LT5: If the GM LF3 were 6.2L.... 725hp!
01-10-2017, 05:21 AM
#41
01-10-2017, 09:49 AM
#42
Team Owner
The LT series engines are the abnormality.
Last edited by JoesC5; 01-10-2017 at 10:59 AM.
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01-10-2017, 05:32 PM
#44
01-10-2017, 05:38 PM
#45
Safety Car
My memory is fading, but I seem to recall people posting that their Z06's were going into limp home mode when they are doing rolls on the street.
Do you believe that I never go over 20% throttle in my supercharged Mercedes or that I never run the twisties through the Ozark mountains in my Mercedes(pushing it pretty hard playing around)?
If you do, then you are sorely mistaken.
I didn't get a supercharged Mercedes sedan because I was planning to drive like a soccer mom(or her 16 year old son) in her Honda Minivan.
I purchased my Mercedes supercharged sedan long before Dodge came out with their supercharged Charger Hellcat. Today, the Hellcat would be a great 4 door sedan for high performance street duties that I would seriously consider as a replacement for my Mercedes. A friend has one, and is extremely happy with it. I sure don't hear of overheating when the Hellcat owners are pushing their cars to the limits(either on the street or on the track).
As for overheating in supercharged Corvettes, several of my friends have them(700 bhp C6 GS with a Maggie, cam, long tubes), and a Callaway C6 GS with 606 bhp, and a C6 GS with a 599 bhp E-Force, and a C6 ZR1 with 638 bhp. They don't have overheating problems.
Other brands have gotten it right, but not Chevrolet with their C7 Z06. That's why GM made some changes in the 2017 Z06 to address some of those overheating problems. We still don't know how effective those changes are.
I feel pretty damn good driving my three Corvettes(one being a C6 Z06 that doesn't overheat) or my supercharged Mercedes sedan(that doesn't overheat). How do you feel driving your mom's minivan(that doesn't overheat)?
Do you believe that I never go over 20% throttle in my supercharged Mercedes or that I never run the twisties through the Ozark mountains in my Mercedes(pushing it pretty hard playing around)?
If you do, then you are sorely mistaken.
I didn't get a supercharged Mercedes sedan because I was planning to drive like a soccer mom(or her 16 year old son) in her Honda Minivan.
I purchased my Mercedes supercharged sedan long before Dodge came out with their supercharged Charger Hellcat. Today, the Hellcat would be a great 4 door sedan for high performance street duties that I would seriously consider as a replacement for my Mercedes. A friend has one, and is extremely happy with it. I sure don't hear of overheating when the Hellcat owners are pushing their cars to the limits(either on the street or on the track).
As for overheating in supercharged Corvettes, several of my friends have them(700 bhp C6 GS with a Maggie, cam, long tubes), and a Callaway C6 GS with 606 bhp, and a C6 GS with a 599 bhp E-Force, and a C6 ZR1 with 638 bhp. They don't have overheating problems.
Other brands have gotten it right, but not Chevrolet with their C7 Z06. That's why GM made some changes in the 2017 Z06 to address some of those overheating problems. We still don't know how effective those changes are.
I feel pretty damn good driving my three Corvettes(one being a C6 Z06 that doesn't overheat) or my supercharged Mercedes sedan(that doesn't overheat). How do you feel driving your mom's minivan(that doesn't overheat)?
I can't take anyone who praises Mercedes sedans for sportiness seriously. These remarks say far more than you think about how hard you drive. Mercedes for the most part (except one model in any year) builds anti-sports cars. Luxury barges that create a complete disconnect between the driver and the environment. Great luxury cars, terrible as sports cars. If the corvette is a sports car with a hint of luxury Mercedes is a luxury car with a hint of sports car. Nothing more.
01-10-2017, 07:27 PM
#46
My memory is fading,
01-10-2017, 09:26 PM
#47
When GM introduced the LS1, I was surprised that it was still a pushrod engine, then I read where they were working on camless engine that used electronic valve activation and I thought that the next step would bypass cams completely. Apparently not.
Now or I see where Koenigsegg (sp?) is close to selling a pneumatic, hydraulic, electric valve control system that eliminates the cam, cam sprocket and chain, throttle body, and some othet stuff on their 4 cylinder test engine.
They are claiming a 47% increase in peak hp and a 45% increase in peak torque with a much broader curve, along with a 35% decrease in emissions.
It it goes without saying that these gains are far more than you would expect than just going from OHV to OHC.
I wonder if if all the references to the LT5 DOHC engine are just a smokescreen for something more radical?
Now or I see where Koenigsegg (sp?) is close to selling a pneumatic, hydraulic, electric valve control system that eliminates the cam, cam sprocket and chain, throttle body, and some othet stuff on their 4 cylinder test engine.
They are claiming a 47% increase in peak hp and a 45% increase in peak torque with a much broader curve, along with a 35% decrease in emissions.
It it goes without saying that these gains are far more than you would expect than just going from OHV to OHC.
I wonder if if all the references to the LT5 DOHC engine are just a smokescreen for something more radical?
01-10-2017, 09:35 PM
#48
Safety Car
When GM introduced the LS1, I was surprised that it was still a pushrod engine, then I read where they were working on camless engine that used electronic valve activation and I thought that the next step would bypass cams completely. Apparently not.
Now or I see where Koenigsegg (sp?) is close to selling a pneumatic, hydraulic, electric valve control system that eliminates the cam, cam sprocket and chain, throttle body, and some othet stuff on their 4 cylinder test engine.
They are claiming a 47% increase in peak hp and a 45% increase in peak torque with a much broader curve, along with a 35% decrease in emissions.
It it goes without saying that these gains are far more than you would expect than just going from OHV to OHC.
I wonder if if all the references to the LT5 DOHC engine are just a smokescreen for something more radical?
Now or I see where Koenigsegg (sp?) is close to selling a pneumatic, hydraulic, electric valve control system that eliminates the cam, cam sprocket and chain, throttle body, and some othet stuff on their 4 cylinder test engine.
They are claiming a 47% increase in peak hp and a 45% increase in peak torque with a much broader curve, along with a 35% decrease in emissions.
It it goes without saying that these gains are far more than you would expect than just going from OHV to OHC.
I wonder if if all the references to the LT5 DOHC engine are just a smokescreen for something more radical?
GM has to make a cheap engine. There is no way it's going to be ahead of the curve by a generation or two. What we will see is basic cam phasing like in the LT4 except with DOHC it's easy to make independent intake/exhaust phasing. It will come with proper casting and coatings and there will be some clever design to improve packaging in small engine bays. That's basically it, and output will be just over 100 hp/L but nowhere near 130 hp/L where top engines are NA.
01-10-2017, 10:11 PM
#49
GM has to make a cheap engine. There is no way it's going to be ahead of the curve by a generation or two. What we will see is basic cam phasing like in the LT4 except with DOHC it's easy to make independent intake/exhaust phasing. It will come with proper casting and coatings and there will be some clever design to improve packaging in small engine bays. That's basically it, and output will be just over 100 hp/L but nowhere near 130 hp/L where top engines are NA.
01-10-2017, 11:20 PM
#50
Safety Car
https://en.wikipedia.org/wiki/Hyundai_Gamma_engine
It probably cost way more money to develop the single CVVT on the LT1 because no one other than GM has this particular design in a pushrod engine.
With DOHC GM has to vary lift at least discretely or have a multiple stage intake manifold to make a wave.
01-11-2017, 05:25 AM
#51
If designing from scratch then GM would do a much more elegant solution. Not to mention if TT from the outset the intake and exhaust geometry would be different. See the Ford ecoboost engines with the intergrated exhaust manifolds for example!
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01-11-2017, 09:21 AM
#52
Racer
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Alternatively, let's think about what this car needs to be a successful "top dog" corvette and deserve the LT5 moniker:
750 hp. Minimum.
Anything less than that is peanuts over the Z06 and too close to the Hellcat. Regardless of how they do it, I predict 750 or more for purely business reasons.
750 hp. Minimum.
Anything less than that is peanuts over the Z06 and too close to the Hellcat. Regardless of how they do it, I predict 750 or more for purely business reasons.
01-11-2017, 12:05 PM
#53
Team Owner
[QUOTE=SBC_and_a_stick;1593839907]GM has to make a cheap engine. There is no way it's going to be ahead of the curve by a generation or two. What we will see is basic cam phasing like in the LT4 except with DOHC it's easy to make independent intake/exhaust phasing. It will come with proper casting and coatings and there will be some clever design to improve packaging in small engine bays. That's basically it, and output will be just over 100 hp/L but nowhere near 130 hp/L where top engines are NA.[/QUOTE
Who says GM has to make a cheap engine for their expensive sports car?
The LS7 sure wasn't cheap nor was the LS9.
Actually, if GM were trying to increase profits they would use a so called "cheap" OHV engine in all the hundreds of thousands of $15,000-$30,000 cars they build each year, instead of the so called "expensive" DOHC engines they do use in those "cheap" cars. That's where the competition is and where very dollar saved per car is multiplied by hundreds of thousands of car instead of the low volume Corvette engine.
Who says GM has to make a cheap engine for their expensive sports car?
The LS7 sure wasn't cheap nor was the LS9.
Actually, if GM were trying to increase profits they would use a so called "cheap" OHV engine in all the hundreds of thousands of $15,000-$30,000 cars they build each year, instead of the so called "expensive" DOHC engines they do use in those "cheap" cars. That's where the competition is and where very dollar saved per car is multiplied by hundreds of thousands of car instead of the low volume Corvette engine.
Last edited by JoesC5; 01-11-2017 at 12:07 PM.
01-11-2017, 01:46 PM
#54
Safety Car
[QUOTE=JoesC5;1593843210]
History and market research. Basically everything.
Expensive sports car? Really? A Miata with a differential is $30K and that's THE entry level sports car. Corvettes can be had for $50K.
Expensive engine? $13k for an LS7 or $16.5K for an LT4 is crazy cheap in this line of work where the next comparable engine is $50K. How much is a BMW or Merc V8, even the entry level ones that don't compete?
They use DOHC engines in cheap cars because OHVs lose their advantage once you move away from at least a V6 configuration. The pushrod advantage is packaging and low cost for heavy duty and performance applications. It is a terrible choice in an economy car.
Here, I did the work. The 414hp BMW V8 NA costs $24K to replace. That's more than any small block V8 Chevy ever sold:
01 Rmfd short engine S65B40A 1 11000442124 $23,885.95 +core
http://www.m3post.com/forums/showthread.php?p=14568306
GM has to make a cheap engine. There is no way it's going to be ahead of the curve by a generation or two. What we will see is basic cam phasing like in the LT4 except with DOHC it's easy to make independent intake/exhaust phasing. It will come with proper casting and coatings and there will be some clever design to improve packaging in small engine bays. That's basically it, and output will be just over 100 hp/L but nowhere near 130 hp/L where top engines are NA.[/QUOTE
Who says GM has to make a cheap engine for their expensive sports car?
The LS7 sure wasn't cheap nor was the LS9.
Actually, if GM were trying to increase profits they would use a so called "cheap" OHV engine in all the hundreds of thousands of $15,000-$30,000 cars they build each year, instead of the so called "expensive" DOHC engines they do use in those "cheap" cars. That's where the competition is and where very dollar saved per car is multiplied by hundreds of thousands of car instead of the low volume Corvette engine.
Who says GM has to make a cheap engine for their expensive sports car?
The LS7 sure wasn't cheap nor was the LS9.
Actually, if GM were trying to increase profits they would use a so called "cheap" OHV engine in all the hundreds of thousands of $15,000-$30,000 cars they build each year, instead of the so called "expensive" DOHC engines they do use in those "cheap" cars. That's where the competition is and where very dollar saved per car is multiplied by hundreds of thousands of car instead of the low volume Corvette engine.
Expensive sports car? Really? A Miata with a differential is $30K and that's THE entry level sports car. Corvettes can be had for $50K.
Expensive engine? $13k for an LS7 or $16.5K for an LT4 is crazy cheap in this line of work where the next comparable engine is $50K. How much is a BMW or Merc V8, even the entry level ones that don't compete?
They use DOHC engines in cheap cars because OHVs lose their advantage once you move away from at least a V6 configuration. The pushrod advantage is packaging and low cost for heavy duty and performance applications. It is a terrible choice in an economy car.
Here, I did the work. The 414hp BMW V8 NA costs $24K to replace. That's more than any small block V8 Chevy ever sold:
01 Rmfd short engine S65B40A 1 11000442124 $23,885.95 +core
http://www.m3post.com/forums/showthread.php?p=14568306
Last edited by SBC_and_a_stick; 01-11-2017 at 01:58 PM.
01-11-2017, 07:07 PM
#55
The point I was trying to make is, if a little company like Koenigsegg is on the verge of introducing the cam-less valve actuators and GM itself may have been working on this technology since the 90's you would think it is getting pretty close.
Developing a new engine has to cost billions of dollars in new investment. The reason the LS and LT engines can be priced economically is because the same basic architecture can be spread out over a number of different cars and trucks.
If they spend billions to develop a brand new DOHC engine for a limited production car and shortly afterwards a new technology is introduced which obsoletes their new engine, it's going to a sad day in the board room.
Developing a new engine has to cost billions of dollars in new investment. The reason the LS and LT engines can be priced economically is because the same basic architecture can be spread out over a number of different cars and trucks.
If they spend billions to develop a brand new DOHC engine for a limited production car and shortly afterwards a new technology is introduced which obsoletes their new engine, it's going to a sad day in the board room.
01-11-2017, 07:29 PM
#56
Le Mans Master
Thread Starter
^^^ Do you have any idea how many times over the years camless and valveless motors have been "just about ready for production" only to never make it to market?
Here's one from 1928: https://books.google.com/books?id=zt...0motor&f=false
But otherwise I agree, and it's why I figured the LT5 should share parts with the LF motors. Basically adding another 2 cylinders of displacement means not reinventing any wheels, tons of parts sharing for valvetrain, and so on.
Otherwise, like you said, I don't think the Corvette market alone merits the development of a special engine. It's just too few units unless done as a marketing exercise.
Sure, but that price is for a very select market: people who have blown their motors and have no other choice. Since GM sells its engines through the GMPP (or whatever) performance channel they have to have a reasonable MSRP. For manufacturers that never sell direct to consumer they can sell to themselves (via warranty) at whatever price they see fit. And the very few folks that have to buy a motor direct from BMW are probably doing it as part of an insurance claim!
Here's one from 1928: https://books.google.com/books?id=zt...0motor&f=false
But otherwise I agree, and it's why I figured the LT5 should share parts with the LF motors. Basically adding another 2 cylinders of displacement means not reinventing any wheels, tons of parts sharing for valvetrain, and so on.
Otherwise, like you said, I don't think the Corvette market alone merits the development of a special engine. It's just too few units unless done as a marketing exercise.
BMW V8 NA costs $24K to replace. That's more than any small block V8 Chevy ever sold
Last edited by davepl; 01-11-2017 at 07:36 PM.
01-11-2017, 07:45 PM
#57
Safety Car
The point I was trying to make is, if a little company like Koenigsegg is on the verge of introducing the cam-less valve actuators and GM itself may have been working on this technology since the 90's you would think it is getting pretty close.
Developing a new engine has to cost billions of dollars in new investment. The reason the LS and LT engines can be priced economically is because the same basic architecture can be spread out over a number of different cars and trucks.
If they spend billions to develop a brand new DOHC engine for a limited production car and shortly afterwards a new technology is introduced which obsoletes their new engine, it's going to a sad day in the board room.
Developing a new engine has to cost billions of dollars in new investment. The reason the LS and LT engines can be priced economically is because the same basic architecture can be spread out over a number of different cars and trucks.
If they spend billions to develop a brand new DOHC engine for a limited production car and shortly afterwards a new technology is introduced which obsoletes their new engine, it's going to a sad day in the board room.
To design the C7 GM got a few hundred million dollars. I don't think you are in the right neighborhood. That's a lot of designing for a quarter billion.
Most engines are obsolete out of the dealer. Consider Honda's variable lift technology. There are still only a handful of cars that can vary lift. consider them obsolete by that token.
The reality is that mass produced cars are higher quality than exotics. What you don't get in fancy composites you get three fold in engineering quality. The reality of most production engines is that they are built to be profitable, and no engine was ever at the top of the game. There are literally dozens of patents on pushrod VVT that never made it to production. Either they cost too much, they wear down too fast, they don't make NVH thresholds or something else.
01-11-2017, 08:12 PM
#58
Comparing the business model of Koenigsegg to GM is really apples-to-oranges.
Other than building cars with 4 wheels, I see don't any parallel between them.
FWIW, I have read much info and watched many videos illustrating what Christian von Koenigsegg has done with his company and it really is inspiring/jaw-dropping.
He does beat the odds regularly and make technologically advanced cars no one really thought possible for a manufacturer his size.
Other than building cars with 4 wheels, I see don't any parallel between them.
FWIW, I have read much info and watched many videos illustrating what Christian von Koenigsegg has done with his company and it really is inspiring/jaw-dropping.
He does beat the odds regularly and make technologically advanced cars no one really thought possible for a manufacturer his size.
01-12-2017, 01:48 PM
#59
[QUOTE=DAVE396LT1;1593846641]^^^ Do you have any idea how many times over the years camless and valveless motors have been "just about ready for production" only to never make it to market?
No, how many?
No, how many?
01-12-2017, 01:52 PM
#60
Le Mans Master
Thread Starter
At least 5 times (which OK, I grant, is not a lot) that I know of, and certainly many more. I've seen pneumatic, hydraulic-pneumatic, and a couple of electromagnetic solutions, plus one that looked really cool with "spheres with holes rotating in a cavity" that looked really smart.
If I were a conspiracy nut I'd assume they were all run out of business by "big oil" or some such thing, but I think it's just hard to displace proven tech.
There are opportunities in things like the Chevy Volt where you can design a motor to run at a particular load/rpm window for recharging, I think. Those motors don't have to contend with the same wide range of operating conditions that a wheel-driving motor has to, so they can get a little more "out there" in the designs.
If I were a conspiracy nut I'd assume they were all run out of business by "big oil" or some such thing, but I think it's just hard to displace proven tech.
There are opportunities in things like the Chevy Volt where you can design a motor to run at a particular load/rpm window for recharging, I think. Those motors don't have to contend with the same wide range of operating conditions that a wheel-driving motor has to, so they can get a little more "out there" in the designs.