Why all the Big NA Engines?

[pup2]

Just wondering -- di ba mas efficient ang turbo? Instead of raising engine displacements such as from 16. to 1.8/2.0for compact cars, why not just add turbos to 1.6 engines?

[Alpha_One]

There's no replacement for displacement.

To be exact, it's a tradeoff. The benefits of a turbo may be had at much less expense through a slightly bigger engine. It would be simpler and none of those turbo quirks like lag, heat, engine knock...

If you're a car designer from the 1950s, or in the 2000's working on an econobox, the turbo may simply be too expensive and complicated for the car in mind.

Also, notice that turbos are much more common on diesel engines. That's mainly because diesel engines tend to be overbuilt due to their nature of operation. Small amounts of boost wouldn't affect anything on a diesel that would cause knock and ping and blown gaskets on a petrol engine (barring huge redesigns).

To put it simply, there's what the economists call There Ain't No Such Thing as a Free Lunch.

[niky]

Cost, I think.

Turbo engines have more components than comparable power NA engines. More in-bay heat. More insulation, etcetera.

Bigger NA engines tend to be smoother in terms of power delivery than turbocharged lumps... traditionally... new variable geometry turbos, high pressure injectors and better computer control help make newer turbo engines act more like NA engines.

But at a cost.

That's why American manufacturers went with big displacement engines for so long. They used more gas, yes, but they cost less to manufacture and develop.

[OTEP]

Turbos are not necessarily more efficient when compared to a large normally aspirated engine. Take a look at the Acura RDX with its 4 cylinder turbo. It has the fuel economy of a V6 while being more complex and not as smooth.

Small engines are popular in some markets because larger displacements tend to be taxed higher. And to make power in a small engine, you had to resort to turbocharging or supercharging.

That was also the prevailing system in the local market unting recently when we went to value based taxation. Since the shift in the tax system, there has been an influx of larger displacement engines in the local market.

http://www.caranddriver.com/comparis...acura-rdx.html

To decrease weight and increase fuel economy, Acura fitted the RDX with a turbocharged four-cylinder engine, its first forced-induction anything. A four-banger in a vehicle costing close to 40 grand is a risky ploy, but the RDX did emerge as the lightest member of our trio, and its 6.5-second sprint to 60 mph makes it an Olympic luge in the world of SUVs. Notice, however, that the 20-hp-more-potent BMW X3 matched the RDX’s quarter-mile trap speed, and by the time both were humping along at 100 mph, the BMW was a 10th ahead. What’s more, the RDX’s observed fuel economy was 3 mpg worse than the ballsier BMW’s. One thing about turbos—they’re thirsty.

[pup2]

Cool. 3 lang sagot but very informative.

Pero paano kung current situation? Would you prefer to have, say, a 1.6 Turbo (gas ha) compact or a 1.8/2.0 compact -- assuming mas mura ng konti yung 1.6 (say, 100k?)? At bakit?

[Jun aka Pekto]

Would you prefer to have, say, a 1.6 Turbo (gas ha) compact or a 1.8/2.0 compact

I'm assuming this is one particular car with different engine options. Chances are the 1.6 turbo will have dramatically more hp/torque than the 1.8/2.0. In fact, hp/torque for the turbo 1.6 will probably approach that of smaller V6s. But, the added strain of a turbo will takes its toll down the road in accelerated wear and tear and high-maintenance costs. That's probably why a number of cars I knew that had turbo 4s initially moved to high output N/A 4's or bigger engines:

Ford Thunderbird (not the convertible)- moved from turbo 4 to V6/supercharged V6
Pontiac Grand Prix - turbo 4 to V6/supercharged V6
Ford Probe GT - turbo 4 to V6
Chrysler Lebaron - turbo 4 to V6
VW Corrado - turbo 4 to V6
Mitsubishi Eclipse- turbo 4 to V6

Other turbo 4 cars simply died out:
Izuzu Impulse RS
Plymouth Laser RS Turbo/Eagle talon TSi
Dodge Daytona

[Jun aka Pekto]

I also have to add an anecdote while reminescing about old times.....

A comparison of my then-new 91 Plymouth Laser RS Turbo and my ex fiancee's Z-28 IROC-Z. We put both cars through the same amount of abuse and even though her car was older, there wasn't any problems with its 5.7L V8. On the other hand, the 2.0L 4G63 turbo engine of my Laser started to develop oil leaks even though it's almost 2 years younger. The stress the turbo engine goes through is enormous.

That's why I haven't bought another turbo car since my 91 DSM. I opted for V6-equipped cars instead. Displacement really matters. Sure, I miss a turbo when tackling the thinner air of snowy mountain roads and a V6 doesn't have the raw power delivery and lighter weight of a turbo 4. But, the overall maintenance costs are a lot less. We have a 95 2.5L V6 Ford Contour SE. The maintenance costs for that has been way, way less than my Laser for the same elapsed time frame.

Turbos should really only be on small sports cars. It's perfect for cars like the Pontiac Solstice (which does have a turbo version) and a MazdaSpeed 3/Miata. I'm divided on having turbos on midsize cars like the MazdaSpeed 6 because of the increasing weight. Like I said earlier, maybe turbo cars have improved. We'll see. I'm on the lookout for the MazdaSpeed 6 long-term reliability reports.