I have a 427 CI with a semi large turbo setup, I want to buy an Inj one time here. Since I have control over fuel pressure will the 160's work fine with a low impedence inj box and good tuning? I could get away with 120's, but Like to do it once if possible.

 

Unless you have a 2000+ hp engine you are way off.

Please provide your expected hp & boost level & I can give you an educated guess. Also do you plan to street drive this or race only?

 

Pretty much race only. 1400+ HP and 20-24 psi boost.

I don't understand Injectors to much, so I am not sure if you can go bigger than needed and adjust the fuel pressure to compensate or what.

BTW, using the Inj calculator in the sticky, it says I need 143 lb inj at 43.5 psi.

 

i think i see whats wrong. 143lbs at 43 psi is 160 lbs at 60 psi

that 160 is what 143lb injectors would be at 60

if you redo the calc at the bottom for 60 psi it should come out around 120

 

Thanks for replying!

yes 120 @ 60 psi is correct and i can use 120's no problem and may be the right way to go.

What i would like to know though, is if I can use the 160's at 40-45 psi. I have a completely different fuel system from stock and I'm not locked into using the stock 58+ psi. i have 160's in my hand right now and would like to use them if possible. If not, more money...

 

If you have the 160's and it's primarily a race car, use them. The idle may be a little rich, but that won't be a problem. If you're making that much power and have to keep the oem computer, at least do a custom operating system like COS5 from EFI Live and use a 3 bar map sensor and tune. That will add some safety plus work well with the injector box. I'd start with the fuel pressure at 40psi, build the VE map and watch the airfuel ratio on a wideband. Good luck.

 

160's rated at 60 would be about 135 at 43

 

Thanks Onfire! I'll give them a shot and see, I may do smaller injector for the first start up and break in though, make sure I don't wash the cylinder. I will be using a 3 bar map and custom 3 bar HPTuner tune. BS3 or XFI will come next year . I will not be going straight to the max capabilities of the motor though, probably keep in the 900-1000whp range and tweek it up to 1200 with time.

With a BSFC of 0.65 and 40 PSI, I get a 158 lb injector at 75% duty cycle. I assume you don't want more than 80% sustained DC, but is 80% a sweet spot, a cut off or what?

Dan

 

80% is just a reasonable target. I've tuned some lower boost cars and had to push the injectors to 91% at 6500 rpm...not really a problem since at 600rpm they were in the 80's. I've seen some boosted tunes from professional tuners with the injectors static (100%) at 4800rpm and betting on the fuel pressure to keep the engine alive....so it's all relative.

3bar tune with HPT and you'll be fine.

 

I'm not sure I would label a tuner, "professional" with that type of craftsmanship.

 

Yeah, scary.

Thanks for the clarification.

Dan

 

"What i would like to know though, is if I can use the 160's at 40-45 psi."
I've been flow testing/cleaning injs since 94. Have yet to see a set of "160s" being rated at 60psi, from thier mfgr. Not saying there aren't such.. Just never have run a set. [Usually are rated at 3 bar.]
using a 60# base FP, if the regulator is boost referenced, you will be putting a really high load on the pump, once boost comes on..
Remember, the pump output declines as op pressure rises..

 

might as well get the BS3 on this racecar

 

I haven't seen one rated at 60 psi either, just 3 bar like you mentioned. I think 60 psi was only brought up as the stock FP rating. My pump can support 120 psi, but obviously won't want to do that for reasons you mentioned plus the extra amperage and heat. Thanks for the tips!

That $4500 will have to wait a bit longer .

Dan

 

I'm doing a similer setup and plan to run 96's. BS3 should be way under 4500....I know mine was...even if you go with all new gauges.

 

Looks like 96's will support about 950 HP at 3 bar.

Not how I optioned the BS3 out with the racepack it doesn't:

BS3-004-019 GEN3 PRO SEFI System -LS1, DAE, DAI $2995
Can Interface to RacePak Hud Upgrade $385
250-DS-UDX-BS3 $895

= $4275 + shipping .

Dan

 

we carry the BS3's at a good price

http://www.harrisspeedworks.com/shop...cat=328&page=1