Has anyone ever tried to do this ?
I vaguely remember someone saying it was not possible with the manual gearboxed engine.

anything is possible but is it worth the hassle.

Really, really, really not.

Lets start with the basics:
Front body loom,
Dash from a honda (for the dash loom)
engine loom
engine
gearbox
gear lever
engine mounts
steering column
power steering...

Not to mention the welding required for the engine mount brackets.

ok i'm bored.

Thank you.

Where there is a will there is a way, just make sure you have a full electrical WSM.
Thinking about the differences between the Honda and Rover engined R8s you will need a whole running 216 as a donor.
As project i fitted the body electrics from a 2002 ZR into a 2005 MK2 R25 suffering the Pektron BCU issues
(Mint low mileage car from a breakers for £100 )
The only R25 wiring that remained unmodified was the engine loom. Bear in mind that both cars were identical except that the 2005 car had ABS and Air con.

1234dist wrote: ↑Sat Dec 01, 2018 4:46 pm anything is possible but is it worth the hassle.

Really, really, really not.

Lets start with the basics:
Front body loom,
Dash from a honda (for the dash loom)
engine loom
engine
gearbox
gear lever
engine mounts
steering column
power steering...

Not to mention the welding required for the engine mount brackets.

ok i'm bored.

I've seen *some* Rover 25 sub-frames that look identical to the Honda one, but without the front engine mount bracket. There are 2 types of front sub-frame and one might swap with a Honda variant. Not sure about the rear but this might also be a straight swap, if you can find one (the K series rear subframe may look the same, but it won't have the bolt pattern for the Honda mount). I realise that only gets two mounts sorted, and you've got left and right to do. You could be optimistic and say that if the R8 was available with Honda and K engines, then *perhaps^ the chassis holes for left and right are common and because the R3 front end is essentially an R8 front end, they kept all the hole and mount point geometry the same. In which case, you just have to nab all the various load-sreading plates/adapters and mounts from a 216. This is pure guesswork, though. The front suspension is basically the same, so a wild guess would be that it should all fit including the driveshafts.

The rest will be fun. Completely different ECU and loom - all electrics completely different with respect to the engine at least. Atmospheric barometric pressure sensor inside the car, ECU controlled anti-resonance chamber tucked away under the offside front wing, different air intake and box, etc, etc. The ECU fits under the passenger footwell in an R8. They probably do that for a reason - it probably doesn't like being outdoors. Not sure where you'd put it in an R3.

It's near-insanity, but then insanity seems to be what drives most projects these days. Good luck!

In short, no its not worth it.

I don't know about a 25 swap but I have changed a manual K series R8 to a auto honda both 1.6 petrol cars.You do ned both cars complete and in addition to the parts already mentioned you will need the pedal box and dash board complete,this for the gear selection lights in the section between the rev counter and speedo.The conector between the front and rear loom requires a couple of the pins to be swapped,or you may find the rear lights don't work as they should.Be prepared to think outside the block to solve any issuses it can be done if you want to.

But for this, you are making it a nightmare for the next guy to get parts from the auto factors.