Fiat Uno engine capacity, bore/stroke and weight

[Gasket]

I'm building a Fiat Uno for endurance racing. Races last usually for about 6 hours and you are only allowed to refuel 20 litres at a time and it has a minimum time of 3 minutes. This means that fuel consumption is a major factor. Minimum weights are 760 kg for under 1350 cc, 810 kg for under 1450 and 860 kg for under 1650. Therefore I've come to a conclusion that a good idea might be to use a 1500 crank in a 1372 block, this combination gives a total engine capacity of 1301 (bore/stroke same as mk1 tie Uno) with a reasonably long stroke. I'm aiming for about a 100 hp with a reasonably low rpm (~6500), power should be enough and reasonable rpms mean low friction losses and therefore good fuel economy. Reliability is also important and I think that under 80hp/l should be ok.

Another alternative would be the 1372 engine, but that goes only a little over the cc limit, almost no power gain and would have to be 50 kg heavier. Third option would be to use the 1372 crank in a 1500 block, resulting in a 1581 (or more with overbore) and a weight gain of 100 kilos over the 1301. Although this would result in a significant power gain (maybe around 120-130). With the bigger engine I could get a better power to weight ratio, but it would also mean higher fuel consumption and increased weight will slow down cornering, wear tires and brakes. These engine choises are based on the parts I already have. Or should I go for a short stroke 1,3? I'll propably use a 304 advertised degree reground cam with a little over 10 mm of lift, since I already have one. The head will come from a 1372 engine with standard 37,5/33 valves. With a little work it should flow plenty for the kind of power I'm looking for. I'm thinking of using a compression of about 10,5 and it should be achievable by shaving the block down to a tight squish. I also can machine the pistons and the head if necessary to achieve the wanted CR.

I'll upgrade the brakes too, but they'll have to fit with 13" wheels (about 240 mm vented) since I think that bigger tires will slow the car down too much on the straightways and gearing will also be better with smaller tires.

Do you think that I'm on the right track? It's an interesting class since the fastest or most powerfull cars don't win. I doubt that the Uno won't be winning material, but it should be pretty close if I'll get the suspension to work.

[kritip]

Continental do a 195/40/14 Sportcontact tyre that retains a low profile on a 14" wheel if you want to upgrade the discs to 257mm vented, whilst keeping ratios roughly equal to 13". This tyre retains the same RR as a 165/55/13 tyre and wheel combo. It is also a very good tyre, thougha bit rare and about £70 per corner.

Can't really help you with regards to the rest though.