Heads, Cam and Injectors?

**ls1camino** · 11-08-2008, 02:08 AM

Stock LS1 injectors are 28#, correct?

With a 224R or 228R cam (haven't decided which one yet) and Ported 5.3L Heads, should I upgrade my injectors too?

**SOMbitch** · 11-08-2008, 03:25 PM

00 are 26.5 #er's but you are fine.

**Frans96ss** · 11-10-2008, 07:26 AM

Originally Posted by ls1camino

Stock LS1 injectors are 28#, correct?

With a 224R or 228R cam (haven't decided which one yet) and Ported 5.3L Heads, should I upgrade my injectors too?

Deff upgrade injectors if you do a heads cam set up. They will max out with most cams.

**mark21742** · 11-10-2008, 06:53 PM

if you have a program that lets you check your injector duty cycle do so. if they get up to 80-85% duty cycle you should get larger ones

**twoolley08** · 11-10-2008, 07:20 PM

how about just cam no heads? which programs can check the duty cycle of the injectors? can dealers do that?

**mark21742** · 11-10-2008, 07:24 PM

Originally Posted by twoolley08

how about just cam no heads? which programs can check the duty cycle of the injectors? can dealers do that?

a tuner can check and see your duty cycle very quick on a dyno or a street datalog. plus there are fomulas if you search for them to figure out what size injectors you need. i found them awhile ago but cant remeber where

**blackbirdbrain89** · 11-11-2008, 06:02 AM

dude im max out my stockers and only puting 341hp to the wheels give or take a few from last dyno more likey give but im am doing a set of 5.3 heads ported and 2.055 valves and im going with 39-42 if i can get a set cheep. http://www.rceng.com/technical.aspx use this site works well and can tell u wich injectors ur going to need

**ls1camino** · 11-11-2008, 08:26 AM

Since I'm not completely sure how much hp I will be putting down with this setup, is it ok to get larger injectors (like 42s) and just have them run at like 70% duty cycle?

**side2000** · 11-11-2008, 09:40 AM

Originally Posted by ls1camino

Stock LS1 injectors are 28#, correct?

With a 224R or 228R cam (haven't decided which one yet) and Ported 5.3L Heads, should I upgrade my injectors too?

the injectors in your 2000 will support (conservatively) about 350 wheel at 80% duty cycle-which is completely within reliability range (i used a conservative .5 BSFC variable for all who may criticize my math). with that cam i'd say you will still be fine. i ran my stockers to the ground at about 95% duty cycle and over 400 wheel.

**side2000** · 11-11-2008, 09:49 AM

Originally Posted by ls1camino

Since I'm not completely sure how much hp I will be putting down with this setup, is it ok to get larger injectors (like 42s) and just have them run at like 70% duty cycle?

yes. you can run a big inj at low duty cycle. that's really what inj's prefer doin but they are just more expensive and "can" be a little harder to tune properly.

**mark21742** · 11-11-2008, 02:17 PM

Originally Posted by ls1camino

Since I'm not completely sure how much hp I will be putting down with this setup, is it ok to get larger injectors (like 42s) and just have them run at like 70% duty cycle?

+1 for side2000, just dont want go too big because you would endup with a large quick burst of fuel from the injector which will lessen fuel atomization and could lead to pooling in the heads.....but yes 70% would work and leave room for other slight upgrades

**SOMbitch** · 11-12-2008, 05:16 AM

You hear so many different opinions on this but the 80% rule is correct. I made 417rwhp/383tq. on STOCK injectors so take that for what is worth. Not sure of my Duty Cycle but my tuner said I was OK.