Fuel Injectors

Chasinsparks · 08-24-2007, 08:00 AM

I have 2004 Gt, With Steen Racing heads Comp 270 Cams Mac long tubes 70 MM Throttle body and Plen, SCT Custom tune by Steen Racing Dyno'ed 314 Rwhp 317 Tq, It was said that my injectors were maxed and I should go to atleats 24lb injectors. With that said

* would I need a retune

* will there be any real benifit to upping the injectors

* any suggestion on brand

mpt_1962 · 08-24-2007, 10:37 PM

i was told to wait for 24's until i get the heads put on...but since you have heads on go ahead and get the 24's...then get it retuned

r3dn3ck · 08-25-2007, 07:56 AM

your stock 04 injectors are 21lb. If they were 19's I'd say yeah definitely upgrade too 24's. At 21/22lbs you should be fine but you are approaching where I'd upgrade so might as well. You're at least taxing their duty cycle pretty heavily at WOT.

Tuning will have to be updated and the maf curve re-done for the bigger injectors. It's a minor update with only usually 2 dyno runs needed to check AF afterward.

I like Ford branded injectors... they're Bosch. Most correctly fitting squirters are bosch made but might as well go FRPP from Randy. Venom also makes nicely blueprinted units.

Chasinsparks · 08-27-2007, 10:13 AM

Hey Thanks for the reply

mpt_1962 · 08-27-2007, 10:39 AM

oh i didnt know the 03 gt's had the 24lb injectors...i didnt ask my tuner about an 03 because i thought they had the 19's also. Well once again red knows all...lol

r3dn3ck · 08-27-2007, 10:48 AM

they don't... they have 21lb injectors. The 02's do too. 01 and down have 19 on GT's

mpt_1962 · 08-27-2007, 10:51 PM

opps...sorry meant to say 21's. Whats the hp rating that the 21's can hold up to red? What can the 24's hold up to?

r3dn3ck · 08-28-2007, 08:24 AM

depends on the duty cycle and fuel pressure. Normally I'd say if you cross the 265rwhp mark that you should look to 24's. My handy dandy calculator says 21's are starting to be taxed at stock power levels. Cross 285bhp and 24s become a need to stay under 80% duty cycle at WOT.

I have to use 32lb units for my new motor.. you do the math.

mpt_1962 · 08-28-2007, 08:34 AM

that is quite a bit of math. Do you have an excel document with the "input your numbers" for it to calculate it for you? Ill be around 270-285hp after the cam install. So i should look into upgrading injectors to 21's on my 2000? Or just wait til i get it dyno tuned to find out if im running lean at WOT? Actually you said 24's after 265 hp...so maybe even 24's IF my engine is running lean though right?

bassman97 · 08-28-2007, 08:50 AM

Go to Holley's website. They have a good calculator to determine the appropriate injector size for you.

r3dn3ck · 08-28-2007, 08:53 AM

with 270rwhp you should be burning gas for at least 315bhp which causes me to say, time for 24's. It's better to go in with enough injector than to lean it out to find out there wasn't enough flow in the first place.

Remember... I'm keeping you at or below 80% duty cycle.

bossman302 · 09-05-2007, 12:41 PM

Forgive me if I hijack this tread but looks like I need to get 30 lbs injectors for my new engine. Since the ford racing injector’s state the will now work with a stock MAF will the turner be able to recalibrate the stock MAF to work?

r3dn3ck · 09-05-2007, 12:50 PM

it's not the maf being calibrated so much as the transfer function associated with it. The only way to properly tune AF ratio is via that, so yes. Your tuner will be able to hand curve the MAF xfer function and you'll be happy as a clam. Most handhelds come with injector options including 30lbs built in. They're never perfect so I still recommend a dyno run with logged AF to check it out.

bossman302 · 09-05-2007, 01:00 PM

Thanks bro, just wanted to check. Was a little worried.

08-24-2007, 08:00 AM	#1 (permalink)
Chasinsparks Member Join Date: Feb 2006 Posts: 80	Fuel Injectors I have 2004 Gt, With Steen Racing heads Comp 270 Cams Mac long tubes 70 MM Throttle body and Plen, SCT Custom tune by Steen Racing Dyno'ed 314 Rwhp 317 Tq, It was said that my injectors were maxed and I should go to atleats 24lb injectors. With that said * would I need a retune * will there be any real benifit to upping the injectors * any suggestion on brand

08-27-2007, 10:13 AM	#4 (permalink)
Chasinsparks Member Join Date: Feb 2006 Posts: 80	Thanks Hey Thanks for the reply

09-05-2007, 12:41 PM	#12 (permalink)
bossman302 Senior Member Join Date: Apr 2006 Location: Sacramento, CA Posts: 177	Forgive me if I hijack this tread but looks like I need to get 30 lbs injectors for my new engine. Since the ford racing injector’s state the will now work with a stock MAF will the turner be able to recalibrate the stock MAF to work? __________________ Mineral gray 2002 Mustang GT manual 5 speed. Maximum Motor sport suspension. Forge 4.6 with VT stg 2 cams. BBK 75mm tb and LT's. JLT RAI. 290 HP and 308 tq at the wheels.

09-05-2007, 01:00 PM	#14 (permalink)
bossman302 Senior Member Join Date: Apr 2006 Location: Sacramento, CA Posts: 177	Thanks bro, just wanted to check. Was a little worried. __________________ Mineral gray 2002 Mustang GT manual 5 speed. Maximum Motor sport suspension. Forge 4.6 with VT stg 2 cams. BBK 75mm tb and LT's. JLT RAI. 290 HP and 308 tq at the wheels.

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08-24-2007, 10:37 PM	#2 (permalink)
mpt_1962 Senior Member Join Date: Jun 2007 Location: Twentynine Palms, CA Posts: 816	i was told to wait for 24's until i get the heads put on...but since you have heads on go ahead and get the 24's...then get it retuned

08-25-2007, 07:56 AM	#3 (permalink)
r3dn3ck Wowbagger hates me too! Join Date: Nov 2005 Location: Magrathea/California Posts: 7,018	your stock 04 injectors are 21lb. If they were 19's I'd say yeah definitely upgrade too 24's. At 21/22lbs you should be fine but you are approaching where I'd upgrade so might as well. You're at least taxing their duty cycle pretty heavily at WOT. Tuning will have to be updated and the maf curve re-done for the bigger injectors. It's a minor update with only usually 2 dyno runs needed to check AF afterward. I like Ford branded injectors... they're Bosch. Most correctly fitting squirters are bosch made but might as well go FRPP from Randy. Venom also makes nicely blueprinted units.

08-27-2007, 10:39 AM	#5 (permalink)
mpt_1962 Senior Member Join Date: Jun 2007 Location: Twentynine Palms, CA Posts: 816	oh i didnt know the 03 gt's had the 24lb injectors...i didnt ask my tuner about an 03 because i thought they had the 19's also. Well once again red knows all...lol

08-27-2007, 10:48 AM	#6 (permalink)
r3dn3ck Wowbagger hates me too! Join Date: Nov 2005 Location: Magrathea/California Posts: 7,018	they don't... they have 21lb injectors. The 02's do too. 01 and down have 19 on GT's

08-27-2007, 10:51 PM	#7 (permalink)
mpt_1962 Senior Member Join Date: Jun 2007 Location: Twentynine Palms, CA Posts: 816	opps...sorry meant to say 21's. Whats the hp rating that the 21's can hold up to red? What can the 24's hold up to?

08-28-2007, 08:24 AM	#8 (permalink)
r3dn3ck Wowbagger hates me too! Join Date: Nov 2005 Location: Magrathea/California Posts: 7,018	depends on the duty cycle and fuel pressure. Normally I'd say if you cross the 265rwhp mark that you should look to 24's. My handy dandy calculator says 21's are starting to be taxed at stock power levels. Cross 285bhp and 24s become a need to stay under 80% duty cycle at WOT. I have to use 32lb units for my new motor.. you do the math.

08-28-2007, 08:34 AM	#9 (permalink)
mpt_1962 Senior Member Join Date: Jun 2007 Location: Twentynine Palms, CA Posts: 816	that is quite a bit of math. Do you have an excel document with the "input your numbers" for it to calculate it for you? Ill be around 270-285hp after the cam install. So i should look into upgrading injectors to 21's on my 2000? Or just wait til i get it dyno tuned to find out if im running lean at WOT? Actually you said 24's after 265 hp...so maybe even 24's IF my engine is running lean though right?

08-28-2007, 08:50 AM	#10 (permalink)
bassman97 blank Join Date: Jun 2006 Location: North Jersey Posts: 1,497	Go to Holley's website. They have a good calculator to determine the appropriate injector size for you.

08-28-2007, 08:53 AM	#11 (permalink)
r3dn3ck Wowbagger hates me too! Join Date: Nov 2005 Location: Magrathea/California Posts: 7,018	with 270rwhp you should be burning gas for at least 315bhp which causes me to say, time for 24's. It's better to go in with enough injector than to lean it out to find out there wasn't enough flow in the first place. Remember... I'm keeping you at or below 80% duty cycle.

09-05-2007, 12:50 PM	#13 (permalink)
r3dn3ck Wowbagger hates me too! Join Date: Nov 2005 Location: Magrathea/California Posts: 7,018	it's not the maf being calibrated so much as the transfer function associated with it. The only way to properly tune AF ratio is via that, so yes. Your tuner will be able to hand curve the MAF xfer function and you'll be happy as a clam. Most handhelds come with injector options including 30lbs built in. They're never perfect so I still recommend a dyno run with logged AF to check it out.