GM cancels new DOHC V8 engine program
by John Neff on Jan 3rd 2008 at 2:25PM 
The Northstar V8 has been a great engine for General Motors, but there's no denying that it's past its prime. GM had been working on an engine program to replace the Northstar with a new high-tech DOHC V8 for its luxury cars, but revealed today that the program's been cancelled. It's kind of easy to see why, as the General's 3.6L direct-inject V6 offers V8-like horsepower with less weight and better fuel economy. In fact, we bet more people choose the 3.6L DI V6 when ordering a Cadillac STS than the 4.6L Northstar V8 since the former is only down 14 horsepower on the latter (320 vs 306). Wouldn't you? And when an honest-to-goodness V8 is really needed, say in a performance model like the CTS-V, GM's got plenty of Corvette engines from which to choose that get exemplary fuel economy on the highway. And that's really what all this is about: looking ahead to the day when a 35 mpg CAFE standard has to be met. Gone will be the days when top-level luxury cars were offered with V8 engines just because they were the most powerful and torquey motors of the time. If the same power can be achieved in a lighter, more efficient V6, expect most automakers to start ditching V8s quickly. Acura's never had one, and the upcoming Lincoln MKS isn't getting one. So is it really surprising that GM may scale back on offering V8 engines, as well? To be clear, the only thing announced today was that a program to develop a new DOHC V8 has been cancelled by GM. Without another overhead cam V8 to take the Northstar's place, however, we think the times they are a changin'. Now, imagine a Cadillac powered by a diesel V8...[Source: Automotive News]
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Reader Comments (Page 1 of 5)
Fabri91 4:13PM (1/25/2008)
Image a caddillac powered by a v8 diesel?
I live in Italy, where diesel engines are quite common, and what i can say is that DI gas engines are the way, especially because diesel's getting more expensive and diesel engines hilariously expensive and complicated.
Trust me, You don't want that. Period.
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naturalyshocked 3:00PM (8/27/2009)
you can't add Direction injection to an pushrod engine.
there is no room for for it.
the only place to put the injector is next to the sprakplug.
the exhaust manifold would be direct below the 'common rail'.
this would heat up the fuel.
http://i270.photobucket.com/albums/jj114/powertvmedia/SEMA%2008/Camaro/General/LS3.jpg
you only wanna heat the fuel a litle on a diesel engine to heat up the tank in 'very' cold conditions.
below 0ºc.
http://en.wikipedia.org/wiki/Multi-valve
Adding more valves improves the flow of intake and exhaust gases, potentially improving combustion efficiency, power, and performance.
Multi-valve geometry also tends to favor the spark plug being located at the top of the combustion chamber, which can be ideal for even flame propagation during combustion. In addition, particularly as the valve begins to open, for equivalent valve/port areas multi-valve geometry allows for increased airflow.
4+ valve engines are better the for the environment.
A 4-valve system optimizes the volumetric efficiency of the engine and provides for a better mixing of air and fuel. Variable valve timing, on the other hand, utilizes advanced electronic, hydraulic, pneumatic and mechanical means to vary the intake and exhaust valve timing and lift. This design enables a smaller engine to match the power and torque output of a larger engine fitted with a conventional valve system. Fuel consumption improvements of 6% to 8% are realizable
Inefficient engines may produce less CO 2 for a given volume of fuel - due to incomplete combustion, but they require more fuel in absolute terms to do the same amount of work of more efficient engines. In addition, a greater volume of pollutants in the form of CO, NOx, SOx, unburned hydrocarbons, and particulate matter are released into the atmosphere.
american should building heritage over heritage.
i have been in U.S companes, like Mobilm, mcdonalds a few more.
everything is build the old fashioned way.
american should stop wining about the pushrod.
i always see the same, you want power and you want it CHEAP, CHEAP.
i have seen comments like weight/power ratio.
grrrr, in other words you like to have unburned fuel leaking on the street.
in the end effect want a cheap car, but waste on fuel?
i rather buy a lilte more expsensive car and save on fuel.
i can tell you, if money stops flowing, live stops as we know it.
(we all experienced 2009)
the average person doesn't need more than 150hp.
if you need power, than rent a vihicle for the specific haul.
FWD is better on wet/snowy roads.
manual drivers have more control over their car and can evade an accident more easily than an automatic.
manual driven cars also use aprox: 2 liter less on the 100km, than automatic.
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Mr. Oak 2:41PM (1/03/2008)
Didn't I read somewhere that they were eventually going to put Direct Injection on the LS engines?
The LS3 DI would be a truly awesome mill, plus more fuel effiency. Sweet.
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Punkcrisis 8:32PM (1/03/2008)
I can hardly believe that GM would ax the V8 program it kind of doesn't make sense for the simple fact the did such a good job with the northstar and the 3.6 DI you think they would carry on the success. And I truly hope they do bring Direct Injection into the LS3's it would be an overall improvement. I hope GM was axing the V8 just to start over and not abandon the idea completely.
Dan 2:43PM (1/03/2008)
Yes, that Cadillac V8 0.4% of the US car market is clearly the tipping point for what the earth can stand.
Sad day for enthusiasts. Good day for smelly hippies.
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Andrew 2:46PM (1/03/2008)
Yeah, because enthusiasts need a V8 DOHC gas powered engine, and everyone else is a hippie. What an idiot.
naggs 5:25PM (1/03/2008)
this is great news
GM will continue to refine the inherently superior push rod v8 for years to come
Dave 8:30PM (1/03/2008)
GM can build their small block chevy (SBC) pushrod engines much cheaper than a DOHC engine. And with Toyota breathing down their necks, they need every financial advantage they can get in the pickup truck wars. So they won't be discontinuing that line any time soon.
Between the SBC, 3.6, GM's upcoming diesels, and dual mode hybrids, there isn't really a huge need for this new engine. (A dual mode DI 3.6 would provide impressive economy and performance in a large Caddy while also providing the DOHC valvetrain required by the marketing dept)
Its an understandable business decision.
In addition, GM just introduced the new ZR1 with a pushrod engine. The original ZR1 was the 80s poster child for DOHC.
Owain Ozymandias Buck 10:49PM (1/03/2008)
That's a good point about refining the OHV pushrod engine. It still has advantages over an OHC configuration, compactness being one of the most important.
It's a different evolutionary path, not a throwback. Roaches are crude, but they've kept up and are doing pretty well in many ecosystems.
About Toyota: maybe they should've borrowed from their NASCAR V8 for the new Tundra. Might have saved them some money. Might have fixed those camshafts too! I bet they could do a good OHV V8 if they tried.
J.Crew 2:31PM (1/05/2008)
All they are doing is dropping the developement of a low volume engine with limited production use. I have no worries about Cadillac and its use of 8 cylinders. GM is looking at profitable growth with an eye on what needs to be developed to meet the new fuel economy standards in the future. They are being smart by not wasting money and talent on a project with a limited future. This engine would have been completed just in time to be hit by the new fuel economy standards to kill it off and people would have been slamming GM for not thinking ahead and knowing that this engine does not fit the times. Seems to me that GM is being smart and most likely looking at other options like using this new diesel:
http://www.gm.com/explore/fuel_economy/news/2007/adv_engines/diesel_061807.jsp
Notice the size and power estimates. It fits in the same space as GM's current small blocks. The N* was larger than the small blocks. Also the torque rating on this new engine would make one hell of a great premium feel in a large Cadillac while making excellent fuel economy...
I am sure you will be hearing announcements from other manufacturers regarding their engine programs due to the new 35mpg standard. GM is the first to step up.
phewop118 2:48PM (1/03/2008)
NOOOOOOOOO!!!! DAMN YOU GM!!!! YOU ARE SCREWED! Cadillac cannot compete in the luxury market unless it has a powerful V8. Mercedes, BMW, and Audi all have nice and powerful V6's, but its their V8's that shine (and sell). I have driven a 3.6 DI STS and 4.6 N* V8 back to back and the 3.6 sucks compared to the "slightly" more powerful V8. Why can't GM make a DI V8, making about 360-400hp, while still getting as good of mileage as the Northstar?
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Frylock350 2:57PM (1/03/2008)
GM isn't dropping powerful V8s, they're just not investing in a new DOHC one. And why would they? Their pushrod V8s are exemplary in producing both power and economy with excellent packaging. Once DI gets into the pushrod motors with AFM you'll see a 5.3L V8 with 400hp and vastly improved mileage and the Ethanol option.
The N* is a pig compared to the LS motors. The LS motors are torquier, physically smaller, more powerful and get better efficiency, all while sounding like an angry grizzly bear (that's a good thing).
jgp 4:20PM (1/03/2008)
The LS motors are fine for the Vette and "ordinary" sport sedans like the G8 and (fingers crossed) a future Impala SS.
But pushrods will always have severe NVH issues, and NVH should never be associated with Cadillac. Not even remotely.
The Northstar is bloody outdated, and the LS isn't fit for Cadillac. The Ultra V8 should have put Cadillac back on the map with a flagship ready to take on the BMW 7-Series and Mercedes S-Class.
The HF w/DI is an impressive engine, but Cadillac's upcoming flagship needs an engine with more than 300hp. I can easily see an HF-based 4.8L V8 with over 400hp (assuming the same hp/cyl as the 3.6L DI V6). Bore it out a bit more (how does 5.3L sound?), and it'd easily surpass the supercharged Northstar.
J.Crew 2:38PM (1/05/2008)
All they are doing is dropping the developement of a low volume engine with limited production use. I have no worries about Cadillac and its use of 8 cylinders. GM is looking at profitable growth with an eye on what needs to be developed to meet the new fuel economy standards in the future. They are being smart by not wasting money and talent on a project with a limited future. This engine would have been completed just in time to be hit by the new fuel economy standards to kill it off and people would have been slamming GM for not thinking ahead and knowing that this engine does not fit the times. Seems to me that GM is being smart and most likely looking at other options like using this new diesel:
http://www.gm.com/explore/fuel_economy/news/2007/adv_engines/diesel_061807.jsp
Notice the size and power estimates. It fits in the same space as GM's current small blocks. The N* was larger than the small blocks. Also the torque rating on this new engine would make one hell of a great premium feel in a large Cadillac while making excellent fuel economy...
Xcountryflyer 2:48PM (1/03/2008)
At the end of the day--does it really matter if its 4 or 6 cylinders pushing you down the street if it goes like a bat out of hell. With today's technology, 6 cylinder engines offer better power and efficiency than V8s of the 90s. Also turbocharging has come along way too boost smaller engines to incredible numbers.
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phewop118 2:58PM (1/03/2008)
There is that immediate feeling of power delivery at all RPMs in a V8 that a V6 or I4 can never offer, even turbos or supercharged ones.
Marc 3:00PM (1/03/2008)
Of course, you do realize that BMW's new V8 is a Twin-Turbo and due in the 5-series very shortly.
Michael D. 3:06PM (1/03/2008)
It is indeed a saw and disheartening day, and I don't want to see GM, especially "Maximum" Bob Lutz sell out to hippies and environmentalists!
Perhaps there's light at the end of the tunnel: maybe the 6.2L small-block will be used company wide, and in different versions and formats, supercharged and naturally aspirated. So maybe the 6.2L V8 will take the place of the Northstar, which has been with us since MY1993. and find it's way into the XLR, V-series editions, and the expected Zeta-based STS/DTS successor. With that 6.2L, perhaps a high-tech, twin-cam V8 would be considered redundant.
Xcountryflyer 3:52PM (1/03/2008)
But then again--with today's technology, you should be able to build more fuel efficient V8s and stick them in cars where the people buying them don't care about gas guzzler taxes.
psarhjinian 5:54PM (1/03/2008)
@phewop118
That feeling of immediate power delivery is inherent to a well-tuned powertrain and a good power-to-weight ratio, not a simple count of cylinders. Drive, say, a Cadillac CTS with the DI 3.6 back-to-back with, say, the anemic V8 in the Ford Crown Vic and tell me you don't prefer the six.
A V8 is a good idea when it makes sense. To install a V8 just to make spec-sheet readers happy is silliness. If my vehicle is light enough and the engineers' throttle tuning sufficiently adroit, why should I care how many cylinders are moving up and down?