Hey I am building a 383 right now with lt1 conversion intake and freer flowing heads with a bigger cam. My qusetion is, will I need bigger injectors. I had brand new stock size ford injectors put rigt before I decided to start the build. Will those work. thanks.

 

Depending on HOW bigger is tha cam ...
my old 383 with SR and 219 cam had FMS 24 lb injectors and I was at the limit of the 80% duty cycles of the injectors at WOT at high rpm with stock fuel pressure.
Before trying to increase the fuel pressure I broke a piston, so I can't say how effective the increase of the FP would-have-been . I think that there is plenty or room to use 24 lb inj on a 383 even with the correct injector constant in the chip if an AFPR is used.
-Beppe-

 

I think the biggest mistake when people make a choice in injector is failing to understand that high RPM duty taxes injectors.

For instance. Its pretty easy to make really good low end pwoer and torque on a small injector. Build a setup like one I just finished on the dyno 2 hours ago that spins 7200RPM and you will have to run a bigger injector.

 

Its really going to depend on hp output. What cam are you running? What hp are you expecting?
Just for reference, I have exceeded the limits of my stock injectors with what is in my signature. They are maxed out and I am going past 13.2 AFR. My only choice would be to raise fuel pressure or replace injectors. Injectors do not run much more then the adjustable fuel pressure regulator and it will leave me room for further power increases.

 

Not to hijack the thread but I have a question for 93 ragtop. How are the 409's on the highway and what rpm are you ending the 1/4 mile in.
I am going with a 44 and am deciding on gear ratio's.

Thanks

Fred

 

Did you look at a gear calculator freddy? 2250 rpm's if my math is correct, and that's at 61 mph(98 km/h). At 80 mph(128 km/h) your talking 3000 rpm's. And at 88 mph(140 km/h) she would be reving quite high at 3300 rpm's. If you had the ZF6, I would say give er'. But man thats alot of gear for a auto.


RPM 1 2 3 4 Gear
500 3 6 9 13
600 4 7 11 16
700 4 8 13 19
800 5 9 15 21
900 5 10 17 24
1000 6 12 19 27
1100 7 13 21 29
1200 7 14 22 32
1300 8 15 24 35
1400 9 16 26 37
1500 9 17 28 40
1600 10 18 30 43
1700 10 20 32 45
1800 11 21 34 48
1900 12 22 35 51
2000 12 23 37 53
2100 13 24 39 56
2200 13 25 41 59
2300 14 27 43 61
2400 15 28 45 64
2500 15 29 47 67
2600 16 30 49 69
2700 16 31 50 72
2800 17 32 52 75
2900 18 33 54 77
3000 18 35 56 80
3100 19 36 58 83
3200 20 37 60 85
3300 20 38 62 88
3400 21 39 63 91
3500 21 40 65 93
3600 22 41 67 96
3700 23 43 69 99
3800 23 44 71 101
3900 24 45 73 104
4000 24 46 75 107
4100 25 47 77 109
4200 26 48 78 112
4300 26 50 80 115
4400 27 51 82 117
4500 27 52 84 120
4600 28 53 86 123
4700 29 54 88 125
4800 29 55 90 128
4900 30 56 91 131
5000 30 58 93 133
5100 31 59 95 136
5200 32 60 97 139
5300 32 61 99 141
5400 33 62 101 144
5500 34 63 103 147
5600 34 65 105 149
5700 35 66 106 152
5800 35 67 108 155
5900 36 68 110 157
6000 37 69 112 160
6100 37 70 114 163
6200 38 71 116 165
6300 38 73 118 168

 

You need to do some research, but yes you need bigger. I would think in the 30 range.