89mm
If thats the biggest blooper we make in our lives, then we doin' jess fine. No appology necessary
Chris

Dodgeman---Sorry, the way these threads are set up looked like your arithmetic was on the ordinary side. Again apologies.

Looks like Mazda pistons are the go!

I'll post progress reports.

when I built my engine SSS in sydney supplied a set of mazda E5 pistons these are 80thou over and set up to go in, had the tops milled to stay just under 10:1 for pump fuel. the small end of the rods had to go to 20mm, turned out good , been for 3 yrs now

89mm
I was replying to the post immediately before the one you refer to. Demojob had refered to some 79mm pistons that he had used in his engine, hence the mathematics.

When i asked "did i get that right?', i meant, would "would 1608cc put you over the limit & disqualify you from the class you wish to race in?'
According to B310GX, it would not. Woohoo!
Chris

looking it up in the cams manual for improved production,it states that 'a vehicle will remain eligible for the nominated class provided the actual capacity does not exceed the class capacity limit by more than 2%'.this means 1600cc + (16 x 2) cc,or 1632 cc.so 1608 looks legal.better order those 79mm pistons to suit a a15 pin height now.

The short answer is "I dunno".

If I can make an engine under 1600cc fairly easily, thats the way I'd prefer to go.

It could make for fewer problems if ever the head is taken off for the purpose of measuring the bore and stroke.

isnt there a % leeway or something on that anyway that allows you to go slightly over the 1600cc legally?

Thanks to all who replied, I'll check all these out and advise the result later.

Stew. McK.

Chris
Your arithmetic is good, you didn't read the original post carefully enough.

78.5mm bore X 82mm stroke gives 1588 cc.--- just the deal for up to 1600cc!

StewMck

Sadly, a 79mm bore with a 82mm stroke would yield 1608cc & i suspect that this would put the car over the limit. Did i get that right 89mm?