Nitrous+Propane injection at the same time.

[jonnyk]

This is very common in the turbo world. A while ago I did some research and found a propane kit made for a company that ORIGINALLY designed it for the 3000GT VR-4's, but I'm sure they have plenty of setups for different types of cars.

Propane is a very high octane fuel, that is liquid when it's pressurized and vaporizes when it decompresses out of the storage bottles. Same idea as nitrous - it helps with sucking up intake charge heat. However, the big advantage to propane is it is a very HIGH octane fuel, much like running pure methanol into your engine. You can then add a much more aggressive tune and make more power. Combining the fuel with the extra oxygen of the nitrous would be a killer setup. Getting the right proportion of propane in there would be critical however, you don't want it to go way lean! Propane is also very cheap and readily available. The injection kit bottles didn't require filling very often either, as I recall.

The downside is propane is a VERY volatile fuel, so having it inside your car would pose a hazard if treated incorrectly (unlike nitrous which is inert at "atmospheric" temperatures). It is heavier than air also and will settle in low areas if there is a leak (by your feet, spare tire well, etc.) which could be rather catastrophic once a spark is introduced. With that being said, everything is "usable" if you take the proper precautions.