Hey gang, how much do you think the 8.1 truck injectors are good for boost wise on an otherwise stock 5.3?

 

Anybody???

 

are you asking for power numbers or boost numbers?

The 8.1 truck 31lbers are good to around 450-500 the 8.1 marine 42lbers are good to around 600-650. I dont have facts just hypothesizing from what Ive seen.

 

I am wondering if I can get away with running 10lbs of boost on a stock 5.3 with these injectors without having too high of duty cycles....?

 

I would go with the 8.1 marine 42lbers

 

I know, but I own a set of the truck ones right now...

 

u need to feed those injectors with a fuel pump

 

Well with stock 5.3L injectors and 10lbs of boost I was turning with them, I blew the tips slap off the tip of the injectors and washed my rings. They can't handle the fuel pressure you will half to run. I've been running 8.1L 38lbs injectors and they have been doing good.

 

38lbs? You mean the marine ones? I thought those were 42?

 

I run a Vortech blown 5.3L with GM 8.1L Marine injectors and 12PSI boost. My injector duty cycle with 5800 rpm shift points are 115-120 %. I have a walbro GSS341 in tank and returnless fuel system. My truck is being torn down right now to add a cam/stage 2 heads, and 1.85 SLP rockers. Yeah 60# siemens are going on also. I tune with HP tuners and have seen high duty cycles since going to the 3.12" pulley.(12 psi) The only way to guage your correct injector size is to log your tune. I logged a radix blown 5.3L today with a 2.89" pulley and 42# injectors. At WOT and 5500 shift points he was logging 93% injector duty cycles. He had just had a dyno tune last week and was putting out 475 ftlbs/480 RWHP. My setup will be dyno'd on Thursday and I expect to be in the 500 RWHP range with my setup. Again, I run a 58 psi returnless fuel system. If you are running a FMU fuel system then the 42 lb should get you through most whatever you do with the 5.3L Hope this helps....