Cosworth YB Turbo Into Elan

[stevebroad]

Wow nice build

Having owned a Dax Rush with 400hp going to the Rear wheels your going to need some sticky tires to put that power down, i used to be able to smoke the tyres at 100mph in 4th gear

Thanks

Yes, traction is a little bit of an issue. I have spent a lot of time researching UK road legal tyres and have decided on these:

[stevebroad]

Steve great build quality love watching your progress do you think you have lightened it enough with only 520bhp LOL
Ian

Thanks Ian

I can never lighten it enough

Just ordered 10 titanium nuts to replace steel items securing titanium bolts.

Gradually replacing steel nuts and bolts with titanium. Doing it bit by bit sort of hides the cost

[661]

Amazing build, thanks for sharing.
Those TB5s look good

[stevebroad]

A milestone in the build. At last a rolling chassis:

Wheels are temporary until I have hardened up on the spec of the proper ones and get them ordered.

Nothing has been set up, hence the figures.

Why do I lose the right hand side of photos?

PS, weights are in kilos.

[Chancer]

Hard to tell with my tired old eyes but are those holes in the chassis swaged?

Superb job by the way, I really miss race car fabrication, been over 10 years now since I have been able to indulge myself, working on my building (which is my current and future income Stream) has its interests and I can indulge myself on whims and obsessions in a similar manner but I really miss the engineering and fabrication.

Maybe another 5 years and I can take it up again.

P.S. That empty blue tray on the shelf on the left of the picture, I have loads of those lining the shelves in my cellar, they came from the loacl restaurant who recieve their mushrooms on them, great minds thin alike eh!

[stevebroad]

Yes all holes swaged.

That tray is one of six that came from a friend who was clearing out her stables. Too useful to throw away.

[john1180]

Don't worry, if you tap on the pics they open to full size! Love the lightening!

[elansprint71]

Nearly nine years since I last commented on this very interesting project. Where did those years go?

What I don't quite get is why you have kept any vestige of the original Elan folded-sheet chassis. They cost less than ?15 when new and, by modern race-chassis standards, are about as torsionally-rigid as a bowl of custard... without the bowl (and that's before you put the extra holes in). Back in the day racing-folks were making them stronger, rather than putting more holes in them.

I'd be interested to hear your reasoning on this aspect.

[billwill]

Right-Click one of your pictures and select View Image and you see the missing right-side of the picture

[stevebroad]

Nearly nine years since I last commented on this very interesting project. Where did those years go?

What I don't quite get is why you have kept any vestige of the original Elan folded-sheet chassis. They cost less than ?15 when new and, by modern race-chassis standards, are about as torsionally-rigid as a bowl of custard... without the bowl (and that's before you put the extra holes in). Back in the day racing-folks were making them stronger, rather than putting more holes in them.

I'd be interested to hear your reasoning on this aspect.

You tell me! Life has managed to get in the way on numerous occasions, lost interest, changed direction, cash flow problems. However, we are now full steam ahead and looking to have it up and running this year.

Lotus put huge holes in the chassis to start with! Flat sheet is not as stiff as flat sheet with swaged holes in it.

I started this project as, you rightly point out, many years ago. The chassis was strenghened to beyond 26R spec and modifed to accept the Cosworth diff. Additional stiffening has been added since.

I had tought of going spaceframe but couldn't afford it at the time. If I have chassis issues I will look at how we solve them, with spaceframe being an option as I can now afford it. However, I would like to keep some vestige of the Elan DNA

The body, originally not part of the structural package, has been stiffened at stategic locations and we are using it to improve overall torsional stiffness.

I have designed and made an adjustable brace for the front struts. Engine and diff are solid mounted.

Roll bar adds stiffness to the rear.

Graham Hatherway, who modified the chassis, reckons it will handle 600bhp and who am I to argue?

The proof of the pudding etc...

[Quart Meg Miles]

A general question comes to mind regarding your inboard rear suspension: does it reduce un-sprung weight?

As the push-rod's pivot is virtually 1:1, I feel that the suspension still feels the full inertia of the spring/shocker assembly so the un-sprung weight is actually increased by the mass of the push-rod and its pivot.

Opinions please!

[Grizzly]

A general question comes to mind regarding your inboard rear suspension: does it reduce un-sprung weight?

As the push-rod's pivot is virtually 1:1, I feel that the suspension still feels the full inertia of the spring/shocker assembly so the un-sprung weight is actually increased by the mass of the push-rod and its pivot.

Opinions please!

Yes in does reduce Unsprung weight because the Push rod is usually the last point that's measured (usually everything that moves with the Wheel as the suspension travels)

Push rod suspension moves weight from the corners to a more central position, it also helps lower the shock/spring weigh in the chassis which also helps handling and cog.

This is interesting http://www.edmunds.com/car-reviews/trac ... round.html

https://www.youtube.com/watch?v=bbgjRBT4ltM

[stevebroad]

Thanks Chris, couldn't have put it better myself.

Another advantage is that you can adjust corner weights without altering the spring seats. You adjust the pushrod length instead.

The main reason for doing this, however, was to allow wider wheels to be fitted

[dougweall]

Steve,

Following your story with great interest, fascinating.

Grizzly,

Thanks for the links, some superb engineering in suspension normally hidden from view.

Doug.

[Quart Meg Miles]

Yes, interesting link, Grizzly, though I'm not convinced by their throw-away comment about the reduced un-sprung weight. Anything that the spring has to move to restore the wheel's position is un-sprung weight, including rotational inertia from components like linkages, and the only improvement in both arrangements is the loss of the shocker's body mass, which is probably not as much as the addition of the link etc. Primarily it has been done for space reasons.

I'm also not convinced of the advantage of the shockers being moved inboard; their increased height above the roll centre is certainly a disadvantage. Now I'll stop hijacking Steve's fascinating thread.