My vote is go new. Caveat is that the source has to produce known good units. Not bashing any of the outstanding rebuilders, but will once again offer that I have gotten bit by even the good ones. New (known good) has yet to let me down.
Check with Leroy as his site still lists new injectors.
For pressure, my vote is to go with the standard pop. Am sure that others might offer different perspectives.
Whatever you do, do not go with marines. I was not happy with them. Got no difference in fuel mileage or power (as measured by the pants-meter). The marines belched at startup. The OE injectors let the engine rev more freely.
Anymore new vs rebuilt is toss up. As too pressure- its like anything else:
Stock will work. Taking the time to learn what pressure is best with your set up makes it better. But how much time & $$ is if you can affordably learn to diy.
And as Marty said- this is exactly the kinda thing that will eat up time.
One lone truck makes it hard to justify. A couple of them makes sense because you build 2 sets 100psi away from each other and test in each truck. Swap in a set& test out for 0-60, hiway towing power, mpg then in goes the next set. 100psi up. Over and over agin until you know what is good for your set up.
When done if one truck like mine- I have a spare set to go in 100,000 miles later. Pull the others & full cleanup & reset.
I believe some of the power and mpg these engines had is lost due to the new fuel. From making diy fuel I learned different viscosity was a real thing even when btu, flashpoint, gel was the same. It changes the atomization and that is MASSIVE.
Atomize to quick and you loose on the full piston stroke being under power but have more total power thats choppy between cylinders so you loose mpg and peak numbers in the higher rpm band.
Atomize too low and you smoke easier, especially at start up. Easy to burn excess fuel without power gains. This is what I think happened when you ran your marines. Running them needs to fit your application. If you aren’t over 75% throttle often then marines are mistake. Running above 75% throttle often means you’re set up & drive style is demanding more fuel most the time. Now there is a CHANCE they help. Tiny gm turbo and a lot of city driving especially not towing and they are still wrong. Hx35 or bigger, towing, high rpm like hummer/hmmwv kn freeway (wind load similar to gmt400 towing a 2 axle camp trailer): then what happens is this (example not actual numbers),
at 1,000 rpm the marines are fueling as if you are at 1300 rpm
1750 rpm marines are acting like 2,000 rpm this is where they begin to help
2.300 rpm they act like you are at 2,500 rpm
At 2,600 rpm they act like 2,750 rpm.
The higher rpm the ip looses output per stroke. It can’t fill the chambers as fast is the basic understanding. So the MARINES put out more fuel per stroke but do so allow the timing flatter on idle and accurate at your desired rpm- and in a boat that is in the 3800 rpm area.
Starting an old diesel and having some have from fuel to ignore is part of it when your focus is high rpm gains.
But doing this- getting them adjusted to YOUR EXACT engine is a must. How you want the reaction and performance and at what rpm range - injectors putting out more fuel per stroke is gonna move around a lot with different turbos, uses, etc.
you have to tune it to your use or you see none of the benifits.
When a guy has two trucks he can easier justify the time involved because mpg gains are doubled. Not waiting 100,000 miles to use the second set doesn’t have to happen - they both go in right away. And if a guy has say one with an ATT and the other a gm5, he will surely learn two different pop settings work differently. So he gains advantages differently.
We all know we can trust Leroy is selling real stuff. But he can’t control manufacturing errors and changes. I know I am chicken little always expecting the sky to fall. But to me having new ones from him tested is a wise investment.
Anyone jumping to marines is making a big mistake not tuning the pressure to your engine. You can do it with one set but it’s more annoying to drive & record- remove injectors, putting in the yellow caps and spend a day diy resetting. Hopefully installed the next day … maybe next weekend if you are having them done. Then go fill up the tank and start the testing over. Two sets means one day to swap and the truck is on the road. Then the next day maybe you get the 8 that came out readjusted, maybe only get 2 done then it’s dinner time. Two more a couple days later, 1 more the next day and so forth fitting them in as time allows.
Now it’s been a week and your day off is coming- you recorded data each day while driving and that day off they get swapped.
Eventually you see falling number and go backwards by 25 psi, 25 psi, and you learn this truck with this exact set up and this driver with his uses - X,XXX psi is the best.
I can tell you from racing the 6.5 before getting crazy with nitro propane:
Tuning the injectors to your set up can be 40-50 hp differnce and 5 mpg gains.
And most of the set ups I did - peak torque gains fell right in line with peak mpg gains. So having your truck that doesn’t tow a lot often, but you want to be a hyper miler, it still applies. But the day you swap turbos- those peak number can change by a couple hundred psi.
remember folks- all marines do is push more fuel in at every revolution. I will be running them and I will not loose mpg- but remember I am the guy who literally leaves the stoplight and the foot hits the floor. If speed limit is 55 then WOT to 55 and let off until cruising at 60 mph. Johnny law next to me? WOT until 50 then ease up till at 55mph.
I have driven dragsters, motorcycles over 150 mph. A 6.5 diesel is never an exhibition of power. If I didn’t spin the wheels I wasn’t showing off or racing. A short video to the judge how my diesel can ruin a set of tires in minutes and when the testimony of the cop says no the tires never spun- means I never was convicted. One actually tried in my hummer. When I showed the judge 0-60 stock is over 20 seconds and takes a full quarter mile, i said “I show off by looking cool and going slow like a low rider guy. This officer is just jealous.” The judge and everyone else laughed (except the cop). I followed up with “your honor, I would have to have lower to exhibit it and this slowest ever rig since the cars of the Great Depression simply doesn’t have it. No tire smoking video made for that court day obviously. Haha
