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JavaScript Injector Sizing Tool and flow converter

437 Views 14 Replies 6 Participants Last post by  blue
3 new online tools:

- Enter HP and it tells you injector size required

- Enter New fuel pressure and it calculates new flow

- Convert from cc to lbs/hr or lbs/hr to cc


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you should have it automatically tell you lbs/hr and cc when calculating injector size based on hp
still stuck at home blue?
stuck at home Achooo :)

Went to doctor yesterday. They gave me a flu shot too. I never had one before and never thought I needed one

Blood tests tomorrow for other problems. I guess I need "servicing" LOL

EagerCrow, I'll add the lbs/hr figure! Thanks for the feed back.
i've had and not had flu shots, hopefully it makes you feel better. I'd go nuts if i was stuck at home.

just have 'em drain and service ya, and you'll be fine. :)
I agree with Bush that flu shots are for the weak and old thus I don't need one but the doc bent my arm and said that since my daughter has asthma, I should reduce the chance of bringing the flu home.

If you wanna get a stubborn person like me to change, you have to use my daughter as leverage LOL

Dad forever!
Thanks for the update Blue, it looks good!

I understand about the father thing I'm not going to get the flu shot either, but if the doc used my kid as leverage I'd be sticking myself with the needle
Actually you need to be able to put in the fuel pressure, especially with a turbo or at least know what the chart assumes the pressure to be. It looks like you assume ~44PSI (?) while a turbo will add the boost pressure to the standard 44PSI of fuel pressure. So while it looks like by your chart you need 426cc/min injectors to make 300HP on a turbo car, you really only need 370's if you're running 15PSI of boost. One could use the lower "conversion" chart but you probably should explain what "static" fuel pressure the upper chart is using? By using RC racing's chart, I figured the 44PSI spec.


I would also leave off the >80% duty cycle as that's the high limit almost every place I've seen sugests running. Otherwise, it's a nice page..
Hi Steve,

The program seems to work?

I plugged in 300 for engine HP

Chose turbo application
Chose 6 cylinder engine
Chose .85 as max duty cyle

and got 370.6 cc

this is close to your "370's" you mention above

I'll take a look at the worksheet and follow up.

Thanks for the feedback!
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For pressure effects, you have to look at the injector mfgr's flow ratings then adjust accordingly. The mfgr specs flow at a pressure.

The tool I made tells you the flow you need in cc/min and lbs/hr. It does not address pressure differences between manufactures as it is not needed.

For example, say you punch numbers into the tool and it determines you need 370cc/min of flow.. and you can get a great deal on 350cc/min injectors that are rated at this flow at 44psi by the mfgr. You then go to the bottom of the page and figure out the psi you need to run the 350 injectors at 370.

In this example it is 49.1723psi
I just did 300HP, turbo, 6 cyl and 85% and it said 401 cc/min. If I click the "low compression" and 85% it comes up 370. Try it again making sure you have 80%, 6 cyl and BFSC of .65 selected, that combo should say 370cc/min for a turbo engine at 15PSI of boost. Like I said the amount of boost changes the fuel pressure so without that "option", you are just guessing at the injector size needed.

And like I said most people say to -never- go over 80% duty cycle in calculating injector size so 85% shouldn't even be an option..

I'm not using MS vitual machine or IE so maybe it only works on a windows machine? It's a neat idea but without knowing the fuel pressure used to calculate this (or taking into account the turbo's effect on fuel pressure) it could easly mislead someone when choosing their injectors.
Nope you are 100% right!

Thanks for pointing it out!

I'll have to go through it again and correct. sorry
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