Ok, I have a 5.3l 99 Silverado with a whipple (7lbs.). I installed 8.1 liter injectors and now need to dial them in with ls1edit. I can't figure out what values to put into the excel formula found on ls1edit@slowcar.net . Stock numbers were 2.74 across the table on the stock tune. I think the 8.1l injectors are 29-30lbs. fuel pressure is stock.

 

I think the 8.1 trucks had a value of 3.77 across the board stock. I would start with an IFR around 3.77 and then fine tune your LTFTs from that.

 

where did you get your injectors metal man, how much were they, and are the just plug and play or did you have to modify some stuff?

 

I got them from the dealer (cost+10%) for about 450 i think.They are just like the stock ones so theres no mod. involved with the install. If you don't need tons of fuel i would go with them. I also still us the whipple injectors, so that makes 10.

 

Looks like you finally decided to post :p How's it going man!!

It seems like no one knows exactly what the 8.1L injector lb/hr flow is from searching HERE versus HERE. I tried gmpartsdirect.com with part number 17124531 which is for a 2001 8.1L injector, but that did not tell the exact flow rate in the description either. They are correct with the 3.77 flow rate that I found reading HERE I know that our trucks do run at 58psi fuel pressure like F-bodies. However, I am not 100% sure what the stock GM (Multech II)injectors are rated at - either 43.5 like most injectors, or 58psi like they opperate at...?

Using that Excel spreadsheet, I put in the numbers 30lb/hr, 58psi fuel pressure, and 43.5 injector rated fuel pressure (which I am not positive of being rated at 43.5 or 58 psi) and the injector scale came up with these numbers for the new injector flow rates:

Injector Flow (g/sec) 7.621021231 7.668517747 7.715721889 7.762638991 7.809274226 7.855632614 7.901719028 7.9475382 7.993094724 8.038393067 8.083437569 8.12823245 8.172781815 8.217089657 8.261159862 8.304996213 8.348602394
that didn't format too well...but just use the lowest number and put it in the 0 spot and continue filling from lowest to highest value, highest should end up in the box under the 80.

I don't know how they are figuring these numbers on the spreadsheet equations, and they seem really high. After all of this being said...I would just try the 3.77 alll the way accross the table first

 

Someone needs to get the offset information for these injectors. I have heard the 3.77 number several timees in the past, so I would think it is correct. I have a set of these injectors that I haven't installed. I was waiting for someone to find out the correct flow and offset first.

 

the injectors that came w/ the Radix are the 8.1L Marine injectors and the had a 4.17 number with the Magnuson programmer.

 

FLEM - besides the 4.17 flow rating, do you happen to have the offset numbers for those injectors? That sure would take alot of the hit or miss out of programming them.

 

Thanks Hohl. Here is what I have so far:

Injector Offset

Its a quick spreadsheet with injector offset values from LS1 edit for a few different years, including my 03 SS and Flem's 02 with Radix. As you can see, the 8.1 injector's offset value are over 100% different in most areas. So much for the idea of leaving the stock offset in the PCM because is close enough.

 

Hey Ryan. Thanks for all the info guys. I will give this stuff a try and let you know how it works in a few days. What do you guys suggest for the injector offsets? Does anyone know how big the whipple injectors are? Thanks