xtian:
I'm not going to be running any NOS or anything like that. I don't want to have to refill bottles, and I want power that is always available. While I'm sure I'll hit the drag strip often, the focus of all my mods is auto-cross/road racing.
The ECU is a completely custom creation, so I can drive or read any kind of signal without a problem. I'm running all Freescale ICs at the moment, and they have a solution for just about everything automotive related.
Are you saying I would be smog exempt because of the diesel motor base, or because of the propane? Not having to run cats would be sweet. Keep in mind I'm in Ontario, Canada. I haven't looked up much related to smog law yet, but from what I can tell I'm still going to have to e-test.
The car I have is a 1989 Trans Am, which is slightly unfortunate because it will always need to be e-tested. 1987 and earlier cars are exempt from e-testing. They changed the rolling 20 year rule last year, so every car that still had to be e-tested will need to be e-tested forever
I'm considering finding a 1987 rolling frame to build off of instead.
EGR won't be there regardless of whether I'm exempt or not...just a risk I'm going to have to take. There's no way I'm going to run all the EGR plumbing on the new motor build.
Diesel motor: I don't want a higher base compression than 10 or 11:1 anyway, so a gasoline motor would be fine in that regard. If I go any higher then I wouldn't be able to run as much boost. I believe HD-5 automotive propane has an octane rating of "only" 104 or 105, and I plan on running at least 16psi of boost, preferably more.
As I said in a previous post, direct injection might be sort of cool, but I just dislike the whole spotaneous combustion thing. I prefer the idea of controlling combustion timing with a spark for whatever reason.
Turbo plumbing is going to be completely custom anyway - the size of the turbos I'm planning to use won't let me reuse any stock piping even if I wanted to.
The LS3 I was planning to use is all aluminium. Aluminium dissipates heat much faster than cast iron, which I assume (although I could be completely wrong) is a good thing for the hotter burning propane.
I'm still stuck trying to decide where to inject the propane. I could do multi-port injection, with liquid injectors, but I hear that can cause burned pistons due to uneven mixing. When it is injected so close to the valves it doesn't have sufficient time to completely vaporize and mix evenly.
I like the idea of injecting pre-turbo but the possibility of backfiring during an engine misfire and blowing off the intake pipes still scares me. I'm also slightly worried that if a boost leak were to form somewhere, it would be leaking fuel/air under the hood and something could ignite it (i.e. a backfire that blows off the intake pipes, lol).
To be honest, I don't really understand the benefit of multi-port injection vs single point injection in a gaseous fuel scenario. It sort of makes sense with gasoline, but I imagine that with a gaseous fuel, the more time it has to mix evenly the better, no?
That leaves me with the final option, which is positioning the injectors where a traditional carburator would normally go, Throttle Body Injection style.
Any opinions?