Im planning to install AFR 190 cc aluminum heads. Will 10.5 : 1 be too much for a 150 shot of NOS?

 

How much compression you can run wether with NOS
or not depends on the octane of the gas you use.
If you can only get 92 octane gas I'd go for 9.5:1 cr with iron heads and 10.0:1 with alumium. If you can get 94 octane gas you
should be ok but no more. Make sure you don't over advance the timing, and run a plug a little cooler than stock. Should be 32 to 36 deg total. When first testing the Nos, retard the timing about 4-5 deg and check the plugs for detonation. Be sure that you are suppyling enough fuel at the designed pressure for the NOS.
I would strongly suggest mixing some 110-114 octane
race gas in the tank 30-50% for your first tests. The cost and bother is minor compared to rebuilding the motor 'cause you broke a ring land (detonation). Forget octane booster....

 

BTW how would you go about reading plugs for detonation?? What would they look like if they are or not?

 

Search my posts I,ve done an extensive speul on the subject.