440cc/3bar injectors potential

[Rocco]

hello guys, do you know (more or less) wich could be the maximun potential of the appel green injectors 440cc/3bar,using them with a 4.2FPR in our 5 cylinder engines using normal timing maps'?



90% duty cycle

[Rocco]

one tuner in Spain said me 450hp as maximun?

[Billman]

i dont think so, apparently the rs2 ones max out at 420ps. did he knows that it is a 5 cyl engine?

[prj]

There is no way you will make 420hp on RS2's when using pump gas.
Not even close.

I'd say 440's at 4 bar are good for around 420-430 hp on pump.
I will update this thread next friday, as I'll have a K26/K27 car with 440cc's (150 558) on the dyno then.
That car was 93-94% IDC when I mapped it on the street.

[Billman]

thats what they use in germany for the K26-27. MAybe my info is wrong. Dont forget he said not 3 bar but 4.2.

[prj]

I do not forget anything.
4 bar fuel pressure, 1.5 bar at redline K26/K27, 440cc @ 3 bar injectors, 90-95% IDC.

I have mapped a few cars with this setup, always consistently max out 440's.
Your info is wrong, or the ponies in said info are really small.

[Billman]

what are the rs2 ones good for?

[prj]

Haven't measured, but I have been able to max them using a K24-7200 on two cars.
I'd guess 360-380hp.

See attachment for RS2's on K24-7200 @ 4.2bar.

[Billman]

At 380hp the rs2 injectors are not at 95% DC. When i was on RS2 setup at 1.1 bar redline the injectors where at approx 82& DC with lambda od 0.82

[prj]

My graph shows 1.2 bar redline and 93% IDC at 12 AFR.
I guess your ponies are smaller than mine, because the information is perfectly consistent.

Of course if you drop compression ratio you can run more timing. If you use water injection or methanol, you can run more timing, and methanol will add more fuel.
I am talking straight pump.

[Billman]

hahaha......nice....whatever man.....

have fun....enjoy.....

[S2central.net]

I can work out what "440" injectors should be able to provide in theory. It will be interested to see how that bears out in real world with a dyno and datalogger.

- 440cc at 3bar scales up to a higher ccpm with 4.2bar... There is a known calc for that

- knowing the max flow at 4.2bar we can scale that by factor of 90% to reflect max duty cycle

- that gives us a volume of fuel which we can convert to fuel mass by knowing the density of petrol

- from mass of fuel it is possible to use other common calculations to estimate the power that results from consuming that mass of fuel on a 5 pot engine at whatever rpm

- you can also use target afr to estimate how much air the engine needs to consume to deliver that power... And with an assumption of VE and ambient condition we can estimate the level of boost required to make that power for say 11.5 afr

- knowing max fuel volume delivery per injector per minute also lets us estimate how much fuel the pump needs to sustain at pressure of fpr_nominal + boost

[S2central.net]

so the 440cc @ 3bar translates to 520cc @4.2bar

using 90% IDC and a BSFC of 0.5 on 5-cyls we get close to 450bhp in theory.
We have to convert 520ccpm into lbs/hr by dividing by 10.5

Est-Power = (520/10.5 x 90% x 5)/0.5 = 446bhp

lots of the generic tuning books suggest using higher BSFC values for turbocharged engines - unfairly in my view as it implies they use more fuel to generate the same power perhaps as a result of very low compression ratio for example.

If you like these things - there are lots of good resources via google searches... I like this one with calcs you can play with too

http://www.stealth316.com/2-air-fuel-flow.htm

I really must blow some dust off my 'turbology' handbook and capture this fuel sizing stuff into things.

Other checkpoints for the use of BSFC = 0.5 are as follows...

stock S2 injectors (320cc @ 3bar) would provide less than 320bhp at 90% IDC when running 4bar ABY/AAN fuel pressure

stock RS2 injectors (360cc @ 3bar) would yield less than 350bhp at 90% IDC on stock 3.8bar FPR... 360bhp on 4bar and 370bhp on 4.2FPR

All of those figures seem to be in the right ball park based on real world experience... It is possible that BSFC nearer to 0.45 is more appropriate for higher tuned cars that are getting colder air into the system and ignition settings that yield more power vs conservative factory tuning... That would allow an RS2 injector to stretch into 390bhp capability when maxxed out for short periods of time but that really is pushing luck.

So suggesting an optimistic BSFC value of 0.45 with the 440cc injectors on a 4.2bar FPR we get up towards 500bhp so I think that is *very* optimistic.

For purpose of system sizing I would go with some margin and aim for IDC no more than 80-85% and BSFC of 0.5... That yields approx 420bhp here.

[prj]

Calculations sound right on the money and are in line with my real world experience.

[S2central.net]

the same old good rule of thumb for 5cyl operation here is that the injector rating of ccpm at 3bar is *broadly* a good guide for the max power when running at 4bar - as long as you remember that yields a slightly optimistic result.

320cc ==> 320bhp
360cc ==> 360bhp
440cc ==> 440bhp

Thats just an accident of how the numbers work on the 5cyl