My build: Status Update 03/02/11
So it all started right around the turn of the new year when I decided to go ahead with a winter/spring project.
At the time I was very unsure of what route I was going to take in terms of the power modifications. On the list of options was. BOE TVS kit (which is now a next generation "Rev" kit), the upcoming Radium "Stage 2" kit, and a custom turbo kit based on the MWR manifold but again for the 2zz. I then spotted the talks about the K-series swap kit from Innovative and got in touch with them about it.
In the mean time I figured no sense in keeping the stock 2zz in there anyways since it was going to be a (mildly) built 2zz or K-series. So I pulled the rear clam, front clam, and engine/transmission:
After doing some thinking for the next week or 2 I finally decided that it would be a K-series kit, but not sure what exact variation. The reasoning behind it was essentially what I posted up in the "Why K-series". Truthfully the k20 is the engine that always *should* have come in this car and its a shame that it's not. One of the best chassis makers in the business combined with one of the best engine makers in the business... what's not to like.
Well price of course. But once you add up and realize everything you actually get with the K-series (power, engine reliability, transmission reliability, end user EFI programming, tons of aftermarket, etc, etc) it makes sense.
So with my mind set on the k-series I officially ordered all the parts from the Innovative kit except the headers (which at the moment are actually through a seperate company Hytech which is known for their great custom Honda headers).
I then began researching exactly which k-series engine I should choose. I have been a forced induction guy almost my whole life, and so I was naturally drawn to that route. And to be honest, the most cost sensitive thing to do assuming you want forced induction is to simply choose the k20a2. The good part about the k20a2 is that it is the least expensive of the more "high output" k-series (k20a, k20a2, k24a2), the swap kits are actually designed electrically to work with the k20a2 (02-04 RSX-S), and best of all they are known to take ridiculous amounts of power on the stock bottom end. So for my goal of around 350whp a boosted k20a2 fit the bill perfectly.
So I began looking for a k20a2 engine and transmission and searched for a few days in the classified ads on k20a.org and clubrsx.com and stumbled upon someone looking to sell his k20a2 engine, harness, and ecu with low mileage for 1600. So I pulled the trigger.
Now hindsight is always 20/20, but I made a minor blunder here. My biggest mistake was assuming the Rotrex k20 kit
would fit. After doing some more research and talking more to Innovative I realized that I highly doubt, in fact I can almost guarantee, it wont. Reason being is that the Rotrex kit mounts the supercharger down by the A/C. However the A/C area is probably the tightest area in terms of fitment in the Elise, even in stock form. If you look closely the A/C unit that is in the stock Elise is a very small unit that I believe was modified specifically for fitment in the Lotus. So therefore a k20 with the k20 A/C unit won't fit, which throws the Rotrex idea out the window since the Rotrex is bigger yet.
So now here I am with a k20a2, and no way to go with the Rotrex. So I had 3 options at this point:
1) Keep the k20a2 and build it N/A
2) Keep the k20a2 and just do a custom turbo kit
3) "Cut my losses" and find a k24 bottom end and build a N/A K24/K20 (Frankenstein build in Honda terms)
So to be honest option 1 (although it was the cheapest) simply wouldn't get me close enough to the power I wanted... I could have probably got 240-250whp and some decent torque maybe 160 ft-lbs, but that was about it.
I was now between option 2 and option 3. Undoubtedly with a turbo k20a2 I could make TONs of power. I suspect I could make 400whp fairly easily with a fairly low spool threshold and not too much boost. The care would have been blisteringly fast in a straight line, and considering I have access to a friend who does some custom fab work it actually wouldn't have been to much money either.
Yet I choose to build a naturally aspirated K24. Why? Well the Elise isn't about being blisteringly fast in a straight line. As well all know it is MORE about being fast in the corners, its more about simplicity, having great throttle response, and most of all being fun to drive. Swapping in an N/A K24 is basically taking everything we all like about the Elise and turning it up a few notches. It keeps the balance and fun factor of the Elise, while giving it the guts to run with the Z06s, GTRs, 911s etc in a straight line. Putting a turbo on it would be faster yet in a straight line, but it would take too much away from throttle response, simplicity, and the fun factor. This is exactly why you find most people that swap to K-series swap in a K24.
So with my mind finally made up I pulled the k20a2 cylinder head off of the engine I bought, and shopped around for an engine builder and exactly how I was going to build the engine.
My engine builder will be RS Machine out of Norwalk, CA.
My parts shopping yielded a mild K24/K20 build which I guesstimate will make somewhere between 270whp-300whp and 200+ft-lbs of torque from 3000 RPM -7000 RPM where it will probably taper off a bit to the 8400ish revlimit. It will consist of the following:
Stock K24A4 (Honda accord/element) block and 99mm crank. Stock sleeves bored .020 over
Wiseco 12.5:1 forged pistons
Eagle forged H-beam rods
K20A2 (RSX-S) oil pump, and aluminum oil pan
Hytech or blueprint oil baffle kit (dry sump is too rich for my blood)
Stock K20A2 (RSX-S) head, with a light port around the at the valves. These heads don't need much as they flow almost 300cfm at .550 out of the box
Supertech dual valve springs, with steel retainers
Kelford Type-B cams (IN 306*/13.5mm, EX 312*/12.5mm)
Skunk2 Intake manifold, and 74mm throttle body
775cc injectors (so I can run 93 oct or e85)
Golden eagle fuel rail
FuelLab FPR, Custom -6 A/N Lines.
Hondata K-pro ECU.
Headers are still up in the air. Either I will get a custom set from Hytech if they are cheap enough, or else I will have to have them made and my buddy Jim says he is up for the challenge.
Other parts that I plan to fix/add during the process:
BOE toe links
Oil cooler fix (either replace with a single cooler+fan in back, or replace all lines and use the stock front mounted coolers with the K24)
LSD (Helical. Either Quaife, or Wavetrac, maybe MFactory)
As for the swap parts. Well they have been a bit slow coming, which I was kind of expecting with it being a new kit. However what has arrived so far has been beautiful.. Very quality pieces.
So far I have:
Driver mount, rear mount
Fuel canister (although I will be going a different route there)
I was told the clutch line, passenger mount, and throttle cable/bracket for the kit should be ready very soon (like end of the week ish).
Additionally, the way Innovative does the axles for this kit is to use Honda (or is it custom) inner CVs, custom axles, and the stock Lotus outer CVs. So I pulled the CVs from my stock axles and they now have them. To pull the CVs you simply pull off the clamp, slide the boot down the axle, and (with a plastic hammer or mallet) hit the outer CV until it comes off the axle. Some CVs are held on by a circlip that can be directly accessed once the boot is off, however in the case of the Lotus the clip is internal to the CV so it just takes a little "persuading" with the hammer and they will come off. If you go the Innovative route. When you send them the CVs to make your axles, you will need to send them the CVs, the boots, and the circlips: