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Discussion Starter · #1 ·
:huh: im trying to find out what is the stock size injector in my 97 ram.i've heard from 1 source its 19lbs and another its 24lbs.im thinking of putting 30lbs in my truck after i get the pcm flashed from b&g chrysler.i would appreciate any and all info. :crazy:
 

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02 R/T & 05 Ram
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19 lbs, and don't waste your time/money on the 30s. There's no way you have enough mods to use those, and the truck will run pig rich. The 19s can support up to a decently fast 408 without issue. Rare is the 5.9 that has the heads & cam combo to even justify 24s.
 

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Dakota for life!
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^^^ What he said x2 ^^^
 

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Ram Racer
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Hmmm only got 1/2 my post here, deleted and finished below
 

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Ram Racer
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Injector size, fuel pump, fuel maps and ignition timing all have to work together especially on a boosted motor.

Driving style and use directly affect fuel needed. If you never go WOT and always keep the rpms well below redline fuel wont be an issue and you can get away with small injectors. First hot day, towing a heavy load up a grade going WOT and you could damage the motor.

Injector size bounced around year to year from what I understand till they stopped making the 5.9s. If its got 19s in it chances are the fuel pressure will be in the 46-47psi range(if rest of fuel system stock). With 24s it will be a bit lower at 43psi give or take.

The B&G needs to be flashed for the injectors used. If you try going from 19s or 24s up to a 30lb you will be running pig rich at idle unless the pcm is flashed for the 30lb injectors. If you run the motor with 19/24s on a 30lb flash you will be dangerously lean.

BSFC is Brake Specific Fuel Consumption. That is the ratio of air to fuel needed per hp.

Naturally aspirated the accepted range is .45-.50
Blown/turbo the accepted range is .55-.60
Its always best to err on the side of caution and have too much fuel so I would go with the higher #S (NA-.5/SC-.6)

To figure out what injectors you need based on the BSFC the formula is as follows
HP(crank) divided by # of cyl div by .80 (max duty cycle 80%) x BSFC
In your case on motor only that would be
310hp div 8cyl = 38.75 div .8(DC) = 48.4 x .50 (BSFC-na/motor only) = 24.2lb injectors. (guessing your make 310 on motor)

Now becuse your motor is blown best you use the BSFC of .60 so the end of the formula above would be 48.4x.6=29lb injectors.

NOTE, this does not include the increased hp from blower. If your KB utilizes a boost refrence to increase fuel pressure with an inline pump the 30s are perfect. If you do not increase fuel pressure and tune with say a FAST stand alone or piggy back tuner and have no inline pump much bigger injectors are needed. You would need 44-48lb depending on hp made plus a bigger fuel pump.

Air to Fuel Ratio's
14.7:1 a/f is stoichemetric ratio for gasoline (gas only ) The stoichemetriic ratio is the name for when a fuel is at its ideal chemical ratio for the most complete burn.
To get best mileage under a light engine load cruisng city streets or highway that is the ratio you need to see. When NA I was tuning my SMT6 to give 14.7-15.0 a/f.

To make the most power requires more fuel than the stoichemetric ratio.
12.5-13.0:1 a/f ratio is needed to make the most power NA
11.5-12.0:1 a/f ratio is needed to make the most power with a blown/turbo motor.

When NA on a mild 360(no heads) I went to the dyno and saw 270rwhp (2yrs ago) I didnt get a wideband reading at the time and was worried about my A/F ratio after so I returned to find out. The dyno operator shut down the first pull @ 4500rpms because the a/f ratio was at 14.8 and climbing fast(19lb inj). WOT that was WAY TOO LEAN. For the next year I installed wide band o2 to monitor a/f, 24lb injectors and SMT6 to tune fuel and ignition.

Sorry for writing the book but only way to give you the info you need to know.
 

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Discussion Starter · #6 ·
thanks i read in larry shepards book "how to modify your mopar magnum v8" .the book states that 92-94 5.2l uses 18.2lbs and 96-04 5.2 , 5.9 use 23.2lbs injectors thats why i am or was confused what size they are in my 97 5.9
 

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Discussion Starter · #7 ·
i also got the #s off the injectors on the engine they are , Siemens deka 53030778 and on the back it has 2150 and the color is grey
 
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