Your G20 already has a SR engine.
SR engines are inline, four cylinder, twin overhead camshaft 16 valve EFI.
RB engines are inline, six cylinder, twin overhead camshft 24 valve EFI.
Both series are turbo capable and have factory turbo version...
There are many iterations of both engines and plenty of members here better placed to tell you all the models but here are some basics...
SR is usually front wheel drive except when used in 200sx [RWD] and Pulsar GTiR[4WD].RB is allways rear wheel drive or 4wd.
Forget RB.
SR's come in 1800cc and 2000cc ie SR18DE and SR20DE.(140-150Hp)
There are turbo SR18DET and SR20DET (190-230Hp), then there's the Neo VVL SR16VE (175Hp), SR20VE (190 Hp) which is a lot like a vtec engine.
The power figures I give are all approximate, but close, and are stock outputs fo each engine at the flywheel.All the SR's will fit in your G20 with little or no modifications and suit the Frontwheel drive application
