For years, an engine company has designed direct-injection (i. e., no pre-chamber), high-compression ratio, turbocharged Diesel engines that operate with one fuel injection per cycle. Due to new advances in controls and injection technology, the company proposes a new Diesel engine incorporating a swirl pre-chamber and two fuel injections per cycle. The first (so called pilot) injection delivers a small of diesel fuel ahead of the main fuel injection. Assuming that at any given operating condition the total amount of fuel injected per cycle is the same for both engine designs and that the injection timing is optimized in both cases, answer the following questions:

1. Will the amount of heat released in the premixed combustion phase increase, decrease, or remain the same for the new engine, compared to the old design, as a result of the proposed modification(s)? Explain.

2. Will the new engine be easier or more difficult to start in cold weather as a result of the proposed modification(s)? Explain.

3. Will the probability of knock increase, decrease, or remain the same as a result of the proposed modification(s)? Explain.