I think by now we have established that our cars come with 235 cc/min <@43.5 psi> injectors. Now at 9 psi boost, HRC says to push my fuel pressure up to 110 psi. Using the RC Engineering equations, my stock injectors should flow 374 cc/min at this new fuel pressure <@110 psi>. This would make me think that getting some 440 cc/min <@43.5 psi> would provide me more than enough fuel at a nice low fuel pressure. Now I go back to RC Engineering's web site, to their fuel injector worksheet. I insert an approximate crank hp of 260 hp, 4 injectors, BSFC of 0.60, max duty cycle of 0.80, and a fuel pressure of 43.5 psi . It says I need 515 cc/min injectors <@43.5 psi>! What am I doing wrong? Is my BSFC too high? Is the duty cycle too conservative? The stock ECU wouldn't run its injectors above 80% duty cycle...would it? I thought they didn't work accurately above 80%. Please check out "http://www.rceng.com/technical.htm#WORKSHEET" and give me some advice. I just put in my S-AFC and am waiting to put in my 440's until I get everything figured out.


Corbin
'95 ESI-T
HRC + FMIC
http://members.nbci.com/cbehnken/

Corbin
'97 GSX dressed like a '95 ESi

you did everything right, but that's only the first part of the equations. by stopping there you are expecting to supply your engine with enough fuel at only 43 lbs of fuel pressure!

you'll still need to raise it up with a boost sensitive FPR, but not nearly as much as if you had stock injectors. for example:

440 cc/min injectors will flow 519 cc/min @ 60 lbs fuel pressure. it's probably a good idea to use your FPR to raise it to about 65 or so and trim it back some with the S-AFC.

I understand that I'll need to use a boost sensitive FPR in conjunction with the AFC to get it all to operate properly under varying conditions. I still don't get why my calculations say I should only need 374 cc/min of fuel to run 9 psi boost . Why does the RC calculator say I should need 515 cc/min. That sounds like too much fuel. Please provide any advice you can.


Corbin
'95 ESI-T
HRC + FMIC
http://members.nbci.com/cbehnken/

Corbin
'97 GSX dressed like a '95 ESi

i re-read your original post and did some calculations for ya. before i go any further, i have a couple of questions. are you sure that HRC said 374cc's for 9psi? that sounds more like the fuel needed for 6psi. and when you put 260hp into RC's equation, is that supposed to be the power output at 9psi? 260hp sounds more like 12psi. considering the fact that it's only 140hp stock, i thought 9psi would put the 420a into the 220+hp range. i use a simple little formula to estimate hp at any give boost pressure. anyway, under my assumptions, here are the numbers i came up with.

boost = HP output = fuel demand (one possible solution)

6psi = 190+hp = 374cc/min (310's @ 65 psi = 381cc)
9psi = 220+hp = 433cc/min (370's @ 60 psi = 437cc)
12psi = 250+hp = 492cc/min (370's @ 80 psi = 504cc)
15psi = 280+hp = 551cc/min (440's @ 70 psi = 561cc)

RC's formulas are also a little generous on the fuel so these number are just a guide. you could probably do with a little less than they say. i'd check with HRC to make sure you were both talking about the same boost level and expected HP output. i can't imagine RC's formula being THAT far off the mark. the 515cc number is definately for 260hp though. i just didn't think that 9psi would give you that much power.

Actually here are some real numbers for the STAR kits !
The following are at the wheel
180hp @ 5psi <<~~ Around 200@ crank ~390cc @43.5psi
240 @ 10psi <<~~ Around 300@ crank ~590cc @43.5psi
The reason i point this out is because when you choose your
injectors and setup your fuel system you need to be sure to look at the HP @ the crank!

LAST EDITED ON 20-Feb-01 AT 03:46 PM (PST)

HOLY SMOKES!!!!!

you mean to tell me that the 420A is more than doubling it's HP output at 10psi?? i didn't think that was possible. in that case, 374cc's DEFINATELY isn't enough for a stage II kit.

boostn' are those dyno'ed numbers? that's great results from just a little boost. i'll have to re-adjust my boost=hp calculation a little, eh? =P

Joe got it right, the Star Kit Stage 2 more than doubles power, and Yes it is Dyno proven. However the 180(actually 178) was at low boost with an intercooler. I have that Turbo Mag. issue

Skrilla
'97 Base Talon NA
"Technology is the Only Substitute for Displacment"
"Peace and Turbo Grease"

*Skrilla
"Honest officer, I thought you were trying to race me"
Talon: 1st 2.4L
'97 Prelude
'04 350Z

Originally posted by etx
Good luck man! Project 'STFU Brian your talon is dead meat' should be on it's feet soon!

All this is in my original post but...I was quoting hp at the crank of 260 hp at 9 psi and 110 psi fuel pressure. At 110 psi fuel pressure, our stock injectors should flow 374 cc/min . Thats where I got the 374 cc/min number. I got the 515 cc/min number from the injector size calculator using 260 hp as an estimated crank hp. I'm still concerned about why these numbers aren't closer. Help...


Corbin
'95 ESI-T
HRC + FMIC
http://members.nbci.com/cbehnken/

Corbin
'97 GSX dressed like a '95 ESi

LAST EDITED ON 21-Feb-01 AT 00:09 AM (PST)

When Star Ran a Dyno fo Eric Z's Car @ 10psi of boost the Air/Fuel ration was 11.5:1. That is pretty damn rich! So questions about enough fuel shouldn't be a problem as long as the 95 NA DSM's get rid of the o-ring at the fuel pump. The pressure pushes the fuel pump out of the o-ring and can sometimes make it impossible to hold any kind of fuel pressure.


Wyatt Leras
http://www.turbogs.com
98 Eclipse GS Star Stage 5,000 Turbo kit

that graph shows mph instead of rpm. what gear were these dyno-pulls done in? 4th gear is a 1:1 ratio, right?

and are you saying that eric was running stock injectors at 110psi for that? if 374cc/min is enough to support 300hp at the crank all the way to redline, then somebody better call RC and tell them that their formulas are wack.

So really which is correct? How much fuel do we need to flow at 10psi of boost???


374cc/min or 550cc/min ???????


And I have a 95 and I really can't figure out how to make it not leak fuel pressure from the o ring...maybe if I sandwich tons of o rings together between 5/16" fuel hoses??



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