I've asked Craig is we can get this incorporated into the GN/TType site for all of us to use. It's pretty cool!
Anyway, Playing with Craig's handy dandy tool... http://home.att.net/~cbwatson/airflow.html
I'm getting some neat info out of it! It's really interesting to see what effects raising and lowering fuel pressure, injector size, efficiencies, etc. have on the whole equation...
Just a brain dump of what I was playing with ... pretty neat stuff!
Default values for efficiency, turbo, gear ratios, etc....
2 psi drop for stretch intercooler
11.5 A/F ratio
45 psi fuel pressure (static)
42.5 009 injectors
22 psi
5200 RPM shift point
28 inch tall tires
0.47 BSFC
Calculations show that we are at about 82% duty cycle. 378 g/s of air flow and about 507 HP. NOTICE THE 5200 RPM SHIFT POINT. Makes a big difference (no surprise). Also, notice the 11.5 A/F ratio ... on the "safe" side.
Some tweaks ...
5% more efficient intercooler, requires ~2% increase in duty cycle (to
84%)
5% more efficient turbo, requires another ~2% increase in duty cycle (to
86%)
90% VE (assuming ported heads, probably optimistic?) results in 100% duty cycle (static) 24 psi of boost results in 108% DC
E.T. Ends up in the 11.24 @ 121+ (pretty much my level) ... keeping E.T. the same, let's see what fuel pressure does?
Add fuel pressure (and put boost back at 22 psi) ...
47 psi = 98% DC
50 psi = 95% DC
52 psi = 93% DC
Up the injector size to 50s...
43 psi = 88% DC
45 psi = 85% DC
47 psi = 83% DC
Now 55s ...
45 psi = 77% DC
43 psi = 80% DC
No surprise to Bruce, I'm sure (or me for that matter)... definitely shows that bigger injectors are controllable at the high HP level. The interesting thing is that the 009s hold up pretty good and the fuel pressure "crutch" works to a point.
A couple of other interesting things (at least to me)...
Put the RPM at idle (650 RPM) and 15"Hg and 14.7 A/F ratio ... 55s @ 43 psi are at 5% DC (about 9 ms)
50s @ 43 psi are at 5% DC
42.5s @ 43 psi are at 6% DC
36s @ 43 psi are at 8% DC
29s @ 43 psi are at 9% DC (about 17 ms)
Makes pretty good sense, the 55s are almost 2x the size of the stock 29s, so it takes half as much pulse width to deliver the same amount of fuel. How fast does an injector react? 2 ms? 4 ms? Reason I ask, I'm wondering at what point it's almost too small to control?
Very cool tool !
Anyway, Playing with Craig's handy dandy tool... http://home.att.net/~cbwatson/airflow.html
I'm getting some neat info out of it! It's really interesting to see what effects raising and lowering fuel pressure, injector size, efficiencies, etc. have on the whole equation...
Just a brain dump of what I was playing with ... pretty neat stuff!
Default values for efficiency, turbo, gear ratios, etc....
2 psi drop for stretch intercooler
11.5 A/F ratio
45 psi fuel pressure (static)
42.5 009 injectors
22 psi
5200 RPM shift point
28 inch tall tires
0.47 BSFC
Calculations show that we are at about 82% duty cycle. 378 g/s of air flow and about 507 HP. NOTICE THE 5200 RPM SHIFT POINT. Makes a big difference (no surprise). Also, notice the 11.5 A/F ratio ... on the "safe" side.
Some tweaks ...
5% more efficient intercooler, requires ~2% increase in duty cycle (to
84%)
5% more efficient turbo, requires another ~2% increase in duty cycle (to
86%)
90% VE (assuming ported heads, probably optimistic?) results in 100% duty cycle (static) 24 psi of boost results in 108% DC
E.T. Ends up in the 11.24 @ 121+ (pretty much my level) ... keeping E.T. the same, let's see what fuel pressure does?
Add fuel pressure (and put boost back at 22 psi) ...
47 psi = 98% DC
50 psi = 95% DC
52 psi = 93% DC
Up the injector size to 50s...
43 psi = 88% DC
45 psi = 85% DC
47 psi = 83% DC
Now 55s ...
45 psi = 77% DC
43 psi = 80% DC
No surprise to Bruce, I'm sure (or me for that matter)... definitely shows that bigger injectors are controllable at the high HP level. The interesting thing is that the 009s hold up pretty good and the fuel pressure "crutch" works to a point.
A couple of other interesting things (at least to me)...
Put the RPM at idle (650 RPM) and 15"Hg and 14.7 A/F ratio ... 55s @ 43 psi are at 5% DC (about 9 ms)
50s @ 43 psi are at 5% DC
42.5s @ 43 psi are at 6% DC
36s @ 43 psi are at 8% DC
29s @ 43 psi are at 9% DC (about 17 ms)
Makes pretty good sense, the 55s are almost 2x the size of the stock 29s, so it takes half as much pulse width to deliver the same amount of fuel. How fast does an injector react? 2 ms? 4 ms? Reason I ask, I'm wondering at what point it's almost too small to control?
Very cool tool !