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20/22R/RE Early/Late Engine Differences

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20/22R/RE Early/Late Engine Differences

Post by a2ndopinion on Sat Dec 15, 2012 10:21 pm

This may end up being a rather long dissertation, but bear with me, as I will dispel some wives tales in the process, and pass on information that I have never seen anyone else discuss on the 'net.

The 22R replaced the 20R in 1981, and had many differences, but some things stayed the same. Electronic Fuel Injection became an opinion in '83 as the standard engine in the Celica GT-S and most GTs, but not in the ST. The fuel injected engine was referred to as the 22RE (E for EFI). Some trucks saw it in '84, and then in '85 Toyota completely revised the block and head, and all '85 Celicas had 22REs, but the trucks and 4Runners had it as an option through 1989, after which it became standard.

The "early motor", from '81-'84 used basically the same block as the 20R, but it had a 92mm bore giving it 2366cc Vs the 88.5mm bore that the 20R had (2189cc), and the pistons had a considerable dome with a dish in the center, compared to the very slight dome that the 20R had. This upped the compression to 9.0:1 compared to the 8.4:1 in the 20R. The 20R and early 22R/RE combustion chambers were virtually identical, although some say the 22R was 1~3 CCs bigger; which is almost impossible to verify now, as finding a virgin head is probably not going to happen. These were "open chamber" combustion chambers - a round, full, hemispherical chamber. They used the same timing covers as well, as long as you are talking about the '78-'80 20R, as the '75-'77 didn't have one return fitting to the water pump. The '81-'82 used the same double row timing chain with steel guides as the 20R that lasted forever (at least 400k miles anyway), but the '83-'84 switched to a single row chain with plastic guides, which only have a normal life of 100-200,000 miles (planned obsolescence?). The early single row chain can be upgraded to the double row chain and steel guides by ordering the set for the '75-'80 20R/'81-'82 22R, and then milling (grinding) 1/4" off of the splined oil pump drive - it's that simple!

All 20/22R/REs used the same forged steel crankshaft with the same stroke and the same length forged steel rods, but the rods changed - apparently sometime in the '85 year run (I've found factory late pistons on early rods). The later rods had additional reinforcement around the oil hole and elsewhere, increasing their weight by roughly 30g. I say roughly because I've seen early rods range from as light as 712.0g to 726.1g, and one that weighed an unusual 735.5g; and late rods range from 741.1g to 758.1g. You definitely don't want to put one of these engines together w/o having it balanced!!!

In '85 (8/84 supposedly), Toyota released the redesigned "LASRE" (lightweight advanced super response engine) 22R/RE block and head. The block can be verified by the circle with an extended oval intersecting it on the left side by the motor mount, which was the boss for the oil return line on the turbo engine. The head has two bolt (stud) holes between the 2 & 3 exhaust ports instead of the one on early heads, and they have keyhole shaped exhaust ports - they melded the port with the A.I.R. hole, and did away with the tubes.
The block was .190" shorter from the crank to the deck, and the head was .130" shorter from the cam to the deck. The difference in the block height was made up for in piston wrist pin height, meaning that the piston sat that much lower in the block. The heads combustion chamber was a "closed chamber", resembling the shape of a peanut, giving a "quench" area - that is where the piston comes to within about .040" of portions of the head, forcing the mixture into a much smaller area, creating a much better burn, but at the cost of shrouding the valves a bit. IMO, the better burn was the biggest reason for the increase in compression ratio, and the reason why the later motor made so much more power, but there were other reasons as well...

More to come!

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DD -'81 Corona wagon - 22R hybrid P&P, Crane stage 3, Si valves, Erson springs/retainers, Weber, Cannon, MSD, Thorley, Borla, 3rd gen Celica front suspension, Cressi Big Brakes, coilovers, Camber plates, RCAs, AGXs, Addco, all urethane bushings, Hilux leafs...
20/22R/RE & Celica Guru, 2nd & 3rd gens - GT-Ss - 'vert, coupes & liftback... & Chevy fanatic

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Re: 20/22R/RE Early/Late Engine Differences

Post by dvrx7fb on Tue Jan 20, 2015 8:32 pm

So quick question what trans can i put on my 22r corona and is there a differential swap i can do to mak it better


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Join date : 2015-01-20

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