Ok its like this and not going into all the math when you can plug and chug through the numbers yourself.....see link below. Easier to just punch in numbers and play than quote formulas. Plus you may actually learn
The old guys on here remember when Tom went over 500Hp on a 16G....what..... how .... Fuel and Compression
You have to have the fuel to make power British thermal units and all but a 16G cant boost and flow up top like a 37R, s366 hx40 etc. etc. Tom had his compression cranked up and then boosted it As I remember this setup on 20 something psi equaled the numbers of what a 7.8:1 was on 42 psi
Turbo doesn't know if its feeding a 7.8:1 or a 15:1 engine. All comes down to total compression but you have to remember total compression is the secret. To much total compression ratio and to much boost makes things go boom. Just like lean is fast right till a piston melts.
Use the formula calculator posted at the bottom and make a list for your altitude
7.8:1 8.5:1 9:1 9.5:1 10:1 10.5:1 and 11:1 playing with different boost levels and altitude. After you play long enough making a chart / spread sheet etc you see the relationship forming. Then you can play with the altitude and understand why Bandimere at altitude is slower than Pomona
Ever notice peoples video's where they're running around 50psi but never say what the total CR is. I did a Compression test on a friends turbo car a few years back and all four holes were right at 190 and he said the car had 8 or 8.5:1 pistons......... /ubbthreads/images/graemlins/rofl.gif Guess he forgot the part about the block being milled and the head being milled numerous times. Even though I did polish up the chambers its still up there. After you start plugin numbers you realize why some 18psi cars run so damn good and blow past cars on 30+. I personally like the feeling of higher compression turbo motors, Spin up faster especially with larger throttle bodies, great for driving around in traffic and as long as you do the homework set timing correcting and also have the tables set up right and run good gas no detonation best of all worlds and also works good to BS other racers. Give them a ride on 12psi and they're amazed because your 12 might feel like their 21. Plus the greatest benefit lower boost pressures exiting the turbo equals a cooler denser charge. I see mine with 9.5 or 10:1 plugs when I put it together.
Now think on this
Old top fuel cars use to run like 2:1 compression but ran like 100+ psi from the giant blowers. Those cars spin like 7500rpm and run 3 and 4 second passes..Now for math that will screw with you
a 7500 rpm monster engine in those cars only makes 250 full revolutions through all events on a pass
7500 divided by 60 seconds then multiple by 4 seconds then divide by 2 since its a 4 stroke.
Those engines suffer 10 times more starting and doing a burnout, idling back in reverse that ever making a pull.
Go play with numbers now. I had this all in Tom_N's old thread from back in the day but is gone now. If some one wants to do up a chart have at it. Now before someone asks when is to much to much do 7.8:1 at 11psi /ubbthreads/images/graemlins/rofl.gif
It all comes down to what you have for fuel and all the support components. a 16G powered engine with 10:1's and cranked to kill want live with 450's and 1680's may be to much....all depends.
I'm hungry and need food.
click me /ubbthreads/images/graemlins/rofl.gif
