Are 780's enough for a Green on 30psi ?
 

I'm installing my green in a few weeks... and I'm having second thoughts about the 780's I put in recently.

I think I might be maxing out 780's when I put in C16 and turn the boost up...

Anyone have any experience with 780's and a high boost Green? Thanks in advance

I have been told the 780's are what alot of people are running with the green. I just bought 780's for the green also.

Those should be sufficient, as you will lean out the A/F a bit probly too with the c16. Thats some potent stuff.

Curious, how much is that going for nowadays?

780s will be fine

780s should be fine.

An easy way to know if an injector size is big enough for a certain turbo is knowing the max flow limit of the compressor on the turbo. Then, it's simple math.

I think the green has shown to max out at around 47-49 lb/min. I remember seeing a few graphs from people running the turbo with the wastegate disconnected to see where the max airflow would be, but I forgot the exact number.

4 780cc/min injectors flow 4*780=3120cc/min of fuel

Gasoline has a specific gravity of about .71, so to change the 3120cc to grams, just multiply by .71.

So, 4 780cc injectors can flow 3120*.71 = 2215.2 g/min
Divide by 454 to get lb/min
2215.2g/min / 454 = 4.88 lbs/min fuel

So, now just multiply that number by your AFR and that's how much airflow the injectors can support:

At 10:1 AFR, 4.88*10 = 48.8 lb/min of airflow

At 11:1 AFR 4.88*11 = 53.7 lbs/min of airflow

At 12:1 AFR 4.88*12 = 58.6 lb/min of airflow


So, even at a very rich 10:1 AFR, your 780s should be able to handle a maxed out green.



Eric

VP gets $630 for a 54 gallon drum these days. Raped!

Those injectors will be fine for C16, or even 93. I am almost maxing out my 1000cc's with E-85 though :(

You're not alone :) Are u getting a dual pump any time soon?

Taking l2r99gst math and applying it to 1000 with E85, albeit i don't what E85 has for specific gravity, so plugging gasoline's .71 and 7.5 AFR, end result is 6.26x7.5 = 47lb/min.
Hmmm..
So anybody know gravity factor for E85 then?

.762 I think, whatever FIA control fuel is allowed at 104 octane.

I am only seeing 70ish% IDC with my 780s and 30psi and that was fairly rich compared to what C16 will let you do. One single Walboro for gas, though I am going to go to 1000's and a twin setup for E90+.

I might go to 1050s since I am pretty sure I have them in the bag now :)

780's are fine for that setup.

Thats some awesome info!!

So 2 + 2 = 5? WTF I don't get it. :confused: lol my head hurts.

US dept of energy says E85 gravity is 0.78 (http://www.eere.energy.gov/afdc/pdfs/40243.pdf)

That means 1000 injectors can support 51.5 lbs/min of airflow at 7.5 afr on E85 (11.2 on gas wideband)
Which means they are plenty enough for E85 on green.

That assumes sufficient flow from the pump. I would wager based on what I have seen with dual walboros that a single wouldnt be able to do that even with 1000's. Dual 255s maxed about 540whp on E85 from what Lucas has found. Those were standard 255's not HO types. Those might get you some more.

maybe my experience will help some people make better choices.

with the HTA 35R I made it right to ~500awhp @ 28psi according to DLL with a single walbro and 780cc injectors before the IDC jumped up to 120% and it started leaning out. I added a kenne bell boost a pump and 880's and the IDC's came back down and the AFR went richer.

I raised the boost to 30psi and saw ~525whp in DLL no problem. I added a BR Race FMIC, the load went up, DLL showed 545awhp and again I noticed I was having to add an unusually large amount of fuel at high rpm and the IDC's shot to 110%.

I've got twin walbro and 1000cc injectors ready to go in now.