Intake valve doesn't even start to open until 13 (or 7, depending on year) degrees BTDC. Reference. I can't find anything on injector timing (with a cursory search) could you site a reference for your numbers?

 

Someone seems really salty....

 

I changed to 4 port injectors when I fitted the FI-Airgap, so I don't know what performance change is actually attributed to the injectors.
Like I've seen others comment on in other threads about 4 port injectors, I did perceive a smoother idle.

 

I'm in that same position but even worse , bigger engine , M1 , 52mm TB , tuner , and headers going on all at once . Which gets the credits ?

I could swap in new after the install as I have 3 sets of stock injectors and a set of new seals , but , I don't want to work on it once it's in .

I do like hearing the smoother idle , that alone tells me it's more efficient . I know the jeep guys love 'em . I just never bothered to try before . I don't see any negative getting them , if anything , knowing they are flow matched will certainly be appreciated by the engine . Your smooth idle is probably 1 result of the flow matching .

 

How about putting the injectors in after the main hardware you listed? Simpler swap out in comparison and you'd have an idea of the change on the build (for that baseline) on injectors.

As an M1 user for the last 3 years(?) I can attribute smoother idle with it and my stock injectors. No way can I say that would be akin to your setup.

What is your air intake setup?

Is this engine going to be a street killer, mixed use, hauler, tow rig?

As for mist vs. flash boil...the mist will always be more efficient due to available surface area. The flash boil is only as efficient as how much liquid contacts the valve or hot surface. The fluid behind the initial contact does not benefit from that as the temp drop occurs.

Anyone have pictures of that valve surface after 150K miles by chance?

 

Just out of curiosity. How can the stream flash boil on initial startup? Nothing has come to temperature yet. Wouldn't this cause the fuel to stay as a liquid causing flooding?

 

It won't. But, the valves will warm up fairly quickly. this is probably taken into account by the PCM...... what it does about it, I don't know. (probably sprays more gas, so that simple evaporation will give an explosive mixture....)

 

I did intake, TB, and injectors at the same time... I already had SCT prior, and changed from 87 to 92 a few weeks after the hardware changes.
The CAI was well before anything else, and the headers & exhaust was the last thing.

Next round will be heads, H&S RR, valve springs, and a cam.

 

I have a back/neck injury so I'm trying to reduce under the hood times . I'm going to get it ready to pull , then get some help to swap , and then button everything up after on my own . Love to do them separate , just not this time .

Air intake hasn't been decided just yet .

Sleeper , but , I live on the hwy with lots of traffic and a 70mph posted . 0-60 is important .Also , with hills , I'm getting tired of dropping a gear in the 5.2 to keep speed . 35 mile commute to the city . If a city dweller , I wouldn't even bother to swap . After all , this 5.2/truck doesn't have 50K . It'll make a great spare engine .

Thanks for the PM

SpilliageI was thinking 1.7 roller rockers would be my next move . Hopefully I can stop at that point , lol .

 

No need to copy/paste the info from reading on the internet,ive done it... The dizzy rotates which passes through the cam sensor and sends a 5v signal to the pcm not only to fire the injector but to locate the #1 cylinder for itself and the crank sensor. So every time this 5v signal is triggered the pcm can locate and fire the #1 injector... Now Back in the day we didnt have fancy scan tools to set the fuel sync so we had to set it manually with a DVOM. Per the FSM This required setting the crank to #1TDC then advancing the crank to the V8 mark which is 17.5 ATDC(piston traveling down) then rotating the dizzy until you read 5volts on the DVOM which fires the injector. Looking at the cam spec we know that the valve is open on the V8 mark which is @17.5ATDC, so the piston is moving down and the cam sensors 5v signal is triggered thus firing the injector into a open valve not a closed valve. There is no 5v signal from the cam sensor when the valve is closed(7-13*BTDC) thus the injector will not fire....Good'ol magnum heads are a 18* HIGH SWIRL wedge head. Which swirls faster/better, heavy raw fuel droplets(stock injector) or a lite fine mist(4hole injector)? Will you see staggering/huge results on its own, no. Add some performance parts like a multi spark ignition,air intake,larger TB,good headers,exhaust ect..ect.. then you will notice the greater improvement the 4hole injectors provide. It is always the sum of the parts working together.