These were my approximate costs for the swap. Your costs will vary but this will give you a good idea of what you’re looking at. Also remember a lot of my cost was due to new replacement parts which theoretically you do not have to buy. And before anyone says I could have swapped a B-series motor in for the same you are most definitely wrong as I didn’t have to: 

1. Buy special mounts that only left me with three mounts instead of four hence mounting the motor incorrectly and not as Honda designed it. Also allowing it to move more freely as there is no front torque mount.
2. I did not have to cut anything to make the motor fit
3. I did not have to bend anything or hit things with hammers
4. Nor did I have to swap my axles
5. I could have easily used my stock air conditioning setup with out buying a special mount
6. My shift linkage is the same as stock so no cost there
7. Another point is that a B-series motor wouldn’t cost $500.00
8. Nor would the replacement parts or the aftermarket tuning parts be as cheap as they are for a D16Z6
9. Plus the D16Z6 weighs less. Not a ton but enough to matter 

Just remember there are a lot of hidden cost in a motor swap so make sure you have some extra money in case you break something and you need the new part to make your car run. I have tried to give you an idea of the cost but remember your engine might come with parts missing or broken so be careful with where you buy it. I am not saying a B-series engine wouldn’t be good in this car I am saying it can’t be done for as little money as this swap. Unless pretty much all of the parts are free.

Motor swap	Cost
D16Z6 motor (Complete)	$  500.00
Exhaust manifold and down pipe	$    75.00
D16Z6 car wiring harness	$    75.00
Clutch set 89-91 Si	$  189.00
Rear main seal	$      8.00
Timing belt	$    45.00
Water pump	$    40.00
Auto tensioner	$    45.00
Crankshaft seal	$      6.00
Camshaft seal	$      6.00
Spark plugs	$    20.00
Pilot bearing	$    12.00
Flywheel resurfacing	$    50.00
O2 Sensor	$    70.00
P28 ECU	$  150.00
Electrical connectors and misc.	$    40.00
S20 Transmission back up switch	$    12.00
Total cost	$1,343.00

Proper wiring harness appropriation

The picture to the right shows you how the D16Z6 engine wiring harness and ECU wiring harness need to be removed from the donor car to make your life easier.

Here are some pictures of how the interior wiring harness or the “car” wiring harness should be cut to leave you with the part you need to follow my swap instructions. In the first picture you can see I have an entire 92-95 Si/EX wiring harness. The red shows where to cut the harness and the blue circle show key parts of the harness you will need. In this first picture every thing to the right of the right most cut resides under the dash and most of it is all on the driver’s side of the car or the center console. All of it is garbage as far as this swap is concerned.

See the top blue circle? Those are the ECU / Engine connectors they reside in the engine bay on the left side by the strut tower there are three you need. See the bottom blue circle? That contains both the ECU connectors and the Data link connectors. See the other pictures for close ups. The top red cut a connector going to parts of the engine bay that are not needed for this swap cut it off. See the fuse box? Cut it off! And see the last red cut mark I haven’t said anything about yet? Cut that off too! Hah!!!

Now in this picture you can see the ECU connectors and the ECU / Engine connectors a bit better. See the grommet in the middle of the wiring harness? That is where the wiring passes through the passenger side of the firewall when the harness is still in the car. Now draw a line in you mind from the ECU connectors to the ECU / Engine connectors. That is the part you want with a bit of the wiring going towards the upper cut so you can splice a few of the wires to the car’s existing wiring harness.

The easiest thing to do when the harness is still in the donor car is to cut off the wiring going to the fuse box and the wiring that goes to the left if you are viewing the portion of the wiring harness that is inside the car from the passenger seat. Next you would cut off the wiring that leads to the connector that is at the bottom of the picture you would see it leading towards the headlights on the passenger side of the car.

Now in this picture you can see the ECU connectors and the ECU / Engine connectors a bit better. See the grommet in the middle of the wiring harness? That is where the wiring passes through the passenger side of the firewall when the harness is still in the car. Now draw a line in you mind from the ECU connectors to the ECU / Engine connectors. That is the part you want with a bit of the wiring going towards the upper cut so you can splice a few of the wires to the car’s existing wiring harness. The easiest thing to do when the harness is still in the donor car is to cut off the wiring going to the fuse box and the wiring that goes to the left if you are viewing the portion of the wiring harness that is inside the car from the passenger seat. Next you would cut off the wiring that leads to the connector that is at the bottom of the picture you would see it leading towards the headlights on the passenger side of the car.

This picture gives yet even a closer shot of the ECU connectors and the data link connectors are at the bottom of the shot. The grommet at the lower side of the shot is the one in the chassis leading to the door like the stereo and power window and locks stuff. All of which is not needed and can also be cut loose while the harness is still in the car.