Archive for June, 2010

Lotus Festival

We’re all prep’d and loaded up now for the Lotus Festival at Snetterton this week.

Here is a sneak preview of the car with all our shiny parts on it.  Come and see us at the Festival, we’ll be there all weekend in the Nitron awning next to the Lotus Cars area in the pitlane paddock.

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GEARBOX & DRIVETRAIN

We have decided to use the Sadev ST90-14 fully sequential straight cut dog ‘box which is well suited to the Lotus chassis, can handle the power (just) and is compact enough to fit .  We will be able to change individual gear ratios for different circuits which will be a real benefit, for example Monza will need very different gearing to say Brands Hatch Indy.

Designing our own installation was the only solution, everything other than the gearbox itself is our own design.  We have designed the driveshafts to use Tripode joints as they run cooler at higher angles and use less power than the Lobro type, the short shafts that the Exige uses mean they run at high angles.

We will be fitting the gearbox with a pneumatic gear change system operated by paddles behind the steering wheel.  This is a closed loop system, where the ECU waits for the gear to drive fully home before bringing the power back in.  The gearbox can even be driven in fully automatic mode, as well as safeguarding against accidental downshifts (he downshifts can be stacked up, only shifting when the road speed allows).

We have had a super-light flywheel made which weights 2.1kg, which is fitted with a twin-plate Tilton 5.5″ race clutch.  This assembly is not only significantly lighter than the stock flywheel and clutch assembly, but has a much lower moment of inertia, both helping the engine ‘spin up’ during down-changes.  The clutch is operated by a concentric hydraulic slave cylinder which runs around the gearbox input shaft, rather than the external slave cylinder systems which flex and are heavier.  However, with the paddle shift system hopefully we won’t be using the clutch much.

SUSPENSION – CENTRE LOCKS

We decided to develop our own centre-lock design to secure the wheels in place with a single nut to FIA specification.  These have a locking system which is deactivated automatically by the air-gun on removal and cannot come off accidentally.  We designed them to run with any kind of normal 4 bolt Lotus wheel using a conversion cup.  They use an FIA size centre-lock nut.

BRAKES

At last we have finally worked out how to use the existing pedal box housing and fit an adjustable balance bar.  The problem has been the ‘drive-by-wire’ throttle which has a bulky mechanism and gets in the way of the balance bar system.

Using 3 separate short master cylinders with their own reservoirs, these are all bolted to a machined mounting block.  Inside the pedal box, we have new custom brake and clutch pedals to fit the adjuster mechanism and its drive cable.

We can now plumb the brakes directly to the front and rear circuits using dash 3 lines, without the ABS or the servo.  We are looking into the Bosch Motorsport ABS system but at this stage it is looking a little pricey!  The road car based system fitted to the car as standard will not cope with the tyre slip percentages that highly aero-loaded slicks can reach.

The brakes at the front are now cooled by 51mm bore silicone hose which is fed by a inlet in the front radiator intake.  The centre of the upright machining is ‘spooled’ to allow the cool air to flow to the inside of the disc vanes via a carbon duct.

At the rear we have revised the uprights to move the calipers to the front side of the upright , allowing a handbrake caliper to be fitted to the rear if required.  Moving the weight of the caliper forward also improves the polar moment of inertia.

We will fit 304mm discs all round and 4 pot calipers at the rear too due to the rearward weight distribution.

AIR JACKS

The Exige requires only 3 airjacks, one at the front due to the light weight and two at the back.  As the Exige has an aluminium structure, the airjacks had to be installed into their own aluminium mountings, which we designed and made to suit the Krontec made Staubli airjacks.  These airjacks are very fast retracting and extremely light as they do not contain an internal spring.  The airjack mounts are bonded onto the chassis and at the rear have a bracket that fits under the chassis to take the load.

Front Air Jack

The airjacks are operated by a fill and release valve which we have placed at the base of the windscreen in front of the driver, where it will not interfere with driver changes or refuelling.  We have plumbed the system entirely in super-lightweight Goodridge PTFE smoothbore Kevlar hose with swaged alloy fittings.  These are more robust than the rigid hard-lines normally used, so are better suited to endurance racing.

PLANNING, PLANNING, PLANNING

Some time has gone by since we started this project, and we even managed to get our donor car up and running and take it to Bedford Autodrome last year, but this was just a trial to check some of the new parts we designed actually worked.  Here is an interior picture of the car as we ran it last year.

However, we were very excited to get started on the next stage of the project so we stripped the car back to the chassis.  Everything came off except for the side cills, the front crash structure and the windscreen frame.  The water heater pipes inside the cills has been removed to make way for the air-jacks, and the entire front end had been stripped ready for the new accessories.  The loom has gone completely, even the screen has come out (ready for the new heated motorsport screen).  So at this stage the car was completely stripped ready for cleaning and build up.

We weren’t completely happy with the first full cage we had made specifically for the car, so we had another one made by Safety Devices to our own specification, this time made as a single piece and going back to the rear of the subframe.

Welcome to the Nitron Lotus Blog for Project N2

What is Project N2?  Well, back in 2004, we decided to build a Motorsport Elise with a 2.3 litre Duratec engine, and got a bit carried away with ourselves.  At that time, it turned out to be a bit of a monster, with over 400 hp per tonne with a normally aspirated engine.  We raced it, learned a lot, and then finally sold it when we became too busy at work to run it any more.

The Lotus Exige Duratec 2.3L built by Nitron during Project N1

That was Project N1… we now have a new car ready for transformation, Project N2.  Over the next year we will transform our new car into a super-modified Elise, changing everything we can to make it go faster on the track, and the road, because it will always remain road-registered, necessary for the Nurburgring.  With Project N1, nearly all the parts were one-offs, some of them eventually becoming available through EliseParts in a production format.  The difference this time is that we are going to make all the parts available to anyone who wants them, as such they will all be fully productionised.

Our intention is to flex our engineering muscles (and brains!), and come up with the best solutions we can, within reason. These will be serious ‘hard parts’, which will all be worthy of the Nitron name.

Project N2 will be extreme, there is no doubt about that, but how extreme only time will tell.  But it will certainly have to be a much bigger step than Project N1 was, as Lotus modifications have come on a bit since we build Project N1

On this Blog is a list of the parts we will work on, and as they are finished they will be listed and available to buy from our online store.  We will of course start with the corners where the shocks bolt on, and work outwards into the rest of the car.

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