Topic: 1980 Toyota 21R Question(s)

[accountant_mechanic_]

Hi all,

I have had my fair-share of Toyota R-series engines in the past. I've had:
1979 20R
1984 22R
1992 22RE
1993 22RE
and now I have added a 1980 21R to that list.


From what I understand, these were a replacement motor for the 20R from Japan. I understand that they were not popular or desirable here in the states. I know that they were used in some forklifts as well as the corona (I think) and also some of the smaller Toyota motorhomes back in the early 80's.

For something that was free to me, it's kind of cool- it has a dual row timing chain from factory with fully metal guides. I have all of the pieces and parts to put it back together, I'm just wondering if it's worth it? Does anybody actually use these engines? Do they hold any value other than a paper weight? It has a 20R sticker on the valve cover so does that mean it has 20R heads? How can I check?

Any and all info (that I can't find on other forums/wikipedia) would be very helpful. Opinions are also helpful.  Thanks

[sirdeuce]

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.

[kneedownnate]

Worst yota engine I’ve run.  Supposed to have something like 30% less power than a 22r, and that’s exactly what mine felt like!

[Lewis Hein]

Ooo so it could have been a serious upgrade from my old worn out 22R

[accountant_mechanic_ [OP]]

UPDATE

I blew it up with a few rounds of 7.62x39. Thanks 

[TXTrey]

From what I did, the 21R block couldn't be bored to 92mm like the 20R could.

I am curious as to why?  I have a 76 Celica with a 21R.  I thought about possibly boring it out to do a "20R head/22R block" style hybrid.  Based on my research the 21R head is the same as the 20R, and the 20R, 21R, and early 22Rs all have identical blocks, and the same stroke, just different bores.  I've considered buying a 22r short block, but I haven't found much in the past year and most are overpriced (the best I've seen is $1200 which is a chunk, considering I see on forums all the time where people have picked them up for a few hundred bucks).  Boring the 21R block and buying 22R pistons seems like a less expensive route.  Does anyone know for sure if it's feasible or not?

Sources: http://members.iinet.net.au/~stepho/eng20r.htm, https://www.enginebuildermag.com/1998/11/just-imports-toyota-r-series/, http://toyheadauto.com/PerformancePages/ToyotaPerformanceValveTrain.html

[sirdeuce]

The 21R has an 84mm bore, 20R 89.5 and the 22R 92. All the castings have about the same cylinder wall casting thickness. The 20R can handle a 92mm bore but shouldn't be more than that. the 22R can go to 94, but can have issues with cooling. the 21R could have issues going as far as 87mm.
As for cylinder heads, the 21R was produced from '78 to '85 or '87, it would be available with both the 20R style head or the 22R style head. Starting in '81 the 22R head would be the head available as the 22R started in that year. Having an 84mm bore would have necessitated a smaller combustion chamber in either head, which would have shrunk the valves as well.  I never liked the 21R so I just canned it when I was done, never went that far into it.
If they wanted to do a better job on the 21R making it an oversquare engine instead of an undersquare engine would have been better. Maybe even a square engine at 86X86 would have been fine.