hey guys, i currently own a 88 prelude si 4ws, i have the b20a5 engine in it. I have a knocking sound, i dont know if it's a bent valve or a rod knock. which would be cheaper, fixing the problem, or just swapping a new engine? im new to the tuner world, and im trying to do a little homework on my car, any soluions?

 

Try doing a valve adjustment. These cars are known for a noisy valvetrain. If any clearences are very far off chances are a valve is bent. If that doesnt help you probably have a rod knock on either cylinder 2 or 3. If the crank isn't damaged you could probably get away with just changing bearings. Only engine swaps you have easily available to you are another b20a5/b20a or the h22/h23/f22/f23 swap. A civic/integra/crv b series will not work in your car without a bit of custom work, you unfortunately have the "bastard b" engine, it has virtually nothing in common with the b16/b18/b20b. Did you over-rev the engine by any chance?

 

As far as I know for engine swaps, no other b series will fit snugly without new mounts. B20a5 or B21n1, I prefer B20A5.
But anyway, observe under your valve cover for suspicious rockers or any visually obvious signs of bent valves. I myself encountered a knock on my 91, and deeply reassured when I examined a cam had come loose! Also, drain your oil and check for metal shavings. See any, and you are toast. Means a rod!
Good luck.

 

as stated, pull the valve cover and take a look around. leave the cover off, do an oil change and inspect the oil. put your finger in it and look for metal flake. if none is seen, check your valve lash adjustment. look for exhaust leaks at the exhaust manifold flange to the head (this can sound like a knock to a newb). if you do see metal in the oil, you have a decision to make. a: cheap way, put new rod bearings in it and roll with it (understand it could also be mains). or b: spend some time searching for a junkyard b20a5 and rebuild that.

another option is the jdm b20a. you can have that shipped over for near the 6-800 range and i would say timing belt new water pump and all new seals before you install it.

you can find these engines on egay, but thats your call. same deal though. do the work before you put it in the car.

as to the b21a1 and b21a(jdm counterpart) stay away from them. they have the frm cylinders in them and are known to chew through some piston rings.

 

knocking sounds can come from a variety of places, are you sure its the engine and not something else like the transmission's throw out bearing?

Also if its a constant ticking...its valve lash.