engine swap question for an 88 2.0 si. b20 - Honda Prelude Forum

ElectricCrayon · 10-11-2010, 04:38 PM

i have an 88 2.0 si that needs a new motor. i have ALOT of things to do to the car before i start thinking along the lines of beefing it up for turbo, but i have one friend telling me to switch to a b18, while another friend tells me to stick with the b20. any insight on the pros an cons of making the switch would be appreciated. eventually i would like to turn it into a monster, but im not educated on honda motors well enough to know what would work best in this particular model honda. i guess what i want to know is which motor can i get the most out of without alot upgrades and money for the time being...

Colfax · 10-11-2010, 05:29 PM

To be honest, the only engines that are more or less a direct fit are either the b20a5 or b21a1, without having to fork over a lot of money for custom parts. Unfortunately, the 3rd gen Prelude 'b' series engines are Honda's "bastard b series" engines, and are not compatible with other Honda 'b' series engines. The engine leans back in the engine bay at an angle in order for the 3rd gen to have such a low hood line. Because of this, you would need custom mounts and axles, among other things, in order to try to fit any other engine in there. Not impossible, but very expensive.

There is one exception to this though. Some guys have swapped the h22a into 3rd gens, and there is aftermarket support for this swap. This swap will end up costing about $5k after all is said and done. But it's worth the cost according to those who have done it, as there is a lot of aftermarket support for this engine. It would also be a good candidate for your eventual monster if you boost the h22a.

A lot of guys just add a turbo to the stock b20a5 engine. This would be your cheapest solution if you want something with more than stock power. Depending on components used, I have read about guys getting more than 400 hp out of one with forged internals.

It all depends on how much you want to spend.

ElectricCrayon · 10-11-2010, 06:04 PM

thanks for that insight! i was not aware of the engine being set at an angle, and i doubt the guy tellin me to swap to a different motor is aware of that.
is there a good variety of heads that i can use for the b20?

chris112818 · 10-11-2010, 10:15 PM

h22s in 3rd gens are awesome i have personally driven one. Made me wanna buy another 3G lude =( sold mine to upgrade to the 01... its a hard swap but well worth it. The guy i know that owns the h22 3G says he can cram a turbo in there (it already looked tight in there)... but if you wanna stay in the b series id say b20 not good enough reasons worth mentioning (personal pref.)

gl on decision.

Colfax · 10-11-2010, 10:38 PM

Quote:

Originally Posted by ElectricCrayon

thanks for that insight! i was not aware of the engine being set at an angle, and i doubt the guy tellin me to swap to a different motor is aware of that.
is there a good variety of heads that i can use for the b20?

The only heads that are bolt on are 3rd gen heads, b20a(5,7,9) and b21a1. You can get a small boost in performance if you use a b21a1 block with a b20a5 head, then use a b21a1 exhaust cam and b18b intake cam. Of course you'll want to use adjustable cam gears and a good tune. And the b18 cam needs be shortened slightly on the gear end.