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4 hole injectors


NAXJA Forum User
Where is a good place to get a good set of 4 hole injectors for a 95 right now? Mine have 300k on them, and it has always taken forever to start so they are probably way past due. I eventually plan on a stroker, I already have a crank and block, so I might as well do a little better than stock now. Or is there something else that will play nice with my current wore out motor but also be good a year from now if it takes me that long to build a stroker?
Seeing as you have a 95, tuning the engine is limited to adjusting fuel pressure, adjusting input voltage to the MAP sensor to make the computer think the engine is working harder than it is or by changing fuel injectors to a higher flow rate.

Unless you update to a 96 ECM, or some aftermarket solution, to gain the ability to tune it, buying fuel injectors now sized for a stock engine will severely handicap your ability to tune for the stroker when you get it assembled and installed.

Dino's website has quite a few different stroker configurations with appropriate fuel injector flow rates estimated for each one. Compare something close to what you're thinking of building to stock injectors and see how much they differ.
It going to be super mild, it's for my mail jeep. Don't need big numbers, kinda just doing it because I came into the parts and have the chance to. I have to do the full machine work on the old motor so not much added cost to what I already have to do. Would like to build an engine that would last me another 300k.
Seeing as it's a work vehicle, you'll save money by staying with the stock flow rate. "Lucky" for you, the 4.0 heads don't flow as well as the stock engine could utilize, so going to 4.6/4.7 with a stock head won't get you the full 18% increase in performance, and therefore demand for fuel, that the increase in displacement would otherwise warrant.

For conversation purposes, let's call it 10% increase in potential power w/ a stock head. Once up to speed and the ECM registers it as "cruising", the O2 sensor will be used to richen the mixture to account for the change. Outside of that "cruising" mode, the ECM won't know any better and will give it exactly the same amount of fuel it is now, saving you money. You give up 10% performance, but being a work vehicle...

I don't know if I'd call it sarcasm, but definitely a certain amount of "knife in my temple" twitch in saying the above. It is completely counter to my gear-head ways. I half became physically ill even typing such words. But the facts aren't wrong. I could make the argument for swapping in a worked over 4-banger to save yourself even more money. But, back to reality...

The Jeep 4.0 is as the reliable beast partially because of it's Rod Ratio, the ratio of the length of the Rod to the stroke of the Crankshaft. On a stock 4.0, it's 6.123"/3.413", or 1.794. According to the post linked to below, Rod Ratios between 1.65 and 1.80 are best, with 1.50 being minimum. With the 4.2 crank and 4.0 rods, it's 6.123"/3.895", or 1.592. Better than the stock 4.2 ratio of 1.508, for perspective. (Source & a lot of other good info: https://www.jeepforum.com/forum/f176/stroker-regrets-997768/#post9154151)

Add the additional wear-and-tear for the 18% more power, oh wait, you didn't get any more power because you're running the same fuel injectors, but anyways... :) Seriously, more power equals more wear on the rod and main bearings, cylinder walls, piston skirts, etc. Long story short, If you're trying to get another 300k, building a stroker is not helpful... Don't get my wrong, we're all in the same boat w/ it costing not much more for a stroker. It's everything else that goes with it that "adds up"...

If I were in your shoes, and even in mine, I would get in contact with Russ P. and make sure that I wasn't painting myself into a corner. SCR, DCR, quench, the list goes on. A few extra $$ spent up front for the right pistons, or camshaft, or ... could save you big $$$$$$ down the road. For a work vehicle, the last thing I'd want is a poorly running, pinging POS that required premium gas. At least yours won't use as much since you'll have undersized injectors... Last time, I swear... :)
Rod length in a 4.0 is pretty irrelevant since it's not known as a high rpm motor. That being said I will go with the long rod anytime over a short rod.
So I'm putting my 258 crank up for sale, im never going to get to building a stroker. My injectors do need changed, it's always taken forever to start and I'm sure they are still the originals. I just passed 310k the other day. So the question remains, where can I get a set of good, matched 4 hole injectors? I've seen several people lately have issues with cheap sets and want to avoid that!