1.7 Roller Rockers just make your cam seem bigger than it really is. It increases lift, and duration at .050. JUST doing the rockers adds about 10 hp/tq. (verified on a dyno too.) It doesn't change mixture ratio, it simply lets you get more fuel/air into the cylinder. Thus, more power.

 

I understand that. Let me ask a question about the operation of an injector on our motors. Are the injectors told by the computer to inject gas at a specific time and duration or do they just inject constantly? I know this question is juvenile but it is to help me get my thought across. Tell me if Im wrong.....In a stock motor the injector is timed to disperse gas when the intake valve is opening and stop dispersing gas just before the valve is closing? if that is true then ( correct me) a valve that stays open longer (from a 1.7rr) is still only getting the same amount of gas dispersed as if it was still using stock rockers. I mean that, just by installing 1.7 RR doesnt tell the pcm to make the injector disperse gas for a longer duration. So what it really is getting more of is air......along with the stock amount of dispersed gas which intern leads to more fuel(gas and air) to be burned which produces more hp. I guess this whole thing is about the injector when does it shoot and when does it stop and for how long......

 

The injection event occurs just as the valve is starting to open. The idea is, the fuel hits the back of the hot valve, and instantly vaporizes, while flow velocity is at it's highest point.

PCM controls "pulse width" (how long the injector says open) according to what the O2 sensors are telling it about oxygen content in the exhaust (closed loop operation), or, according to data tables it consults (open loop operation)

It is a sequential system, in that only one injector is firing at a time, at "just the right moment"......

PCM doesn't care how long the valve stays open, or even how far it opens, in determining pulse width, it's all about what the O2 sensor is telling it. So, having the valve open faster/further, allows more air into the cylinder, the PCM sees that, and adds more fuel.

Clear as mud?

 

Thanks! I forgot all about the 02 sensors! Duh! Thats why you are the master and I am but the learner.

 

Yep I'm talking about injectors. You see on facebook groups all the time where guys will tell you to put on a cold air intake, headers, throttle body, and ford mustang 4 hole injectors. Here's where the problem lies. Like HamBone has said and HeyYou (iirc anyways) have stated in this thread and others, these trucks were designed with pencil stream injector with the fuel vaporization idea. 4 hole injectors simply mist 4 round patterns and the air is used more to carry it in. Waste of time, money, and headache. On a stock truck the 4holes run too fat and rich down at low rpm and can hurt idle quality IF you got a quality set that isn't in fact something completely different. For example, I bought a set of what was labeled as Ford Cobra Mustang 24lb/hr @ 43.5psi EV6 injectors off eBay (first mistake) for my own experimentation. They arrived and after checking p/n's and contacting rebuilders, I found out that they are in fact rated (more specifically) at 23.6lb/hr @ 3bar (43.5psi) vs our 22lb/hr @ 3bar and 236cc/min vs our 220cc/min, from a CADILLAC SEVILLE/DEVILLE. BUT I got lucky and they are high impedance like our stockers, 12ohm vs stockers 14.4 ohms. If you look at my sig you'll see what I have done, so I swapped em in and ran em for a full month. Here is what my experiment yielded:
IDLE: no change
LOW END: slight more response for the initial takeoff, then as soon as 02 sensors kick in, lag in throttle and dead spots
MID RANGE/CRUISE: dead spots. They run more richly and the PCM can't trim them back very quickly so you get spots where it's extra lean
TOP END/WOT: she screamed, noticeably torquier. I attribute this to being a little richer and the PCM ignores 02 readings at WOT
In the end the dead spots became annoying and irritating beyond belief. Swapped stockers back in a week ago, kinda pissed at myself that I didn't wait though because I have a bung for a wideband 02 getting welded in on Monday. Kinda wanted to get a/f readings vs stock. Kept em though so I still could, it's just a pain in the ***. Truck starts and idles the same with stock, smoother pull throughout the rpm range though. Overall the truck is quicker with the stockers.

 

I *think* the idea behind the four-hole injectors is: Better atomization of the fuel. Now, does that actually make any difference to our engines? No clue. I would dearly LOVE to see side-by-side dyno runs with the injectors being the only difference.......

 

Hats off to dapepper9 and hey you for taking the time to explain it all...thoroughly.....Thanks guys.

 

... well, I guess the injector idea is no longer something I need to worry about. One less thing to spend money on.

 

Depending on the age/condition of your current injectors, it may still be a worthwhile upgrade. Consider how long yours have been in there..... just doing to a set of balanced/cleaned stockers could make a difference in how your engine runs. (and probably will..... )

 

Our engines are the exact opposite of the sort whose induction systems exhibit the problem the finer atomization solves, so all else being equal, which it likely ain't, just knowing that finer atomization is happening in there would probably make it all better in a surprisingly large number of cases.