Compression ratio 5.7l

[Scott Danforth]

stock GM Vortec heads (both the 062 and 906) are listed as 64, measure about 65. not sure what the Summit head is.

 

[Scott06]

stock GM Vortec heads (both the 062 and 906) are listed as 64, measure about 65. not sure what the Summit head is.

Probably this head https://www.summitracing.com/parts/sum-151124

not sure if the runners are modified or stock shape and volume. Reading the text would be concerned if they are made for marine rpm or typical hot rod rpm with gearing …

 

[carlos515]

Ahh ok , I did not realize there was a difference in heads between the marine and hot rod . I think i will just go with the 906 / 602 castings from rock auto then. The 151124 head from Summit is what I was considering. Rock Auto has the Engine Quest heads re bagged as Engine Tech.

 

[Scott06]

Ahh ok , I did not realize there was a difference in heads between the marine and hot rod . I think i will just go with the 906 / 602 castings from rock auto then. The 151124 head from Summit is what I was considering. Rock Auto has the Engine Quest heads re bagged as Engine Tech.

Im just saying you want basically a stock replacement head vs soemthing with port design made for automotive performance applications which tend to focus on higher rpm than a marine low rpm torque application. i would talk with what ever vendor you chose first about the application .

 

[carlos515]

I gathered that. I just did not think about the rpm and torque curves. But I will stick with stock replacements.
Thanks,
Carlos

 

[Scott06]

I gathered that. I just did not think about the rpm and torque curves. But I will stick with stock replacements.
Thanks,
Carlos

its all the combination if parts cam, heads, intake, carb working together and correct for the application. Typical marine application is more akin to a truck, rv, trailer pulling application where torque is king. A boat is under constant load like these applications.
typical street performance application will enhance power and airflow at higher rpm, and may sacrifice low rpm torque, using steeper rear end gearing to get out of the hole. These types of parts that make power up 6500 rpm are typically bad choices for a marine build. Good luck with your build. Others who have weighed in here have good experience on what parts work well for marine builds.