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TOY CAR ON TRACK

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Old 10-14-2008, 08:13 PM
  #16  
Sean F
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Here is the page with motor specs, etc:


http://www.almost.co.za/special%20feature.htm
Old 10-15-2008, 01:34 AM
  #17  
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Default MORE DETAILS

Thank you all for the kind words. I shall endeavour to answer your questions relating to the car. Starting from the front of the car and working towards the rear:

OIL COOLING
The air intake housing conceals two oil coolers that are ducted to have the air exit over the top of the bonnet. The oil coolers are placed in parrallel meaning that the one is placed close the the entrance of the duct and the second one is placed near the exit. Oil from the engine is routed through the second cooler first and then fed into the one in the front. With this arrangement you get some pre-cooling of oil.

TOW HOOK
The tow hook that protrudes through the bonnet is secured to the tower struts. The front end of the car is fragile and did not have an appropriate mounting spot for the tow hook hence our decision to mount it on the bonnet. This also helps as the tow vehicles generally have a high tow position. I shall post a picture tomorrow of the inside so you can see the attachement mechanism.

RED PANELS ON THE FRONT FENDERS
In an effort to contain slow corner understeer, especially when the thottle is applied, we, in our engineering shop came up with a design of a very wide track front suspension. The front track of the car was increased by 6" (150 mm). With this width there is no way that the top of the front struts can be contained inside the car. Note: Wideining the front track induces oversteer (not understeer) characteristics in slow corners. To curb the induced oversteer in fast corners aero is used to control it.

With the old configuration we found that as soon as the throttle is applied the car tends to push and the only way to make the car stay on line is to momentarily lift the throttle. Now the car just follows the steering wheel.

SPRING STIFFNESS
Since January this year we have moved to DOUBLE the spring rates front and rear. Initially we thought that the car would be as stiff as a kart but at speed it gives a comfortable drive. More importantly with the older springs the car was always "3 yards behind the steering wheel". Don't be shocked but our front spring rate is 130 N/mm (740 lb) and the rear 220 N/mm (1250 lb). The total weight of the car with full fuel load and driver on board, ready to race, is 1060 Kg (2332 lb).

I shall post more details later.

Johan
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Old 10-15-2008, 03:14 AM
  #18  
Pierre Martins
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Car is looking good Johan. Pity about the gearbox, would've been nice to see it in action this past weekend.
Old 10-15-2008, 03:50 AM
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Default TORQUE

Pierre.

Thank you. This picture shows what torque does to a 4th gear at 180 km/h. After going into fouth gear around the long and flat out turn 3, the engine just started to hit the rev limiter. I backed off the throttle, coasted for a while then found that I had 3rd gear. I limped back to the pits and phoned for help at M&R Motors.

I was told by Mario that he had never seen this kind of destruction of a 4th gear.

Luckily we managed to source a new fouth gear and will race at the last race of the season with the 915 gearbox. For next year we will probably have to go to a G50 with all the cost and fabrication implications.

Regards
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Old 10-15-2008, 04:03 AM
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Pierre Martins
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Make Willie de Beer an offer on that sequential box he bought from Porsche Centre a couple of years ago. That will make your car complete.
Old 10-15-2008, 04:25 AM
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Amazing build, great website....not in love with the looks but I don't matter. Have fun.
Old 10-15-2008, 09:01 AM
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beautiful!!!!! nicely done!!!!!
Old 10-15-2008, 10:30 AM
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Jarez Mifkin
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I really like this picture:

Old 10-15-2008, 03:02 PM
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Larry Herman
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Again very nice. Just to let you know, IIRC 915s were only rated for 350 hp max by the factory. Spray oil-cooling of the gears would raise that somewhat.

Why would we be shocked by your spring rates? I ran over 1400 lb springs on my old RSA with fantastic results (though my car was 400 lbs heavier). The 964 tub is a lot stiffer though. Are your front suspension points tied into the cage?
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Old 10-15-2008, 03:57 PM
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Originally Posted by Larry Herman
on my old RSA
You sold your car???? where the eff have I been???
Old 10-16-2008, 02:33 AM
  #26  
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ENGINE
Attached is a picture of the engine that would explain the horisontal fans. In picture are sprayers that spray a mixture of Methonol and water on the intercooler. This reduces mixture intake temperatures by about 17 degrees Celcius. Currently intake temps on a hot summers day is about 47 degrees C.

The centrifugal supercharger is seen on the right hand side. Power output is 500hp on the rear hubs.
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Old 10-17-2008, 03:40 AM
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This picture shows the tow hook, second oil cooler, fuel tank, fuel and oil filters and oil reservoir.
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