Injector size - what's the solution?

DestinWahoo · Mar 1, 2007

I contacted Aeromotive and Anderson Ford Motorsports for Injector size.
I got two very different answers. Aero says 50lb injectors, where as, AFM says 38lb injectors will work fine.
My calculations show the 38lb in range, but I want to get right the first time and not rebuy.
The engine arrives next week and I need to get my tail in gear.

Here is the specs on my engine for reference;

LONGBLOCK: 347 SB2002 PRO BULLET FT/TW:
347 cid short block Balanced to racing tolerances and blueprinted.

RODS: 4340 forged steel ultra-lite 5.400" I-beams w/ ARP bolts & full floating pins

CRANK: nodular iron 3.40" stroke,

PISTONS: forged Pro-X # 4320 (FT/TW -3cc),

RINGS: moly E-458K,

ROD BEARINGS: tri-metal CB-634P,

MAIN BEARINGS: tri-metal BC240J,

CAM BEARINGS: tri-metal CC440

MAIN SUPPORT SYSTEM: 6061-T6 X 3/4" ALUMINUM

CYLINDER HEADS: Trick Flow Twisted Wedge 185CNC ported heads, 2.02/1.60 valves, #51400004-C01

INTAKE: Trick Flow Track Heat (TFS-51511002)

ADAPTER: Trick Flow (TFS-5150SN95-11)

PHENOLIC SPACER: 1Ã¢â‚¬Â (TFS-51520008)

TIMING CHAIN: Pro Gear 3 Position

430HDSTK LIFTERS: Ford Racing

RETAINING HARDWARE: Hydraulic

PUSHRODS: 4130 .080" Wall Seamless

HEAD BOLTS: ARP 8740 Hex Head Bolts

HEAD GASKETS: Fel Pro Graphite 8548 PT2

ROCKER ARMS: DSS Aluminum Roller Rockers

T-WASHERS: 1/2" to 7/16" reducer bushings for cylinder heads

CAMSHAFT: Comp Cams XE274HR Roller (.555"/.565" 224Ã‚Â°/232Ã‚Â°@.050"
112Ã‚Â°LSA 2200-6200RPM) (35-518-8)

BALANCER: 28oz SFI Steel/Aluminum balancer 1 (208SA)

FLYWHEEL: Fidanza SBF 157T/late model SFI aluminum flywheel
(28oz balance,replaceable friction surface) (186501)

WINDAGE TRAY: 5.0 Stroker Pro Tray 1 (7005)

ARP flywheel bolts: 7/16" x 1.00" 6pcs (manual trans) (100-2801)

ARP balancer bolts: 289-460 except 351C (150-2501)

OIL PAN: OP7050 DSS low profile 7qt oil pan with pickup and
passenger side 3/8" NPT baffled oil return hole (for supercharger/turbo).

OIL PUMP: OP1000 DSS 302 std volume oil pump kit Includes pump
w/ adjustable pressure, heavy duty oil pump and pickup
fasteners, and an ARP heavy duty oil pump driveshaft.

DISTRIBUTOR: MSD #8455

THROTTLE BODY: PP 75mm (69212)

http://www.fishingdestinflorida.com/cobra/MyFavoriteToy/index.html

Adam · Mar 1, 2007

38lb injectors will support 675 crank hp. If this is an NA motor, (looks to be) 38's shold be plenty.

DestinWahoo · Mar 1, 2007

Yes it's NA. Thanks for the help! DSS thinks it will be around 450 FWHP.
I am using electric water pump and anything else I can think to squeeze out extra HP.

94twinscrew · Mar 1, 2007

50's?! that's way overkill for the new NA combo.lol 38's would leave you PLEANTY of room to grow in NA form. Hell,for that matter,it could be done with 36's.

IceMan · Mar 1, 2007

if you are staying N/A 36-38 lb should be fine... even 42's might be an overkill...

Adam · Mar 2, 2007

Good injector calculation is:

(number of injectors X size of injectors=total lbs of fuel per hour)
____________________________________________________
divided by BSFC(.45 on NA or .60 on Blower cars)

8 X 38lb= 304lbs of fuel per hour/ .45 =675hp at 100% duty cycle.
You can figure out any injector with this calculation

DestinWahoo · Mar 2, 2007

Thanks Adam, I was looking to run at an 80% duty cycle to prevent abusing my injectors.
But, I find everybody has a different opinion as to the right size.

DestinWahoo · Mar 8, 2007

Decided to go with the 38 pounders, but now It occured to me that I need to ignite the fuel.
Looking for suggestions on the best plugs for this build.
I will post pictures of the tear down and rebuild as soon as I can.

Adam · Mar 9, 2007

DestinWahoo said:
Decided to go with the 38 pounders, but now It occured to me that I need to ignite the fuel.
Looking for suggestions on the best plugs for this build.
I will post pictures of the tear down and rebuild as soon as I can.

Thats a good plan. Even at 80%, thats still 540hp, I think you will be fine.