of points:
1. Efficiency factors in power output, not just fuel consumption. In this case, Coyote wins, and this goes against your 2nd sentence which stated that a 4-valve engine will always make more specific power than a 2-valve engine. For if that is the case, then the 4-valve engine will always be more efficient.
2. I will give you height and width. Weight? Completely depends on what the engines are made of as well as their components.
3. The Pent-roof design (4-valve and many 2-valve engines) is about as good as it gets regarding chamber design. The only design that was potentially better for maximum power output was the hemispherical chamber, but it gave up low RPM performance and offered poor combustion characteristics (read: it burned dirty) when engine speed was low enough that the swirl effect was not promoted.
I don't think that GM having the "ability to optimize chamber shape" here is really a benefit, especially if it appears to do nothing to increase power output, which, at this point in the game, we have nothing showing us that it does. Certainly at 450HP for a 6.2L "ground breaking" pushrod engine vs 444HP for a 5.0L DOHC engine that is now a few years old, it doesn't demonstrate this characteristic.
I think the big advantage here is that it (the pushrod architecture) is compact and easy to manufacture. And likely this is why GM continues to use it.
This engine makes approximately the same HP/L as the LS7, which was very impressive when that engine debuted. This is not the same achievement nor does it deserve the same same level of recognition that the LS7 garnered for that very reason.
1. When I say efficiency, I mean brake thermal efficiency and BSFC, measures which include the effect of engine friction. When I say specific output, I mean HP/cubic inch. It's all clear to me.
2. Oh come on, we both know that the LT1 and Coyote both have aluminum blocks and heads and plastic intake manifolds.
3. 4-valve pent-roof and classic 2-valve Hemi combustion chambers lead to port designs and valve sizes that are best at flowing air at high engine speeds, so they are good for specific output. But they inherently have lower swirl than 2-valve wedge or bathtub chambers, and require compromises in intake port design to generate tumble to make a fast-burn combustion chamber. In the case of the modern Hemi, Chrysler has gone to dual-spark and squish pads at the sides of the chamber to generate air motion to speed up the burn. The space inside a 4-valve chamber is so dominated by the valves that there is not much ability to place an injector without getting into cylinder wall or intake valve wetting problems. At this point, it becomes necessary to limit valve sizes to put in the injector, then specific output begins to suffer.
4. GM having the ability to optimize chamber shape is the major reason they pursued the redesign, judging by the amount of resources they put into optimizing the combustion system. Do you mean to say that they wasted their time? Remember, they have to improve CAFE if they want to sell cars, and DI is one major piece of the puzzle. Obviously, putting DI on the Corvette is only the start. The technology will spread to the rest of their OHV engines, especially trucks.
My point is that specific power output is only one aspect to look at when judging the "goodness" of an engine. You seem to only consider specific output.
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I like BOTH powerplants, and I REFUSE to get into a Blue Oval vs. Bowtie war.
That being said, given material and displacement similarities, the single in block cam, overhead, 2 valve per cylinder deal will ALWAYS have lower weight, and as previously stated, a lower center of gravity, and possibly a lower internal coefficient of friction.
That being said, given material and displacement similarities, the single in block cam, overhead, 2 valve per cylinder deal will ALWAYS have lower weight, and as previously stated, a lower center of gravity, and possibly a lower internal coefficient of friction.
Technologically dated but I guess it still works.
The trend these days seems to be smaller displacement and forced induction, but GM doesn't really follow trends. They are the only company out their still using push rod V8's.
The trend these days seems to be smaller displacement and forced induction, but GM doesn't really follow trends. They are the only company out their still using push rod V8's.
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