B20 In A Crx?

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Junior Member
I was wondering if a b20 would fit in a 91 crx. I already have a 91 b18 in there now. If you could, what do I have to do. do I have to get different motor mounts? I was also wondering if the b18 head would fit on the b20. I have the head worked on so I would like to put it on if I could.
yea you will need to use the ls manifold, and your head will swap no problem. You will want to switch pistons most likely, to get ones with a higher cr, or not if you want to go turbo. It all depends. Good luck

Dont listen to mwasnp,

All you need to do when you get the b20 is like the first guy said is to swap the Intake for the LS one. Keep the LS throttle body and all of the sensors.

Dont swap the Heads.....LS is a 81mm piston and the b20 is a 84mm piston...

Other than that the whole setup is exactly the same as the LS.

Also, swap the Distributors, The b20 is an OBDI and the LS one should be a OBD0.

You wont be sorry for the swap. The b20 has hella torque.

Good luck bro,
ya listen to Fx, what he said is truth because i did the same like about a yr ago when i had my b20-vtec in my car..the only problem i ran into is that the b20 with the vtec head (B16 in my setup) is way taller then the regular LS that lead to a fatty bump on my hodd from me banging gears with that set up so just check for clearnce becasue the lump i had on my CRX was ugly but one thing i liked was hearing the "bang" on my hood when ever i was baninging gears hard...but that led to me getting another hood from ecology cuz bumps look ugly
Thanks for the info. I just have one question. Why can't i swap heads? does the piston size matter when you swap heads?
You can swap the heads. There is NO difference in a LS od B20 head.
You can swap the heads.....but why?

If you get a b20 with a b20 head, then why would you swap it for an LS. Besides like I said before, the LS's head is only 81mm wide in the combustion chamber to match the block. While the B20 is 84mm in the combustion chamber.

The only time you need to worry about any of this is when you start trying to adjust the cam gear sprockets. Also before you swap any head on any car it is recommended that you clay it. That way you can see if the valves touch the pistons or if the the pistons touch the head.

Also I wouldnt swap the heads unless its for a V-tec one.

Anyways I would put the b20 in and sell off the LS stuff in order to get a v-tec head.

I have been saving parts up to build a b20 now for a year. I have a ported gsr head, eagle rods, and JE 12.1/5 pistons. All of the gaskets and so on.....lol. All I need is a b20 block and b20 or LS crank.


your on the right track.

Good luck,
that motor will fit in the CRx but its a waste of time and money all the custom work ur going to do to get that motor to fit u could have had a b16...
STOP!!!!! dude you guys...like he said the ls and b20 are almost the same exact engine...hey kid that wants the b20 your going to have to take the engine out to swap it correct? yes, so heres a better idea...why dont u go find a b20 crank on a crv at a junk yard or just buy one and put it in your b18 and add the b20 head?? then you would have the same stroke so you would get your torque you want BUT in a crx or light car your gonna need a good clutch bud cause when you hit torque like that in a tiny ass car you arent gonna stop those wheels from spinning...and if you want to drop another .250 sec or more off your ET...put the b16 tranny on from japan(cable) and if ya want put the LS integ final drive in the b16 so you can save a little gas when ur cruisin.....and there isnt no custom work to get it to fit its the same damn motor ofcourse it will fit...but save yourself some time with the wiring and just get the crank pull the motor oil pan off, PUT GSR OR B16 OIL PUMP ON!!!! real good idea take rod caps off new crank seals put crank in and bam ur done when ya put it together
nooooo! dont do what crxfreak is telling you (no offense) the only difference between the ls motor and the crv motor is not the crank, the only difference is the piston size (84mm=crv 81mm=ls) they both have the same crank (89mm stroke). go under articles and click on displacement chart for bored-out motors.
The only difference between the LS and Crv block, like stated above is the size of the cylinder. LS=81 MM CRV=84MM That bigger displacement is what gives ya more torque. Swapping the crank wouldn't do anything for ya. I recommend you go and find a VTEC head and use that. Trust me, it's well worth it. Even if you were to use the stock CRV block with a VTEC head, you would be running 13's easy with a B16 tranny. Your car is so light, it would snap your neck if you went with a CRVTEC conversion. I just built one with all the internals, ported head and chipped ecu, Stage 2 (My specs, of course) Cams, b16 tranny. It ran a 12 flat on slicks, untuned. My buddy is just waiting for his Hondata and his conversion to OBD 1 harness. Then we should see even better HP and Tq. figures. This is street car, driven everyday, not a track car. Keep an eye out for him, it's a Lightning Silver-colored 88 REX. I'm moving back to H town in about 6 months and for now, he represents my crew overthere. Hope I helped a bit. Peace.