Quoting Larry Steckel <lorenzoscribe@hotmail.com>:
> - If you were going to design an affordable sports car with the intention
> of
> buyers using it as a weekend racer, how would you design it?
>
> I would use front engine/rear wheel drive, with a five or six speed tranny.
>
> Mid engine is nice, but hard to service, and expensive when it breaks.
> Remember torque is preferable to six figure RPM redlines on the autocross
> course.
>
We chose a mid-engined transverse layout for several reasons. One big one is
that it's much easier and cheaper to find engines and trannies in this layout
since there are so many FWD cars around. Another is that it's not possible to
design a good monocoque for such a small car and have the engine in the front
with RWD -- the exhaust pipe and driveshaft would take up too much space.
To solve the service problem, the entire rear body can be removed from the
chassis.
Regarding engines, we haven't had any luck with contacting Honda and Mazda
doesn't sell their Renesis engine at OEM prices, so high-revvers probably won't
be put into our car. Currently we're looking into the engines found in the Opel
Speedster and Volvo S40 T4, both of which are relatively meaty engines
(especially for a 750 kg car).
> Please give me a solid front crossmember so I can jack the front of the car
> up from the front center, rather than fuss from both sides.
>
Good tip!
> I would have the oil filter positioned to be accessable for changing with a
> simple oil filter wrench without dumping a quart of oil on the crossmember
> and steering rack. I would have the air filter accessable without using a
> crow bar. I would also have the spark plugs accessable for easy changing.
>
Hmm, the parts on the upper side of the engine are pretty easily accessed, but
getting to the oil filter would require more effort since there will be a flat
underbody tray for aerodynamics. I will keep it in mind to design the tray to
be easily opened for oil changes.
> Simple shocks or struts. Don't add a silly tab or a minor suspension
> component to the shock. I have seen that move shoot up the aftermarket
> price to astronomical proportions because it now a one car only custom
> application. Don't do something like Ford where a heater core change takes
> 13 hours. That is completely brain dead.
>
Parts such as the dampers, brakes, etc will be sourced from currently available
cars, so the cost for aftermarket parts should hopefully stay low.
> Don't let the stylists so tart up the engine bay that you need fifty special
>
> tools just to find the spark plug wires.
>
> Inside, I would have pre-drilled and tapped holes for a roll bar. Make the
> bar to meet the SCCA rules to be above the head of a six foot driver and
> still be able to put the OEM top up. Provide harness mounting points on the
> floor for wide lap belts and on the roll bar assembly for shoulder
> harnesses. Don't forget an attachment point for the submarine belt.
> Autocrossers will love you. Offer the bar through the parts department of
> the dealer, or give plans to someone like Autopower.
>
Actually, the car is already designed with a roll cage integrated with the
monocoque. Albeit it's one that's not such an eyesore for the nonracer. Also
built into the design are mount points for a racing harness. We're probably
going to use Sparco or Recarco shells for seats, so optional harnesses should
fit in naturally.
> Pre-design a tow hitch capable of pulling one of the small trailers
> autocrossers use for tools and extra tires.
>
Never thought of that one before; I will add one if possible.
> And as to tires, do we really need 17-18-19 inch tires? 15 inch tires
> should work just fine on a 1600 lb car, and be much cheaper to replace.
>
Here is where the stylists and europeans don't agree with you. :P Currently
we're using 16" front and 17" rear.
> Oh yea, and don't forget that some of us out here (ahem are built more in
> the wide body mode as opposed to the twig style. Give us enough room to sit
> down in the thing.
>
That is one of the hardest things to design. A monocoque with a roll cage is
very contradictory to big people getting in and out. Try sitting in a Lotus
Exige and you'll know what I mean!
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