The conventional spark-ignition (Otto) automobile engine

Question

(The following passage was adapted from a work published in 1978.)

The conventional spark-ignition (Otto) automobile engine has inherent virtues that become more apparent when alternative engines are considered. These virtues include a respectable efficiency (especially under partial load), lightweight, ease of starting, acceptable emissions (with control devices), and a negligible requirement for expensive fabrication materials (and hence a low manufacturing cost). Nonetheless, concern about air pollution has focused attention on alternative engines that are potentially more promising with respect to achieving minimal emission levels-the compression-ignition (Diesel) engine, the steam or vapor-cycle (Rankine) engine, the gas turbine (Brayton engine), and the Stirling engine.

The conventional automobile engine is indeed at a disadvantage with respect to exhaust emissions because many pollutants are formed as a consequence of the intermittent combustion process, with its rapid chilling of the combustion products. The engine has been substantially cleaned up but, with one or two exceptions, this task has called for catalytic emission- control devices that tend to degenerate rapidly. All the continuous-combustion engines emit far smaller quantities of pollutants than the spark-ignition engine emits in the absence of emission-control devices; in fact, experimental models of vapor-cycle engines, gas turbines, and Stirling engines have surpassed the most stringent emission requirements yet established. Although the Diesel engine is an intermittent-combustion engine, it has the advantage of operating with excess air, so that Its carbon monoxide emission is negligible. Moreover, hydrocarbons are normally only a small constituent of Diesel exhaust. However, because oxides of nitrogen are formed in hot flames and are retained as a result of rapid chilling, the Diesel engine would not be able to meet stringent oxides-of-nitrogen standards. There are also unsubstantiated suspicions that Diesel-engine exhaust particulates carry carcinogens.

If emission standards were to necessitate the replacement of the Otto engine, the Stirling engine would be the most promising candidate. The part-load efficiency of some experimental Stirling engines (40 percent) is the highest of any of the alternative engines. The engine has the further advantage, shared by steam engines and gas turbines, of being able to operate on almost any fuel. It is very quiet, is the easiest of all alternative engines to start, and operates satisfactorily in freezing temperatures. Since the Stirling engine works on a gas cycle, it has the potential of operating at still higher temperatures and pressures than it does at present, which would make it even more efficient and lighter. Unfortunately, because present experimental models need a substantial amount of metal capable of withstanding high temperatures, they would be expensive to manufacture, but there is hope that alternative ceramic components can be developed.

In conclusion, at present the venerable spark-ignition engine remains largely unsurpassed except with respect to emissions. But if an alternative engine must be developed, automobile makers would be wise to invest in the Stirling.   1 
 1. According to the passage, the carcinogenicity of Diesel-engine exhaust particulates is

(A) an insoluble problem 
(B) a known fact
(C) a common belief
(D) an unsupported hypothesis 
(E) an unacceptable risk

2 
 2. The passage suggests that the major disadvantage of the spark-ignition engine would be greatly reduced if which of the following were to occur?

(A) A starter that makes the engine much easier to start is invented.
(B) A method of removing oxides of nitrogen from the engine's exhaust emissions is devised.
(C) An emissions-control device that maintains its effectiveness is designed for the engine.
(D) Materials that make the engine much less expensive to manufacture are developed.
(E) Manufacturing materials that make the engine much lighter in weight are developed

3 
  3. According to the passage, the Rankine, Brayton, and Stirling engines are similar in which of the following respects?

I. They are continuous-combustion engines.
II. They can operate on almost any fuel.
III. They meet very strict antipollution standards.

(A) I only
(B) I and II only 
(C) I and III only 
(D) II and III only 
(E) I, II, and III

4 
 4. It can be inferred from the passage that the major purpose of developing ceramic parts for the Stirling engine would be to replace some current metal components with parts that are

(A) less expensive
(B) lighter in weight
(C) easier to manufacture
(D) more capable of withstanding freezing temperatures
(E) more capable of withstanding high temperatures

5 
 5. The passage implies that which of the following is currently a disadvantage of at least one of the alternative automobile engines?

(A) Rapid degeneration
(B) High manufacturing cost
(C) High cost of fuel
(D) Excessive carbon monoxide emissions
(E) Excessive hydrocarbon emissions

6 
 6. The author's attitude towards the potential of the Stirling engine can be best described as

(A) ironic
(B) derogatory
(C) confused
(D) cautiously optimistic
(E) completely neutral

7 
 7. It can be inferred from the passage that which of the following events, if it were to occur, would immediately cause the most difficulties for manufacturers of automobiles that have Diesel engines?

(A) Emission requirements for carbon monoxide are made more rigid.
(B) Emission requirements for oxides of nitrogen are made very strict.
(C) A study is undertaken to determine whether Diesel-engine exhaust particulates are carcinogenic.
(D) Researchers find that catalytic emission control devices create a by-product that is harmful to health.
(E) Researchers find that all continuous combustion engines have a serious, previously undiscovered drawback when used as automobile engines.

8 
 8. Which of the following best summarizes the author's main point?

(A) Except in the area of oxides-of-nitrogen emissions, the Diesel engine is nonpolluting; of the other alternative engines, the Stirling engine is the most promising.
(B) Except in the area of exhaust emissions, the conventional automobile engine is currently better overall than alternative engines; of these, the Stirling engine most warrants further development.
(C) Although the conventional automobile engine has many advantages, its failure to meet stringent emission standards makes the development of the Stirling engine essential.
(D) Although concern about air pollution has focused attention on the emissions of alternative automobile engines, it has not led to the full development of any of them.
(E) Once automobile makers become fully aware of the advantages offered by the spark- ignition engine, they will realize that even the very efficient Stirling engine is not worth developing.

honneeey · Answer

8 minutes, All correct!

1. According to the passage, the carcinogenicity of Diesel-engine exhaust particulates is

(D) an unsupported hypothesis- Correct,  refer "There are also unsubstantiated suspicions.."

2. The passage suggests that the major disadvantage of the spark-ignition engine would be greatly reduced if which of the following were to occur?

(C) An emissions-control device that maintains its effectiveness is designed for the engine.- Correct,  refer "In conclusion, at present the venerable spark-ignition engine remains largely unsurpassed except with respect to emissions..."

3. According to the passage, the Rankine, Brayton, and Stirling engines are similar in which of the following respects? 
I. They are continuous-combustion engines.- Correct, refer "All the continuous-combustion engines .."
II. They can operate on almost any fuel.
III. They meet very strict antipollution standards.-Correct, refer " in fact, experimental models of vapor-cycle engines, gas turbines, and Stirling engines have surpassed the most stringent emission requirements yet established.."

(E) I, II, and III- Correct,  this option only has both the choices.

4. It can be inferred from the passage that the major purpose of developing ceramic parts for the Stirling engine would be to replace some current metal components with parts that are

(A) less expensive-  Correct,  refer "Unfortunately, because present experimental models need a substantial amount of metal capable of withstanding high temperatures, they would be expensive to manufacture, but there is hope that alternative ceramic components can be developed.."

5. The passage implies that which of the following is currently a disadvantage of at least one of the alternative automobile engines?

(B) High manufacturing cost- Sterling is an alternative automobile engine and refer this part "Unfortunately, because present experimental models need a substantial amount of metal capable of withstanding high temperatures, they would be expensive to manufacture, but there is hope that alternative ceramic components can be developed.."

6. The author's attitude towards the potential of the Stirling engine can be best described as

(D) cautiously optimistic- Correct,  refer "if an alternative engine must be developed, automobile makers would be wise to invest in the Stirling."

7. It can be inferred from the passage that which of the following events, if it were to occur, would immediately cause the most difficulties for manufacturers of automobiles that have Diesel engines?

(B) Emission requirements for oxides of nitrogen are made very strict.- Correct,  refer "However, because oxides of nitrogen are formed in hot flames and are retained as a result of rapid chilling, the Diesel engine would not be able to meet stringent oxides-of-nitrogen standards.."

8. Which of the following best summarizes the author's main point?

(B) Except in the area of exhaust emissions, the conventional automobile engine is currently better overall than alternative engines; of these, the Stirling engine most warrants further development.- Correct, . Author says Otto is best overall except in the area of exhaust emissions. However, Sterling looks promising provided the cost of manufacturing is brought down.

SWAT09 · Answer

3. According to the passage, the Rankine, Brayton, and Stirling engines are similar in which of the following respects?
I. They are continuous-combustion engines.
II. They can operate on almost any fuel.
III. They meet very strict antipollution standards.

(A) I only
(B) I and II only 
(C) I and III only 
(D) II and III only 
(E) I, II, and III - correct

3rd para..
"The engine has the further advantage, shared by steam engines and gas turbines, of being able to operate on almost any fuel"

aragonn · Answer

P1 - an engine is best but concern is AP.
P2 - disadvantage of engines while advantage of others.
P3 - alternate of an engine proposed . why it is good?
P4 - final verdict.

1. According to the passage, the carcinogenicity of Diesel-engine exhaust particulates is

(A) an insoluble problem
(B) a known fact
(C) a common belief
(D) an unsupported hypothesis ---- There are also unsubstantiated suspicions that Diesel-engine exhaust particulates carry carcinogens.
(E) an unacceptable risk

-----------------------------------------

2. The passage suggests that the major disadvantage of the spark-ignition engine would be greatly reduced if which of the following were to occur?

as mentioned in P1 and in P2 - biggest problem in this engine is clean up issue. inside engine. cause of which air pollution happens. Something that improves it. only C is supporting fact on these lines.
(C) An emissions-control device that maintains its effectiveness is designed for the engine.

-------------------------------------------

3. According to the passage, the Rankine, Brayton, and Stirling engines are similar in which of the following respects?
I. They are continuous-combustion engines.
II. They can operate on almost any fuel.
III. They meet very strict antipollution standards.

(A) I only
(B) I and II only
(C) I and III only
(D) II and III only
(E) I, II, and III - correct, all 3 can easily found in passage.

-------------------------------------------

4. It can be inferred from the passage that the major purpose of developing ceramic parts for the Stirling engine would be to replace some current metal components with parts that are

Unfortunately, because present experimental models need a substantial amount of metal capable of withstanding high temperatures, they would be expensive to manufacture, but there is hope that alternative ceramic components can be developed.

(A) less expensive

---------------------------------------

5. The passage implies that which of the following is currently a disadvantage of at least one of the alternative automobile engines?

they would be expensive to manufacture

(B) High manufacturing cost

----------------------------------------------
6. The author's attitude towards the potential of the Stirling engine can be best described as

P4 describes it.

(D) cautiously optimistic

---------------------------------------------

7. It can be inferred from the passage that which of the following events, if it were to occur, would immediately cause the most difficulties for manufacturers of automobiles that have Diesel engines?

However, because oxides of nitrogen are formed in hot flames and are retained as a result of rapid chilling, the Diesel engine would not be able to meet stringent oxides-of-nitrogen standards.

(B) Emission requirements for oxides of nitrogen are made very strict.

-------------------------------------------

8. Which of the following best summarizes the author's main point?

(B) Except in the area of exhaust emissions, the conventional automobile engine is currently better overall than alternative engines; of these, the Stirling engine most warrants further development.

jawele · Answer

Hi

I see the guys had no reservations about "antipollution standards". To me, "the most stringent emission requirements" is just a subset of the whole package of "antipollution standards". Pollution standards belong to a much broader category, including at least air and water field, whereas "emission requirements" exclusively deal with air pollution. Nevertheless, I may be mistaken.

Could anybody perhaps point out to a flaw in my thought process as regards Q3?

Thanks

u1983   GMATNinja   SajjadAhmad   workout   GMATNinja Two  Gnpth

GMATNinja · Answer

To evaluate the third statement in question #3, we need to determine whether the engines  all  "meet very strict antipollution standards." This is different than saying that they "meet  all  very strict antipollution standards."

Because we know from the passage that they surpass "the most stringent emission requirements yet established," we can say that they meet very strict antipollution standards even if emissions are only one aspect of pollution as a whole.

I hope that helps!

mSKR · Answer

There are also  unsubstantiated suspicions  that Diesel-engine exhaust particulates carry carcinogens.

Maybe my doubt sounds very silly . Apologies. I did this Q wrong.

Can unsubstantiated suspicions not mean a common belief?

unsubstantiated== Unsupported 
suspicions == doubt

belief  can also be based on  unsupported suspicion.

I rejected hypothesis because hypothesis is based on some theory but here no theory is mentioned about. Just a plain suspicion. suspicion should also be a type of belief.

Please suggest.  IanStewart   CrackVerbalGMAT   ExpertsGlobal5

Thanks!

IanStewart · Answer

We are trying to find the answer choice that acceptably paraphrases "unsubstantiated suspicions" in the passage. It's fine to rephrase "suspicions" as "belief". But nothing in the phrase "unsubstantiated suspicions" suggests those suspicions or beliefs are  common , so "common belief" is not a good answer. Nor does "common belief" convey the important meaning that there is no established factual basis for the suspicions. I actually like "hypothesis" less than "belief" as a paraphrase here, since "hypothesis" suggests a formal scientific proposition, while "suspicion" is more informal, but "unsupported hypothesis" importantly conveys that there are no facts (yet) supporting the suspicion, and it avoids the problematic word "common".

Sneha2021 · Answer

Can we infer question 5 from this para? (Ans - High Manufacturing Cost)

"Unfortunately, because present experimental models need a substantial amount of metal capable of withstanding high temperatures, they would be expensive to manufacture, but there is hope that alternative ceramic components can be developed"

mSKR · Answer

5. The passage implies that which of the following is  currently a disadvantage of  at least one of the alternative automobile engines?

alternate automobile engines= the compression-ignition (Diesel) engine, the steam or vapor-cycle (Rankine) engine, the gas turbine (Brayton engine), and the Stirling engine.

(A) Rapid degeneration
 Conventional automobile :  The engine has been substantially cleaned up but, with one or two exceptions, this task has called for catalytic emission- control devices that tend to  degenerate rapidly.

(B)  High manufacturing cost 
1st: The  conventional spark-ignition (Otto) automobile engine  a respectable efficiency (especially under partial load), lightweight, ease of starting, acceptable emissions (with control devices), and a negligible requirement for expensive fabrication materials (and  hence a low manufacturing cost ).  Nonetheless, concern about air pollution  has focused attention  on alternative engines  
>> conventional spark-ignition automobile engine have low cost advantage.

2nd: Since the  Stirling engine  works on a gas cycle, it has the potential of operating at still higher temperatures and pressures than it does at present, which would make it even more efficient and lighter. Unfortunately, because  present  experimental models need a substantial amount of metal capable of withstanding high temperatures,  they would be expensive to manufacture 
>>Sterling high cost to manufacture

So B is correct answer.

(C) High cost of fuel
Not mentioned

(D) Excessive carbon monoxide emissions
o that Its  carbon monoxide emission is negligible.

(E) Excessive hydrocarbon emissions
  hydrocarbons  are normally only a  small constituent  of Diesel exhaust.

krittapat · Answer

IanStewart   CrackVerbalGMAT   egmat   VeritasKarishma   GMATNinja 
Could you help explain why choice C in the question 8 is wrong?
Thank you for your favor.

GMATNinja · Answer

Question 8 
 
To understand the author's main point, you would usually first have to determine the purpose of each paragraph, and from that analysis figure out what the author cares about most (see  this article  for a more comprehensive breakdown of this process).

However, the GMAT gods have given us a rare and amazing gift in this particular passage. The author point-blank states his/her main point at the very end of the passage:

In conclusion, at present the venerable spark-ignition engine remains largely unsurpassed except with respect to emissions. But if an alternative engine must be developed, automobile makers would be wise to invest in the Stirling.

So, does (C) capture this main idea?
 
This is a bit off. The author thinks that " IF  an alternate engine must be developed," it should be the Stirling. That's different than saying that it definitely  IS  essential to develop the Stirling engine, as stated in (C).

We can eliminate (C) for that reason.

Compare that with (B):
 
This is a much better fit. The author thinks that the conventional engine is pretty great, but that the Stirling is the best of the other options.

(B) is the correct answer to question 8.

I hope that helps!

soondoobu · Answer

3. According to the passage, the Rankine, Brayton, and Stirling engines are similar in which of the following respects?
I. They are continuous-combustion engines.
II. They can operate on almost any fuel.
III. They meet very strict antipollution standards.

(A) I only
(B) I and II only
(C) I and III only
(D) II and III only
(E) I, II, and III

How is statement II correct? Only Stirling is able to operate on any other fuel, but not Rankine and Brayton. Can someone please help?

GMATNinja   MartyTargetTestPrep

MartyTargetTestPrep · Answer

Notice that the passage says the following about the Stirling engine:

The engine has the further advantage, shared by steam engines and gas turbines, of being able to operate on almost any fuel.

That means the following:

The (Stirling) engine has the further advantage, shared by steam engines (Rankine) and gas turbines (Brayton), of being able to operate on almost any fuel.

Thus, we can see that the passage supports statement II.

VerbalBot · Answer

Automated notice from GMAT Club VerbalBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.

The conventional spark-ignition (Otto) automobile engine

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Reading Comprehension (RC) Questions

The conventional spark-ignition (Otto) automobile engine

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards