Single Turbo RX-7's Questions about all aspects of single turbo setups.

figuring out pulse width of large injectors at idle

Thread Tools
 
Search this Thread
 
Old Nov 13, 2008 | 12:04 PM
  #1  
Chaotic_FC's Avatar
Thread Starter
Banned. I got OWNED!!!
 
Joined: Dec 2007
Posts: 946
Likes: 0
From: paradise Florida
figuring out pulse width of large injectors at idle

now i am looking into a large set of injectors for my next project

mike moran has a set of injectors that put out 600 lbs/hr.



now this injector has a pulse width of 1.5 milliseconds.


now according to my this calculator i copied and pasted from another site, i should be technically able to get all the fuel i need from just these two injectors, but still have a stable idle at 1000 rpm:


calculator website:

http://www.rbracing-rsr.com/calcinjpulse.html



Engine Displacement (CID): C.I.D. -80

Idle Target RPM: Idle RPM -1000

Peak RPM: Your rev limit may occur before the peak value. Peak RPM - 10000
Volumetric Efficiency at Idle is typically 15% to 20%: % - 20

Number of injectors in the System: Injector(s) - 2

Brake Specific Fuel Consumption (.5 for 2 Valve, .45 or less for 4 valve): B.S.F.C. -.65

Idle in Inches of Mercury (In Hg.)
If Idle in Kilopascals (kpa): Then kpa / 3.3864 = In Hg " Hg - 8

Expected Peak Horsepower Peak Hp - 1100

Millisecond (Ms) Injector minimum open time ( 1 to 1.25): Ms. - 1.5

Your Installed Injector size (lb/hr): Lb/Hr - 600

Number of injections per cycle (batch 2, sequential 1): #/cycle - 1

How many strokes per cycle (four stroke = 4): Stroke - 2

Results
Injector Size @ 80% recommended duty cycle (lb/hr): Lb/Hr - 446.875

Max Hp with recommended injectors @ 85% duty cycle: Peak Hp - 1168.750

Max Pulse Width Permitted @85% duty at peak rpm: (Ms): Ms Peak - 5.100

Max HP with Your Installed Injectors @ 85% duty: Max Hp - 1569.231

Idle Millisecond Pulsewidth: Installed Injectors Ms Idle - 1.551

Projected cc's per minute: Installed Injectors, per injector at idle: cc's / Inj. - 17.107


is there something i am missing here???

or could i really have a stable idle with a 600 lb/hr injector?

i would be planning on running haltech E8 by the way.

Last edited by Chaotic_FC; Nov 13, 2008 at 12:14 PM.
Reply
Old Nov 13, 2008 | 12:13 PM
  #2  
fritts's Avatar
Mad Man
Tenured Member: 20 Years
iTrader: (5)
 
Joined: Aug 2002
Posts: 2,128
Likes: 4
From: Indiana
160's usually idle around 1.5 ms range. Which I would consider the absolute limit for a minimum pulse width. I couldn't even get a set of my 160lbs to acurately fire at 1.5 ms. Your talking an injector almost 4 times that size at 600 lbs. It aint gonna happen. I would say you may be able to get a 12-13 afr 1000 rpm idle with a 200 lb and 1.5 ms. That's a just rough guess though.

Also they don't talk about lag time in the description. When I'm talking 1.5 ms I'm talking total time so lag time plus map opening. So if there is a normal large injector lag of over 1 ms your gonna be in trouble.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
Jul 1, 2023 04:40 PM
stickmantijuana
Microtech
30
Apr 23, 2016 06:37 PM
incubuseva
2nd Generation Specific (1986-1992)
14
Sep 3, 2015 12:37 PM
imitek
3rd Generation Specific (1993-2002)
9
Aug 28, 2015 05:28 PM




All times are GMT -5. The time now is 09:24 PM.