I am trying to find out what size my old stock 88 Blazer (350/700R4) TBI injectors are. I did a search and the results have me confused. I found two sizes but they are very different. The two sizes that I have found are 22 lb/hr and 55 lb/hr. One thread also mentioned that the Holley 650 TBI comes with 85 lb/hr Delphi injectors. Is this correct?

I've replaced the stock TBI with a Holley (which I also need the injector size verified for) and am going to start tuning a new chip from scratch becasue of the many mistakes that I've made.

What I am planning on doing (to start with) is to reduce the base pulse width ("bpw" on the 7747.ecu ...correct?) by the difference in fuel flow rates between the injector sizes to get me back in the ballpark, and start on the VE tables from there. Does this sound like a reasonable way to lean things back out?

 

To determine the size of your OE injectors you need to read the color code on the injectors. The color code is located on the top of the injectors. You will have to remove the connectors to view them. The color codes are as follows;

Green/White 40#
Orange/Black 55#
Yellow/Brown 68#
Blue/Black 75#
Dark Red/Dark Blue 85#

I believe the GM Injectors are rated at 13psi. The 350 Truck TBIs were usually 55# injectors. The 7.4 liter used small injectors and high fuel pressure in '94-'95.

I have the Holley 670 replacement intended for my old L03. I believe they stated it had 45# injectors (I heard they were rated at 20psi. Not 100% though). If Holley is consistant, your injectors should be in the neighborhood of 55-60# if it was bought to directly replace the stock TBI (again speculation).

 

[QUOTE=Bones232]To determine the size of your OE injectors you need to read the color code on the injectors. The color code is located on the top of the injectors. You will have to remove the connectors to view them. The color codes are as follows;

Green/White 40#
Orange/Black 55#
Yellow/Brown 68#
Blue/Black 75#
Dark Red/Dark Blue 85#

I believe the GM Injectors are rated at 13psi. The 350 Truck TBIs were usually 55# injectors. The 7.4 liter used small injectors and high fuel pressure in '94-'95.

[QUOTE]

Green/White 55#
Orange/Black 61#

Turbo City - Rock-It Parts

 

Thanks, I had to dig through my box of spare and extra parts to find it though. I took the connectors loose and all I could find on the top of the injectors was a very small dab of black paint. Soooooooo this would mean that they are 55 lb/hr injectors right?

Now to call Holley tomorrow and find out what they rate thier injectors at. Then the fun begins.

 

Green/White 55#
Orange/Black 61#

Turbo City - Rock-It Parts[/QUOTE]

What pressure does turbocity rate their injectors at? I pulled the original injectors out of my old L03 (5.0L) and they were Green/White. IIRC GM rated them at 40pph @13psi.

This site has GM part numbers: http://www.diy-efi.org/gmecm/compone...injectors.html
This site jives with the previous: www.cfm-tech.com/gm_tbi_fuel_pressure.htm

I'm curious which is correct? If these sources are incorrect, I've been using incorrect info for sometime now.

later

 

What pressure does turbocity rate their injectors at? I pulled the original injectors out of my old L03 (5.0L) and they were Green/White. IIRC GM rated them at 40pph @13psi.

This site has GM part numbers: http://www.diy-efi.org/gmecm/compone...injectors.html
This site jives with the previous: www.cfm-tech.com/gm_tbi_fuel_pressure.htm

I'm curious which is correct? If these sources are incorrect, I've been using incorrect info for sometime now.

later[/QUOTE]

Well, I tweaked on my stock 305 with white/green injectors and had the BPWC setup for 55 lb/hr. I used to work at a place that had an injector flow bench. The pair I had flowed 55 lb/hr at 12 psi, that is enough to prove to me. 4.3 injectors are 45 lb/hr. 2.8/3.1 injectors are about 35 lb/hr as well. The orange/black set that I have were 61 lb/hr. I also have flowed a set (I6 injectors OE 1 per engine) at 125 lb/hr.

Let me use math to further prove the point. 40 lb/hr injectors would not be sufficient to feed the 170 HP L03 (180-185 in trucks and vans with the same white/green 55 lb/hr injectors).

HP=lb/hr / BSFC(lb/hr/hp)x2
HP=40 / .500 x 2
HP=160

HP=55 / .500 x 2
HP=220

 

"I flowed them on a flow bench" would have been sufficient

Thanks for clearing that up.