Lightest engine and gearbox options

[Balidey]

Budget is yet 'undecided' but honestly, it will be as little as possible. I will be making almost everything from scratch, partly as I want to, partly to save as much initial outlay as possible.

And I was kind of hoping a 1.6 (or similar) would weigh less, be less desireable, therefore.... cheaper

[Balidey]

Some research gives me these figures to think about....

Zetec SE 1600, 100bhp, 81kg (aparantly sometimes called the Duratec 1600)
Zetec 1800, 105 to 130bhp, 115kg
Zetec 2000, 135 to 145bhp, 115kg
Duratec 2000, 145bhp, 97kg.

So, the 1600 saves 34kg over the Zetec, but loses anywhwere between 5 and 45bhp in stock trim. But the Duratec seems to hold all the aces, its powerful and light. But I would guess the premium is its price. I'll start looking for whats about.

[Balidey]

Thanks Adrian, I got the above figures for the engines from there, but I didn't know the g/box info was on there too.

[deezee]

I suppose instead of the Ford option, try a 20v 4AGE from a MR2. Its a 1.6 supercharged knocking out around 170bhp. All aluminium engine. Use the aluminium RWD gearbox from Toyota again and it will save a fair bit of weight.

[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

[Bimbleuk]

Originally Posted by deezee

I suppose instead of the Ford option, try a 20v 4AGE from a MR2. Its a 1.6 supercharged knocking out around 170bhp. All aluminium engine. Use the aluminium RWD gearbox from Toyota again and it will save a fair bit of weight.

The MR2 mk1 had the 1.6 16V 4AGZE which was supercharded and iron/ally. Don't bother its old tech and very heavy with all the cast iron bracketry and inefficient Denso blower.

The Mr2 mk3 had the all ally 1.8 1ZZ-FE. Not too heavy but only about 140BHP and quite bulky like most of the all ally engines.

The blacktop 1.6 4AGE 20V engine from Japananese imports only is one of the lightest and most compact small engines (excluding bikes of course) you can fit. 150-160 BHP and around 90kg if you include the manifolds and standard individual throttle bodies (fitted as standard). Due to a light flywheel and lightened internals compared to all previous 4AGEs.

However you will still be hard pressed to beat the Rover K series engines for lightness. Again a bit more bulky due to the all ally design but about the same or lighter than the Zetec SE and up to 1800cc.

I found the very early Sierra diffs are about the same weight as the Freelander diff at about 17-18kgs. All later Sierra diffs I believe are at least 22 kgs or above. The only draw back is the driveshafts are unique to the early diffs as the input diameter is smaller for the driveshafts.

[deezee]

Originally Posted by Bimbleuk

The MR2 mk1 had the 1.6 16V 4AGZE which was supercharded and iron/ally. Don't bother its old tech and very heavy.......

However you will still be hard pressed to beat the Rover K series engines for lightness.

I can appreciate that its not the most advanced engine out there, but half the "engineering" on new engines is for emissions, which hardly matters to home made sports cars. Also, like I've mentioned before, surely bhp/tonne is the figure that important here and the 4AGZE is well over 50 bhp/tonne better than the K series

Besides, don't you have a Toyota engine in your car

[Bimbleuk]

Originally Posted by deezee

Besides, don't you have a Toyota engine in your car

Yes have I been busted? I'm a Toyota fanatic I suppose and bought a 4GZE for the short block recently as the bottom end is stronger. I was just looking at it at the weekend (trying to get inspired to pull it apart) and all bracketry is thick cast iron and thankfully most of it holding on the power steering, aircon etc so can be junked.

To be fair you can simply slap on a bigger crank pulley to the 4AGZE to increase it to 180BHP with decent torque.