I had a motorcycle based V8 idea...

[aspetuck]

I would like the same character as a bike engine, with more displacement and power. I don't relish the thought of forced induction particularly.

[andylaurence]

Given that the current available engines are in the £20k ballpark, I'd suggest that's probably a starting budget if you're doing it yourself. Why don't you just use two bike engines in the car? Drive one rear wheel with each and do away with the need for a differential. Two bike engines will significantly cheaper and I doubt it'd weigh much more. A Hayabusa is about 85kg with the gearbox. A Hartley/RPE V8 is about 90kg, but needs a 45kg gearbox on the back, so 170kg plays 135kg. What's the target weight of the vehicle and how much will that 35kg really matter?

[aspetuck]

It would be much more about packaging and simplicity than weight

[Tim.Wright]

Given that the current available engines are in the £20k ballpark, I'd suggest that's probably a starting budget if you're doing it yourself. Why don't you just use two bike engines in the car? Drive one rear wheel with each and do away with the need for a differential. Two bike engines will significantly cheaper and I doubt it'd weigh much more. A Hayabusa is about 85kg with the gearbox. A Hartley/RPE V8 is about 90kg, but needs a 45kg gearbox on the back, so 170kg plays 135kg. What's the target weight of the vehicle and how much will that 35kg really matter?

I know its been done before, but I shudder when I think about what would happen when one engine misses a gearshift...

[andylaurence]

Given that the current available engines are in the £20k ballpark, I'd suggest that's probably a starting budget if you're doing it yourself. Why don't you just use two bike engines in the car? Drive one rear wheel with each and do away with the need for a differential. Two bike engines will significantly cheaper and I doubt it'd weigh much more. A Hayabusa is about 85kg with the gearbox. A Hartley/RPE V8 is about 90kg, but needs a 45kg gearbox on the back, so 170kg plays 135kg. What's the target weight of the vehicle and how much will that 35kg really matter?

I know its been done before, but I shudder when I think about what would happen when one engine misses a gearshift...

That's a fair point, but it wouldn't take much to take a feed off each gear position indicator and cut the ignition on the higher geared engine if that happened. I could do that with my data logger using just two inputs, two outputs and about 5 lines of LUA...