Payne’s are old school , understate and overdeliver, they have decades of machine work behind them ,I doubt they would have any issue with a reline ,having done 1000,s .
when increasing power ,it’s always the extra
Heat that is produced that is the issue , the smaller the engine , the less mass there is to dissipate the heat , oil films , clearances , hot spots , cracking and so on now become the problems
The quality and design of the original parts has a huge impact here , some engines by design can cope with large power increases and size matters .
A 4 cylinder, 2 litre making 400 hp has 100hp of heat per cylinder , A six cylinder 3 litre making 400 hp has 66 hp per cylinder .
The heat path is the same , via spark plug threads or valve seats ,valves ,guides to head and on to the coolant /oil
Or via piston , to rings to block and water/oil , aluminium does not like cyclic heating and cooling ,it cracks and ages .the larger the part the more heat tolerant or better it dissipates .
Of course all the tuning companies will promise to “love you long time “ but defying physics,expect a
Quickie....lol
The quickie can still be great fun ...
