Lightest engine and gearbox options

[Balidey]

As I thought it was about time I 'started' I am trying to get my plans together. One thing I want to do is (as per Mr Chapmans original concept) is to get the overall car as light as possible.
My thoughts were to use a Zetec engine, either 1.8 or 2.0. But which is lighter? Surely the 2.0 as the holes in the engine are bigger :D
But are there other engines to consider. I only want 'moderate' power so I could perhaps drop an engine size to loose weight, and maybe use foeced induction to make up for the loss of capacity. ie instead of a 2.0 how about a 1.6 s/charged, would that be lighter? Or do I go even smaller? What about the newer Ford engines, are they 1.4 Duratecs? S/charge or turbo one of those? There are hundreds about now.

Gearbox was originally going to be MT75, but again is the type9 lighter?

Rear diff. Something small and light. I have heard the Freelander diff is sometimes used, is that lighter compared to the Ford items?

I don't really want to go the BEC route, but the car is really going to be cut down to the basics. My friend has a Luego with an RV8 and massive alloys. And although its a nice car (which I helped build) its nothing like what a 7 should be. Its huge, heavy, thirsty and a bit too 'bling' for me. My car will be cheap, small, light, nimble, more fuel efficient. I'm thinking of using round tube for the chassis, making alloy skin seats as per the book, or possibly GRP seats. All the bare minimum.

So can you offer suggestions to a suitable power plant and drive train?

[Balidey]

A quick read up on Burton Power website suggests that the 'duratec' I thought was fitted to Fiestas etc is infact a Zetec SE.

Also I considered the Mazda rotary, but I think cost will rule that one out.

[HandyAndy]

don,t know if its worth considering but i used to have a Fiesta with the 1.25 zetec engine & that was one nippy little car, very good on fuel too, tho if fitting to a Roadster then you,d need the cat too, but it was a nice little revvy engine, cheap on fuel & insurance, hmmm :) , in a very light weight "7" it might be reasonably quick enough ;) :)

andy

tho its not rear wheel drive but maybe something can be done to facilitate it, was just trying to express what a good engine it is for its size/weight.

[Balidey]

I have always been a fan of small, light cars with small capacity revvy engines. I currently run a Cinquecento Sporting. Old 1108cc engine, small light car, rev the nuts off it and it can emabrase most of the big German cars that think they can cut me up at roundabouts :D

Which is why I am not too bothered about a huge engine, I know what a small engine is capable of.

So if the smaller Zetec engines are all part of the same family then I can seriously think about using one, if the weight reduction is noticeable. If there is only a kg or two in it then I may as well stick with a larger Zetec.

[AshG]

you want a new duratec 2.0 they are ally block and head where as the zetec is a cast iron block and ali head.

the most import question here is how much do you have/want to spend as it can somewhat limit what you aim to achieve.

[Balidey]

Budget is yet 'undecided' :D 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

[fabbyglass]

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]

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:)

[Bimbleuk]

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]

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 :D

[Bimbleuk]

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

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.