engineermike

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It’s quite obvious they don’t care about hp/L, but if they do in fact want to reduce displacement while maintaining competitive power, then you can’t avoid the math.





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Elp_jc

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GM already has a 5.5L DOHC V8
Which car is using it? If none, then it's like it doesn't exist, since it might never make it to production. Never heard of that engine before.
 

martinjlm

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Which car is using it? If none, then it's like it doesn't exist, since it might never make it to production. Never heard of that engine before.
So far it is the engine in the C8.R, the racing version of the new Corvette. It is also expected to be used in the C8 Z06 (naturally aspirated) and ZR1 (twin turbo).

C8 Z06 Engine

Ironically I am at this very minute working on my forecast for GM engines. I have both those engines in my forecast. Equally interesting.... as I look at each of GM's engine products and develop the forecast for them, GM's small block V8 is expected to be the 2nd highest volume engine in their portfolio through the current decade, possibly longer.
 

martinjlm

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It’s quite obvious they don’t care about hp/L, but if they do in fact want to reduce displacement while maintaining competitive power, then you can’t avoid the math.
True, but the thing is, reducing displacement is a result, not a goal, EXCEPT in markets that tax for displacement. GM has all but pulled out of Europe, so that's no longer an issue. Engines used in China are made in China, so that is also not really an issue. The US doesn't tax displacement, so GM's focus is to be power and fuel economy competitive in each segment in which it competes. The displacement will be what it is. They have 1.2 and 1.3L engines in Trax and Trailblazer and 6.2L engines in Camaros, Corvettes, and trucks. In none of these situations do they really care what the displacement of their direct competitors may be. Just the performance and fuel economy.
 

engineermike

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@martinjlm I understand completely. Where I’m stuck is when comparing the 2020 truck 5.0 vs 5.3 v8, the epa mpg is identical but the 5.3 is down 40 hp and 17 ftlb. I’m struggling to understand gm’s next move. It would be tough to match ford’s power and torque without either adding valves or displacement, but adding displacement will undoubtedly put them at an mpg disadvantage.

Yes gm doesn’t care about power/displacement, as they shouldn’t, because it doesn’t matter at the end of the day. But the march towards more power and better mpg usually pushes displacement down and competition pushes power up.
 

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Reliability? particularly in the commercial and semi commercial (or whatever you call hot shoters).

Big displacement, low mpg million mile lasting engines must have a place in someone's heart?
 

Norm Peterson

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Reliability? particularly in the commercial and semi commercial (or whatever you call hot shoters).

Big displacement, low mpg million mile lasting engines must have a place in someone's heart?
I think they're called truck drivers. The kind that puts their trucks to honest, hard work as opposed to image-building.


Norm
 

Erik427

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^^^ I'm more expecting GM to bring their engines down in displacement to more closely match Ford . . . no, that doesn't fit the 'more's better, too much is just enough' mindset very well, though.


Norm
Been thinking that for years since almost all the competition is well below 6 liters.
On another note, I don't see the LT going away anytime soon.

Then we have the 1/2 ton trucks.......
 

martinjlm

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@martinjlm I understand completely. Where I’m stuck is when comparing the 2020 truck 5.0 vs 5.3 v8, the epa mpg is identical but the 5.3 is down 40 hp and 17 ftlb. I’m struggling to understand gm’s next move. It would be tough to match ford’s power and torque without either adding valves or displacement, but adding displacement will undoubtedly put them at an mpg disadvantage.

Yes gm doesn’t care about power/displacement, as they shouldn’t, because it doesn’t matter at the end of the day. But the march towards more power and better mpg usually pushes displacement down and competition pushes power up.
GM has already shown their hand here. Cylinder Deactivation. First there was Active Fuel Management (AFM) which shuts down the same four cylinders under light load. For a while it was only available on the old 6.0L, then when that went away, the 5.3L. Then they added it to the 6.2L and made it more aggressive. Even my Camaro's LT1 engine has it. I've seen my car doing 80+ mph running in V4 mode.

Now they are in the process of replacing AFM with Dynamic Fuel Management (DFM). DFM has each individual cylinder making a "fire / don't fire" decision on every engine cycle. In theory, the engine can deactivate up to 7 cylinders at the same time. This is available on 5.3L and 6.2L engines.
 

martinjlm

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The 7.3 and it's variants will be much cheaper to build.
Demand will decide who lives and dies when it comes to these engine families.

There are early rumors of a alloy smaller displacement version of the 7.3, only time will tell.

I can say it's been since 1973.........Time to match gm in displacement.
Absolutely! Part of the reason for Ford to make them OHV instead of OHC and CI instead of aluminum. The other reason being usable low end torque. For trucks. Big trucks.

Here is the southern Detroit Metro topography, showing location of Ford's engine plants. From some floors at GM HQ you can actually see both plants. If Ford wanted the 6.8L to be an alloy block F150 / Mustang motor, they would have put it in the same plant that today builds alloy block F150 /Mustang motors. Instead, they put it in the same plant that builds the cast iron block Super Duty motor. It's gonna be a cast iron block Super Duty motor.
Ford Engine Plants in Ontario.jpg


Fun facts....Belle Isle is the location for the Detroit Grand Prix. And yes, Canada is actually SOUTH of Detroit in this area.
 
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Hi-PO Stang

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As I understand, the new Corvette is using a 5.5 liter Flat Plane Crank engine in the current C8 Corvette race car. I try to listen for the difference in sound of the FPC engine but can not detect a difference over the other race engines. I wait for someone to say during racing coverage that the new Vette is using a FPC engine but do not hear mention of a FPC engine. Ford was known to have produced a larger displacement engine than other FPC car builders. If the Corvette race car has a FPC engine , it appears to be quite durable. If it is so difficult to work around the vibration issues of a large displacement FPC V8 , what have the Corvette engineers done to make the engine durable in long distance races ?
 

Norm Peterson

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As I understand, the new Corvette is using a 5.5 liter Flat Plane Crank engine in the current C8 Corvette race car. I try to listen for the difference in sound of the FPC engine but can not detect a difference over the other race engines. I wait for someone to say during racing coverage that the new Vette is using a FPC engine but do not hear mention of a FPC engine. Ford was known to have produced a larger displacement engine than other FPC car builders. If the Corvette race car has a FPC engine , it appears to be quite durable. If it is so difficult to work around the vibration issues of a large displacement FPC V8 , what have the Corvette engineers done to make the engine durable in long distance races ?
At a guess, lightweight forged pistons and a substantially oversquare bore to stroke arrangement. The Voodoo is essentially a 'square' design at 94 mm bore x 93 mm stroke.


Norm
 

Erik427

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As I understand, the new Corvette is using a 5.5 liter Flat Plane Crank engine in the current C8 Corvette race car. I try to listen for the difference in sound of the FPC engine but can not detect a difference over the other race engines. I wait for someone to say during racing coverage that the new Vette is using a FPC engine but do not hear mention of a FPC engine. Ford was known to have produced a larger displacement engine than other FPC car builders. If the Corvette race car has a FPC engine , it appears to be quite durable. If it is so difficult to work around the vibration issues of a large displacement FPC V8 , what have the Corvette engineers done to make the engine durable in long distance races ?
My guess would be larger bore spacing, thus larger bores, thus allowing a shorter stroke.
The length of the stroke is the problem with a FPC.
 

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