Originally Posted by
elkapitan
Can I use a 30% on a .12 and . 21 nitro onroad engine? Some said that 20% is the highest nitro percentage for an onroad engine. Don't have any idea sorry. Just planning on getting into onroad
for the factory recommended, .12 using 16%,.21 using 25%. If you want to use 30% in your .12 engine,you need to add 0.3mm head shim.(0.1mm shim for 5% nitro increase)