D sleeves are good for a lot more than people give them credit for.

 

^ yes very true

 

With what reliability would one expect to run 12 psi on 11.5 cr? For how long, and would that be driving it hard or taking it easy?

 

depends on who you get to tune it as well as the quality of parts your using.

 

I, on the other hand, believe that lower compression is part of building a reliable F/I motor.

A lower compression engine will run cooler, will last longer (especially the rings), and be more reliable/easier on parts that a high compression motor with boost.

I'm not saying you CAN'T run high compression, but I don't think it's the proper way to do it.

 

Let's just use stock internals as the meter on this scenario. How long would the stock internals hold up under that pressure? We'll say going to the track twice a month, and using it as a daily driver. I subscribe to the lower compression school of thought.

 

wow i didn't realize that you guys made this a sticky... cool

 

Is 12,000 miles a fair estimate? Or am I underating stock internals on a K series motor?

 

A little long but I hope this helps you

There are a few manufacurers making what they call "light boost" motors.. They run normal compression ratios and small turbos with
light boost for a little more top end.

Kappa22 and Larsenracing as well as others gave you some good advice..
You had better have a well built motor and high end controllers to control things such as ignition timing retard etc. if you plan on doing this...

The more compression you have the more cylinder pressure you create. Aspirtating the engine creates huge cylinder pressure..

As we know. engines are air pumps. Simplfied, as there are hundreds of variables... Let's say one cylinder normally contains 25 cubic inches of air. With a good turbo or S/charger @ about 15 PSI that cylinder will now have about 50 cubic inches of air.. So your engine acts like it is twice it's size..
Now comes the downside.. The compression in that cylinder is now probably 15-1 or more.. So you need controllers to properly handle that much compression.
You need to greatly reduce the total ignition timing and add enough fuel to light this off..

With lower compression pistons, you can still pump in that same amount of air and gain that cubic inch increase without as much compression increase as you would with high compression pistons..
That is the reason most turbo motors run lower compression ratios.
I hope this helps you..

 

its been true for me to get more power out of 5psi with a good tune then 12 psi with a poor tune.just my .02