I started with a 1973 2002 that had very little rust but a weak engine. I stripped the car down and fixed the floor boards and rocker panels. I then did some (new to me) body work. The goal was performance with stock appearance, not show car looks so it still has dents here and there. I farmed out the paint to Maaco (was Riviera, now Taiga) and the engine tuning to a local tuner but I did most other tasks. I also got wonderful advice online from Chargin; great guy with an AP1 2002.
Meanwhile I got an 2007 Honda F22C AP2 S2000 engine and tranny on eBay. The engine fits fine. The F22C is a bit torquier than the AP1 F20C but I made a major mistake. The AP1 only needs a few wire connections to run but the AP2 is throttle-by-wire with a much more sophisticated antitheft system. Unless the key, throttle sensor, gauge cluster, ECU, and wiring are all happy the fuel injectors will not open. Even the 10 lbs antilock brake module has to be plugged in. The tuner had to use a huge percentage of the original wiring harness (and there are several in the S2000!) to get everything to work. Luckily I found a brilliant tuner, Chris, in Spokane, WA at R-Tuned Motorsports. He almost gave up a few times, but it was an intellectual challenge for him and he pushed on. Everything is stock and the engine thinks it is in an S2000. I turn the Honda key, hit start, and it turns on like a modern car. With an aftermarket ECU you have more flexibility, but you start from scratch. I’m happy with stock S2000 performance (minus 400lbs) so I went with Honda reliability and an OBD II plug. Unfortunately I now have an anime-style gauge cluster (gives me speed, RPM, temperature, check-engine light). Autometer’s #2652 fuel gauge works with our stock 2002 sender. Chargin got his stock gauges to work using Speedhut with his AP1 so you could go that route if you persevere.
The only major drawback is where do you stuff 20Lbs of Honda wiring harness? It is too short to reach the rear seat and even though I took out the stock heating system, it still didn’t fit. I ended up just stuffing it where the passengers’ feet go. Admittedly not an elegant solution.
I had to modify the radiator support (still stock from the outside) to get a bigger radiator to fit and Chargin provided the engine and tranny mounts. I modified the firewall to fit the taller tranny. I used a S2000 pedal. I bought a used S2000 driveshaft and a new E30 driveshaft. A local shop married them together. I also had a guy use E30 limited slip differential parts in my 2002 3.64 case (the engine has plenty of torque for a 3.64). I modified the Honda header and made my own exhaust system with a generic cat, resonator, and muffler. It hangs down too far but that is fixable.
I bought a generic aftermarket wiring harness and ran that separately. Basically, there is the Honda wiring that I do not understand and I don’t touch, and then everything else (lights, signals, radio, wipers, etc). I power the nonHonda wiring with one switch. I also installed an aftermarket Vintage Air (#674013) heater/AC. Also some Wilwood front brakes. I cheaped out on Subaru Impreza seats (Hey! the engine/tranny was 9K!). I installed Esty’s carpet kit and made my own rear seat delete. I hid all the new wiring harness under the old rear seat.
It took about a year in my free time and my skills are average. As long as one can weld (and you use an AP1) anyone can do this. At 240 hp this is the perfect engine for the 2002. Not scary at all but plenty fast. It is similar to a stock Subaru WRX or Golf R. Simply due to price - if I would do it again - I would do a K-swap, but as of 2022 I don’t think anyone has a simple K-swap kit available (too hard to fab everything on my own). There is one for the E30 but not the 2002.
Edited by Georges