Put my motor on the virtual dyno, experienced rodders.

[enkeivette]

So Cambria put down 432 which is 521 flywheel calculating a 17% loss. But this was with a leaking HG & intake gasket which only allowed the blower to build 5lbs of boost. Also a 15:1 AFR. I've also port matched the intake and upped the lift since then. So what do you think she's putting down now at 13lbs of boost and a 12:1 AFR?

Just curious what you guys think. Yes, I know what a dyno is.

•383ci SBC
•9:1
•Forged Scat Crank
•Forged Scat 6" Rods
•Forged Aluminum SRP Pistons
•AFR 195cc Aluminum Angle Plug Heads w/8032 Upgrade
•Comp Hyd Roller Cam & Lifters .576 in .594 ex Lift 239in 245ex Duration @ .05
•Comp Chromeoly Pushrods
•Harland Sharp 1.65 Full Roller Rockers
•Edelbrock Victor Jr - Port matched.
•MSD Pro Billet HEI (Limited to 24 total because I run only 91 octane)
•Mighty Demon 750 Annular (11.8-12.5:1 AFR at WOT)
•Procharger D1SC 4" pulley (13lbs of boost), K&N filter

•Long Tube Equal Length Ceramic Headers 1 5/8ths
•Dual 3" Mandrel Bent Pipes
•Magnaflow high flow catalytic converters
•Dynomax bullet mufflers

 

[pcf_mark]

Fact: for every 14.7 lbs of boost an engine will double it's naturally aspirated output. A 300 HP engine natrually aspirated will make 600 HP with 14.7 lbs of boost. Of course there are increased pumping loses etc but you get the point.

In your example the engine made 432 Hp with 5 lbs of boost or 1.33 it's naturally aspirated value. This is 432/1.33 or 324 naturally aspirated.

With 13 lbs of boost you are 13/14.7 or 1.87 the naturally aspirated value. This puts you at 324*1.87 = 608 HP at rear wheels or 711 HP at the crank (using 17% loss)

Plus any gains you made from tuning or tweaking but boost makes up for many ills. AFR of 15:1 you are lucky your rings and pistons are still alive! Blowers like to run rich so it is posible you pciked up 30 - 50 HP going to 12:1 alone.

 

[enkeivette]

Thanks! :friends: Very interesting.

 

[69427]

Several things here don't make sense to me, but I'll limit it to the virtual horsepower numbers.
What is the efficiency of your supercharger (it is not 100%). Turbos are more efficient, and their numbers fall frequently in the 70-75 percent range. I also notice that there's no intercooler mentioned. A not-insignificant portion of the boost is just temperature induced pressure, not increased mass airflow pressure. Unless you know the mass flow or compressor efficiency numbers, the vitual horsepower thing is just a guess.