Compression Ratio on built motors

A low cr like 12 or 13:1 will need somthing to make up for the loss like 100+psi of boost or lots of nitrous. The lower comp will help with pressures but will make the engine less effecient IMO without alot of boost to bring back the ratio on the top end. I have seen engines like this that never stop white smoking with about 12:1 cr and a single turbo. Even at WOT at the end of the pullin track its got a white/dark grey mix in the smoke, to me thats just not gonna make good power.

I would keep it up in the 16:1 range for a street driver, just IMO.
 
CC the top of a piston, gasket thickness and deck height and it will soon tell you what you will have for C/R


Scott
 
How low of compression ratio can you go on a diesel? I have a friend with a pulling truck that says the c.r. of his truck is under 9 to 1. it is a heavily built motor that requires starting fluid unless its 100 degrees out side.
 
There are many variables, I'm going the other way on a high Dollar 2.6 build up. Around 17.5 static, but there is a lot more to it, such as cam timing and intake runners. You also can run a dramatic amount more compression with a Common rail engine. The common rail has the ability to limit power as the engine goes through the destructive peak torque part of the power curve.
I am adding 20 degrees to the intake-closing event
The cam will have a 115 intake lobe center line, and a 125 lobe separation angle, along with a .450 lobe lift
 
i know more tractor pullers (at the 3.0 inch) are sticking with a closer to stock compression ratio
 
I dont know why some people would want the 12 13 or 14:1 for dd vehicles, i run 12:1 in my 3.0 truck, i struggle each and everytime to start that thing, plus a street ruck isnt going to need that much relief, cause you arent going to be making that much power. I would go no lower that 15:1 on the street, and at that i would think that cold weather starting would be hard sometimes, i think you are on the right track, being aroun 16 16.5:1.
 
around 14.5:1 on a 12v 3.0 puller
let it sit for a week, or if it gets below 60* overnight, it needs a little assistance to start.
 
15/1 on my 12v with 13mm and II race twins. its damn hard to start in cold weather no heater grid and no fuel warmer. It hazes no matter what.
 
compression ratio in hot motors really varies with boost. i am running 40 lbs on stock compression. i would start to lower after 55 to 60 lbs, but not a whole lot.
 
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