My motor is in process and I was looking a head a little bit. About what size injectors will I need? What is everyone running on their setups? What duty cycles are you seeing and what is a good low impedence injector? Thanks for the replys in advance....John

 

Really depends on your HP level...

What are you expecting to make?

Going off boost isn't gonna say much since we don't know your exact setup.

Throw out some #s and then you'll get your answers

Ohh, expected fuel pressure would be needed also if anything different than stock.

 

hmm. Try this... http://www.rceng.com/technical.htm

 

Thanks for the chart. That was exactly what I was looking for.

 

i'm runin 36lb inj. on 383ci and 8lbs of boost...........but i have yetto be tuned! So will see whats up!


(i'm tryin to get my junk together)

on my old power plant, i had 40(some)lb injectors 15lbs of huff and puff and 650rwhp!


but i sold that motor!

 

383 with 15lbs. If you have decent flowing heads and a good intercooler you should be able to make 700 HP pretty easy. With a 45lb base fuel pressure, 1 to 1 rising fuel pressure and a 11.5:1 tune up you will need 75lbs injectors. I tried a set of 55's on my 355 and they were done at 500hp at the wheels. I now use 85lb injectors on it and its currently making 650 to the wheels . With the 85's i will have some room when i get my IAT down.
I use smokemup.com for my calculaters

 

I'm going with a forged 383 9.0-1c.r.,ported stock heads (Lloyd Elliot) custom cam (220-230 area) no fmu, P600b for the time being, running 12#. I also will be putting in a 255 walbro intank pump. Will I still need my inline pump that came with my ATI kit? I was thinking 72# seimens would be sufficeint. Iwas looking at the brands, what is a good brand for that big of an injector? Lucas, Delphi, Seimens? What is everyone running? Thanks for the info guys, I only want to buy things once for now on......John

 

Just a few things to point out.

72lb injectors for that setup is overkill. The good thing is that it allows for growth in the future when you step to a bigger blower.

As far as brands go I have always had good luck with Sieman injectors. Also remember that 60 lb injectors are the biggest high impedance injectors available for our cars. If you plan on runnning 72lb injectors than you will need an Acceloronics impedance box.

I would take the inline pump that was sent with your ATI kit and throw it in the garbage. IMO it is POS. You may want to look at a boost a pump setup.

 

I emailed you. Let me know if you got it.

 

IDOXLR8: I know that they are alittle much, but I do want room to grow. I also know about the Acceloronics impedance box, which I am also saving up for.Thanks for the lookng out though. What is a boost a pump set up? Where do I find out about it? Thanks.

RealQuick: I did get your email. I will email you back. Thanks.

 

A boost-a-pump increases voltage to your electric pump, allowing it to pump more fuel.
Here are some links:
Kenne Bell Boost-A-Pump $220-240 on their pricelist
Aeromotive Billet Fuel Pump Controller $260 at Summit
Ramchargers Volt Blaster $60

If I were to go this route, I would get the Kenne Bell due to the design & features specific to SC applications. The Ramchargers item (had not heard of it before) states it raises the alternator output (as opposed to just the fuel pump voltage), which could cause some other issues. Usually, you get what you pay for.

I also used a program to check the output of your injectors at higher fuel pressure. If you run a 60# injector @ 60 PSI, it will flow 70#. You could save some $ by running high impedance injectors at higher pressure w/ the boost-a-pump. If my math is right, at 11 PSI on your setup, you should be around 730 FW HP. A 70# injector at 80% duty cycle with a .55 fuel consumption will support about 815 HP, and will require 282 LPH of fuel.

Saw some of your other questions- I run Siemens 55# units, good injectors. The P600B will not make enough power in your setup, and you probably won't see much more than 8 PSI with it from a 15# pulley- which needs a 12 rib belt (someone here used the analogy of a small straw {stock 350} = higher PSI, big straw {383 w/ good heads} = lower PSI.)

 

rc engineering has a 75 lbs/hr HIGH impedance injector that works pretty good....i know you can get um from www.musclemotors.com

the guy is based out of cali but has deceint prices

 

I checked the Musclemotors website, and he has empty links to RC Engineering units, but no other information (you can't buy them). Also they are 750 CC/MIN injectors, which factor out to a 71 LB/HR unit, still the largest high impedance injector I've seen. These injectors are $99 each on the RC website, vs. $550 for all 8 for the Siemens 60# at Musclemotors. You can find a better deal on the 60# injectors ($440) at Racetronix who I think is a supporting vendor here.

 

Our 60's are flow-matched

 

Thanks guys for the info. How many of you guys run a boost a pump set up? What would just my walbro 255lph in tank support as far as hp? I was looking on the Kenny Bell website and it has a graph of smaller fuel pumps also. What size is the stock one rated at. Is it safe to run 60# of line pressure at all times if I wanted to? I would much rather run the Acceloronics impedance box and bigger injectors with a normal fuel rail pressure. I want to go to a D1 in the future so I want buy just one more set of injectors. What would the 60's support as far as hp with a 43.5 rail pressure? How is there tunablity and or drivablity. Is there any tuning issues with that big of a high impedence injector. Awhile ago I remember people having problems with 50#, not sure what brand they were. So many dicisions, such little money. Thanks again guys, and please shed some light on me......John