I've done a ton of research and am building a propane specific motor (400)- wondering where some of your info is coming from.

First you NEED to be concerned about DCR regardless of SCR. SCR, being a simple calculation has little to do with how your motor will operate. You can easily go to a massive SCR of 13:1 plus but you still need to keep DCR down at , around or below 9:1 or you will have a short life motor and heat beyond managing. Nascar motors can be 16:1 or better but have cams that run DCR down to 9:1 or so and they are massive cams- build a lot of power and drain off a lot of compression and I bet you don't want that kind of motor, drivability issues, durability etc.

Many have converted stock motors and have done ok. I could not find a publishable propane build for a 400 or any ford v-8 that really delved into what you need but have been able to apply a bit of trig and work some things out. So, while some of the info above seems a bit off...I would sure like to know where the info is at!!!!

i've looked into some acknowledged regional experts and have learned a bunch and think i have a good, long term, build sheet that would not come close to 13:1 SCR but did the desktop dyno at about 360+hp and 440+ftlbs from a rv, mileage build. Achieving over 400hp and 450 tq would be fairly easy but beyond what i want as i expect good to great mileage as well.

I'm happy with that but would sure like to get as much new info as possible!! I know how i would go about building a race motor using propane as well and i would have SCR over 13:1 and a big cam. A strip motor would have even more of both and some air too.

Propane is comparable to any other fuel but, again is not if you want to get into a great build. Anyway..there is much more to deal with than compression and detonation or everyone would be using it. HEAT!!!!