Suggested injector size??

jam77 · October 14th, 2007, 10:27 PM

ok im going to be changing my setup and was curious what size injectors i should get, i was thinking 42's but let me know what you guys think. My setup is going to be trick flow heads, stage 1 or 2 cam ( have yet to decide), typhoon intake manifold, novi 1000 supercharger (going to crank the boost up to approx 8 pounds), 70mm throttle body, 90mm mass air meter, afm power pipe, bbk shorty headers, bbk or x-pipe, flowmaster cat back. Do i need to install an inline pump for 42's i already have a 255 in tank?

Speedstang302 · October 14th, 2007, 10:51 PM

42lbers will be fine, i'd get an AFPR too...

jam77 · October 14th, 2007, 10:54 PM

yeah i got one already and im going with a pms to tune it. Do i have to get an inline pump to drive the 42's if i have a 255 lph in tank pump?

ryans88gt · October 14th, 2007, 11:01 PM

I certainly wouldn't go any bigger than 42 lb/hr, you should be good to about 500 HP with those.

you will not know if you need a booster pump until you monitor the fuel pressure on the dyno. You'll probably be OK without it.

jam77 · October 14th, 2007, 11:16 PM

would 30's be enough?

Iwannagofast · October 15th, 2007, 02:41 AM

i found this equation for injector size

motor horsepower / 8 * .50 / .85

Speedstang302 · October 15th, 2007, 09:37 AM

Originally Posted by Iwannagofast

i found this equation for injector size

motor horsepower / 8 * .50 / .85

that says 36lbers are good for 500hp

and 42lbers for 600hp..

i well what hp you pushing to the crank..cuz 30lbs with a s/c maybe too small

nolife · October 15th, 2007, 09:57 AM

That equation is a good start.
Try this online calculator page for a little more detail and a description of that equation.
http://kgparts.com/index.php?page=fuel-calc

Here is another page with some maximum numbers for different injectors which assumes 100% duty cycle which is not something you should be at anyway.
http://www.motorsportsdigest.com/tech/perform2.htm

vfast · October 15th, 2007, 04:01 PM

keep using charts as they really don't mean shit , just a starting point

dude you need and inline pump I will not install any S/C without one...want to know why? what if the intank pump fails on a high rpm run, we all know..but with a 75 lph or even a 110 lph you can atleast save the engine and can even limp it home. as for cam I couldn't say unless I had more info...the stock cam also works great in the 5-7 psi range with some longer rocker, even the terrible e-cam work well with it

Iwannagofast · October 15th, 2007, 05:53 PM

As the saying goes better safe than sorry.....its always better to have injectors a lil too big than too small....running rich isnt near as bad on an engine as running lean

vfast · October 15th, 2007, 06:20 PM

so very true! a tuner is almost a must with 42's unless you like having to push the pedal to the floor to start it up

jam77 · October 15th, 2007, 08:13 PM

im just going to order 42's and be done with it, i will put in a t-rex or some other inline pump just to be safe, i will be running a pms so that should take care of the hard start.

ryans88gt · October 17th, 2007, 12:40 AM

Originally Posted by vfast

keep using charts as they really don't mean shit , just a starting point

dude you need and inline pump I will not install any S/C without one...want to know why? what if the intank pump fails on a high rpm run, we all know..but with a 75 lph or even a 110 lph you can atleast save the engine and can even limp it home. as for cam I couldn't say unless I had more info...the stock cam also works great in the 5-7 psi range with some longer rocker, even the terrible e-cam work well with it

If the intake pump fails, god himself couldn't suck an ounce through it, so it wouldn't matter if you had an inline pump or not (which only push, the don't pull). You cannot draw through a non-functioning intank pump, it would still run lean and blow up. A 110 lph inline pump would slow down a 255 in tank pump. If you have a 255 intank pump, you need a 255 lph boost pump, there is no mixing and matching here.

October 14th, 2007, 10:27 PM	#1
jam77 Enthusiast 1987 Mustang GT Join Date: Apr 2007 Location: IL Posts: 685 iTrader: 0 reviews	Suggested injector size?? ok im going to be changing my setup and was curious what size injectors i should get, i was thinking 42's but let me know what you guys think. My setup is going to be trick flow heads, stage 1 or 2 cam ( have yet to decide), typhoon intake manifold, novi 1000 supercharger (going to crank the boost up to approx 8 pounds), 70mm throttle body, 90mm mass air meter, afm power pipe, bbk shorty headers, bbk or x-pipe, flowmaster cat back. Do i need to install an inline pump for 42's i already have a 255 in tank? __________________ 87 GT, typhoon upper and lower,70mm tb, 90mm maf, bbk shorties, bbk x-pipe, flowmaster cat back, 3:73 gear, pro 5.0 shifter, novi blower,afm power pipe, load IO, Trick Flow heads, Anderson B-31 cam, Anderson PMS, 42 lb injectors, t-rex fuel pump.

October 14th, 2007, 10:51 PM	#2
Speedstang302 I Post Entirely Way Too Much 1996 Mustang GT 13.64@101mph Join Date: Apr 2007 Location: Massachusetss Posts: 5,828 iTrader: 1 reviews	42lbers will be fine, i'd get an AFPR too... __________________ 1990 GT- GT40p Heads\| Anderson N41 cam\| Crane 1.6 RR's\| Trickflow Intake\|MGW Short Throw\| Aluminum d/s\| 3.73's.....still slow....

October 14th, 2007, 10:54 PM	#3
jam77 Enthusiast 1987 Mustang GT Join Date: Apr 2007 Location: IL Posts: 685 iTrader: 0 reviews	Suggested injector size?? yeah i got one already and im going with a pms to tune it. Do i have to get an inline pump to drive the 42's if i have a 255 lph in tank pump? __________________ 87 GT, typhoon upper and lower,70mm tb, 90mm maf, bbk shorties, bbk x-pipe, flowmaster cat back, 3:73 gear, pro 5.0 shifter, novi blower,afm power pipe, load IO, Trick Flow heads, Anderson B-31 cam, Anderson PMS, 42 lb injectors, t-rex fuel pump.

October 14th, 2007, 11:01 PM	#4
ryans88gt MM Fanatic Join Date: May 2007 Location: Bloomington, IL Posts: 4,737 iTrader: 0 reviews	I certainly wouldn't go any bigger than 42 lb/hr, you should be good to about 500 HP with those. you will not know if you need a booster pump until you monitor the fuel pressure on the dyno. You'll probably be OK without it. __________________ 88 GT CHI headed 351w 10.8 @ 125 - still figuring it out. 03 Cobra 2.3 whipple 10.7 @ 129 - sold it 04 Mach 1 12.7 @ 109 mostly stock - sold it 89 LX procharged 302 515 hp 497 ftlbs 10.7 @130 mph - sold it

October 14th, 2007, 11:16 PM	#5
jam77 Enthusiast 1987 Mustang GT Join Date: Apr 2007 Location: IL Posts: 685 iTrader: 0 reviews	Suggested injector size?? would 30's be enough? __________________ 87 GT, typhoon upper and lower,70mm tb, 90mm maf, bbk shorties, bbk x-pipe, flowmaster cat back, 3:73 gear, pro 5.0 shifter, novi blower,afm power pipe, load IO, Trick Flow heads, Anderson B-31 cam, Anderson PMS, 42 lb injectors, t-rex fuel pump.

October 15th, 2007, 09:57 AM	#8
nolife MM Fanatic 91GT, 88GT, 02GT Join Date: Dec 2006 Posts: 3,057 Blog Entries: 3 iTrader: 0 reviews	That equation is a good start. Try this online calculator page for a little more detail and a description of that equation. http://kgparts.com/index.php?page=fuel-calc Here is another page with some maximum numbers for different injectors which assumes 100% duty cycle which is not something you should be at anyway. http://www.motorsportsdigest.com/tech/perform2.htm __________________

October 15th, 2007, 04:01 PM	#9
vfast Banned Join Date: Aug 2005 Location: shimmy shack takeout Posts: 1,084 iTrader: 0 reviews	keep using charts as they really don't mean shit , just a starting point dude you need and inline pump I will not install any S/C without one...want to know why? what if the intank pump fails on a high rpm run, we all know..but with a 75 lph or even a 110 lph you can atleast save the engine and can even limp it home. as for cam I couldn't say unless I had more info...the stock cam also works great in the 5-7 psi range with some longer rocker, even the terrible e-cam work well with it

October 15th, 2007, 06:20 PM	#11
vfast Banned Join Date: Aug 2005 Location: shimmy shack takeout Posts: 1,084 iTrader: 0 reviews	so very true! a tuner is almost a must with 42's unless you like having to push the pedal to the floor to start it up __________________ EVERYONE IS ENTITLED TO MY OPINION:cool: 6'ers are for kids 1965 chevelle SS 421 sbc 6 speed, 3.90 gears,alum d-shaft, brodix heads,roller cam,925 AED carb...grocery getter[COLOR="Red"]RIP[/COLOR]

October 15th, 2007, 08:13 PM	#12
jam77 Enthusiast 1987 Mustang GT Join Date: Apr 2007 Location: IL Posts: 685 iTrader: 0 reviews	Suggested injector size?? im just going to order 42's and be done with it, i will put in a t-rex or some other inline pump just to be safe, i will be running a pms so that should take care of the hard start. __________________ 87 GT, typhoon upper and lower,70mm tb, 90mm maf, bbk shorties, bbk x-pipe, flowmaster cat back, 3:73 gear, pro 5.0 shifter, novi blower,afm power pipe, load IO, Trick Flow heads, Anderson B-31 cam, Anderson PMS, 42 lb injectors, t-rex fuel pump.

Remove Advertisements Sponsored Links
Ford Mustang Forum Advertisement

Threads Similar to: Suggested injector size??
Thread	Thread Starter	Forum	Replies	Last Post
Injector Size	mmvi	V6 Mustangs	11	November 10th, 2007 04:11 PM
Injector size and MAF conversion?	Never2fasst	5.0 Mustangs	1	August 28th, 2007 04:16 PM
Fuel injector size/colors?	fastsvtss	5.0 Mustangs	3	April 19th, 2007 03:40 PM
Fuel injector size?	WAR-PARTY	5.0 Mustangs	4	February 19th, 2007 09:50 PM
injector size?	92_LX_5.0	5.0 Mustangs	6	February 11th, 2007 01:42 AM

All times are GMT -4. The time now is 02:47 AM.
Contact Us - Modded Mustangs : Ford Mustang Forums - Privacy Statement - Top
Modded Mustangs is ©2005-2008, All Rights Reserved, And is Not Affiliated with Ford Motor Company. Forum is powered by vBulletin ©2000 - 2012, Jelsoft Ent. Ltd. & SEO by vBSEO 3.3.2 ©2009, Crawlability, Inc.