After considering several options, it came down to either building another Westfield or trying my hand at a Caterham. My Westfield has a number of custom touches to better align the car with my tastes and preferences. After living with those mods for years, I wouldn't do any of them differently. This means building another Westfield -- while vastly cheaper -- would simply be a rehash of the previous build. Not much of a learning experience or challenge. With the Caterham, both the assembly process and things I wish to change from stock are new puzzles to solve.
Unfortunately, Caterham won't sell a kit without a drivetrain, and my original workaround of buying a 360R or 420R and simply swapping engines with the Westfield turns out to be anything but simple or cheap. Packaging differences mean the Caterham's intake would need to be replaced with Jenveys or their equivalent, then a programmable ECU to accommodate that change, followed by an engine loom for the ECU, and several other minor items. Yes, I could avoid this slippery slope and take cheaper shortcuts, but the Westfield is a great car and I want to keep it that way for the next owner.
Surprisingly, the alternative of keeping the Westfield as-is, selling the 420R crate engine, and building a new, more powerful 2.4L Duratec is only marginally more expensive. The upside from this approach is a better Westfield that needs no effort to prep for sale, a much faster Caterham, and I can spend all my build, design, and fabrication cycles on the new car rather than plotting to pull the soul from an old friend.
I've gone with the SV which compares favorably to the Westfield in shoulder width. As for the engine, some may wonder why the 2.4L and not another hot 2.0L if I like my current engine so much? Short version: weight and expectations for dollars spent. When introduced, there was a reason the SV quickly earned the nickname Fat Bastard. With its extra weight, it would be a touch slower than the Westfield with the same engine. If I'm spending a lot money to change cars, I don't want to go slower. I want to go faster. Much faster. With that mindset, the 2.4L makes sense.
Since Caterham won't sell me what I want, I've broken down the spec into two parts: what's on the Caterham order sheet and the planned mods. Some of this is subject to change given the months I have to evolve the plan.
- 420R SV
- 620R nosecone
- Roulette Green (special order)
- Lowered floors
- Carbon Fiber seats with padding (Tillet B6 as used in 620R)
- Plain black leather tunnel cover from Signature catalog (not a fan of the standard carbon-look leather)
- Full weather pack
- Trackday roll bar
- Track suspension
- AP 4-Pots
- 3.64 diff
- 13" black wheels
- Engine - 2.4L short block from Esslinger Engineering that combines a forged 2.3L keyed crank with a deburred 2.5L block, includes various oil gallery sealing mods, forged 12:1 pistons with a slightly thicker head gasket to lower static compression to ~11.75:1, forged, longer-than-stock rods, fully balanced, ARP fasteners, etc. Ported 2.5L head, Jenvey 50mm (possibly 52mm) DTHTB, Emerald K6+. Cam investigation is ongoing, but I'm currently leaning towards the Esslinger Stage 4 or Raceline RDL 270. VVT and balance shaft delete. Dry sump. The stock Caterham exhaust manifold and silencer will probably limit power to the 250hp-260hp range, which is plenty for now. A future upgrade will be a custom exhaust that should lift output to ~270hp.
- Traction control - either the native system in the K6+ or RaceTCS
- Higher flow fuel pump. This might take the form of an external pump with return hose with inline regulator.
- Raceline compact bellhousing, flywheel and starter. This places the bottom the sump and bellhousing on the same plane rather than have the bellhousing about 35mm lower.
- Carbon dash with custom configuration. Currently leaning towards 620R style toggle switches. BlinkStop wireless steering wheel buttons (4) to cover horn, turn signals/hazards, and high beams/flasher. Includes programmable self-cancelling function on turn signals. AIM MXS 1.2 Strada display that covers all gauge, warning light, and shift light needs and connects to the Emerald K6+ via a CAN bus.
- Lighting - front & rear LEDS with clear lenses. Roll bar mounted 3rd-brake light.
- Lithium battery
- Create cold air intake from intercooler duct in 620 nosecone.
- Locking boot lid - I have some ideas for this. More later.
- Hidden interior storage. I did this to the Westfield, but it's not yet clear how to achieve this in the Caterham without having the car on hand. That said, I do have an idea.
- Complete 420R engine w/ dry sump, injectors, intake & filter, bellhousing, flywheel, clutch and pressure plate. I'll likely hold onto the alternator & bracket, COP, and clutch slave.
- Caterham MBE ECU w/ engine wiring harness
- Carbon dash with gauges and switches