How to calibrate the time constraint of an exam for a new course? I am preparing an exam for a course I'm running. It's an engineering course; the exam problems require students to apply conceptual knowledge and quantitative skills taught in lectures and labs.

It's the first time the class has been offered, so I don't have a frame of reference from previous years. There haven't been any in-class quizzes or other opportunities for me to find out directly how long students would take to solve problems similar to the ones on the exam. I also haven't found any similar exams from other universities to serve as a reference.

Obviously, I am much more experienced in the material than my students, so I can't really generalize from how long it takes me to solve these kinds of problems.

This question is for the more experienced educators out there: in a scenario like this, are there any methods or general rules for determining how long you can make the exam, given the time allotted?

I don't want time to be a major issue on this exam; I want most students who are reasonably well prepared to be able to complete the exam in the given time.
This is totally unscientific, but for my exams (mathematics) I use the following rule of thumb:

After writing the exam, I sit down with a stopwatch and work the exam from start to finish. Of course, I know how to solve the problems (since I wrote them) but I go carefully through all the steps and write what I would consider a thorough and exemplary solution. I note the time I spent  on each problem.

Then I take the total time and multiply it by 3 (or sometimes 4). If this exceeds the allotted time for the exam, I remove or simplify some questions. (This is where it helps that I wrote down the time I spent on each question, so I can remove a question and recompute the time without actually retaking the whole exam.)

As a side benefit, this also helps ensure that I haven't made any mistakes in creating the exam, and that all the problems have the solutions I intended. It also gives me an answer key.