It is in some of the 4th gen Ludes I believe.
edit: I did some research:
The B20A, B20A3, and B20A5 engines consisted of closed-deck aluminum blocks with thicker-than-average iron sleeves where as the B21A1 had some special material.
The B21A1 was basically a re-worked B20A5 with an increase in bore to 83 mm. The external block dimensions had to stay identical to the B20A5 block so Honda called upon Saffil to create a thin but strong cylinder liner called FRM (Fiber Reinforced Metal) which basically consisted of a carbon fiber matrix, aluminum alloy, and aluminum oxide to make a very strong cylinder sleeve. These sleeves are so strong that they often do not lose their factory cross-hatching marks after 200,000 miles! A lot of B21A1 engines burn oil and have low cylinder compression numbers because the FRM material is so strong that it tears up piston rings. Good news though, you can usually replace the piston rings without any honing to the sleeves and go another 100,000+ miles without any sleeve wear.
B21A
(16-valve, DOHC, PGM-FI)
* Found in:
o 1990-1991 Honda Prelude Si States
* Very rare, it was only produced for the "Si States" models in Japan
* Power: 185
B21A1
(16-valve, DOHC, PGM-FI)
* Found in:
o 1990-1991 Honda Prelude Si
* Power: 140 hp @5800 rpm
* Torque: 135 lb.ft @5000 rpm
* Engine cc: 2056.03
* Cylinder cc: 514.0075
* Deck cc: 10.191
* Head cc: 51.0
* Compression Ratio: 9.4:1
Torque (lb.ft. @ rpm): 135@5000
I wanna see somebody boost the hell out of a B21A... wonder how much those sleeves can take
Posted: Fri Nov 10, 2006 5:10 pm