750cc injectors, suitable for how much?

[techghost]

I currently have 750cc RC and outflowing them at 19psi, sounds rite?

I was expecting them to cater 23/25psi but my dsmlink log shows they are over 90% at 19psi

Sounds ok to you? what injectors shall i go for if i'm aming to hit 30psi and 28psi daily?

 

[RoryBarron]

We have no idea what turbo you are running, you need to update your profile to match your current mods.

 

[techghost]

hx35 with 12cm2 housing, crower 272/272 cams bc srpings and ti retainers, act 2900 clutch set dsmlink2.5 fmic etc

 

[RoryBarron]

that is saying you are flowing in the range of 43-53lbs a min, which doesn't sound right on 19lbs of boost. Do you have a rewired fuel pump and such? here is a repost from another thread.

Originally Posted by spyderturbo007 View Post
Alright, I've decided to spend some time at work and crunch some numbers on the most commonly used injector and fuel pump sizes. The list below will provide you with the maximum amount of air that a give fuel system component can handle. There are some assumptions that I had to make for the calculation to function. Such as:

1) Everyone is running 93 octane fuel @ a base pressure of 43psi.
2) The Denso stock replacement fuel pump supplys the same flow, at a give pressure, as the stock Mitsubishi pump.
3) Everyone's fuel pump and injectors are working at peak performance.
4) Target AFR is 11:1
5) I can't have everyone's injectors flow tested, so we have to assume that if you bought 550cc injectors, that they flow 550cc/min.

On to the numbers

Injectors

390cc @ 100% IDC will support 27.99lbs/min
390cc @ 80% IDC will support 22.39lbs/min

450cc @ 100% IDC will support 32.30lbs/min
450cc @ 80% IDC will support 25.84lbs/min

550cc @ 100% IDC will support 39.48lbs/min
550cc @ 80% IDC will support 31.58lbs/min

580cc @ 100% IDC will support 41.63lbs/min
580cc @ 80% IDC will support 33.31lbs/min

650cc @ 100% IDC will support 46.66lbs/min
650cc @ 80% IDC will support 37.32lbs/min

660cc @ 100% IDC will support 47.37lbs/min
660cc @ 80% IDC will support 37.90lbs/min

720cc @ 100% IDC will support 51.68lbs/min
720cc @ 80% IDC will support 41.34lbs/min

750cc @ 100% IDC will support 53.83lbs/min
750cc @ 80% IDC will support 43.07lbs/min

780cc @ 100% IDC will support 55.99lbs/min
780cc @ 80% IDC will support 44.79lbs/min

850cc @ 100% IDC will support 61.01lbs/min
850cc @ 80% IDC will support 48.80lbs/min

880cc @ 100% IDC will support 63.17lbs/min
880cc @ 80% IDC will support 50.53lbs/min

950cc @ 100% IDC will support 68.19lbs/min
950cc @ 80% IDC will support 54.55lbs/min

1000cc @ 100% IDC will support 71.78lbs/min
1000cc @ 80% IDC will support 57.42lbs/min

1150cc @ 100% IDC will support 82.54lbs/min
1150cc @ 80% IDC will support 66.04lbs/min

1600cc @ 100% IDC will support 114.85lbs/min
1600cc @ 80% IDC will support 91.88lbs/min

Fuel pumps

Numbers will be arranged in the following format:

"X psi = Y lbs/min"

where X = Boost and Y = Max airflow supported by pump

Stock 2g pump

10psi = 33.29lbs/min
11psi = 32.61lbs/min
12psi = 31.90lbs/min
13psi = 31.17lbs/min
14psi = 30.41lbs/min
15psi = 29.63lbs/min
16psi = 28.84lbs/min
17psi = 28.01lbs/min
18psi = 27.16lbs/min
19psi = 26.28lbs/min
20psi = 25.38lbs/min
21psi = 24.46lbs/min
22psi = 23.51lbs/min
23psi = 22.54lbs/min
24psi = 21.54lbs/min
25psi = 20.52lbs/min

Stock 2g pump (Rewired)

10psi = 42.08lbs/min
11psi = 41.51lbs/min
12psi = 40.92lbs/min
13psi = 40.30lbs/min
14psi = 39.67lbs/min
15psi = 39.00lbs/min
16psi = 38.32lbs/min
17psi = 37.61lbs/min
18psi = 36.88lbs/min
19psi = 36.13lbs/min
20psi = 35.35lbs/min
21psi = 34.55lbs/min
22psi = 33.72lbs/min
23psi = 32.88lbs/min
24psi = 32.01lbs/min
25psi = 31.11lbs/min

Walboro 190lph

10psi = 46.48lbs/min
11psi = 45.89lbs/min
12psi = 45.26lbs/min
13psi = 44.58lbs/min
14psi = 43.86lbs/min
15psi = 43.09lbs/min
16psi = 42.28lbs/min
17psi = 41.43lbs/min
18psi = 40.54lbs/min
19psi = 39.60lbs/min
20psi = 38.62lbs/min
21psi = 37.60lbs/min
22psi = 36.53lbs/min
23psi = 35.42lbs/min
24psi = 34.26lbs/min
25psi = 33.06lbs/min

Walboro 190lph (Rewired)

10psi = 60.68lbs/min
11psi = 59.85lbs/min
12psi = 59.01lbs/min
13psi = 58.16lbs/min
14psi = 57.29lbs/min
15psi = 56.40lbs/min
16psi = 55.49lbs/min
17psi = 54.57lbs/min
18psi = 53.63lbs/min
19psi = 52.67lbs/min
20psi = 51.70lbs/min
21psi = 50.71lbs/min
22psi = 49.71lbs/min
23psi = 48.68lbs/min
24psi = 47.64lbs/min
25psi = 46.58lbs/min

Walboro 255lph

10psi = 63.53lbs/min
11psi = 62.88lbs/min
12psi = 62.20lbs/min
13psi = 61.48lbs/min
14psi = 60.72lbs/min
15psi = 59.93lbs/min
16psi = 59.10lbs/min
17psi = 58.23lbs/min
18psi = 57.33lbs/min
19psi = 56.39lbs/min
20psi = 55.41lbs/min
21psi = 54.39lbs/min
22psi = 53.34lbs/min
23psi = 52.26lbs/min
24psi = 51.13lbs/min
25psi = 49.97lbs/min

Walboro 255lph (Rewired)

10psi = 72.15lbs/min
11psi = 71.47lbs/min
12psi = 70.77lbs/min
13psi = 70.04lbs/min
14psi = 69.29lbs/min
15psi = 68.52lbs/min
16psi = 67.73lbs/min
17psi = 66.92lbs/min
18psi = 66.08lbs/min
19psi = 65.22lbs/min
20psi = 64.34lbs/min
21psi = 63.43lbs/min
22psi = 62.50lbs/min
23psi = 61.55lbs/min
24psi = 60.58lbs/min
25psi = 59.58lbs/min

Walboro 255lph HP

10psi = 64.64lbs/min
11psi = 64.19lbs/min
12psi = 63.74lbs/min
13psi = 63.30lbs/min
14psi = 62.86lbs/min
15psi = 62.42lbs/min
16psi = 61.99lbs/min
17psi = 61.56lbs/min
18psi = 61.13lbs/min
19psi = 60.71lbs/min
20psi = 60.29lbs/min
21psi = 59.87lbs/min
22psi = 59.46lbs/min
23psi = 59.05lbs/min
24psi = 58.64lbs/min
25psi = 58.24lbs/min

Walboro 255lph HP (Rewired)

10psi = 74.29lbs/min
11psi = 73.86lbs/min
12psi = 73.43lbs/min
13psi = 73.01lbs/min
14psi = 72.58lbs/min
15psi = 72.15lbs/min
16psi = 71.72lbs/min
17psi = 71.28lbs/min
18psi = 70.85lbs/min
19psi = 70.42lbs/min
20psi = 69.99lbs/min
21psi = 69.55lbs/min
22psi = 69.12lbs/min
23psi = 68.68lbs/min
24psi = 68.24lbs/min
25psi = 67.80lbs/min

Denso US EVO 8 Stock Pump

10psi = 39.96lbs/min
11psi = 39.10lbs/min
12psi = 38.12lbs/min
13psi = 37.31lbs/min
14psi = 36.39lbs/min
15psi = 35.45lbs/min
16psi = 34.48lbs/min
17psi = 33.49lbs/min
18psi = 32.49lbs/min
19psi = 31.47lbs/min
20psi = 31.47lbs/min
21psi = 29.35lbs/min
22psi = 28.26lbs/min
23psi = 27.15lbs/min
24psi = 26.02lbs/min
25psi = 24.87lbs/min

Denso EVO 8 Stock Pump (Rewired)

10psi = 51.23lbs/min
11psi = 50.36lbs/min
12psi = 49.48lbs/min
13psi = 48.60lbs/min
14psi = 47.72lbs/min
15psi = 46.85lbs/min
16psi = 45.97lbs/min
17psi = 45.09lbs/min
18psi = 44.20lbs/min
19psi = 43.32lbs/min
20psi = 43.32lbs/min
21psi = 41.55lbs/min
22psi = 40.67lbs/min
23psi = 39.78lbs/min
24psi = 38.90lbs/min
25psi = 38.01lbs/min

Denso Supra 260

10psi = 70.70lbs/min
11psi = 70.06lbs/min
12psi = 69.42lbs/min
13psi = 68.77lbs/min
14psi = 68.12lbs/min
15psi = 67.45lbs/min
16psi = 66.78lbs/min
17psi = 66.10lbs/min
18psi = 65.42lbs/min
19psi = 64.73lbs/min
20psi = 64.03lbs/min
21psi = 63.32lbs/min
22psi = 62.60lbs/min
23psi = 61.88lbs/min
24psi = 61.15lbs/min
25psi = 60.41lbs/min

Denso Supra 260 (Rewired)

10psi = 82.91lbs/min
11psi = 82.38lbs/min
12psi = 81.83lbs/min
13psi = 81.28lbs/min
14psi = 80.73lbs/min
15psi = 80.17lbs/min
16psi = 79.60lbs/min
17psi = 79.03lbs/min
18psi = 78.46lbs/min
19psi = 77.88lbs/min
20psi = 77.08lbs/min
21psi = 76.71lbs/min
22psi = 76.11lbs/min
23psi = 75.51lbs/min
24psi = 74.91lbs/min
25psi = 74.30lbs/min

Although these are the maximum values that the fuel system components can support, I do not advocate running the fuel pumps at their maximum flow. I also don't recommend running your injectors above 80% IDC. Why, you might ask.....

Lets say you are running on the 190lph Walboro @ 20psi and are flowing about 37lbs/min of air. At that point you are within the tolerance of a perfectly functioning pump. For some reason your voltage drops because of a bad alternator, or the boost starts to creep for some reason. Now you are pushing more air than the pump can support and the car starts running lean. At that point there is a chance of melting something, which we would all like to avoid.

Anyway, I just thought I would crunch some numbers so that everyone has a reference.

Also, if anyone sees any errors, let me know and I will make the appropriate corrections. There was a lot of numbers to crunch and transpose, so it is possible that I made a mistake.

EDIT -> Added additional data for injectors (750cc, 850cc, 950cc and 1000cc). Also, please note that these flow rates are calculated at the fuel pump outlet and not after traveling through the system. Just another reason not to try and approach the maximum limits listed above.

I just added the US EVO 8 stock pump and the Denso Supra 260 as requested.

I also adjusted the injector calculation because I screwed up the mass of 1 gallon of water in my calculation, which led to the incorrect mass of 1 gallon of fuel being used.

 

[techghost]

i have a rewired aeromotive 340lph

 

[crazyquik22023]

First off, very good info RoryBarron. Very useful information. Anyway with the hx35 on 30 or so psi I would recommend PTE 1000cc injectors. I use them on my car and they only see about 80% duty cycle at 30 psi with a 6262.