Why Did They Let Them Do It?
Thread Starter
Heel & Toe
Joined: Sep 2022
Posts: 24
Likes: 7
Why Did They Let Them Do It?
I think the new LS6 engine is a very rare automotive event. Historic in fact! I plan to take full advantage, waiting for my build date for a 27 Stingray. Take the 13 to 1 compression ratio. Its a standard hot rod move. Everyone knows the benefits. Everyone has known forever that you need more than pump gas to use it. The Corvette team said we want to use it so lets work on the octane problem and find a way for pump gas to work. And they did! Why did the bean counters let them do it? It cost money to find the answer and will cost money in production on going. They could have told them to make due with a lower number. I think the $billion problem that is the 6.2 engine is paved the way to produce the best product they could despite the cost.
Le Mans Master
Joined: Jan 2007
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From: Omaha NE
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The compression ratio in my '21 Camry SE is also 13:1...
Burning Brakes
Joined: May 2005
Posts: 1,091
Likes: 35
From: Coldville
The Hot rod Move was to Increase Displacement IMO.
Increase Bore and Stroke Instead of adding Cams or adding Valves and the cheapest to the 6.2.
They may have had it ready in R&D back when the C8 was introduced but instead used the 6.2 to save money, then bring it out
after a couple years.
But what do I know I'm just speculating.
Increase Bore and Stroke Instead of adding Cams or adding Valves and the cheapest to the 6.2.
They may have had it ready in R&D back when the C8 was introduced but instead used the 6.2 to save money, then bring it out
after a couple years.
But what do I know I'm just speculating.
Drifting
Joined: Sep 2022
Posts: 1,395
Likes: 1,077
I think the new LS6 engine is a very rare automotive event. Historic in fact! I plan to take full advantage, waiting for my build date for a 27 Stingray. Take the 13 to 1 compression ratio. Its a standard hot rod move. Everyone knows the benefits. Everyone has known forever that you need more than pump gas to use it. The Corvette team said we want to use it so lets work on the octane problem and find a way for pump gas to work. And they did! Why did the bean counters let them do it? It cost money to find the answer and will cost money in production on going. They could have told them to make due with a lower number. I think the $billion problem that is the 6.2 engine is paved the way to produce the best product they could despite the cost.
The higher the compression ratio the higher the efficiency.
I'm disappointed that they only got 40 more HP from the new engine, but I guess they were aiming mostly for higher torque, since they got 50 more foot pounds.
6.7 will be a great engine for the pickup/SUV crowd.
Race Director
Joined: Oct 2008
Posts: 16,648
Likes: 7,719
From: NJ
As long as they can make the mpg and emissions numbers work they will do whatever needs to be done whether it's head design, compressiin, or displacement increase.
The reason we had a C7Z that used a sc was because the technology at the time of development wouldnt allow them to make another 7.0 ish engine and pass emissions.
The LS6 exists because it's cheaper than going dohc and they can meet the emissions/mpg target while making alot more power.
The reason we had a C7Z that used a sc was because the technology at the time of development wouldnt allow them to make another 7.0 ish engine and pass emissions.
The LS6 exists because it's cheaper than going dohc and they can meet the emissions/mpg target while making alot more power.
Melting Slicks
Joined: Jan 2006
Posts: 2,298
Likes: 1,860
From: Oregon
13/1 is the Static Compression ratio. That is calculated from BDC to TDC.
On the compression upstroke, the intake valve is closing but not completely closed at BDC.
The cylinder does not start making compression until the intake valve is completely closed, so that totally changes the calculation.
When you use intake valve timing in the calculation, that is called Dynamic Compression. That is the accurate way to determine compression ratio.
Modern engines have something called the Atkinson (?) cycle. They leave the intake valve open longer because that makes more power.
That changes the dynamic compression ratio. Static compression is still the same because it does not consider the valve timing.
In the old days you would need high octane race fuel to run 13/1, but with direct fuel injection, digital spark timing, and intake valve timing, it's a different world.
With a longer intake valve duration, you may think you have 13/1 compression, but the accurate dynamic compression number is way less.
On the compression upstroke, the intake valve is closing but not completely closed at BDC.
The cylinder does not start making compression until the intake valve is completely closed, so that totally changes the calculation.
When you use intake valve timing in the calculation, that is called Dynamic Compression. That is the accurate way to determine compression ratio.
Modern engines have something called the Atkinson (?) cycle. They leave the intake valve open longer because that makes more power.
That changes the dynamic compression ratio. Static compression is still the same because it does not consider the valve timing.
In the old days you would need high octane race fuel to run 13/1, but with direct fuel injection, digital spark timing, and intake valve timing, it's a different world.
With a longer intake valve duration, you may think you have 13/1 compression, but the accurate dynamic compression number is way less.
Last edited by C5racecar; May 24, 2026 at 02:44 AM.
Melting Slicks
Joined: Aug 2000
Posts: 2,415
Likes: 1,184
From: Early 2020 Z51 Coupe, Original Owner, Ahwatukee Foothills, AZ
It's great having the a new C8 engine that brings an additional 40hp. But before we go and anoint the LS6 as being a "very rare automotive event", for that determination we should let this engine arrive to the public and consumers.
Biggest issue for the performance guys is the next-generation Gen VI LS6 which powers the 2027 Corvette Stingray, Grand Sport, and Grand Sport X will be that this engine utilizes a brand-new, GM-developed engine control module, the E94. For tuning on the GM E99 it took 4 years to crack the LT2 ECU. If we assume the same for the LT6, we still have a long way to go! This new engine will also not have a lot of bolt on mod availability the first year or two.
However, some do and some don't like any oem changes and fully understand this doesn't matter to some owners who prefer to keep their C8's performance completely stock, but also at the same time prefer cosmetic mods.
Biggest issue for the performance guys is the next-generation Gen VI LS6 which powers the 2027 Corvette Stingray, Grand Sport, and Grand Sport X will be that this engine utilizes a brand-new, GM-developed engine control module, the E94. For tuning on the GM E99 it took 4 years to crack the LT2 ECU. If we assume the same for the LT6, we still have a long way to go! This new engine will also not have a lot of bolt on mod availability the first year or two.
However, some do and some don't like any oem changes and fully understand this doesn't matter to some owners who prefer to keep their C8's performance completely stock, but also at the same time prefer cosmetic mods.
Last edited by ArizonaZ06; May 22, 2026 at 06:02 PM.
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Melting Slicks
Joined: Jun 2007
Posts: 2,686
Likes: 1,808
From: Myrtle Beach SC/Charlotte NC
Race Director
Joined: Mar 2007
Posts: 11,373
Likes: 8,530
13/1 is the static compression ratio. That is calculated from BDC to TDC.
That calculation does not consider the closing of the intake valve.
On the compression stroke, the cylinder does not start making compression until the intake valve is closed, so that totally changes the calculation.
Modern engines have something called the Atkinson (?) cycle. They leave the intake valve open longer because that makes more power.
There is a lot I don't understand there, but I think that is why we are seeing higher compression numbers. Static compression is not the whole story.
In the old days you would need high octane race fuel to run 13/1, but with direct fuel injection, digital spark timing, and intake valve timing, it's a different world
That calculation does not consider the closing of the intake valve.
On the compression stroke, the cylinder does not start making compression until the intake valve is closed, so that totally changes the calculation.
Modern engines have something called the Atkinson (?) cycle. They leave the intake valve open longer because that makes more power.
There is a lot I don't understand there, but I think that is why we are seeing higher compression numbers. Static compression is not the whole story.
In the old days you would need high octane race fuel to run 13/1, but with direct fuel injection, digital spark timing, and intake valve timing, it's a different world
I was gonna add, regarding effective compression and valve timeing, that it has VVT, but it looks like it does not have that. I could not find anything saying it does. The LT2 does have VVT.
Safety Car
Joined: Jun 2002
Posts: 4,750
Likes: 2,497
From: Buckeye, AZ
St. Jude Donor '12-'13
I really suspect LS6 was designated for C9 but finished development early, and GM felt it would be advantageous to release it now to kick up sales. For me that is not enough to make me go buy a new C8 as the LT2 is so damn quick as it is. HP is top end and most C8 drivers I know rarely go faster than 85mph. Lol I will hang tough for C9.
Racer
Joined: Oct 2024
Posts: 483
Likes: 416
From: Old Dominion
I really suspect LS6 was designated for C9 but finished development early, and GM felt it would be advantageous to release it now to kick up sales. For me that is not enough to make me go buy a new C8 as the LT2 is so damn quick as it is. HP is top end and most C8 drivers I know rarely go faster than 85mph. Lol I will hang tough for C9.
Last edited by ZORANGE; May 23, 2026 at 12:12 PM.
Melting Slicks
Joined: Jan 2006
Posts: 2,298
Likes: 1,860
From: Oregon
Biggest issue for the performance guys is the next-generation Gen VI LS6 which powers the 2027 Corvette Stingray, Grand Sport, and Grand Sport X will be that this engine utilizes a brand-new, GM-developed engine control module, the E94. For tuning on the GM E99 it took 4 years to crack the LT2 ECU. If we assume the same for the LT6, we still have a long way to go! This new engine will also not have a lot of bolt on mod availability the first year or two.
However, some do and some don't like any oem changes and fully understand this doesn't matter to some owners who prefer to keep their C8's performance completely stock, but also at the same time prefer cosmetic mods.
However, some do and some don't like any oem changes and fully understand this doesn't matter to some owners who prefer to keep their C8's performance completely stock, but also at the same time prefer cosmetic mods.
Sad but true. I had HP Tuners for my C5 LS3 big cam racecar and it was a blast to tune. Computer was unlocked, tuning was interesting.It is unfortunate that C8 computers are locked and it costs $1200 (?) to unlock. Tuning software is not cheap. For a stock engine there is not much to gain but if you have
a lot of engine mods, tuning really pays off.