I know this subject has been beatin to death but i want to do everything right when i start to mod my car. I have an 08 civic si and my goal is 300whp but i also want it as a dd. so my question is when i turbo it which would be better high or low cr. correct me if i'm wrong but from what i understand from reading all around the forms is the low cr would be better because it would be more reliable where as high you have more a risk of blowing the motor. but won't you get more pwr with a high cr and still have the torque ( that i guess you would loose a bit when you lower the cr). i heard from a friend that if you got high cr then your turbo should spool quicker and that high cr is ok as long as you get a reliable and right size waste gate (i trust my friend on his car knowlege and mechanic abilitys but he doesn't persnoally own a turbo powered car so i would like to varifiy). i also hear that the k series engines could stand having the boost with there stock cr ratio. if i have to lower the cr or do what ever internals that are recommened i would prefer to only tear the engine down once.

i just ask all this cause i want to boost my car but want to have all the knowledge i can and all the ins and outs before i start even shopping for the project.


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i just asked a similar question, but you'er right about losing some torque but adding alot of reliability with the low comp pistons. High comp would make more power initially, but you're putting your engine at risk and it wont be as reliable (although a REALLY GOOD tune would help with the reliability issue). I'm not sure what engine you have but you can find low compression pistons around online, but if oyu have a D series, you can get Vitara pistons, and they fit perfectly into the cylinders, and they lower the compression to 8.5. They can be had for cheap too ($130 on ebay)

 

i got one of the new k series i believe its a k20z3 i forget. i would know the type if i saw it again got to get it when i get home today. but yea i fig if i'm having this as a dd i want it pretty reliable and i'm not gonna take my chances on my tune not being really good and blow my motor.