Raising CR on 250I6

I was doing some research and seen where the cr on a 1977 250I6 is about 9.2. What I can't seem to find is what percentage of increase you get when going to 10:1. Just running some numbers for my upcoming upgrades to include a cam, headers and 2v conversion. Was thinking about having the head surface milled since it will be off the car anyway

 

'77 250 C.R. is 8.0 to 1
If you're serious about making any power with a six...get The Ford Falcon Six Cylinder Performance Handbook

 

And I don't know this to be fact, just what I've been told by some people I would believe in, in a small block 1 point of compression ratio is equal to 100 hp. Not gospel, just roughly, never asked about a 6 cyl. though.

 

...get the hand book.

 

The max gain is not as much as most think it is. However.. it's the AVERAGE gains that are most advantageous to perceived power increase. Figure on about 5-7 horsepower peak gains.

Here's an interesting article that paints the clearer picture as to what's required to take the most advantage of CR increases.

http://www.popularhotrodding.com/tech/0311_phr_compression_ratio_tech/

BTW.. you'll need to go with 0 quench and heavily milled heads to gain even a full point on that motor. +2 point gain will take domed pistons and/or aftermarket head.

 

You need to talk to someone that has a clue...

 

Thanks for all the information! I have had experience with small blocks but I am learning a bunch about these 6 cyl. engines!!!