10 replies to this topic

[DUF2]

I was marshaling on the Northumberland Mini Rally at the weekend. There were various larger capacity engines which started me thinking how theses were achieved.

i believe a standard 1275 if over bored 20 thou becomes 1293, but what about other capacities?

[stuart bowes]

I found this with google, I'm not in any position to confirm it is 100% accurate but if it is it could prove useful to anyone interested

 

https://www.classicm...ical/enginesize

[cal844]

1460 with a different crank and some other wizardry is possible

[mini13]

off the top of my head the most common combinations are  ( and some of these are not that common...)

+20  1293
+40  1310
+60  1330
73mm  1360
73.5mm   1380

74mm      1400

73.5 & 84mm stroke  1430

73.5 & 86mm stroke  1460

and then i actually opened stuarts link..... LOL

Edited by mini13, 20 March 2024 - 09:14 AM.

[DeadSquare]

I wonder how long a stroke could be used before things started hitting the gearbox, if the cam lobes were ground off ?

[bpirie1000]

At a 1479cc the cylinder walls will be very very thin and the stroke would be amazing.

All a balance of reliability, practicality and fun....

Use there will be plenty other things to look at like running different octane fuels.

Heat displacement would also be a very critical factor. Cooling it down and getting the gasses out of the engine ASAP.

Still amazes me that these little engine still continue to give engineering developments 50 years later...

[Steve220]

You can also get custom piston sizes to make the size you want. For example i'm on +44 which makes the engine 1314cc.

[mini13]

91mm has been done, and i think one slightly longer, i remember Oselli did a combination making 1610cc, I think with 73.5mm pistons so that would be just under 92mm...

 

 

I wonder how long a stroke could be used before things started hitting the gearbox, if the cam lobes were ground off ?

 

[PoolGuy]

This is quite useful, can't remember where I got it from, so if it's yours, let me know and I'll be happy to credit you.

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[Spider]

 

91mm has been done, and i think one slightly longer, i remember Oselli did a combination making 1610cc, I think with 73.5mm pistons so that would be just under 92mm...

 

 

I wonder how long a stroke could be used before things started hitting the gearbox, if the cam lobes were ground off ?

 

 

I've been following this thread and wondering if that one would get a mention. The 1596 was a 91 x 74.7 mm is the biggest I'm aware of, but it was found it had next to no 'advantage' over those around 1500, the limiting item it seemed was the cylinder head and getting enough flow through it.

 

While different block varieties, it's somewhat amazing that the A Series has covered capacities, in a very large number of individual sizes from 803 cc to 1596 cc.

[DeadSquare]

 

 

91mm has been done, and i think one slightly longer, i remember Oselli did a combination making 1610cc, I think with 73.5mm pistons so that would be just under 92mm...

 

 

I wonder how long a stroke could be used before things started hitting the gearbox, if the cam lobes were ground off ?

 

 

I've been following this thread and wondering if that one would get a mention. The 1596 was a 91 x 74.7 mm is the biggest I'm aware of, but it was found it had next to no 'advantage' over those around 1500, the limiting item it seemed was the cylinder head and getting enough flow through it.

 

While different block varieties, it's somewhat amazing that the A Series has covered capacities, in a very large number of individual sizes from 803 cc to 1596 cc.

 

I have often pondered, just for the hell of it, trying to make a 1606, doubling the original 803, with a lobeless camshaft and a BMW 16 valve twin-cam head...........................but I don't think I'll ever get around to it.