Fuel Injector sizing calculator

[Russ Jerome]

Kind of neat from RC, I hate trying to do math.

http://www.rceng.com/technical.aspx?UserID=425967&SessionID=4DEnRuwVyWdy9Rm4R3k3

[Russ Jerome]

And if you are setting the inj's up on a stand-alone setup:

The primary advantage of low impedance injectors is a shorter triggering time. When large injectors are fitted to high output engines, low impedance injectors will often give a better idle quality because of this fact. The primary advantage of high impedance injectors is the fact that less heat is generated in the drive circuit and often no external resistors are used.

That info stole right from SDS's site:
http://www.sdsefi.com/injectors.htm

So Russ what did you do for x-mas?
Well I spent 4hrs researching inj's and driver circuts for race
purposes as it relates to standalone fuel managment......

[t3rse]

haha! i was there earlier today to figure out what injectors we need to turbo my brother's rock crawler...i gave him my old (less than 50 passes on it) t3/t4 for xmas.

[BadAssPerformance]

Nice tech find Russ :thumb:

[BIGBRUDDA]

RUSS YOURE STILL ALIVE!! How it hangin man?:thumb:

[Russ Jerome]

RUSS YOURE STILL ALIVE!! How it hangin man?:thumb:

Took a year off for serious drinking, getting my oldest girls situated
in college and visiting relatives I forgot I had out East :)

Winter is here and of coarse my brain is thinking race car, weather
wont agree but I'd like to see everyone this year at SDAC.

[BadAssPerformance]

Kickass! :thumb:

[Turbodave]

Been trying to get a year off to get some of my drinking done as well, just can't seem to get work to pay for that sabbatical. Welcome back Russ, one of these days I gotta get up to a thirsty thursday or something.

[rbryant]

There is a big article on the srtforums about how RC uses a different fluid to flow their injectors. It means that they are actually a little smaller than the corresponding injector size from Mopar.

I think I have it bookmarked on my home PC if you can't find it in the search there.

It isn't a huge deal but it is interesting....

-Rich

[Russ Jerome]

There is a big article on the srtforums about how RC uses a different fluid to flow their injectors. It isn't a huge deal but it is interesting....

-Rich

By all means post it. When you realy want to stay below 80%
duty cycle but size your inj within 50hp of your terminal goal
its all important from what I have read. In reality the available
sizes are limited, beyond that low imp more available (cheaper)
so Im leaning towards 92-100# or 900-1000cc inj for larger than
I need now but minimal for a future motor Im dreaming of.

[rbryant]

Here is the link:

RC injectors vs. Mopar injectors (http://www.srtforums.com/forums/f187/wrong-info-injector-flow-math-info-chart-399569/)

[Frank]

They obviously don't understand turbo motors. They state the following...


In most cases a naturally aspirated engine will have a B.S.F.C of .50. This means that the engine will use .50 lbs. of fuel per hour for each horsepower it produces. Turbocharged engines will want to be at .60 lbs. per hour or higher.

Their statements are text book answers that are not applicable to the market in which they are selling. Most people who are purchasing their injectors are performance folks in which case those numbers are not even close! A 0.60 BFSC would be something like a carborated, non-intercooled engine.

So my point is, if you are going to use their calculator, use the following numbers that I have derived....



Assume/Estimate

.36 BSFC - Turbocharged Intercooled Diesel
.38 BSFC - Turbocharged Non-Intercooled Diesel
.42 BSFC - Race Engine or Older Diesel Engine *
.47 BSFC - Hi Performance Engine *
.51 BSFC - Modern Stock Engine or Light Modifications Engine *
.55 BSFC - Supercharged / Turbocharged Non intercooled Engine

* - These include N/A Engines or Supercharged/Turbocharged Intercooled Engines.

Better yet, I have proof. :) James Reeves, according to Ken a few years ago, would run out of fuel with his +40s at 420whp or so. Do the typical cheater and assume 483chp because of a 15% tranny loss. If you assume a 55psi rail and 0.80 duty cycle, my BFSC of 0.43 actually works for his motor. This is the number that helped to drove the above BFSC table I created. I also used some material from books and other dyno'ed engines that I had a decent amount of build data to go with.

Anyway, hopefully that will help someone in injector selection. I honestly think their numbers came about from old books that dealt with turbocharging and supercharging where there were no intercoolers and/or really bad head and manifold designs. For example, a 0.60 would be a non-intercooled, turbocharged carb'ed version of the 2.2L with a stock everything and 2.25" exhaust. Granted that combo doesn't exist, but if it did, it would lean towards that 0.60 in a hurray.


V/R
Frank

[BadAssPerformance]

...would run out of fuel with his +40s at 420whp or so. Do the typical cheater and assume 483chp because of a 15% tranny loss. If you assume a 55psi rail and 0.80 duty cycle, my BFSC of 0.43 actually works for his motor.

I would say "run out of fuel" would be closer to ~100% DC.

[Frank]

Well that depends on how much control you have over the Duty Cycle. I think I remember in Reeve's case, he was running into the 90's and his fuel pressure was up there also. In either case, the point still stands.

[Russ Jerome]

Better yet, I have proof. :) James Reeves, according to Ken a few years ago, would run out of fuel with his +40s at 420whp or so. Do the typical cheater and assume 483chp because of a 15% tranny loss. If you assume a 55psi rail and 0.80 duty cycle, my BFSC of 0.43 actually works for his motor. This is the number that helped to drove the above BFSC table I created. I also used some material from books and other dyno'ed engines that I had a decent amount of build data to go with.



You are correct to a point, this brings up many arguments from
10yrs ago on the HP ability of 52pph (+40) on the FMML. If Gus was
here (he is watching) he would point out others like Larry had dynoed
at or over 500HP (100% duty cycle by way of grounding the inj at
18psi thru a pair of Hobs switchs) and others with 95%dc programming
could only muster 380. A lot of variables from vehicle to vehicle.

The lowest record of BSFC ever was .35 for Wright Cyclone TC3350
compound turbo aircraft engine. Having James nearly tie the world
record for BSFC wouldn't surprise me at all!

http://i11.tinypic.com/67du0di.jpg
Buddy of mine (and me in the pic!) with his little Toilet Corolla pushrod
four. 1000cc (100#) inj running 43psi boost and mid 8's. No bog or stall
with the huge injectors. He's set my mind to rest on buying too large
inj if your programing your own stand alone setup. A lot of interesting
stuff out there to read, wish I was'nt bi-polar or whatever a got.........

[Frank]

You are correct to a point, this brings up many arguments from
10yrs ago on the HP ability of 52pph (+40) on the FMML. If Gus was
here (he is watching) he would point out others like Larry had dynoed
at or over 500HP (100% duty cycle by way of grounding the inj at
18psi thru a pair of Hobs switchs) and others with 95%dc programming
could only muster 380. A lot of variables from vehicle to vehicle.

The lowest record of BSFC ever was .35 for Wright Cyclone TC3350
compound turbo aircraft engine. Having James nearly tie the world
record for BSFC wouldn't surprise me at all!

http://i11.tinypic.com/67du0di.jpg
Buddy of mine (and me in the pic!) with his little Toilet Corolla pushrod
four. 1000cc (100#) inj running 43psi boost and mid 8's. No bog or stall
with the huge injectors. He's set my mind to rest on buying too large
inj if your programing your own stand alone setup. A lot of interesting
stuff out there to read, wish I was'nt bi-polar or whatever a got.........

Ya, I would agree with that.

Holy cow, 0.35! That is impressive!


Frank