Lightest engine and gearbox options

[AshG]

be carefull of the 1600 as i dont think it will easily mate to a type 9 or mt75. i find it hard to believe that an 1800 is the same weight as a 2000. i would reccomend an 1800 out of an escort gti as they come stock with 130bhp

Fly in the ointment from me.....If you want light and lots of geeeewhizz then has to be a bike motor.

[snapper]

Don't use the Freelander diff unless you have a bike engine.
The ratio is 3.2 to 1 giving you 120 mph in 3rd, 145 mph in 4th and 175 in 5th at 6,800 rpm.

With the aerodynamics of the Roadster being what they are (brick like) you would probably hit peak road speed in 3rd and have quite slow acceleration.

There are not a lot of light options for the diff but the 7" will be lighter than the 7 1/2" and both lighter than a fixed axle

[ACE HIGH]

Why not look at a Harley Davidson 1340 or 1500 cc bike motor.I believe that torque is more important than Horsepower and while there engines are around 85 hp unstressed they are very well made,I am not up to date with the latest Harley motors/gearboxes,do any of them have a reverse?,not as silly as it sounds as the big Harleys are around 300/350 kg and must be a problem at times to manouver when stopping.Maybe they make them bigger than 1500,or perhaps the bigger Honda cruisers,they would present some cooling problems but would be light weight,which is the way to go,not excessive horsepower .David

[deezee]

When building a sports car, your best putting in a sports engine. Harley bikes are built for cruising and not acceleration. The 80 lb/ft torque of a slow revving VTwin is embarrassing compared to the 150 lb/ft from a stock zetec.

[Balidey]

Originally Posted by snapper

Don't use the Freelander diff unless you have a bike engine.
The ratio is 3.2 to 1 giving you 120 mph in 3rd, 145 mph in 4th and 175 in 5th at 6,800 rpm.

There are not a lot of light options for the diff but the 7" will be lighter than the 7 1/2" and both lighter than a fixed axle

I thought that Westfield used the Freelander diff in their cars?

As for engine choice, I think it will be eventually be the lighter all alloy Ford item, so the Duratec / Zetec SE will be the ones I will be looking out for. Not sure on capacity just yet.

I am not 'anti-bike-engines' its just I think its more sensible to me at the minute to go car engine.

[deezee]

Both the Duratec and the Zetec SE required a fair bit of mucking about to get them running. Plus they are more expensive than a plain old Zetec. If your car weighed in a 600 kgs @ 100bhp (165 bhp/tonne) for the SE and 635Kgs @ 140bhp (220 bhp/tonne) I'd go for the plain cast 2L Zetec.

[Balidey]

Good point, well made. Thanks.

[ACE HIGH]

NZ's most successful home made sports car was an air cooled Lycoming aircraft engined special with a home made 3 speed gearbox,engine around 4 litres,max revs around 3900 rpm,built around 1956,max speed about 140 mph ,developed to about 160mph.weight about 700 kg.This car could out accelerate many exotic formula 1 racers of the day and when one hears it racing it sort of just chugs around,the diff ratio was about 2.1 to 1.The point is:there are horses and horses and while the Harleys are cruisers with poor road holding they can accelerate OK.I believe that an 86hp Harley would give a much better spread of power than the 125 hp Toyota I had in my Chevron 7 and coupled with the light weight I believe it would have gone faster.Google ralph watson lycoming for a look at an interesting vehicle and an incredible engineer.David