so on the new 5.0s the estimated compression ratio is 11.0:1 and i think its 13.5ish:1(or 14.5?) thats really the highest you want to go for a street DD but with some kick in it. i'm wondering how CR is maintained at a level that'll allow for that sweet kick while not going overboard and causing det. when you throw in boost, say 6psi? i'm sure it has something to do with the air/fuel mixture because ppl are obviously driving boosted new 5.0s, i just cant seem to get it. thanks yall!

 

11:1 is pretty much the limit on pump gas. 13.5:1 is absolutely race fuel territory.
when you add boost to that, you need very specific measures in controlling ignition timing and intake air temp.

Go with a proven arrangement and get pointers from the developer or you will have to learn the hard way.

 

The plan is forged bottom end, 11:1 compression, 15 psi, and e85. Should be fun. Also realize that there is a difference between dynamic and static compression and the TIVCT helps with managing the compression.

 

I didn't think there was such thing as a dynamic cr...can't change deck height on the fly and piston height/dimensions I guess could be but it wouldnt be plausible.

 

dynamic compression ratio is refering to the effective change in cylider pressures that can be had through high velocity intakes, valve overlap, ram air, etc.

Static compression ratio is a mathmatical equation of volume that rarely exists in the real world. Say the intake is too restrictive, you might have a vacuum in the cylinder when the intake valve closes, thus you will have less than the full volume to compress. A more common way of manipulating dynamic compression ratio is to use valve overlap, lobe separation and cam timing to adjust where in the compression stroke the cylinder is actually closed. It's combined with precise fuel control and ignition control to allow engines to run higher cylinder pressures (compression ratio, boost, etc.) than would have been possible just a decade ago.

 

Ok. So that's how these new 5.0s are getting around boosted without damaging internals. Thank you.