21R was a JDM engine built to get under Japans engine displacement regs. 84 bore 89 stroke and a relatively low compression, I believe it was 9 to 1. Had lower hp and torque due to the bore and compression. I think the cams was a little longer on duration and lower lift, had to spin higher for what hp it did have, From what I did, the 21R block couldn't be bored to 92mm like the 20R could.
Block is best used as a boat anchor. Never did anything with the head, too disappointed with that engine.
Don't waste your time.
