FAQ: Motor work

[bigrcr]

I have been getting a few questions about the motor and what "modified" really means. I hope the simple explanation below may help!

So what are all these terms that get thrown about in regards to modified motors such as 'blueprinting', polish (polished what?) ported (ported how?) or is that trade secret? I know I forgot to include some terms but I'm curious as to what the terminology means. Still trying to figure out if Stage I, Stage II, etc is an industry term or a manufacturer term and what it means.

"Stage 1" basically means that this is the first step in modifying the motor. I guess you could conclude that that means there will be a "stage 2" and so on. The modifications are done in a series of "steps" to ensure the motor performs as intended without taking a huge step in modification and then find out that something you did created a problem.

'Blue printing"- is used loosely nowadays. Generally it means that you have taken all of the measurements of the motors "guts" and all of them meet a tight specification of what you want. This does not happen from the factory as the parts are made and assembled by line workers using "bin" parts and general Procedures. They don't have the time to individually fit and measure each part for tight tolerances and assemble it the same.

Polishing- Usually happens after the machining work has been completed. This would include complete de-burring, smoothing the intake and exhaust ports to make the gasses move with less friction, etc.

Porting- Means to do work on either the intake porting, the exhaust porting or both. The porting delivers the fuel mixture from the crankcase to the top of the piston where it can be compressed and from the top of the cylinder out and through the exhaust opening . What you do here can effect the way the gasses flow through the motor. The better the gasses can flow, the more flow you can have and the more power you can make. The porting job can even change or modify when (timing) the gasses and to what extent for each cycle.

Balancing- This can mean several things but generally it is to make the piston/rod weight match the crank counter weight so that the motor runs smooth. Many things can effect the "balance" such as friction, weight of parts and compression.

All of the things (and more) above effect the way the motor runs and makes it's power. The engine builder uses knowledge and experience to make the changes to produce more horsepower, more torque, different RPM ranges or user friendliness.