Butane Gas Ignition Pressures and Temperatures

What is "pre-ignite"?

wouldn't the question be

spark ignition or diesel?

No. It's too off the wall to be taken seriously, and the OP says, "I'd rather not use glow plugs to pre-heat the cylinder."

Well it's a bit 'language', but the OP means "the charge" - a bit like small aero engines do. Sort of compression aided by a hot spot ignition.

It is inconceivable to me how you can possible infer that from the original post.

You must count mind reading among your many talents.

Sorry Lyn

But the question is fairly straight forward. OP wants to know what the compression ignition parameters are for low temperature starting of a 'diesel' running on gas (not the petrol kind)

Of course there is a lot more that he/she hasn't considered, but that may or may not come out later in the thread

No need to apologize.

1. Do you mean the compression ratio required to attain the auto-ignition of butane

2. You can estimate from the polytropic compression equation. Coupled with gas law, we can deduce the following relationship:

T2/T1 = (p2/p1)^m

where m = (k - 1)/k/polytropic efficiency.

k is the specific heat ratio.

3. Auto-ignition of butane = 405 C

4 Use absolute P & T in the above equation

Check this Wikipedia link for an article which explains a lot including "pre-ignition" http://en.wikipedia.org/wiki/Engine_knocking

Autoignition of butane is 420 (c) or 788 (f) and like most fuels these temperatures can vary can because of the chemical mixtures. For instance propane is still propane even though it has varing amounts of butane or methane etc.

This article http://www.mech.kuleuven.be/en/tme/research/Thermotech/Contents/2008_Norman.pdf has a lot of information you can use including a formula for combustion ignition which is what I think you may be looking for.

This sure has the bang of a Home Work Question in Auto-101a