K20 Swap EF Civic Build: Turning a Honda Challenge Car into a NASA ST6 Track Weapon

So I am a Honda boi now.

This car is an old Honda Challenge survivor. It last raced in 2012.

It has a rear disc upgrade already, and has an oversized 1.75" but minimal attachment point cage, intended to cover it for budget endurance racing as well as sprint racing. That cage never got painted...

It cam with a pile of spares, spindles, calipers, bumpers, a second hatch with a lexan window, pads, two pairs of wheels, etc.

It last(only?) ever had a D series engine. I understand that there was some partial prep to bring it back out with a B series somewhere around 2015 but that effort stalled and fizzled.

The purchase deal came with some B swap related parts, including an Integra B18 LS transmission, B18 header/exhaust, parts of an engine mount and shifter swap setup. Not a complete swap kit, but enough "free" parts that I was initially fully sold on a B swap.

Everything moved into my own shop:

More Background / Decision Making

More background/decision making before I start the heavy photo journey...

Remember when I asked "have yall looked at vtec honda B series prices lately?!"?

Budget very quickly ruled out a proper, sexy, fun B16 engine or even a grey area B16/18b "poor mans type r". The rules prevent a hot B18c type R or even a GSR swap, as the GSR motor has to stay in a dc chassis Integra due to appendix C, above.

Similar to the GSR b18c, the B20 CR-V motors have a key rulebook disallowance, in this case regarding the transmission. My EF Civic is legally allowed to receive a B20 CRV motor, but I must use a transmission that matches the host car or the donor car. The CRV never shipped with a 2wd manual transmission, the manuals are all 4wd. I am not allowed to put a CRV engine next to a a DA Integra transmission in an EF Civic. That engine/trans pair must go into a host car that came stock with a B series manual transmission, like a DA Integra or EK civic. The EG civic would be in the same position as my EF.

So I am allowed and can afford an Integra B17 or B18b because I need to also use their matching B series transmission.

I bought a sight unseen B18b1 before i even brought the chassis home, but it turned out to have a spun bearing and a very, very blue crank journal. Fortunately that seller and I agreed on a 50% refund, so I now own a potentially rebuildable core block/crank, and full b18b1 cyl head. If anybody wants it...

I poked around for almost a month trying to source a second known-good B18b1 swap...

GRM forums make me wait an hour between posts, so im combining two....

Pivoting the Build Direction

"You sold your Honda K swapped racecar to build... another Honda K swapped racecar?"
Turns out, yea.

The K series engine family needs no introduction, but I had to do even more reeducation to get one into this low power class.

We have the transmission hurdle to jump, not just the horsepower limits to play in.

Additionally, the EF hood line makes K24s pretty difficult. Let's get the k24 discussion out of the way...

K24 Limitations

The max power rule doesnt allow any "high compression" or dual-vtec K24 engines. Period. These would be the fun/sexy jdm K24a and jdm/usdm k24a2. Also not allowed are the high comp k24z motors, z2, z3, z6 and z7.

The only K24s allowed are the low compression "Eco" variants: K24a1, a4, a8, and z1. The z1 never came with a manual transmission, so its out. The K24a1/4/8 would also require using the Accord's 5 spd box. Not the end of the world, just have to find a whole driveline donor and deal with the height of the 24.

K20 Options

The K20 family is similar story. The fun ones are illegal, and the allowed list is even smaller, but it would fit better.

High comp K20a and a2 straight up not allowed. Low comp "Eco" K20a, a1, a4, 6/7/9 would need a JDM/EUDM donor allowance on case by case basis.

High comp k20z1/3/4/5 variants, not allowed. Sole outlier is a Canadian/EUDM k20z2 that would need a series director allowance.

That leaves the extremely well renowned base model USDM RSX and 01-05 Civic Si K20A3.

The other reality of K swapping an EF civic is that you need/use several RSX or EP3 civic Si parts; the shifter, shifter mounting box, shifter cables, both axles, the intermediate shaft and the ECU, engine harness, etc...

Decision Made

Done. Decision made. I am K20a3 swapping a 1988 Civic to replace my K24z3 swapped 1999 Miata. What a time to be alive.

Sourcing the Drivetrain

What is the easiest way to source a known-good 20 year old engine, transmission, and all associated swap parts?

It is NOT to drive 3 hours for a $200 longblock.

So I find myself the owner of a potentially rebuildable core K20a3....