Injector size and fuel delivery February 07, 2021 01:04PM
The service manual for a 4490 states 504bdt injectors are 5x.013 with .012-.014” valve lift and and 504bdti injectors are 4x.015 with .014-.016”. What would deliver more
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Re: Injector size and fuel delivery February 08, 2021 03:15AM
The 4x.015 have more total hole opening area than 5x.013.
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Re: Injector size and fuel delivery February 08, 2021 03:33AM
My math might be off but 5 by .013 has more total opening than 4 by .015
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Re: Injector size and fuel delivery February 08, 2021 04:35AM
I agree 5x.013 = .065 total 4x.015 = .060, even though the hole size smaller on the bdti injectors, will the extra so called valve lift make up for that? I always see people saying use the 4690 injectors (bdti) for pulling but I’m wondering why that is.
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Re: Injector size and fuel delivery February 08, 2021 05:07AM
You have to use 3.1416 times your hole size,that will show that the 4 hole injectors will put out more fuel stock than the 5 hole injectors
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Re: Injector size and fuel delivery February 08, 2021 06:35AM
4 x .015 x 3.1416 = .188496
5 x .013 x 3.1416 = .2044204

That is what I get in with my amish slide rule.
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Re: Injector size and fuel delivery February 08, 2021 07:18AM
Did not know that but regardless the 5 holes are still larger as stated below
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Re: Injector size and fuel delivery February 08, 2021 07:28AM
No. The 4 holes have 6.5% more area of openings and more lift. Based on that, they "should" flow more provided supply pressure, efficiencies, etc are identical across both bodies. Only real way to know is call a shop that's benched them both and ask.

CP
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Re: Injector size and fuel delivery February 08, 2021 08:04AM
The formula for area is

Diameter x Diameter x 3.1416 / 4

5 x 0.013 holes equals 0.00066 in2

4 x 0.015 holes equals 0.00071 in2

So the 4 hole have slightly more flow area
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Re: Injector size and fuel delivery February 08, 2021 09:52AM
I guess I am lacking in the math department LOL. Thank you for the replies, question has been answered.
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Re: Injector size and fuel delivery February 09, 2021 12:47AM
Quote
RCP
The formula for area is

Diameter x Diameter x 3.1416 / 4

5 x 0.013 holes equals 0.00066 in2

4 x 0.015 holes equals 0.00071 in2

So the 4 hole have slightly more flow area

I'm sure I'm just missing something here but the area of a circle is: 3.14 x (radius x radius). Can you help me understand where diameter comes in and why you divided by 4?

edit....I get it now. I think the order of it was confusing to me.



Edited 1 time(s). Last edit at 02/09/2021 02:01AM by TripleAlphaProcess.
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Re: Injector size and fuel delivery February 09, 2021 01:52AM
[www.calculatorsoup.com] Figure the area of a hole for each injector and multiply by the number of holes. I come up with RCP posted for numbers.
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Re: Injector size and fuel delivery February 09, 2021 12:51PM
Tripple is correct! Area of a circle is (3.14xRadius Squared). Then you multiply by the number of holes. Just putting in my 2 pennies in agreement with Tripple.
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Re: Injector size and fuel delivery February 10, 2021 02:35AM
r²×pi is the area of a circle
r = d/2
(d/2)²×pi = d²×pi/4 is also the area of a circle
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