AVR - Tech Blog

AVR RX7 FD3 wheel & tyre upgrade

When we first ran the RX7 in OSCA we were aware that the car was under tyred. The car was originally built to the Sport Saloons regulations which did not allow any major modifications to the wheel tubs - so when it came time to run in OSCA a 265/625 slick was about the biggest that would fit. To get a readily available good compound slick meant a significant step up in diameter and a little wider. The previous Rays 17x9 rims were pawned off to make way for the new Enkei 18x10.5 rims. We thought the Rays were light but despite being a larger piece of metal the Enkeis are actually 1/4 of kg lighter per wheel.

Above the new rims & tyres are fitted and the car reset to the previous ride hieght. As you can see there are a few issues with clearance with the tyre resting on the top of the tub front & rear.

Hmmm, what to do?????........................................ - only one thing for it -cut off disk time!

The first cut is the deepest. Quite a large part of the factory top chassis rail has had to be removed. The rollcage picks up the suspension tower quite well but new reinforcing will be added to help brace the outer edge of the tower back into the remaining top chassis rail.

Many thanks to Don 'Hopper' McLaren for help with this after school project.

If the driver can man up to the increased grip after this project is complete there should be some good gains in lap time.

More updates to come.

AVR RX7 FD3 13B PP turbo race car at the Ruapuna Tier-1 race meeting

Racing in the Sport-GT class at Ruapuna on the 10^th of December 2011

A very enjoyable weekends racing! It was also one of those rear motorsport weekends where the only attention the car required was topping it up with fuel.

I also managed to shave half a second of my personal best lap time (to a 1:29.5). However with the calibre of the field this left me well down the grid, but none the less fun times were still to be had as there were a host of cars of similar pace.

The main area the car lacks in is outright grip. The RX7 was originally built for the Sport Saloons series where the tire size and wheel tub modifications were limited. So the next step is to modify the wheel tubs and fit up some larger rubber, we will keep up updated on this new project.

Michael’s three rotor NA peripheral port engine assembled

The montage below shows the assembly sequence for the short crank triple rotor peripheral port engine.

Some small details need to be completed on the sump plate before the engine can be fitted to the car. From there the inlet manifold, cold air intake, and exhaust can be fabricated.

Riley’s RX7 FD3 Bridgeport turbo complete

Riley took delivery of his revamped FD3 in time for Christmas. With a conservative tune to suit the variations of pump 98 fuel it delivered just under 480hp at the wheels at 18psi boost. Should Riley require more an after market inlet manifold would unleash the full potential of the full bridgeport 13B. At this stage though the boost is set at 15psi for the high switch setting & 9psi for the low.

Quick spec list;

Engine; Mazda 13B REW full bridgeport with studkit & unbreakable 3mm apex seals

Turbo; Garret T04Z, Tial 60mm wastegate

Injectors; 2x ID1000cc, 2x ID2200cc

Fuel pumps; twin Siemens 315L/hr in tank pumps

V-mount intercooler/radiator, Pipercross air filter, Greedy pulley set, Tial BOV, SX fuel pressure reg.

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