| Standard Rebuild Work | Tuning Work | Pictures Of The Rebuild |
| Picking Up The Engine |
It was obvious from the things that were wrong with the engine (see list on the previous page), that it needed a complete overhaul. The following new parts and work was carried out:
As the engine would need to be completely dismantled anyway, I figured that it would be well worth the money to have the engine 'slightly' fettled to make it more 'efficient' (read MORE BHP). In order to improve on this already fast and solid motor, the following work was carried out.
I can hear you thinking, 'why would you spend extra money tuning an engine, is it not excellent already?' In short, the answer is short, 'NO'. Although Cossie engines are aleady in a higher state of tune than 'normal' engines, these too have room for improvement. The reason for this, is that engines are produced with fairly tolerances for imperfection. These imperfections may singularly be very small but in combination can add up to a significant loss in power.
By weighing and balancing the different aspects of the engine, the efficiency of the engine is improved by channeling all of the available energy into forward propulsion rather than loosing this to vibrations and imbalances. A good comparison, is a car tyre, if this is not balanced properly it will alter the feel and 'balance' / stability of the entire car.
One of the most significant gains is not only to be had from the work on the head, but also from the lightening of the fly-wheel. Although opinions differ with respect to whether a fly-wheel on a turbocharged car should be lightened or not (there are equally strong arguments for doing this as there are for not doing it), I decided after some careful consideration, that I would have it lightened. One of the drawbacks of the Sierra Cosworth engine and particularly of the turbo bolted onto it, is that it 'suffers' quite badly from what is referred to as 'turbolag'. This is the time between giving full throttle and the engine actually delivering this power. The time is similar to that of an automatic car's 'kick-down' time lag.
Theory says that the lighter the flywheel, the less torque the engine produces low down in the rev range and the more rev happy the engine becomes. This is excellent in race situations on the track where most time is spent at the top of the rev range anyway, but less suited to the road or rally racing where torque low down in the rev range is desired. However, my thinking was that the faster the engine could / would rev up to the 3500 rpm critical point, the less turbolag it would have. Hmmm whether this will prove to be the route to go will only become clear looooong after writing this. Probably during the summer of 2003!
Ahh, lovely new (read expensive) 1st over-size pistons with new top-end and bottom-end bearings.
The block after it has been bead-blasted and rebored but before it is re-sprayed in satin black.
This is what a balanced crankshaft with flywheel looks like. For those of you that aren't at home in the world automotive mechanics, this is found at the bottom of the block and is what the pistons are connected to via the conrods.
Notice the shinny bit on the bottom lobe (bottom right of the picture). This is just one of the places on the crankshaft where it has been grinded away in order to balance the whole part.
I have to note at this point, that the balancing / tuning of this crank is a lot less high-tech than I had originally envisaged. I don't know why, but I had expected it to be much more than it is. The result of this knowledge is a very sobering one, much like when you first discover that father Christmas really doesn't exist. Some of the mystique and 'saucery' out of motorsport tuning is gone, yet at the same time has been replaced with a new level of confidence, namely that I could do this if I really wanted to.
This picture (although out of focus) shows a close-up of the grinded crank in-order to balance it.
The above picture is of the flywheel, which is found on the gearbox side of the engine at the end of the crank. At the bottom you can see the clutch basket which contains the clutch plate. In the middle of the picture you can see how the flywheel is tapered down from the centre outwards. This is ordinarily also tapered, but not to this extent. In addition to having removed metal here, Mike removed a fair amount of metal from the flat surface you can see (touching the teeth running round the periphery of the fly wheel). All in all he removed something in the region of 2 - 3 kilo's of weight from the flywheel, which should significantly help in increasing the speed with which the engine is spun-up (revved).
Some people say that the sum of the total is a culmination of its parts. The picture below shows the bottom-end being finished of. Notice the oil syphon (looks like a mushroom - could it be magic?) for the oil pump in the middle, top of the picture.
The stupidly grinning wolly in the picture is me with my new engine. I think I was still smiling at this point as I hadn't paid yet!
Before you think it, no, we are not a couple of gays fighting over a condom! I was reluctantly parting with my money and Mike was trying to speed up the process by pulling it out of my hand!
And finally I even got to take it home! Notice the special trolley I made for the engine. It makes moving the engine around the garage a whole lot easier!
