6th gen Camaro Z/28

[kevm14]

I guess it is official. Well, more official than what we were speculating only a few days ago with the announcement of the ZL1 1LE.

There's big stuff here, especially if you were dying to know how the LT engine lineup would be expanded (i.e. LT5, LT7, etc.).

http://gmauthority.com/blog/2017/03/rep ... v8-engine/
http://blog.caranddriver.com/a-new-chev ... g-we-know/

Getting there will take a few more months. It remains a distinct possibility that the Z/28 could use a 750-ish-hp version of the supercharged pushrod small-block V-8 slated for the 2018 C7 Corvette ZR1. But tantalizingly, as we speak, GM engine dynos already are revving the latest and what should be the greatest small-block V-8 ever conceived. Breaking cleanly from Ed Cole’s 1950s brilliance, the coming LT6 and LT7 designs finally will dispense with pushrods and two-valve combustion chambers.

Car and Driver has reported major changes are inbound for the sixth-generation Camaro Z/28 as the ZL1 1LE keeps the Camaro in a track prowess holding pattern. According to intel, General Motors is working on a naturally aspirated, 5.5-liter small block V8 that will push 700 hp. And that engine is supposedly being readied for the next Z/28 with an LT6 designation.

The new engine family is said to break away from the norm and use an aluminum block and head, dual overhead camshafts, four-valve combustion chambers, direct, but possibly in combination with port, fuel injection, titanium connecting rods, and a flat crankshaft. Sound good? You bet it does.

However, that’s not all. The report goes on to state a twin-turbo variant of this LT6 will also come to fruition and be dubbed the LT7. It’s likely this engine family is being developed in conjunction with the all-but-confirmed 6.2-liter LT5 DOHC V8, slated for the 2018 C7 Corvette ZR1. The LT6 and LT7 may also serve as the basis for the Chevrolet’s worst-kept secret: a mid-engine Corvette.

More info on the next Z/28:
http://gmauthority.com/blog/2017/03/spy ... amaro-z28/

[kevm14]

Let me see if I can sort out what we think we know:
C7-based Corvette ZR1 (front engine, RWD): LT5. LT5 will be in the exact spirit of the original. A displacement-of-the-time engine (6.2L) but with DOHC. I would assume it will be supercharged with similar packaging as the LT4. Obviously we can expect pretty big power out of this. Maybe 700 hp.

6th gen Camaro Z/28: LT6. LT6 is basically what I thought the LT7 would be (i.e. an LT-based replacement to the LS7). Except it will be 5.5L, DOHC, flat plane crank, and naturally aspirated. Power estimates are upwards of 700hp. I just want to say the 5.5L rumor has been around for a long time now, as I think the C5-R used a 5.5L (race reasons) so the rumors were always that some version of that would end up in production. That hasn't happened yet. I've seen no one mention any linkage to Corvette racing so I don't really know what's going on here. I think the power estimate is aggressive to achieve N/A but GM has been consistently out-performing their initial estimates. Or at least meeting them.

C8 mid-engine Corvette: LT7? Basically take the LT6, make some adjustments, add turbos.

Will GM maintain two V8 lines? One lower power, lower cost, for trucks and lower power applications? And one for craziness? That is a break from convention. The kind of break that will hurt the future of junkyard hot-rodding or other mix and match builds that GM has always supported the best of, well, any automaker. Or will they just shift to an entirely LT5+ based DOHC architecture for everything? Some hot-rodding spirit is maintained with the commonality but 4 cams? Twice the number of valve springs? Less friendly to the DIY hot-rodder. More like how it works with the Coyote. Which isn't all bad but it ain't no LS engine.

[kevm14]

http://backfires.caranddriver.com/forum ... ng-we-know

Some trolling based on the Accord V6 (C/D Backfires inside joke) starts this...

"Wouldn't be the first GM with a Honda engine. People forget the 2004–07 Saturn Vue had the 3.5 Honda V6."

i remember that motor. It angered GM as they thought it was going to be the Accord V6. But Honda had secretly substituted an engine out of the Odyssey that was not known for its speed. The resulting deception not only began the demise of the entire Saturn Division but also led to the Bankruptcy of General Motors, the Worldwide economic downturn of all the banks and Markets of the world, but also was the source of Dieselgate scandal from Volkswagen, and the Russian tampering of an American election that helped Trump become President.

[kevm14]

On the DOHC thing, really, I want to know how it compares to the LT1/4 design.

Volume
Dimensions (width, height)
Weight
Cost
NVH/sound
Power characteristics

Then later....ECM tuning. Aftermarket support. DIY build commonality/ease/cost. Oh, and the LS-swap legacy. That has some time to mature as LT swaps are pointless due to the very significant cost/benefit advantage of the LS line at this point in time.

Huge questions. And they are particularly relevant if this new architecture takes over the entire line. Which would make me sad.

[kevm14]

6th gen Camaro Z/28: LT6. LT6 is basically what I thought the LT7 would be (i.e. an LT-based replacement to the LS7). Except it will be 5.5L, DOHC, flat plane crank, and naturally aspirated. Power estimates are upwards of 700hp. I just want to say the 5.5L rumor has been around for a long time now, as I think the C5-R used a 5.5L (race reasons) so the rumors were always that some version of that would end up in production. That hasn't happened yet. I've seen no one mention any linkage to Corvette racing so I don't really know what's going on here. I think the power estimate is aggressive to achieve N/A but GM has been consistently out-performing their initial estimates. Or at least meeting them.

I'm pretty sure that GM will only make a technological leap into the 20th century here, and the 700+ numbers are for the turbocharged variations, not the naturally aspirated ones. Of course, 750 hp from a 5.5 liter N/A engine are entirely possible in a Ferrari or Porsche, but these engines usually cost more than an entire GM car ...

Of course GM didn't announce anything so I still think that 700hp number is not naturally aspirated. At least not out of 5.5L. Maybe 6.2L.

[Bob]

I was thinking it's not totally insane to get 700 HP out of a 5.5L NA V8. The specific output would be identical to that of the Ferrari 458 with one extra liter.

[kevm14]

More info on the LT5.

http://gmauthority.com/blog/2016/12/con ... -corvette/

For now it sounds like Corvette-only, which I guess makes sense.

I'm thinking now that this is going to be a true LT5 successor. An LT1 architecture small block with 6.2L but with DOHC and a lot of power. GM pushrod heads flow well, but pushrods and big valves make high RPM a challenge. So I expect power gains to be had more from higher operating RPMs than just from sheer head flow (supported by head flow of course). For power, I'd say it is totally possible to see 600 hp N/A.

I think the LT6 and LT7 are going to be some combination of flat plan crank (one or both) and turbos. LT7 "should" be a pushrod, big displacement N/A engine but I don't know if they'll go that direction.

[kevm14]

Let me add a few things about the flat plane crank.

I don't think it makes sense to add a turbo to that. That's just uninformed dreaming, imo.

But going further, I wonder if GM doesn't need to chase Ford on the crank configuration. One commenter actually said he doesn't really like the change in sound character, which turns pretty buzzy at high RPMs, and sounds kinda crappy at low RPMs.

[kevm14]

Slightly different rumors:
http://www.autoguide.com/auto-news/2017 ... om20170316

Car and Driver’s Don Sherman reports the Z/28 is far from dead, Chevrolet is simply keeping its powder dry as it works to develop the most powerful naturally aspirated engine to ever grace the Camaro from the factory. Sherman alleges the Z/28 could use a new family of LT engines that will do away with tried-and-true two-valve pushrod designs; he calls it the greatest small-block V8, like, ever.

It’s expected the LT6 will show up with all-aluminum construction, four-valves per chamber, titanium con rods, dual overhead camshafts and a flat-plane crank. Pegged for 5.5 liters of displacement, the LT6’s rap sheet looks like something stolen from the Ferrari factory. Like the 6.2-liter LT1, there will be a blown version of the LT6, except this time Chevy will trade the supercharger for twin turbos and call it the LT7, expected to make at least 700 hp and possibly as much as 750.

These engines are expected to proliferate with the next-generation of GM performance products, starting with the Camaro Z/28 in 2019. Following the Camaro, the Corvette should get one when the C8 eventually rolls around, along with the next generation of Cadillac V-cars.

What is the LT5 in the context of this? Is a 6.2L DOHC engine with a regular crank? And the LT6 is the real screamer?

[bill25]

This has nothing to do with the car, but what is up with the naming conventions? Why would you call a dual overhead cam engine an LT? Also, I thought the rumor was Cadillac was going to do their own thing and do dual overhead cam. Why would there be 2 different dual overhead cam engine designs that are not shared? It all seems kind of weird.

I could see if they wanted to make Cadillac more separated from Chevy and doing DOHC would be a differentiator but if they are both doing it, what is the point of different designs? Who knows, maybe they decided against different designs and both companies will use these new engines. They should still have used a different name than LS or LT for the DOHC stuff.