27-12-2018, 08:26 AM
Simon that lightened flywheel of yours looks a proper job, radiused corners are right, it's probably a pound lighter, and you still have a full pressure plate + ring gear
For a road car this is perfect, its definitely a case of less-is-more when lightening road car flywheels, too much off and you loose rotational inertia and you literally have nothing to carry the car up a slight bump, on a race car where the throttle response is much like an on-off switch this isn't an issue, but having an all or nothing motor in a road car is miserable. The flywheel on our '28 Model A is a colossal thing, we actually lifted it up with the engine crane before fitting it. A friend lightened his one and while it revs faster, our A is actually quicker on the road as we can climb hills in top while he is bleeding off speed while scratching for 2nd gear... and with a 3.3 litre engine, torque is your secret weapon.
With the mouse motors in our Sevens, you need a little rotational inertial to carry you up the inclines, the standard flywheel does very well, but a just a little rotating mass off, makes a big difference in rev response when shifting gears. It's probably the second most noticeable thing you can do the the motor, the biggest is to balance the motor. Despite the blue race car being an offset single seater with an offset short prop shaft and a Yamaha 650 shaft drive and universal joint driven off the nose of the crank to put the blower straight out front, it's probably the smoothest 7 engine we've ever built, but I balanced everything meticulously - you can see where I ground the casting flashing on the big end caps to equalise the weights of the rods, they were also balanced end to end. The pistons were balanced to 0.1g as were the rods and then the whole assembly was taken to an engineering works for balancing.
This is the flywheel from the Green Job - 2.5lbs lighter than standard as per the period 750 Bulletins, no ring gear and lightened pressure plate, so no need for the pedestal machining as we are already at target weight - the rev response is fantastic, it spins to 6000 with ease. The Blue job looks much the same - I'll report back after the Simola Hillclimb !!
Aye
Greig
For a road car this is perfect, its definitely a case of less-is-more when lightening road car flywheels, too much off and you loose rotational inertia and you literally have nothing to carry the car up a slight bump, on a race car where the throttle response is much like an on-off switch this isn't an issue, but having an all or nothing motor in a road car is miserable. The flywheel on our '28 Model A is a colossal thing, we actually lifted it up with the engine crane before fitting it. A friend lightened his one and while it revs faster, our A is actually quicker on the road as we can climb hills in top while he is bleeding off speed while scratching for 2nd gear... and with a 3.3 litre engine, torque is your secret weapon.
With the mouse motors in our Sevens, you need a little rotational inertial to carry you up the inclines, the standard flywheel does very well, but a just a little rotating mass off, makes a big difference in rev response when shifting gears. It's probably the second most noticeable thing you can do the the motor, the biggest is to balance the motor. Despite the blue race car being an offset single seater with an offset short prop shaft and a Yamaha 650 shaft drive and universal joint driven off the nose of the crank to put the blower straight out front, it's probably the smoothest 7 engine we've ever built, but I balanced everything meticulously - you can see where I ground the casting flashing on the big end caps to equalise the weights of the rods, they were also balanced end to end. The pistons were balanced to 0.1g as were the rods and then the whole assembly was taken to an engineering works for balancing.
This is the flywheel from the Green Job - 2.5lbs lighter than standard as per the period 750 Bulletins, no ring gear and lightened pressure plate, so no need for the pedestal machining as we are already at target weight - the rev response is fantastic, it spins to 6000 with ease. The Blue job looks much the same - I'll report back after the Simola Hillclimb !!
Aye
Greig