Help with Injector Sizing - Program I made

[AirStrike]

I got board today so I whipped up a quick app for you all to work out what size injectors you need, or how much HP a certain injector can handle. Ill add more and maybe make it a bit prettier soon.

[nathans1987]

thats a nice little program, how did you make that?

[AirStrike]

thats a nice little program, how did you make that?

Good old Visual Basic. Was an ace back in the day but its been a while.

[m62vpute]

That is a nice little neat program you got there(Y)

lets hope you get a bit bored again

[AirStrike]

That is a nice little neat program you got there(Y)

lets hope you get a bit bored again

LOL!! Tell me what you want and ill whip something up.

[m62vpute]

Where do I start

Maybe something 6ft tall and blonde that could be pretty nice, actually the more I think about it the more that I could ask for but I am not greedy

just kidding


Just little programs like that are so handy to have and it is really cool to see people just making them and letting others use them

I am just starting to play around with the whole memcal tunning process and just little tools like this are great

[1991_Vn2nV]

Dont spose you could make a program to input cam specs and it tell you the overlap, and how much boost you would be losing if its forced induction

Because that could come in handy

[AirStrike]

Dont spose you could make a program to input cam specs and it tell you the overlap, and how much boost you would be losing if its forced induction

Because that could come in handy

As long as I can find a formula for it I can.

[immortality]

nice work there airstrike, did u take into account that you really don't wanna run injectors much over 90% duty cycle

[PaRaDoX]

heh, not bad but you should put in another table for the first calculation for cyclinders to calculate total HP for all the injectors

also thought about a kinjflow calculator?(kinjflow is the injector flow rate, when you fit bigger injectors you need to reduce this factor so you dont flood the engine) kalmaker have a table for the formula i think or you could go off the stock injector rates and use that as a basis something like my formula, ie
assuming stock injectors are 176cc on a V6 (v8 is probbly diffrent)
please check them i know there somewhere round that

now stock kinjflow for the stock injectors is 0.13 grams

soo the effective formula would be

X= Injector Size in CC
Y= Multplication factor

X/176 = Y, 0.13 / Y = Kinjflow

now lets put that to use (my injector flow rate)

570cc/176cc = 3.2386, 0.13 / 3.2386 = 0.0401 Kinjflow
im not too sure about working it out for 2 bar, they're might be some aditional formuala's required

you could also use the LB/H rating on the injectors such as
55lb/17lb = 3.2386, 0.13 / 3.2386 = 0.0401 Kinjflow

i could be completely wrong but it should be close if im wrong someone please correct me

[AirStrike]

nice work there airstrike, did u take into account that you really don't wanna run injectors much over 90% duty cycle

All calculations are based on a 80% duty cycle.

[AirStrike]

heh, not bad but you should put in another table for the first calculation for cyclinders to calculate total HP for all the injectors

also thought about a kinjflow calculator?(kinjflow is the injector flow rate, when you fit bigger injectors you need to reduce this factor so you dont flood the engine) kalmaker have a table for the formula i think or you could go off the stock injector rates and use that as a basis something like my formula, ie
assuming stock injectors are 176cc on a V6 (v8 is probbly diffrent)
please check them i know there somewhere round that

now stock kinjflow for the stock injectors is 0.13 grams

soo the effective formula would be

X= Injector Size in CC
Y= Multplication factor

X/176 = Y, 0.13 / Y = Kinjflow

now lets put that to use (my injector flow rate)

570cc/176cc = 3.2386, 0.13 / 3.2386 = 0.0401 Kinjflow
im not too sure about working it out for 2 bar, they're might be some aditional formuala's required

you could also use the LB/H rating on the injectors such as
55lb/17lb = 3.2386, 0.13 / 3.2386 = 0.0401 Kinjflow

i could be completely wrong but it should be close if im wrong someone please correct me

If its correct then ill add it mate. Is the Kinjflow a constant on all cars or as I would assume different. The code is the easy/quick part, the making it pretty takes time

[vt1538]

I have an excel spreadsheet that calculates injector size from RPM, VE, Boost
pressure, engine size etc if you want to take a look at it Airstrike. You may be able to add bits to yours to make it a bit more multipurpose. If you want it PM me your email addy.

[AirStrike]

PaRaDoX616 - Is that formula correct?

[m62vpute]

Ok from memory this is how i worked out my flow rate

I used the stock value of the vn which is 0.14 and they are 19/lb injectors

So how i worked it out was

The difference your 55lb injectors are to the 19 lb injectors is 2.894 times

Then use the old kinjflow value of 0.14 and divide it by 2.894 giving you a total of 0.048375


Then multiply that by 1000 to get your new kinjflow value in mGrams/Sec

48.36 mGrams/Sec

This is the formula i gave to PaRaDoX616 and is the formula that i use and works fine so if we are saying the same thing then it does work

[PaRaDoX]

heh airstrike its partially correct ill update it abit as ive been corrected on some of the values

KINJFLOW is a constant i believe

remember most KINJFLOW values are read in grams, not mGrams/sec only redefined definitions are read in mGrams you can change the decimal places in tuner pro


X= Injector Size in LB
Y= Multplication factor

X / 19 = Y, 0.14 / Y = Kinjflow in Grams/second

that is the correct formula for 1 bar tuning so go on and add it

[AirStrike]

heh airstrike its partially correct ill update it abit as ive been corrected on some of the values

KINJFLOW is a constant i believe

remember most KINJFLOW values are read in grams, not mGrams/sec only redefined definitions are read in mGrams for greater accuracy when retuning


X= Injector Size in LB
Y= Multplication factor

X / 19 = Y, 0.14 / Y = Kinjflow in Grams/second

that is the correct formula for 1 bar tuning so go on and add it

Cheers mate, ill add it tomorrow.

[PaRaDoX]

Just tested on stockys car,

worked out the kinjflow

(this is for ANYONE with cream top injectors btw, they flow at 21lb/h)
21 / 19 = 1.1052
0.14 / 1.1052 = 0.1266

his kinjflow should have been 0.1266

changed it to that (effective) and it runs better with no stallage anymore :P
my formula is very close, i think the only thing that isnt spot on is the stock injector flow rate...

does anyone know the EXACT flowrate of stock injectors, somehow i dont think 19lb/h is right i think its closer to 17/18...

anyway tested and it works... its very close..airstike hurry up and add it to the program!

[m62vpute]

0 280 150 901 's flow 18.55 lbs/hr from a spreadsheet i have laying around here

think most people just round it up to 19 pound

[PaRaDoX]

aight that sounds good about spot on, i tuned stockys for 19lb/h and he said it was alot better yet still not perfect!


updated formula

X= Injector Size in LB
Y= Multplication factor

X / 18.55 = Y, 0.14 / Y = Kinjflow in Grams/second

ok so for creamtops


21 / 18.55 = 1.1351, 0.14 / 0.1233

so for creamtops the correct kinjflow is 0.1233

[m62vpute]

sorry i disagree PaRaDoX

I think the value you should have neded up getting was 0.11

Only because i am 99% sure the creamtops run at 24 pound and not 21 pound like you have posted



Vn Groupa the kinjflow setting is 0.11 they work out to be 24 pound

As listed below

Difference the 24lb injectors have over the stock 18.55lb/hour is 1.2938 times more flow.

So 0.14 / 1.2938 = 0.1082 Grams/Sec

Becaue the file only reads 2 digits after the decimal place i would assume that they rounded the figure to get 0.11

[m62vpute]

Just tested on stockys car,

worked out the kinjflow

(this is for ANYONE with cream top injectors btw, they flow at 21lb/h)
21 / 19 = 1.1052
0.14 / 1.1052 = 0.1266

his kinjflow should have been 0.1266

changed it to that (effective) and it runs better with no stallage anymore :P
my formula is very close, i think the only thing that isnt spot on is the stock injector flow rate...

does anyone know the EXACT flowrate of stock injectors, somehow i dont think 19lb/h is right i think its closer to 17/18...

anyway tested and it works... its very close..airstike hurry up and add it to the program!

I think stockys car would be running a bit rich using 0.1266 try and do another 1 if you get a chance at 0.11 and i think you will notice a big difference in power

[PaRaDoX]

we have tried it at 0.11501 and it runs LEAN, getting him to try 0.1233

but according to him 0.1266 ran ok so it must be close

remember hes probbly down a few psi on fuel pressure :P

[tysons_2001]

His injectors must be clogged or he's not running enough pressure, heres my calculated injector flows:
_______________inj rate____lb______kinjflow
red_____________0.153_____30_____0.096849
cream___________0.175_____25.5___0.110775
blue____________0.186_____23.4____0.117738
std black________0.206_____19.5____0.130398

NOTE: these injector flows suit the v6 only!
I calculated these figures from the kalmaker website:
http://www.kalmaker.com.au/page57.html