Test Results: Compression vs. Ignition

[oppositelock]

Personally, I've been running maximum ignition timing since I've started playing the game. After watching one of Killrob's videos where he mentioned diminishing returns with spark advance, I decided to test various combinations of compression and ignition to see if that was really true. I thought you guys might find the results interesting.

This is the test engine I started with, for reference. Run-of-the-mill eco four banger: http://www.mediafire.com/?8tjha04twkasb75



Maximum power and fuel economy were achieved with an ignition setting of around 80, while more spark is better for response and emissions. I haven't tried any other engines yet, if I notice a large discrepancy with other motors I'll try to put up those results also. Feel free to post your own tests in this thread, as well.

[Killrob]

Good stuff!

[SnipeUout]

Nice test! Just proves that there is a balance between compression and timing.

[LeroyP]

Theres no real comparison in that test. With 2 variables per result, theres no telling whats really going on. Wouldnt a better test be to show results from 4 different ignition timings (perhaps in increments of 10) over a given compression ratio (increments of 0.5?). That way we can see the increased response and better emissions as a result of the timing, not a by-product of increasing compression.

[oldgreg]

Theres no real comparison in that test. With 2 variables per result, theres no telling whats really going on. Wouldnt a better test be to show results from 4 different ignition timings (perhaps in increments of 10) over a given compression ratio (increments of 0.5?). That way we can see the increased response and better emissions as a result of the timing, not a by-product of increasing compression.

I disagree.

Raising either compression or ignition timing will increase power, improve efficiency, lower emissions, etc. and at no point will raising either of them not be a good thing until the engine starts to knock. The problem is that we are limited by the octane of the fuel we choose for the engine so we cannot simply max out both compression and ignition; at some point you will have to lower one to raise the other. The point of this test is to show that for a given set of engine parameters there will be an optimum ratio of compression and ignition either for power/efficiency, or response, or emissions, etc.

[oppositelock]

What he said. In each of the above configurations the engine is tuned to the edge of detonation for optimum performance. Building engines with an octane requirement drastically lower than the specified fuel is basically pointless.

[LeroyP]

I see. Fair enough.