Since the thread linked below took a turn towards an overall discussion of the Ariel Atom, I started this thread for those that want to continue or expand on that topic.
viewtopic.php?f=6&t=5681
First of all, here's a couple of my track videos.
From Laguna Seca:
http://www.vimeo.com/899517
Me and a friend in his 400+hp Atom, equiped with Formula Atlantic tires, at Reno-Fernley Raceway:
http://www.vimeo.com/1168859
About the Atom's rearward weight distribution - yes, its weight is rear biased, approx 60/40, which is similar to a Porsche 911. It seems part of Porsche's solution has been to match tire widths to the proportions of weight at each end, resulting in significantly wider rear tires. This would likely work on the Atom as well, if there were bespoke tires for it as there are for Porsches. But the problem is that there's no street tire with the right construction for Atoms, they're all too stiff in terms of compound and sidewall for a car this light. Atoms can't get enough heat into the tires, and using wider rears would result in less heat and thus less traction, but more weight.
One idea is to use a bias ply racing slick, made for an open wheel car of similar weight. The other Atom shown in the video above is the 1st to do this, using Formula Atlantic tires. But this car isn't sorted out yet, so it isn't taking full advantage of those tires. The biggest problem with using this type of tire is that it will put more pressure on the rear wheel bearings, which are already a weak point. For various reasons including wheel bearings, I'm limiting myself to one set of wheels, with street legal tires on them. Of course "street legal" still allows various near slicks including autocross tires like Hoosier A6's, which might work well. If I ever decide to use A6's, the question will be what's the max rear size that will still get up to temperature?
On my Atom, I've already spent some time on the suspension, alignment, and tires. I log the tire & brake temps, tire pressures, lap times, etc, for every session I run. My changes to the car have already resulted in big lap time improvements. Of course part of this is due to me learing how to drive the car. My prior experience included shifter kart racing and track days in a Porsche 996.
With 245hp and only 1,350 lbs, my Atom has an equal power to weight ratio of a 3,000 lb car with 545hp. That should be plenty of power. Acceleration is no problem compared to cars like the Z06 or GT3RS for example, and many race cars too. But once the speeds go over approx 100mph, these other cars pull away from the Atom. Mine's a NA Honda K20 engine. Atoms are available with superchargers on this engine, making 300hp. Although this would be a pretty simple bolt on upgrade, since I'm not a fan of boosted engines, I plan to leave mine NA.
I don't think the gear ratios are the high speed problem, because I've got a 6 speed transmission, and never use 6th gear on track.
That's just the tip of the iceberg. Let me know if you'd like to be bored with more details.
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thus the suspension "items" I was talking about. A way different ride height means a different suspension geometry and a stiffer suspension. Then your driving must also adapt to all these and that is the funny thing.
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