The following options are the ones I considered. There is no reason why other engines shouldn't fit.
Ford 1.6 CVH- Cheapest option by far, as it already runs on a down draught carb and has no fancy electronic ignition trickery to worry about or overcome. You can pull the engine with gearbox, driveshafts & uprights out of a Mk2 Fiesta XR2. This is the setup that Sam Howell uses in his Mojo. Unfortunately I fancied more than ~90bhp... While it is possible to tune this engine up to ~130bhp with twin webers and a hot cam, I preferred the idea of a more modern 16 valve unit; however, as a budget build the CVH is hard to beat.
Toyota 4AGE- I was very tempted by this option. Revs to ~8500rpm, gives ~135bhp with twin Webers. Can be pulled out of a Mk1 MR2 or late 80s / early 90s Corolla Gti. The MR2 is the preferred option, as you can probably use a lot of the MR2 loom, the gear linkage, maybe instruments, etc etc, as the MR2 is of similar layout to the Mojo (Mmm, even the names are a bit similar...). However, most of the donor cars have high mileage (100k +). You can get units impoted from Japan from RAW or Fensport, but this then starts getting more expensive. The engine is physically small so fits into a Mojo relatively easily, although trying to retain the original distributor may not be possible as it will interfere with the bulkhead. Just go with an aftermarket ignition system (such as Omex) and the problem is solved...
Honda VTEC- This engine also really appealed. In it's original installation in a Civic CRX, 158bhp was on tap. However, the engine is not well used in kit car circles, and hence has limited tuning options. I felt it was therefore a more risky option. zzzzzzzzzzzzzzzzzzzzzz zzzzzzzzzzzzzzzzz zzzzzzzzz zzzzzzzzz z z z
Rover K-series- The K-series is a well respected kit car engine. It does service in many Caterhams, and is also used in the Lotus Elise. It is a light, modern unit that loves to rev, and will give respectable power. It also has a bit of a reputation for blowing head gaskets, but this shouldn't really discount it as an option. However, Sylva do not yet have experience of fitting a K-series into a Mojo.
Ford Zetec- The 1.8 litre Zetec engine was used in the Mojo race car, so is an obvious option to consider. The 2.0 litre variant is externally the same size as a 1.8 so could be fitted, but requires the swapping of some parts from a 1.8 to operate correctly, as it has some significant differences- namely the sump, oil pump housing and water pump.
3 variants of the 1.8 litre Zetec have been installed in Ford vehicles- 105, 115 & 130bhp versions. Given that the original Ford ECUs are usually binned in kit car applications, the only significant differences are that the 130 has different cams and oil spray jets aimed at the underside of the pistons. It is possible to fit 130 cams to the 105 or 115 units, but it is likely to be cheaper to source a 130 in the first place- they were fitted to the early 90s Fiesta RS1800 and Escort XR3i 130 (Beware!- the XR3i also comes in a 105 variant). Fitting a Weber Alpha kit to a 130 results in ~155bhp. Similar figures are quoted for other ignition options (such as Dunnel) running Weber carbs.
I finally decided on the Zetec option for the following reasons:
- Availability of lower mileage units
- Relatively low cost
- Widely supported kit car application
- Plenty of tuning options, including off-the-shelf ignition ECUs.
- Eligibility for the Zetec race series should I choose to go racing!
- My discount on Ford parts as a Land Rover employee