Project66impala

iTrader: (3)

I have a ls3 that made 493 rwhp with a carb set up, i changed it to fuel injection and im running seimens dekka 80# hr injectors@42 psi, im starting to think the holley system cannot compensate for the injectors being too large?? Im running target afr at idle 15.1 and its running @ 11.1 at idle.. but cruizing and mid throttle im 14.5 and wot im @ 12.2, should i drop down a few injector sizes?the car smells rich at idle as well

Project66impala

iTrader: (3)

The motor is naturally aspirated

Ed Wright

iTrader: (1)

The Holley Commander will certainly handle them if tuned correctly.

soundengineer

iTrader: (16)

First off..., which Holley system are you using....

the issue may be as simple as the fact that those injectors cant react fast enough at idle..
bigger injectors on an engine that doesnt require them, is a bad idea

at idle, an 80lb injector may be looking for an idle pulsewidth close to 1ms.....which most high impedance injectors do not do well trying to open and close that fast.

you may simply need to change to a low impedance injector and change the setting in your holley EFI unit to make it work

Making 493 HP, you really dont need anything larger than a 42# injector
even a 36# injector should work Just fine (I was making 550 on pump gas on a 36# injector at approximately 83% duty cycle)




Please dont post half *** answers.....the OP said nothing about his holley unit being a Commander.

and as a matter of fact.. looking back at his previous posts, he even says in one of his other threads...

Ed Wright

iTrader: (1)

I would think the half-assed answer would be your guessing about big injectors. I don't know how many aftermarket ECUs you tune (I work with most of them), but his Holley (whichever he has) ECU will certainly "handle" 80lb injectors. It is a tuning issue. Is twice the needed injector a dumb choice? It absolutely is.
I realize I probably haven't tuned that many more vehicles than you. Probably no more than four or five times as many. But I have also tuned many boosted engines with 80 lb injectors. They idle clean and run fine at low RPM. Different than tuning small injectors, but very doable.

Btw, my 596 HP 358" LT1 also uses 36lb injectors, at 87% duty cycle.

soundengineer

iTrader: (16)

siemens dekka injectors have issues when they get down to around 1.5ms...
theres a huge dead spot down low where the injectors just dont respond well...

spray pattern is great for an LS motor, but an 80lb injector is going to be near that 1.5ms speed at idle rpm...
its a 92lb injector at 58psi...

its not a guess....its having tuned these injectors on a small turbo car on the stock pcm..

with the Holley HP, he can and should make sure he is using closed loop fueling at all rpms...especially at idle...
if the Holley PCM still cant correct, then you know that the pulsewidth needs to be smaller than the injector can react to, which means he needs smaller injectors, or different injectors to say the least.






I'm not going to get into a pissing match about tuning....i dont even care about how many cars you've tuned, and you would probably be surprised at just how many cars I have tuned over the past 10 years...there was a time when I made a pretty good living tuning cars...I just got tired of tuning cars all day long every day.




Truth of it is... these are the wrong injectors for the application...
Unless the OP has plans of adding a supercharger, a turbo, a dry nitrous kit, or changing to E85...

Ed Wright

iTrader: (1)

I have tuned those injectors with no problems. You were missing something. I just tuned a set last week. I really don't care for them, but they work. They are a very dumb choice for an NA application.