well to make a long story short, i had a holley tbi, but one of the injectors stuck, so i ditched it and i'm back to the stock tbi and injectors. it runs much much nicer now, but i know it is too lean. i've just been putting it around as much as possible, but i'm gonna get Rbob's EBL, when he starts shipping, and i figure i need bigger injectors.

brian at tbichips, said i would be ok with stock injectors at 14 psi. i'm at 10 psi now. i will be modding the tb unit as soon as my schedule permits, but it seems to me that my injectors won't be able to keep up.

he said that based on my cam (comp roller 210/220 .480/.480 112 lsa) and my heads (193s pocket porting and 1.6 exhaust valves) that i don't need bigger injectors.

i asked over on fsc.com, but no one really gave me any responses over there. hopefully you guys can help me out some more.

 

I have 85lb injectors in my holley TBI at 15psi... for a 4.3L. I think your 383 is for sure going to need some more injector.

Teeleton

 

Stock injectors at 14 psi, yeah right and I got some ocean front property in Arizona for ya too. LOL I'm starting to wonder if this guy has even seen a TBI motor before. Come on Brian respond to that we all know you lurk on here. (I really need to quit instigating stuff around here)

Any way, you'll probably be making around 300hp with that setup so you'll need some bigger injectors. I'm running 70 lbers at 22 PSI and they just feed my motor which makes around 300 Hp maybe slightly less, JPrevost runs 65 lb cop car injectors at around 28 psi I think and he just feeds his 330hp Vortec motor. If you have the stock 350, 55 lb/hr injectors or even worse the stock 45 lb/hr 305 injectors you HAVE to upgrade. You'll spend too much time trying to find out why your motor hits a magical wall at about 3500 rpm. Your motor will also be a good candidate for a 454 TB, which will have your bigger injectors as well. You could probably get away with the smaller TB since this motor is primarily going to be a torque monster. Do some research, there are some good formulas floating around on what size injectors you need for different HP levels as well as some formulas for figuring out what your new flow rate of your injectors will be with higher pressures. I unfortunately don't have my notes with me or I would post them up. Your definitely on the right track with the EBL.

 

well i ordered up some 454 injectors yesterday. they'll be here either tomorrow or monday. hopefully with that EBL and these injectors this damn thing'll run the way i intended it to when i built it like 2 years ago. if only i would have known about thirdgen, and fsc back then.........i woulda done some stuff differently, but at least i'm getting it straightened out now.

i don't want to have to run 20+ lbs of FP because then i'd have to get another pump, and i don't really want to do that. the one i have is good to 20 i think.

and thanks for the replies guys.

 

Almost any pump will make 100 psi, the regulator governs how much pressure you'll have.

What pump do you have? If it's a stock intank pump you may be in trouble. Most stock TBI pumps won't even keep up with a stock 350 let alone a 383. A 190L walbro will feed anything you can put under TBI for around 110$.

 

i did put in a new pump last year. thing is......i can't remember if it was a 155 or 190 lph. either way, its better than stock, and its nice and quiet too.

 

You should be good shape then. I like to look at pumps as supplying volume, and a regulator as what governs pressure. If the pump can’t supply enough volume then you’ll get a drop in pressure. Also pumps are rated at different flow rates at different pressures. So a 130 lph pump that was rated at 40 psi will actually flow much more than that at our TBI 10-20 psi. Hence the reason I run an on the frame stock ford truck pump. It’s cheap and readily available at most parts stores (plus it flows 130 lph@40psi). Plus I was doing a retrofit onto a vehicle that didn’t have FI.

 

well ok, then do you think i'll need more than the 20 psi that the stock regulator gan give me? fast335 desktop dynoed my motor, and came up with about 315 hp and 470lb/ft or torque, so i won't need to support over 300hp too much. plus i'm at 7500ft, so i'm making even less power than that.

 

Possibly not, it's kinda hard to say because every motor is different. If you do need more pressure you can get a stiffer spring for less than 20$ from TDS. I say you'll be ok because you power peak will be relatively low with that cam and the SP heads should be have a good BSFC.

 

ya, the peak power/torque is pretty low with my setup, but it works nice in a 6K lb pickup. i do rev the crap out of it sometimes though, so i don't want it to run out of fuel.

what does BFSC stand for? i know its something about the injectors, and that it goes into calculating how much power you can make based on the size of your injectors, but i don't know what it stands for, or what it is for BBC injectors.

 

Brake Specific Fuel Consumption, or in lamens terms how much fuel an engine requires to make a certain HP. An efficient engine with a smaller cam will generally have a high BSFC, while an overcamed crappy headed engine will take more fuel for each HP produced. Your vortec heads and mild cam should give you a good BSFC, which means you'll need less fuel for any given HP level than most engines.

 

i have 193 heads, not vortecs.....i was too poor to do anything at the time i built it.

 

sorry, got ya confused with someone else, the SP heads are pretty efficent too.