 |
Alfa Pages
A forum for help with the Alfasud And Alfa 33
|
|
|
| View previous topic :: View next topic |
| Author |
Message |
paddy granger
Alfa Sprint
Joined: 12 Aug 2003
Posts: 248
|
 Posted: Sun Oct 10, 2004 12:27 pm Post subject: |
 |
|
Here is the Google cache from the Sirius page!
Design.
The basis of the car is a tubular steel space frame chassis, the majority being 25mm square tubing, with the occasional 32mm x 25mm section where extra strength was required. In the design, we erred on the side of safety and strength rather than ultimate lightness.
The space frame is panelled with 1.2mm Aluminium sheet above the floor line, with 1.6mm Aluminium being used to double skin the floor pan which is completely flat and the lowest part of the chassis. Rolled Aluminium side pods are rivetted to the side ladder frames and bottom hinged aluminium doors with small Lexan wind deflectors complete the sides, from screen to roll over protection bar.
Fore and aft body-work is moulded fibreglass (my own design). The front is completely removable for access to the brake pedal box and front suspension, the rear hinged for access to the engine and transaxle.
Suspension is all fabricated. The front uses 105 Alfa caster arms and ball joints formed into upper wishbones and lower trailing links. Lower control arm is tubular steel with spherical bearings. Front discs, calipers and hubs are from TE Gemini. Discs are drilled to Porsche pattern and fitted with Hardie Ferodo Excel disc pads. A twin master cylinder pedal box with bias bar adjustable from the cockpit for Front/Rear bias takes care of the hydraulics. The steering rack is a modified Alfasud unit.
Rear suspension consists of unequal upper and lower wishbones with trailing links fully rose jointed and adjustable. Brakes are Brembo inboard Alfasud discs and calipers, with discs also drilled, but using Mintex pads. Drive shafts are 1.5litre Alfasud. Hubs and carriers are my own design, are fabricated from steel and use Alfasud front hub bearings. The engine, transaxle and rear suspension form a sub-frame which is removable from the rest of the frame by removing 6 Hi-Tensile M10 steel bolts, for ease of servicing and replacing these units. Spax adjustable coil-over shocks take care of the damping. Fuel tank is foam filled , made from 2mm Aluminium has a capacity of 30 litres and is mounted in its own sealed compartment directly behind the passengers seat.
OH!!! I forgot to mention, SIRIUS is a 2 seat Group A sports car as per CAMS manual. Weight without driver is approx. 550 Kg
SIRIUS was designed and manufactured in my backyard workshop, although certain specialist machining and welding was, to use a modern buzz phrase out sourced. A complete mock-up body was constructed on the chassis using many different fabrication materials and techniques, the most widely used materials being 2 pack Polyurethane foam and Polyester body filler (bog).
This body was completely finished i.e. shaped, smoothed, painted, polished and then waxed, although totally useless for anything but producing a mould from. The mould was laid up over this body after a liberal coating of release agent, removed, cleaned and waxed ready to mould the final Front & Rear body shells from. The mock up body was then destroyed and dumped. Body panels were made using these moulds, from 1 layer of woven roving and 2 layers of chopped strand mat, with an exterior finish of white gel coat. The panels were then trimmed, fitted and painted (red of course). The total package resembles a mid-70's design sports racing car reminiscent of Elfin 400 or small version of Mclaren M8
ENGINES
The original engine in 1987 was a 1200 Ti Alfasud unit, bog standard except for a pair of 40DCOE Weber Carburettors feeding directly into the heads through a cast alloy goose neck manifold (my own design). This motor, although slow, was very reliable and only broke while doing laps at the 1989 Adelaide F1 Grand Prix Sports car demo.
Engine development went through various stages of capacity increase, modifications and tune (all normally aspirated) concluding with the last highly modified, high revving version in 1993. This, or should I say these, latter engines were an over-bored 1490cc Alfasud flat 4 with 2.5mm machined from each side of the block to give a final compression ratio of 12.6:1. The Mondial cast pistons were machined to accommodate the valves and then balanced to within 0.1 grams. The valves were 2mm oversize stainless steel units made by Richard Bendall to my sample profile. The valve guides were manufactured from aluminium bronze and the seats from nickel bronze.
Camshafts were 11.5mm lift Autodelta units, valve springs triple flat wound Cosworth. The complete engine was balanced, 105 Alfa con-rod bearings were used and the flywheel was lightened by 2Kg s. Fuel was supplied initially through 2x40DCOE Webers, then 2x40DCOE Webers, then 2x44IDF Webers and finally 2x48IDA Webers using specially fabricated alloy manifolds and long series trumpets. Fuel was 100LL Avgas . We managed to squeeze 130-140 HP from this engine at 8200 RPM. Unfortunately (although very quick) the pistons could not withstand the pressure and 3 of these motors detonated during the last season of racing.
I was not having fun any more, paying out large sums for engine rebuilds, so the natural progression from here was to build a, relatively, lightly stressed engine with torque and reliability. Hence the blown 1430cc unit using all standard Alfa components.
Future developments will include increasing the capacity to 1600cc using the 1500cc block and 1700cc crankshaft, fitting the large valve head with the high lift cams, fuel injecting and water / methanol injection. The ultimate aim is to produce 180 reliable HP using 10-12 lbs boost but with a massive increase in available torque. In the words of the Guru Carroll Smith, Horsepower sells cars, Torque wins races .
LSD
The diff. is locked at between 55 and 75 ft/lbs depending on requirements, and works extremely well, with smooth transition to normal operation. I have also manufactured 4 others for Alfasud Racers and 1 for street use, and after many Klms, none have complained of the car being hard to steer or drive. The ratio changes were achieved by the mix and match method, using a number of different ratio boxes and diffs. It is also possible to cut and shut the cluster gear to change ratios and I may try this in future, as we used this method to produce a close ratio box from the Datsun 280ZX 5 speed we ran in a Rally car.
A pic of the racer:
 |
|
| Back to top |
|
 |
burgo90
Alfa Sprint
Joined: 29 May 2003
Posts: 118
|
| Posted: Sun Oct 10, 2004 2:02 pm Post subject: |
|
|
| paddy granger wrote: |
ENGINES
The original engine in 1987 was a 1200 Ti Alfasud unit, bog standard except for a pair of 40DCOE Weber Carburettors feeding directly into the heads through a cast alloy goose neck manifold (my own design). This motor, although slow, was very reliable and only broke while doing laps at the 1989 Adelaide F1 Grand Prix Sports car demo.
Engine development went through various stages of capacity increase, modifications and tune (all normally aspirated) concluding with the last highly modified, high revving version in 1993. This, or should I say these, latter engines were an over-bored 1490cc Alfasud flat 4 with 2.5mm machined from each side of the block to give a final compression ratio of 12.6:1. The Mondial cast pistons were machined to accommodate the valves and then balanced to within 0.1 grams. The valves were 2mm oversize stainless steel units made by Richard Bendall to my sample profile. The valve guides were manufactured from aluminium bronze and the seats from nickel bronze.
Camshafts were 11.5mm lift Autodelta units, valve springs triple flat wound Cosworth. The complete engine was balanced, 105 Alfa con-rod bearings were used and the flywheel was lightened by 2Kg s. Fuel was supplied initially through 2x40DCOE Webers, then 2x40DCOE Webers, then 2x44IDF Webers and finally 2x48IDA Webers using specially fabricated alloy manifolds and long series trumpets. Fuel was 100LL Avgas . We managed to squeeze 130-140 HP from this engine at 8200 RPM. Unfortunately (although very quick) the pistons could not withstand the pressure and 3 of these motors detonated during the last season of racing.
I was not having fun any more, paying out large sums for engine rebuilds, so the natural progression from here was to build a, relatively, lightly stressed engine with torque and reliability. Hence the blown 1430cc unit using all standard Alfa components.
Future developments will include increasing the capacity to 1600cc using the 1500cc block and 1700cc crankshaft, fitting the large valve head with the high lift cams, fuel injecting and water / methanol injection. The ultimate aim is to produce 180 reliable HP using 10-12 lbs boost but with a massive increase in available torque. In the words of the Guru Carroll Smith, Horsepower sells cars, Torque wins races .
|
Kittens a duck is all i can say lol
_________________
http://www.novaload.net/features/viewfeature.php?ref=881 |
|
| Back to top |
|
|
evanbottcher
Alfasud
Joined: 12 Mar 2003
Posts: 53
Location: Melbourne, Australia
|
|
| Back to top |
|
|
burgo90
Alfa Sprint
Joined: 29 May 2003
Posts: 118
|
|
| Back to top |
|
|
|
|
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
|
