A lot is talked about the different wings that have appeared on the Lotus Esprit. Starting in 1989 with the SE, up to the present V8 (see wing & wheel history). The Esprit started life without a spoiler and carried on this way for around 12 years. The first Esprit to carry a wing (spoiler) was the SE (although the US marketed X180R was officially the first) in 1989. From then until today the Esprit has been fitted with a wing, expect the basic modelled GT3 and V8-GT, to which some owners opted for a wing.
Above shows the way the Esprit wings have progressed.
Starting with the very low winged SE on the left. Followed by the short run
SE high wing. "A new distinctive high-mounted rear wing, new tailgate
design, and revised front bib all combine to achieve lift and drag reductions
as well as visual appreciation of the new model. The improved aerodynamic
handling balance, stability, and drag reduction have led to an increase in
maximum speed, to 165mph." as Lotus say in there press release. Followed
up by the 94 S4, with the same height (roughly) wing as the High Wing, but
moved dramatically forward.
The Sport 300, S4s and early V8's all had the same swooping wing attached to the rear wings. With the later V8's using the same wing on stilts. The 1999 Sport 350 uses a higher mounted carbon fibre wing on aluminium uprights. So that brings us up-to-date on the history of Esprit wings.
So with all the different wings that have nested on the Esprit, which ones work and which are pure show. Has the wing evolved over time to produce better downforce or is it just a fashion thing?
The next selection of wings have been photographed on either Racing Esprits or High-Performance Road Esprits. You can clearly see a marked difference from the above standard wings. All the wings are larger, higher and have a square effect to create downforce. Compare these to the factory wings and you can see the difference in design.
Any wing will cause drag, against downforce. More drag equals more downforce. From what I've learnt of the Esprit shape, the air-flow coming over the roof line and towards the wing, is very disrupted. This reduces it's effectiveness in producing downforce. For a wing to work on an Esprit it needs to be very high and the only part of the wing that will produce any useable downforce is 1/8th at each end. The middle part of the wing creates no useable downforce.
If you look at the picture (below left) of Lotus' GT1 (produced by Lotus at a cost of £10 million), you'll see what I mean. Only the two ends showing are producing any real downforce. This is not true of every car. Porsche's 911 Turbo Spoilers produce much more downforce due to the different shape of the 911.
Any useable downforce from an Esprit rear wing is only present from around 80mph. Up to 80mph all they do is produce drag. Effectively slowing down acceleration. GT Racing, which is what the Esprit ran in, have rolling starts with cars rarely dropping to low speeds and only accelerating from a starting start at pit stops. So a Racing Esprit is always at a high enough speed for the wing to produce useable downforce, compared to the drag.
So from the information gathered, it seems the factory fitted wings create no useable downforce for road use, only drag and extra weight. The other side to the argument is stability. A rear wing can be use to create better high speed stability, but that's a whole other story I sort of got lost in while researching this article.
Below is information from the Factory about the Aerodynamic work done on the Esprit and the various wings, including the Transom (rear lip). This information confirms that none of the wings that have appeared on the Esprit are there for purely visual means, but have been wind tested and set up to give the Esprit the downforce and stability required.
Whether each new wing is better or just match to the particular power output was unknown until recently when LEW received some information direct from Lotus. Below is an explaination to which wings create better stability. The Esprits wings (as we thought) create very little useable downforce.
From Lotus Cars Ltd
All Lotus Esprit vehicles have had the Aerodynamics developed in a wind tunnel followed by track & road appraisal and are fully Type Approved. All the Esprit Production vehicles were built to a tested & approved specification.
In simple terms the main visual difference in the production build has been whether the car has had a separate bolted on 'Wing' or an extended Transom. Changing the visual appearance of a vehicle by attaching / removing a bolt on wing is an easy aftermarket exercise. What is not usually appreciated is the change that can be made to the rear downforce by this exercise.
It should be noted that the production vehicles built with a bolt on wing have the short (low) Transom (V8 SE's & Sport 350's) and cars without the bolt on wing have the long (high) Transom (V8 GT's & GT3's). The exercise of bolting on a wing to a car with a long (high) transom does not replicate the original factory built car and the removal of the wing without the addition of the correct Transom is not totally correct. Both will result in a change to the rear downforce, drag and overall balance of the vehicle.
Many wind tunnel test hours and much track time (and lots of ££££) is spent developing 'wings' that actually work (for downforce & drag) – they are not for decoration only. The latest variation – Sport 350 – had a Race Type wing developed to give the car an association with the Esprit Race Cars but still had to produce the required (balanced) downforce for the road car. What also needs to be appreciated is that all wings including the Sport 350 variant has to conform to the relevant Type Approval requirements.
1. Lotus Carbon fibre rear spoiler with end plates (Sport 350) and short transom provides BEST BALANCE.
2. Any Lotus rear spoiler with the longer transom promotes UNDER-STEER.
3. Removal of Lotus rear spoiler, leaving short transom is worst scenario, this promotes OVER-STEER.
4. No rear Lotus spoiler and long transom (GT3 & V8 GT) is LOTUS APPROVED.
5. Any of the Lotus rear spoiler with short transom is LOTUS APPROVED.
6. Fitting of the front rubber Bib is SATISFACTORY, reduces lift but increases drag.
NOTE: All the above comments are applicable when the Esprit is fitted with approved Springs, Shocks at recommended Ride Heights.
Now some of the technical points have been cleared up (but by no means all). What about adding wings to older or wingless Esprits and removing wings off wing'd Esprits. Lotus advised that the set up on the Esprit when sold is type approved and fully tested.
Firstly any useable downforce is only going to effect the handling of the car at high speeds, as is any extra stability. For an Esprit driven on public roads this is not going to be noticed by the driver. Those who do higher speeds and/or track days may notice a difference in high speed cornering and stability.
In the end it's up to you what you do with your Esprit. Safest option is to stick with what Lotus have tested and approved (see above). Those with 'road' cars may which to remove/add a wing for cosmetic reasons, which is fine as long as they know that they will be effecting the set up of the car. The guide above will help you make the best choice.
Things become even more complicated when you start to looking at other modifications that may effect weight and Aerodynamics. Things like adding a front spoilers/splitter, changing exhausts (removing weight from the rear of the car) and removing the spare wheel (removing weight from the front of the car). All this can unbalance the car from what the manufacturer has set up, then take into account worn tyres and worn/different suspension and you're looking at something a long way off what Lotus built at the factory.
Last World (maybe!)
LEW's view is a wing will have little real world effect on a 'road' driven Esprit at legal speeds, leaving the choice down to the owner as to whether to add or remove a wing. If you're looking to track your Esprit or use it for higher speed driving, then it would be advisable to stick closer to what Lotus have approved. So if you are removing a wing, add the larger transom and via versa if you're adding a wing to either a GT3 or V8-GT. But with so many other things that could possibly upset the handling, I would advise firstly to make sure your vehicle is well maintained, with good brakes, suspension, tyres at the correct pressures before worrying if the wing will effect high speed driving.
I'm sure this article will open a 'can of worms' with so many different views and experts. So if you wish to add your comments to this page email them to the address below and I'll add the most constructive ones below for everyone to see.
If you comments on this article, feel free to e-mail me with your Verdict at firstname.lastname@example.org