Hi,
I have an 88 GTA with a 305 engine. Where I live lowest octane is 95 and recently 98 octane become available here (which are sold for same money)
I want to build my engine to use 98 octane efficiently. My goal is to make around NA 300rwhp.
Can you recommend me parts for high octane engine rebuilding?

Also my car is currently at 65000 miles however my car had more than 1 previous owners and I'm not sure that's the original mileage (Engine is currently in a bad condition, oil reserve draines in 400 miles ) Is there any way to find the original mileage of the vehicle?

Thanks

 

The buildup itself is the same. There are no such things as "high octane cams" The only things i can see changing are the overall compression ratio (you can run higher compression with the higher octane). and maybe the timing. I have never run a higher octane engine, so im not the most familiar.

 

I'd verify that the gasoine is in fact "98 octane fuel"

Pump gas octane rating is an average of Research octane and Motor octane divided by 2.
R+M /2

Some fuels are only rated by their "research octane" number.

The "motor octane" rating is always lower.

If the fuel is in fact 98 R+M /2 octane rated then you can build the motor with higher compression.
About 11.70:1 measured compression ratio is good.

Ignition timing requirements will be the same.

Keep in mind if you travel out of your local area you may not be able to get this fuel.
Substituting a lower octane fuel risks engine damage.

 

I'd keep the compression ratio no higher than 10.5:1 or so...that way you have the option to substitute a lower grade gas if necessary.... And 10.5 is still pretty high. To take advantage of the higher octane then, just get a custom chip burned with more aggressive timing curves, and bump the base timing up.