LS1LT1

It has happened of course but I don't know if I'd call it a lot or often, especially bone stock ones.
I know of cases of it happening on modified ones but that's an entirely different category/set of circumstances.

tuxnharley

Did I miss something along the way? Where does the reference to
"LT-1" come from as being the designation of the C7 engine?

LS1LT1

That's one potential designation that's been passed around for this new motor. I personally don't think it will be the label used but it had been 'revived' once before so it is of course plausible that it could be again.
I'm thinking more along the lines of 'LS5' or 'LS8'.

tuxnharley

Thanks! I had a 1970 LT-1 engine in my '67 at one point years ago, and my '92 was the second iteration, so I was wondering if it was time for me to go for a third time around............

LS1LT1

Yeah I always loved the early ('70/'71) LT-1s and of course my very first Corvette was a '95 LT1.

Jinx

GenII was LT1, LT4, yes?
GenIII is LS1, LS6, yes?
GenIV is LS2, LS3, LS7, LS9, yes?

I doubt GM is going to keep using LS to describe GenV. They'll want a different code to emphasize how much of a technological leap it is. (The actual size of that leap isn't so important.) Also, LS* is nearly full, and the highest (best) is already used.

.Jinx
hoping for a 5.35857L displacement... just because it would be cool.

LS1LT1

That makes some sense, yes. But considering just how much different an LS9 engine is from an LS1 engine (and yet they're both still called 'LS') it does dictate that it could still be the prefix/designation.
But I also wouldn't be surprised at all if this changeover is treated just like the '1996 to 1997 transition' and an entirely new set of letters are utilized either.
And true, the LS1-LS9 range is almost full...but the LS10-LS99 (I know I know, they always use only 3 digits, not 4 LOL) range is wide open.

LS1LT1

Yes, a true 327 would be kind of cool and nostalgic, but I don't want to lose any of that famously desirable and totally satisfying 'LS3 torque' in the process either.

sdurg24

Can you imagine, 327 cid with 427 hp!!

LS1LT1

Yes.
But I can imagine 376cid with 485hp much more easily LOL.

sdurg24

LOL, but I guess the point of this is that we're not getting the same size engine in cid. Not sure if that is good or bad but I must say that given the direction of Corvette engineers over the C5 and C6 development that I'm willing to trust them to come up with a world class engine in the next generation. Given that scenario a 327 with gobs of hp and torque is fine with me.

LS1LT1

hig4s

totally illusionary statement. Or bait and switch, or apples to oranges, whichever you prefer.

Sure if you compare new smaller high tech engine with an larger old tech engine the smaller may even be better overall hp and torque. But put that same technology they are talking about for the new 5.5 DI in a 6.2 or (GASP) a 7.2 DI engine and viola, you have more of everything and again displacement wins.

Vicarious.

Isn't it better to have smaller pistons for sustained high RPM though? Displacement beats all, but a smalller engine that revs to 8k would accomplish the same task minus a little bit of torque.

briannutter1

So the DI is nice up to a point, but the injector opening time window can be a constriction due to the need for the piston to be in the proper place to intercept the fuel and atomize it properly. As the piston moves away from TDC, the window is closed prematurely. The Solstice LNF 2.0 is a good example of this for people that want to learn what will be possible. Tuners will up their game though to master their window of opportunity. Piston design changes can be made to widen the window and auxiliary injectors can be added for those of us looking for boost.

I don't think they would lower deck height or reduce bore spacing, so the aftermarket can help for the guys who like 427+ ci.

I'd hoped for Cam-in-Cam like the Viper, but that may not be happening based on the rumors. I hope they went 5 or 6 bolt with the heads. I appreciate the under-head-cam to make the engine as narrow and as light as possible. Allows for better suspension geometry and keeps weight off the nose. I'd appreciate some more space around the bellhousing/frame area for the aftermarket to add turbos. And purely for the sound, I wonder if they've ever tested a flat-plane crank for 100k miles.

And call is a LS8,10,12 or whatever. It's evolution.

5knives

Actually I don't prefer any of those.

You're reading way too much into my statement. It was a simple comment meaning they don't have to go bigger to make good power. Nowhere did I say a smaller engine will make more power than a bigger engine with the same technology. Let's say GM has a 485hp target for the C7. They don't have to go to 6.3/4/5/etc., liters to achieve it. I did not say a 5.5L DI engine will outperform a 6.2L DI engine. Which is why I was careful to phrase it "The old adage, there's no replacement for displacement isn't 'as' gospel as it once was. Technology is doing amazing things."

Jinx

I'm guessing 327 cu in, 425 lbft and 440hp from a mild torquey cam -- simply because those seem like the targets GM would pick. They can compare it favorably to the base-exhaust LS3 (technically an increase!) and crow all day long about how high-tech and efficient it is, and how a lighter curb weight and handling refinements make C7 the quickest base Corvette ever, even slightly outdoing the C6 GrandSport (admittedly a modest aspiration). All this with a new skin and slick interior and "see? we listen" different seats. Then maybe a year or two later they give us a 396 cube Z06...

Actually I think they won't bother targeting 327 cu in and we'll end up with a few more cubes and a weird-sounding number. (Since the LT1 they've given us 346 and 364 and 376, and even the LS7 rounds to 428.) Maybe it'll be dictated by racing commonality.

.Jinx

MitchAlsup

Err, backwards::

In order to achieve higher RPMs and stay under the 4500 fps of piston speed, it is the stroke that needs to be smaller--which requires the bore to be larger in order to maintain displacement.

So, if you decrease the stroke by (say) 20% you increase the bore by 9% and the displacement stays pretty much the same and you can rev the engine 20% higher.

tuxnharley

..........and probably both decreased the peak torque and made the torque curve "peakier" if all other aspects of the engine stayed constant.

McGirk94LT1

Which wouldn't be so much of a bad thing per say for overall traction. The ls3 makes peak hp at 5,900rpms, peak torque at 4,600 rpms, and redlines at 6,500.

In the interest of comparing apples to apples, let's say the 5.5 with direct injection also redlines at 6,500 and makes the same 428 peak torque at 4,600. If it has a more radical cam to supplement the loss of cubes, the torque curve might not be as fat down low, however it wouldn't fall off as hard after it peaks either. So as long as the heads/intake can keep up, it might make even more peak power but at 6,300rpms. Now you have a car that doesn't need more then the current 285 rear tires, wouldn't be as vicious coming out of a corner, but for all that it lost down low, it pulls even harder/longer up top. Keep the close ratio trans but say a 3.55 rear vs 3.42 and it would probably be an overall better performer then the c6 by a good margin especially if the car weighs sub 3200lbs. I feel like too much pressure is put on "WE NEED 1,000LB FT AT 1,000RPMS!" when any given race involves anything over 3,000rpms. Obviously at a track the rpms can vary more in the corners, but as light as the corvette is, low end torque has never been a huge concern for it. I'd GLADLY loose 10% torque from 1,000 to 3,000 for a 15% increase in horsepower from 4,500 to 6,500.

And we're forgetting a potentially huge aspect. If the next engine has variable cam timing, that right there will be able to help balance out the low end/high end power curves despite the possible decrease in displacement.