What is the "optimal" Intake Valve to Exhaust valve ratio for a strong engine? I've read 70-80% is about the right ratio to maintain low end torque and driveability for a street motor. What have you guys experienced? I'd like to run a 2.02 intake and a 1.64 exhaust valve. That would put my ratio about 80% (the upper threshold from what I've gathered....)
What engine ? What build ? Heads..cam etc. Sounds maybe like a SBC..but without more details it's difficult to know what to say. A stock low CR head with mild cam really not going to do much more..maybe less with 2.02s..
1.94 intake valves and 1.50 exhaust valves should do the trick on the street. Just don't bolt on anything bigger than 1.500" primary tube headers... If you have the 1.600 exhaust valves, you could go with 1.625" primary tube headers...
The ratio is not determined by a simple linear comparison of the diameters of each valve. You need to compare areas. In this case the area of a 2.02 valve is 3.2 squ. in. and the 1.64 valve is 2.112 squ. in. The ratio of exhaust to inlet then become 0.66:1 or 66%.