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CarScoops: Flagship, 3L Twin-Turbo, Corvette to share 4.5L Turbo V8


Bruce Nunnally

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We learned that it's [un-named Flagship; LTS?] arrival in the market in sedan form has been confirmed for 2016, with available powertrains to include a new 3.0-liter turbocharged V6 as well as the current 3.6-liter turbocharged V6, which produces 420hp in the CTS V-Sport. While nothing was mentioned, we can't imagine a range-topping Cadillac without a V8, so the turbocharged unit we mentioned earlier should also be available.

Read more: http://www.carscoops.com/2013/09/we-learn-gm-plans-45-liter-v8-turbo-for.html

Bruce

2016 Cadillac ATS-V gray/black

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Most of the new engines are still a bit of a mystery, and some of them aren't ready yet and we will see them in a month or two. I think that a whole new world will unfold over the next six months.

Car & Driver, in their first road test of a Northstar in 1992, predicted that "this engine will end up in the Corvette." That was more than a bit premature but if indeed one of the high-performance Cadillac drivetrains is offered in a Corvette for 2014, well, there you are.

The 6.0/6.2 liter bowtie V8 first appeared in the Escalade, then in the CTS-V in 2005. In 2009, with additional supercharger technology from Corvette, the LSA engine that is so beloved by me for its power, easy driving in parking lots and crowded city streets, and authority in any situation on the freeway, and it's uncanny reliability.

An interesting thing to watch for is VVT. Pushrod engines have only one VVT angle for both intake and exhaust, but twin cam OHC engines have two VVT angles, one for intake and one for exhaust. I have no idea how important this is but it's predictable that any significant or even measurable advantage will be part of the selection process as the industry, and buyers, demand more economy, power, and driveability while at the same time lower emissions, maintenance, and cost.

I can't figure out how to have two VVT angles with a pushrod engine with one cam. Two cams could be used, one above the other, with one cam operating intake valves and the other operating exhaust valves, but the cam drive would have to be either two cam chains or a complex gearing or another timing chain on the cam sprocket.

Some exotic racing engines have desmodromic valves (extra rockers that close the valves) hydraulic valve springs, etc. These engines, and aircraft engine development in WW I and WW II, originated and developed concepts that we see in all modern auto engines today, such as cam overlap (Harley!), overhead valves, hemi combustion chambers, superchargers, fuel injection, to mention a few. Perhaps there are technologies out there that will give us enhanced VVT.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Dual-independent VVT on a 'single' cam engine is already in production on the Viper:

http://www.mechadyne-int.com/vva-products/concentric-camshafts

I can't figure out how to have two VVT angles with a pushrod engine with one cam. Two cams could be used, one above the other, with one cam operating intake valves and the other operating exhaust valves, but the cam drive would have to be either two cam chains or a complex gearing or another timing chain on the cam sprocket.

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Wow, KevinW, thanks. I had thought about concentric cams but didn't see a good way for the inner cam to control lobes. The Mechanidyne cams at your link use slots, and pin lobes riding on a bearing on the outer cam through the slots.

The Achilles heel of the Mechanidyne cams is a life of 1000 hours, OK for a racing engine but not for a daily driver or, really, for any street car. Whatever they do on the Viper may be similar but clearly the Viper cams are reliable enough for whatever the Viper warranty is. So, the Viper proves by example that the technology for dual VVT in pushrod engines is here.

This is quite important. If you compare the published specs of the SST-V and CTS-V engines, 4.4 liters at 469 hp or 106.6 hp/liter, and 6.2 liters at 556 hp or 89.7 hp/liter, you see that the dual VVT of the STS-V is important. The CTS-V does not have VVT at all.

Hey, I never ran the specific output of the CTS-V before. Only 90 hp/liter. My 1990 Pontiac Grand Am with its Quad 4 HO had 80 hp/liter, and there was a 195 hp version for the Olds 4-4-2 that had 87 hp/liter. No wonder the LSA has eutectic pistons instead of cast, and doesn't have VVT, etc. GM was just not letting it all hang out with the LSA. It was just good enough to be the best out there for five years. Now, BMW and Mercedes are catching up, but a whole new platform series (V-sport) and V-series engine are coming.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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