Whats the point of GM's 4200 Inline-6 "atlas" engine?

I don't represent GM, so these are my opinions.

When the 4.2 came out, they probably didn't even plan to fit the V8 in the SUV family. Marketing. Buzzwords. The 4.2 has also been sliced into the 5 cyl in the Colorado. It has overhead cams, which means something to some people.

Honestly, a lot of car stuff doesn't make sense. My 2001 Firebird Trans Am came with an auto as standard and the stick was optional at extra cost. A 2001 Firebird Formula came with the same powertrain, but the stick is standard and the auto is extra cost. Go figure.

I also don't think GM thought the V8 would be as popular of an option as it was.

Ray

I'm not a big fan of GM, but give me an inline 6 over a V anything, any day. The V8 can produce a lot of power and torque. And yes, it can be smooth. But when you've driven a free-revving inline 6, you will wonder why V8s are so popular. The inline 6 is a MUCH better designed engine. If you think that the V8 is smoother, that is probably because it's hard to push that puppy past 3 grand or so. The V8 needs the extra torque because it has to be geared to run slow. But honestly, either engine would probably be a joy to drive, with an automatic tranny. With a manual, you better hope that you've got the inline 6 under the hood. :)

That's a good question to pose to someone with direct connections to GM because cost to manufacture is only one reason for picking an engine design.

This article provides some interesting background.

Are the power curves different? Not knowing much about either engine it would appear that the inline 6 is a more advanced engine in that the valve train (and possibly other components) are more sophisticated. Consequently it may allow more flexibility in controlling emissions and milage.

I would guess that the I-6 may be more compact and lighter, which would offer packaging advantages. I'd be interest to know how it compares weight-wise and if GM is ever planning on offering it as a base engine in a RWD car platform...

nate

Forgot to mention, an I-6 should actually be smoother running than a V-8; a straight six has theoretically near perfect balance. (so does a V-12 but that is irrelevant to the discussion)

nate

Good questions. I wonder if this may be the base engine of the future for several GM applications. It's configuration may allow it to be repositioned for new body style still in the works.

Volvo did the same thing when they switched over to front wheel drive in the 1990's. The inline engine was offered in 4, 5 and 6 cylinder versions on a variety of front wheel drive models. But Volvo has recently introduced the Yamaha designed V8 in their SUV line and a high-end S80, which shows it's really difficult to project where car manufacturers are headed and why they make specific decisions.

Yes, an inline 6 can be a very smooth running engine at an idle, although engines like the current Toyota 4 cylinder are quite smooth in my experience as well. And certain inline 6 cylinder engines have a detectable vibration, such as the 6 used by Volvo. Engine vibration at highway speed is in my experience all but unnoticable on most cars I've driven. The exception might be on a low-end Kia or similar car.

It just shows that manufacturers are swapping hand-me-downs among their own divisions and the advertisers are spinning it as "new and improved!" Ford is using the hand-me-down S80 chassis for their new 500/Montego, and they're sticking their Volvo division with the hand-me-down v8 from the Taurus SHO. :-/

Not sure I understand what the problem is with using a chassis (or any other component) in more than one application. Volvo used the S80 chassis in the latest V70 line and vastly improved it's looks and handling in the process. Maybe you can tell me what specific features about the S80 chassis that are poorly chosen for the 500 series and how you would improve them.

Surely you are not saying that car manufacturers should step back into the cottage era of car manufacturing design a whole set of new components for each and every model are you? If so why. The only reason I can think of would be to needlessly increase the cost of many models.

Actually, I think there's nothing AT ALL wrong with keeping a good chassis (or engine) design around for 50 years, if its doing the job and keeping up with demands. What rubs me the wrong way is that the advertisers can't come to grips with the fact that sometimes "old" is "good," and do everything they can to make everything seem "new and improved."

Now whether or not the S80 chassis is one of those worth keeping for a long time is not something I know much about. OTOH, while the original SHO/Yamaha v6 was an exceptional engine, my Ford-o-phile friends have never had too much good to say about the Yamaha v8 that succeeded it. I don't know how improved the version in the Volvo SUV might be.

Now there's an area where carmakers have gone the WRONG way! Back in the

60s and 70s, common components were used across multiple car-lines, and used for 10+ years. Even when components were changed, the basic architecture often was re-used. For example, I just upgraded my '66 Dodge to disk brakes using parts off a mid-70s Chrysler, and it was a simple bolt-on. Even the brake lines were routed identically and used the same retainer clips. The disk brake steering knuckles bolted right up to the same upper and lower balljoints that the drum suspension used. Not only does that save costs up front, it means that a single aftermarket part can support models spanning a decade, so finding maintenance parts for those cars 40 years later is still easy, because the applications are so broad that its worth it for suppliers to keep them in production. You rarely see that kind of thing nowdays.

None of this relates much to the GM I6. All I can say on that front is that in the rental vehicles I've had with the I5 version, I was fairly impressed. I can imagine that the engine bay in some of those applications might be too narrow for a V8. If the engine bay is too skinny for a v-type engine, then that sorta justifies an inline. Otherwise, give me the V-type any day.

I would imagine that the 5300 would have a better torque curve because it has such a large displacement advantage. And the mileage ratings are identical.

I don't know about the 5300 but the series-III 3800 motor has SULEV emissions and it is a similar OHV 2-valve non-VVT design.

No way. I will pick an I-6 over a V-6 every time, unless there's some other overriding reason. The only real disadvantage to the I-6 is overall length, it will be longer than an equivalent V-6 by necessity. This also can cause crank flex in really high torque applications, but this can be mitigated somewhat by using seven main bearings. But the inherent balance of the I-6 makes it creamy smooth, and the firing order makes exhaust system layout a breeze - just split the manifold front three/rear three and it works out really well. I miss my old BMW

535i... that was a hell of an engine. By comparison a V-6 is rough as a cob and the exhaust note sounds like crap compared to the ripping-cloth goodness of a well tuned I-6.

nate

Don't forget, it's not uncommon to have overlapping engine capabilities as the engine families evolve.

An example would be the (in)famous GM 2.8 V6. It's since evolved into a

3.9L V6. You can also buy a 3.8L V6 and a 3.5L V6 from GM which are two completely separate engine designs. Sometimes the new engine replaces the old design, sometimes the two continue in parallel for some time.

The GM Gen-II Small Block was used 92-96 in Corvettes, and 93-97 in the F-Body (Camaro/Firebird) before being replaced by the Gen-III (LS1.) AFAIK, the Gen-II never made it into the trucks, they were served by the "classic" smallblock until they went to the Gen-III. So, in 1997, you could get a Gen-I in a Van, a Gen-II in a Camaro, and a Gen-III V8 in a Vette. All with a 5.7L displacement.

Ray