NightStalker

Im running 600cc injectors with stock fuel pump, etc... Im at 10 psi right now and just about to go to 14 psi, but the problem of not having enough fuel has arisen. Will there be a problem with 500 CRANK hp with my current fuel setup. I never thought of not having enough fuel so this is all kinda new to me

Scorpion

Here is the formula for calculating injector size in pounds per hour:

Injector lbs./hr. = horsepower x BFSC/number of cylinders

BFSC is short for Brake Specific Fuel Consumption, which is the amount of fuel required to produce one horsepower. According to Accel, a BFSC of .45 is a good general figure for normally aspirated engines, and .65 is good for supercharged engines.

So for a 500hp S2000...

X= 500 x .65 / 4
X= 81.25

Now to get that to cc/min rather than lbs/hr...

cc per minute = lbs per hour x 10.2
So..

81.25 X 10.2 = 828cc/min

Now that's just a gauge, there are variables. For instance, RC injectors rate there injectors at 43psi, increasing the fuel pressure rases the flow rate. RC Engineering has a great page with calculators and all the information one could want on fuel. Check it out here.

http://www.rceng.com/technical.htm

Hope this helps

NightStalker

Thanks for all the info, thats a great site. So i should be able to manipulate the fuel pressure to increase the flowrate and decrease the size of my injectors required. I think fuel pressure stock is 45 psi, could i make a large enough change with the fuel pressure to compensate for my smaller injectors? Can i do this by simply changeing out my fuel pump?

JDMKID35

get 1000cc injectors ... I know it sounds big but for what HP ppl are looking for you will not run out. I ran out of 1000cc but I shoot for bigger numbers that most ppl... but with 1000cc you will never have to worrie about running out

NightStalker

I was also concerned with the driveability of the car. I thought that the larger the injectors the more difficult to drive in stop/go traffic. Im still on emanage so that might be enhanceing that problem.

Scorpion

If tuned correctly, you should have no drivability issues with any size injectors. Also, yes you can manipulate the fuel pressure to effectively increase injector flow rate, however there is a point. Stock fuel pressure in the S is like 47psi +/- 3psi. You have to remember that when you add boost, you are going to be increasing the FP anyway, so at 10psi of boost, you are now sitting at 57psi of fuel without changing anything. So just think it through before you add 15psi of fuel to make up for too small of an injector. One last point to consider, the higher the fuel pressure, the more the spray pattern of the injector gets distorted. Basically think of it going from a mist to a stream, it's not going to mix as well with the air and will not ignite properly.

mpi tuner

Derek get bigger injectors. Dont even try to go to 14psi without them MAYBE Yyou could try like 12 or so and see ,But the last thing you want to do is blow her . After thinking about it ,You probaly should go with the aem if people say it is a good sytem to run and is ok for daily driving. I still think my setup on my car is good Drives stock out of boost then bam Got fuel . I get great gas mileage too. Just think the stockl ecu you cant beat can do way more than any stnadalone for a daily driver .