Alternator and Weights

Managed to pick up an 106 8 valve model type alternator during the week. These run on a v-belt rather than a multi-ribbed belt like the GTI engine. The difference between them is weight, the actual v-belt type alternators are lighter, but the real weight saving comes in terms of the rotating mass – the crank pulley wheel is almost 1kg lighter. Unfortunately I couldn’t get the mounting brackets from that breaker, so I had to try a different one for those and picked these up at lunch time. I suspect that having seen the amount of cast iron used in the mountings from the multi-rib belt fitting (which also uses a tensioner pulley wheel setup), this will be significantly heavier that the more simplistic tensioning system and cast alloy mountings on the v-belt type.

Engine builder Sandy Brown has pointed out that the downside to the V-Belt is that it is prone to inverting at high RPM, so the multi-ribbed belt is preferable. As a result I have been in contact with Cornish machining expert Colin Satchell, who is sending me some of his alloy multi-ribbed belt pulleys. So when these turn up I’ll get them fitted. Swapping alternators has been far from simple, but the weight advantages in total should make this conversion worthwhile.

V-Belt Type

5.34kg Alternator, belt and pulley wheel
0.48kg Crank pulley
4.82kg Alternator
0.92kg Standard Bottom Mounting Plate and Tensioner
0.16kg Modified Tensioner
0.15kg Alloy Top Mounting Bracket
0.11kg Steel Top Mounting Bracket

Total: 5.76kg

Multi-Ribbed Belt Type

7.84kg Alternator, belt and bulley wheel
1.32kg Crank Pulley
5.44kg Alternator
1.06kg Tensioner wheel assembly
1.12kg Mounting brackets

Total: 10.02kg

A worthwhile and relatively cheap saving. Should get a further slight saving by moving to the alloy pulley wheels when they arrive. Started polishing the cast residue off the upper alloy mounting. I’ll get this a bit better finished and then it will be either painted or anodised.

Cut the tensioner out of the plate. The plate mounting doesn’t fit on the 16v block so is useless anyway.

A few other jobs are now on the agenda:

• Remove the exhaust manifold, heat wrap it and fit proper brass nuts. This should help prevent some radiant heat damage and also improve engine performance slightly.
• Fabricate a robust alloy heat shield for the oil level and pressure sensors. In addition to the above.
• Remove the wishbones and treat with POR. These were the new one fitted last year and are already corroding.
• Remove the air/oil cooler and fit a coolant/oil cooler. This is what the car had as standard and it is not getting the oil up to temperature due to over cooling.