Donald125

ye.. 225 HPpump also....
but is 310 cc injector enough or should i get the 440?...
if bottom end allowed...250+whp would be my goal

45psi

just keep reading dude.

Chacko

well general rule is 18 hp per lb of boost.

Keep in mind you can do some other upgrades like a better intake manifold (D16Y port it out, bigger charge pipes, bigger throttle body, ported exhaust manifold.

10 psi should be good for 180 horsepower if the car is properly tuned. In reality you'll probably notice 140 horsepower unless you get a good engine management system.

Kevin325isBMW

Another rule-of-thumb estimate of engine power is turbo pressure-ratio being run time N/A engine power. For example. 10-psi boost (PR = (10+14.7)/14.7 = 1.6 time stock whp would be a rough estimate of the boosted engines power. This formula works reasonably because engine power (to first approximation) is related to air mass flow through the engine and turbo-compressor pressure-ratio closely scales the N/A mass flow to equivalent boosted mass flow.

Several effects alter the accuracy of this estimate.
1) whether or not an intercooler is being used and if so how effective is it.
2) turbocharger efficiency at pressure-ratio being used.
3) fuel octane rating and allowable ignition advance.
4) etc...

still as a first cut it is not a bad estimating formula to use.

Kevin

Chacko

hey kevin do you happen to have the equation laying around for how to calculate maximum horsepower based on a fuel injector size (and # of cylinders?)
I remember reading about this in an SCC magazine from like 2 years ago.
Its a rather lengthy equation but I'd like to save it It was also very good to tell you about how big of an injector you needed for X amount of CFM

WhiteTeg24

If your looking for a good rod then use the Integra LS rods, shave .040 off the big end, and a have a machine shop press in some copper bushings so the piston pin will fit snug. We did this on our race car and worked great. Best part is stock LS rods are cheap and good up to around 500HP.

Kevin325isBMW

Estimating engine horsepower potential using fuel injector sizing is demonstrated in the following example:

Engine injector size: 240 cc/min
convert this to (lb-fuel / hr) by dividing by 10.36 = 23.17 lbf/hr
multiply by number of engine cylinders (assume 4-cylinder engine)
23.17 x 4 = 92.68 lbf/hr
adjust for a maximum injector duty-cycle of 80%
92.68 x 0.80 = 74.14 lbf/hr

and lastly divide by appropriate BSFC (Basic Specific Fuel Consuption)
BSFC = 0.45 lbf/hr-hp (typical value for N/A engines -- can be as low as 0.35 for well designed race engines)
BSFC = 0.55 lbf/hr-hp (typical value for turbocharged engine -- this high BSFC value reflect using a fuel-rich mixture to suppress detonation A/F ratio below 12:1)

Hence continuing the example 74.14 / 0.55 = 135 hp. Turbocharged or,
74.14 / 0.45 = 165 hp N/A (Normally Aspirated)

Note if a rising-rate fuel-pressure-regulator is being used, the injector flow rates will be altered. Lets assume ramp rate of 6-lbf / lb-boost and 7 lbs boost ( 6 x 7 = 42 increase in fuel pressure) However, the injector is discharging into the boosted pressure in the intake manifold. So the true increase in injector pressure (above manifold pressure is 42-7 = 35-psi). Now if no-boost fuel pressure is 43.5-psi (3-bar), effective boost fuel pressure will be 43.5 + 35 = 78.5-psi. Injector will flow additional fuel equal to the square-root of the ratio of the boosted / no-boost fuel pressures (across injectors) ie. sqrt(78.5/43.5)= 1.343.

Therefore continuing with the example:

74.14 x 1.343 = 99.57 lbf/hr
99.57 / .55 = 181 hp potential turbocharged using 6:1 rising rate reg.
Note on small bore engine such as Honda's (75-81mm bores) BSFC lower than 0.55 for turbo'd engines can often be safely used. If BSFC of 0.50 is planned, 99.57 / .50 = 199 hp can be supported.

Kevin