i have a set of aluminum heads made by trick flow. i am looking for a good streetable engine . what is a good compression and how do i come about getting that. the other componets are tpis mini ram, eagle h beam rods 6.0, scat 9000, all in the 383

 

Compression ratio is a neat thing. Some believe the bigger the better up to a certain point. When trying to determine what your ideal CR should be, the entire engine as a system needs to be taken into account.

Now you mentioned alum heads, 6" rods, 383, and street bound. What about your camshaft? I will assume it will be mild given the above criteria of streetable. Lets say duration limited to 224*. For me, I would stay around 9.5-10:1. You didn't say anything about forced induction, so I will assume you plan on staying NA, natural aspiration. Some would say to go higher, 10.5+. I wouldn't.

Now to get to where you want to be can be tricky. You need to know the volume on the combustion chamber and then you can guesstimate it based on what piston manufacturers state in catalogs. To get the CR dead on, you need to measure the volume of the combustion chamber, the cylinder volume, and then calculate it. There are CR calculators on the internet that work pretty well also, but they need some accurate info to work correctly. Basically, CR will be mostly dependent upon your piston choice and combustion chamber volume.

Hope this helpful...

 

Alright now "383 is for me", you neglected to mention the real reason for this engine upgrade: your buddys dad has a sweet 85 IROC thats stock, and all you ever seem to see of it is the spoiler!I'd probably go through the engine you have now, sell all usable parts to your buddy & his dad (tires!), part out "Shamu", and cut your losses!