Standard valvers will do 0-100 in 21-23 seconds. Standard Willys 2-3 seconds quicker and can sneak in just under 20 seconds. Remember these cars were built in the early 90s and at that time, those sort of performance figures were pretty hot. Nowadays they are put in the shade by things like the 172/182, CTR, Focus RS etc which are running closer to 200bhp and tend to do 16-19 seconds pretty easy. Anything below 15 seconds is damn fast for a road car. You might say those new hot hatches are heavier, so old valvers and Willys should be able to match them for power-to-weight, but the fact is that at 100 mph, weight isnt so much the issue, power/torque is the decider. Thats why Caterhams dont do 200mph.
Of course both valvers and Willys can be modded to go faster, lots of us have done it, but a filter and exhaust wont get an otherwise standard valver to 100 in under 20 seconds.
The best way to get 0-100 timing done properly is to go quarter miling and then try and work backwards from that. If you can quarter mile at over 100mph then you knock off a bit to get back to your 0-100 time. If you quarter mile at 90 odd mph then add a few seconds, depending on how far off you are. My rough rule of thumb would be for every 2mph under the 100, add *at least* another second, plus an extra second just for good measure. So say you quarter mile in 14.5 seconds at 92mph, add another 5 seconds to get your 0-100 of 19.5. Look at ANY set of road car performance figures and you will see that 60-100 takes almost double the time 0-60 does, a lot of cars take far far longer. This is another worthwhile thing to remember for any car, in any state of tune. E.g. 0-60 = 7 seconds. Multiply by 2.5 to get a rough 0-100...7x2.5=17.5 Which conveniently is near enough to real life figures. And it works the other way round too...if you think you are doing 0-60 in 7 seconds, first check that to see if you are anywhere near 17-18 seconds for the 100. If not, then keep dreaming LOL