It's common to see posts in the forums asking "do I need my 400kw rotary shoehorned into a corolla engineered and will I need to upgrade the leaky 4 wheel drums" or something to that effect.
There are a few things that should be considered before the question is asked.
Where are you?
Typically, answers to said questions often start off with "well in Adelaide you can do this but you're in Botswana, so I dunno if that counts". In Australia, state laws vary widely, so its almost pointless asking someone across the continent what they have done etc, because it won't count. The first and formost authority is your local transport authority: The DTEI in SA, Vicroads in Vic, the RTA in NSW and so on.
Over time I will try compile more state by state specifics on the FAQ.
Common sense dictates that the more insane the conversion the harder it will be to do. Upgrading to a 5k might not be a problem at all in some states, whereas Rolls Royce Merlin engines will need considerably more effort. (Oh and by the way its been done into a 55 chev)
Yep, thats right. If you ever hear the words "this bloke I know said....". If you walk in to register your car and give them that line, see how likely you are to walk out with a shiny new rego sticker. Once again, the first and foremost point of contact is your local transport authority.
Use your head
Cars registered for road use should be roadworthy. Thats right, roadworthy. So if you've done a nice engine conversion, great, but if the ball joints are shot, the seatbelts are frayed and its only on odd occasions that your right rear brake light decides to work, then think again. Start with a car that is clean and tidy and would pass a roadworthy inspection THEN start thinking about engine conversions etc. No engineer or registration authority will even think about passing you if you can't even meet the basic requirements
It can go, but can it stop
This is not necessarily fact, but it is fairly safe to say that if your car goes hard, it's going to need to stop hard. And part of stopping hard comes down to suspension.
Are you serious?
Ok cool, we all have dreams, but if you sat down and do the numbers on what it costs to build a 300hp street legal tyre shredding monster, you will see that it is a lot of time, money and effort. I'm an engineer by trade and I like money, so keep that in mind if you want to do it.
It will never be a case of drive in drive out an hour later with an engineering cert.
What year is it
Laws change frequently, and this goes for engineering laws. Coming back to the hearsay problem, it's important to keep in mind that what happened as far as cars go might not be the case anymore. Over the last few years i've heard of all sorts of rules of thumb, such as "percent capacity increases", "percent horsepower increases" and "any engine in the same family" and so on. I don't disbelieve any of these rules of thumb, but it would seem that they are not the case anymore, they have made way for much more comprehensive regulations etc.
So before you embark on the exciting (and it is exciting) journey of engineering a car, just consider these points first. I will try compile an overview of what is the case for individual states based on what I have researched myself. Keep in mind that they may have changed since I dealt with them though, and good luck!