LCR splitter, aerodynamics and performance

[t32er]

Do they make fast diesels?

es they do, i met one monday night, the smarmy turd.... out pulled me in a 50mph rolling start to about 85 LOL i couldnt grasp it my self, i asked what he had done, just said mapped and stuff then drove off LOL

fair play for doing all the work, its good to see DIFFRENT things being done rather than all the normal stuff we all seem to do...
1 thing though, take a lokk on VX220 discussion sites, i found this when i was chatting to my bro in law who had a 300bhp vx220 turbo, i said to him to put the LCR splitter on it as it will look mental, he found out on a site it was the worst splitter they had tested on the vx220 apparently it was shocking and did next to nothing and a lot of it was to do with the gap in it and how flimsy it is
and the fact that we would need to make the entire of the underside of the car flat will put the price of making it work up a hell of a lot and the extra weight we needed to add would prob counteract the gains...
also we would need to lower the car to an inch of its life to create the down force under the car, in turn this will also put more stress on tires and probably effect forward momentum

 

[Nautilus]

LOL. You have given the right answer: you were sure.

It's not a Diesel, it's a 1.8T

Continental European LFRs are the same mechanical specification as the UK-market LCs, 1.8T/180 (AUQ-code) engine, 312mm brakes, 02M gearbox, suspension, but with FR badge, wheels, interior and mirrors.

A complete yet not detailed list of mods can be found here:

http://www.seatcupra.net/forums/showthread.php?p=2364764&post2364764

~Nautilus

 

[Ape]

It's hardly an equivalent to a remap is it

Maybe not, but if you're not able to get a remap, then where's the comparison? He's experimenting, where's the harm in it?

 

[carlossus]

It's people like this that make the work a great and interesting place.

My view is that mass acts to reduce mpg always, drag only makes a difference at high speed.

 

[M20FES]

Unless it's a high performance car and running at high speeds I can't see spoilers etc doing anything for it's aerodynamics or groundforce. Most sporty looking parts on road cars are just for show and nothing else. If you enjoyed doing the work then nothing else matters.

 

[t32er]

functional spoilers start working from around 40-70MPH depending on designe. i think its the only bit on the leon that comes oem that would work though as it doesnt have much choice but to work as its on a hatchback and is at roof level

 

[Nautilus]

Weird Aerodynamics - Myths and Misconceptions

There are a few myths which have been endlessly repeated by such media as the Fast & Furious series to the point they became ingrained in "automotive common knowledge". Which should have been no great deal, but in an age of credit crunch and inflated fuel prices they are not as innocuous as they seem.

Myth #1 - Wings and spoilers are the same thing.

Wrong. Wings had been invented some time ago to provide downforce to rear-wheel-driven race cars having simultaneously amidships-mounted engines, rear-biased weight distribution, different sizes of tyres front to rear and horrible oversteering.

From all points of view, on FWD / AWD cars with front engines, weight distribution biased towards the front and generally understeering in OEM condition (people go to great lengths with wheel spacers, ARBs, sports suspensions and so on to induce oversteering) they are worse then useless: they generate drag. Race cars have the power to compensate for the drag. And fuel paid for by the team.

Spoilers are slightly different, although they look similar: they keep the airflow over the back of the car, preventing turbulence over the rear and therefore lift, and also reduce drag in the manner of a "fastback".

The higher a spoiler is, the more efficient. Small spoilers fitted on the boot lid of a 3-box car are useless.

Our OEM spoiler is flush with the roof and functional.

Myth #2 - Aerodynamic devices and airfoils are strictly for racing.

Aerodynamic devices serve many purposes: they can reduce the drag and therefore the fuel consumption needed for achieving the same speeds, they can aid in stability at high speed, and, last, but not least, aid in engine bay cooling.

For example, the engine bay and SMIC bay in a LC/LFR/LCR do not have the plastic undertrays simply to protect the engine from mud and dirt, neither are the bumpers designed as they are simply for looks: the shape of the bumper (stepped inside where the lower grilles are) creates a high pressure pocket at speed, while the undertrays smooth out the airflow below the car, allowing the air to flow quicker and with lower pressure. The air goes into the radiator and SMIC in a high pressure area and exhausts into a low pressure flow under the car - the forward movement of the car becomes a pump which sucks the cooling air out. (Just how did people think the ICs cooled themselves through such a small, hand-sized opening, and even while not having any sort of fan as the coolant radiator does?)

Myth #3 - Aerodynamics work only at high speeds.

This should have been busted a few decades ago, by the generation of our grandparents

Aerodynamic devices act even at speeds as low as 60 km/h (under 40 mph) - anyone who had watched closely a FIA GT race on a tight and complex track saw the sharp hairpin curves (when aerodynamic stability is needed most) are taken at low speed. (Off-topic but it should be noted: the highest stress in a race car does not come from speed runs, but from the continuous cycles of acceleration to 250-300 km/h on straights, braking from 200-250 km/h to 60-80 km/h just before the curve, accelerating again after the apex... our forum comrades who did trackdays saw their tyres and brake pads almost melting themselves like in a thousand-mile trip after a few runs. GT racers change a few sets of tyres per run.)

The generation who took the drawing board just before WWII understood aerodynamics would help even the low-powered cars the general population could afford back then, even at ridiculous speeds from the point of view of a modern man. Adlers, Tatras or VW Bugs were quick for their day (although slow for modern drivers), but achieved their speed with the sort of engine power that would make even the slowest modern econobox laugh it's ass off. And, in practice, they would have needed only a fraction of that power to run at 100 km/h for all day long.

As afterwards came decades of cheap fuel, busy motorways and baroque designs, car aerodynamics slowly began to mean "the noble art of making yourself a cheap ricer also known as a brainless chav"

Regards,

~Nautilus

 

[Allan_84]

any one tryed this on a leon?

the front of this is 8cm longer in front of the car then the bumper.

 

[Allan_84]

yes you are right, but what if the front of the undertray in the picture is the LCR splitter?

 

[welchy]

yes you are right, but what if the front of the undertray in the picture is the LCR splitter?

Allan, do you know who made that, im very keen to have one set up for mine.

 

[M20FES]

i reckon the extra weight of spoilers, splitters etc outweighs the performance gains on most road cars. most are made of fiberglass that isn't light compared to carbon fiber

 

[Allan_84]

Allan, do you know who made that, im very keen to have one set up for mine.

yes, but its home made here in denmark, its for a BMW E46 M3 track car. but if you get the wood you can do it your self i think if you have the tools and the mechanical skills.

this is how its made:

 

[Nautilus]

And, finally, Myth #4 - Airfoils are the shaped pieces added to a car for looks and supposedly aerodynamic purposes is almost entirely wrong. There may be pieces attached to a car for aerodynamic purposes, but the car itself is the airfoil. (Think about it for a moment, we do not have a different atmosphere at the rear of the car compared to front, the same flow of air that comes in must also come out.)

The flat shape of the LC/LFR/LCR nose allows for making a flat undertray like in Allan_84's post with very simple plastic panelling (note: it must end exactly where the engine undertray curves down, otherwise it impedes the flow of cooling air through the engine bay), but another flat undertray from the engine backwards is more complex.

We can take as a model another VAG car which comes with undertray from factory, Audi A8 in D4 version (2010-present, not coincidentally praised for the fuel economy):

As we can see, it has the same problem as our 1.8Ts, the exhaust has to remain in the open air, otherwise we risk overheating and fire.

So, a plastic undertray for a Leon has to fulfill the following requirements:

1. It has to be lightweight.

2. It has to be insulated from noise. Either by having closed-cell foamy insulation pressed between it and the metal floor, or by having thin foamy insulation glued on the outside, or both. Otherwise it will resonate like a drum an break your patience and your very eardrums in a few miles.

3. It has to be in at least 2 pieces, left-right, to allow the exhaust and catalytic converter to stay in open air.

4. It has to be flush with the petrol tank. Beyond the tank, the complex shape of the rear axle makes any attempt to cover and smooth it it rather futile.

The LC/LFR/LCRs have from factory part of the fittings needed - there is a series of metal supports with bolt holes to hold the door sill skirts, and the plastic panels can be bolted on them, like we can see in the Audi picture above. There is also the central bracket which holds the exhaust, on which at least 2 bolts can be fitted.

A plastic underbelly panel can be built as such: sandwich shaped, 16-20mm thick closed cell foam on the inside, glued to plastic panel on one side and to car metal belly on the other side with strong spray adhesive, then bolted on the brackets for door sill skirts and to bracket for the exhaust. On the outer (lower) side of the plastic panel, glue a layer of thin foamy insulator, 3-5 mm thick, to avoid noise from stones and other debris hitting the panel.

(Fitting Audi TT jacking stands on the front alleviates the need to raise the car by the sill.)

Of course, it has to be made flush with subframe and with fuel tank by rubber gaskets.

The sole problem here is the sealing against water. Both plastic and polyfoam sheet are immune to water, and the underside of the Leon is coated with a rubbery goo from factory (yellowish in color, it can be seen by scratching the dirt underside). But it has to be prevented at all cost the ingress of water between foam and metal - if the foam is glued to the goo-coated metal with strong spray adhesive, it should be caulked enough to prevent rust.

Regards,

~Nautilus

 

[MPJ88]

yes, but its home made here in denmark, its for a BMW E46 M3 track car. but if you get the wood you can do it your self i think if you have the tools and the mechanical skills.

this is how its made:

This just reminds me of when topgear made their own and it set on fire

 

[Nautilus]

Some one needs to get laid

I would, but your mother charges too much for an hour.



~Nautilus

 

[LEE69]

I would, but your mother charges too much for an hour.



~Nautilus

 

[welchy]

Thanks for removing my posts trying to reason here, the seatcupra.net mafia seems to have stepped in!rofl!

 

[Nautilus]

After performing the mods to the cooling air intakes described here, did some coasting tests on open road and also fuel economy tests over the same route.

Right now, the aero mods are as following:

- flat undertray under front bumper, from edge of LCR splitter to factory under-engine plastic fairings;

- fairings (or "air deflectors") glued on the undertray in front of the tyres and suspension links, made after this article;

- smoothed and caulked gaps in the plastic & foam construction;

- sealed bodywork gaps as described before, including non-essential gaps in the front like above and below headlights;

- small "thorn" radio antenna.

Most mods are invisible from outside the car.

Tests have been done on the same 35 km stretch of road, part of it city, part highway, all of them in similar traffic conditions, same hour, similar temperatures (in the 32-36°C range), always with A/C compressor on.

Results:

Coasting ability has improved visibly.

Indicated fuel economy on this stretch of road was in the 9.5-10.8 l/100 km prior to any mods. It's in the 8.4 to 8.8 l/100 km range right now, more often closer to the lower figure.

Fuel economy tested on a long (hundreds of kms) open-road trip was 7.4 l/100 km recorded last summer, before all aero mods had been performed. Should have been improved by now by the same percentage as mixed-traffic economy.

There is no adverse effect on car stability up to 150 km/h, it handles just as before.

Wind noise had been reduced significantly.

Factory Cx on the Leon 1M bodywork is 0.32.

Using the approximate frontal area of 2.20 sq m (Golf Mk 4 has 2.22 sq m) and recorded speeds in a fixed timeframe when coasting on a level road, a simple Excel calculator of drag indicates much lower figures, in the 0.28-0.29 range. Regardless how I play with rolling resistance of the tyres in the 0.008-0.01 range (F1 Asymmetrics are reputed to be low-Crr tyres but official figures are not available), they never exceed 0.30. These figures are not very realistic, but they may become realistic if there is also fitted a flat undertray for the entire car.

~Nautilus