Swapping an Engine in a Honda CRX

Joel Guerra
6 min readMay 11, 2021


Today is the day! The engine I’ve been building is going in the autocross CRX! I’ll go through the whole project step by step. To read about the engine build itself check out this post.

1990 Honda CRX Si

Step 1: Have a friend who has a lift.

Step 2 (optional): Paint your ugly block.

Step 3… ok I’m not numbering the steps anymore. Take off the wheels, traction control bar, ball joints…

Drain the forbidden nectar (gear oil).

Drain the forbidden Gatorade (engine coolant).

Pull the headers. These Megan racing headers will go back in later but will eventually be replaced with an AE-RACE turbo manifold.

Pull the radiator. This will go back in with the new engine but will also eventually need to be replaced with a half-size radiator to make room for the turbo.

Disconnect the harnesses and hoses. No matter how sure you are that you got them all there will be more that you didn’t see when you start pulling the engine, so double check.

Disconnect the shift linkage. I’m going from a stock B20B to a built LS/V and will be using the same GSR transmission so this shift linkage will still be used going forward.

Position an engine cart just below and disconnect the engine mounts. If you are not fortunate enough to have a lift make sure your crane chains have tension right now so you don’t have a catastrophic falling engine.

Slowly lift the car back up leaving the engine behind… keep an eye on things because you definitely left some hoses or wires connected and you’ll need to deal with that.

Since the engine coming out and the engine going in are both B-series I get to reuse the transmission, alternator, starter, wiring, hoses, distributor etc. So they all need to be swapped over.

Swapping over some bits!

Put the fly wheel on.

This clutch is going back in for now but won’t hold up to boost later.

The transmission and starter can go back on now.

This engine is ready to be mounted. Position the engine under the car and bring it back down.

Make sure to not whack anything on the way down.

Line up the engine mounts!

Bolt up the engine mounts and reinstall the headers.

Reinstall the radiator and hoses.

Install the new shiny VTEC oil feed line that you definitely should have done while it was still outside of the car.

Lift it back up a bit to install the shift linkage.

Reinstall the traction bar and bolt up the exhaust down pipe.

Reinstall the axles, reconnect the knuckles, put the wheels back on. Basically re-do everything you undid before.

Next install the new spark plugs and bolt up the valve cover because for some reason you never did this when building the engine.

We’re getting there… Plug everything in and reconnect all the hoses.

The Type R cylinder head I have didn’t come with an intake manifold so here’s the new Skunk2 Ultra Street intake manifold I’m using.

Here I have new OEM coil packs (OEM for an Acura RSX Type-S). This CRX was already converted to coil-on-plug but the old non-VTEC engine was using D17 (2002 Honda Civic LX) coils packs which won’t work with this new VTEC engine. If you want to read about converting to coil-on-plug check out this post.

The intake manifold is on, the new 70mm throttle body on, the old intake pipe is on and the new coil packs are in. This intake manifold has straight runners that take up more horizontal space than the previous engine’s stock B20B intake manifold did so I had to relocate some of the things on the firewall.

We are using the original B20B fuel injectors and fuel rail. They will need to be upgraded before we go turbo but they work fine for now. Don’t forget to connect the old throttle cable to the new throttle body.

So this is the part where you scratch your head and look all over the place to find the wires and hoses you haven’t reconnected yet and fill the engine with fluids… and then finally approach that moment of truth and turn the key…. and it doesn’t start… why? Because we didn’t plug the coil-on-plug harness back into the ECU yet! I’m actually not sure why in this process I ever disconnected the coil-on-plug harness from the ECU…

But once we did VROOM!

Thanks for reading!



Joel Guerra

Software Engineer / Racecar Driver