Topic: 1995 2.5l injector size? and fuel regulator question.

[wrangler387]

I'm starting to look into putting megasquirt onto the jeep as a fuel only set-up for now and havn't seen anything posted on the stock injector size for a 1995 2.5L, any help would be appreciated. I also noticed that the YJ fuel pressure is only 31psi, where as the TJ is higher(i dont remember the number, just that it was higher). Anyone know if i can put the TJ regulator on the YJ to boost the fuel pressure up. I'm assuming the YJ will have a somewhat ok injector size with a fuel pressure of only 31psi. If it is a small injector, has anyone tried putting dsm 450cc injectors on their jeep (they are a little big but really cheap). Or if anyone has put an adjustable fuel pressure regulator on their jeep would be helpfull also.

[littleredbeater]

I think the TJ fuel pressure regulator is in the tank where as the YJ is near the fuel rail. I could be wrong but I think I remember reading that somewhere. If your raising the fuel pressure I doubt you'll need bigger injectors unless your going the go FI and run a decent anount of boost.

[wrangler387]

I am going FI, i'm hoping the injectors are a decent size so that raising the fuel pressure up to 45 will let me keep using the stock injectors for the initial super low boost turbo set-up.

[wrangler387]

since there is practically no info on the 4 banger and a lot of the 6 and what injectors can be swapped... The 4 and 6 use the same size injecotrs right? (as in they are interchangeable)

[Jeffy]

From what I understand the 2.5L YJ has the lowest psi injectors.  I think it's around 18 but I'm not certain.  1995.5 and TJ 2.5L's use alightly larger injectrors. 4.0L's use a 24psi injector, I believe.  The 5.0L mustang injector will swap in it's place.  Not all injectors will swap back and forth since the plug on the end of the injector may have been changed from year to year.

[snowbrew]

Venom also makes a larger injector for the 2.5L.  I am not sure how much bigger it is, but it sure does make a difference.  I have been running the venom injectors for about three years and really like them.  The only downside is when I run the RPM's up and shift, sometimes I get a backfire.
I thought I had a problem and I put the stock injectors back on and what a difference.  The jeep felt really sluggish.  I put the venom back on and the power was back.
If you are going to be doing some serious engine mods then I would recomend the larger injectors.

[Jeffy]

What's the PSI of the Venon Injecotrs?  I suspect they might be using 5.0 Injectors though.

What your gas mileage like with and without?

[snowbrew]

The PSI remains the same at about 31 lbs at an idle.  The venom injectors are suppose to give an additional 10% increase in flow rate.  
As far as the milage goes, I lost only about 1-2 miles per gallon.

[MA2LA]

the injectors for the 4.0 changed over the years since they kept changing the rial pressure. most 4.0 were rated at 19lb ans for about to years they were 21lb. the mustang injectors do flow a little more but its also the spray pattern is much better. for my new moteor i'm goikng to step up to the 24lb injectors since its camed, header and bigger tb and mild port work, for the stock ecm you can use a map adjuster to dial back the fuel if need be.

[wrangler387]

Thanks everyone, i found all the information on what swaps over into the 4.0, but i wasn't sure if the 2.5L and 4.0L injectors were the same actual dimensions (not flow rate, but physical size is waht i wanted to know). I definately won't be keeping the 2.5L, i might get the 5.0 injectors. Does anyone know of an adjustable fuel pressure regulator for the YJ? i really dont like the fact that it is only 31psi.

[BK2LIFE]

your stock 2.5 injectors will flow more than youll need.  swapping to the 4.0 injectors will give you more fuel flow, but i doubt you will ever use it.  your prolly just gunna run way to rich which is bad.  5.0 injectors, wow, there is no way you would ever need this much fuel.  google injector swap, there is a huge write up about it.

[wrangler387]

^ haha. I'm sure i will outflow the stock 2.5L injectors no problem after seeing how small the 4.0 injectors are. You do realize that WOT on a turbo car is typically tuned between 11.5:1 to 12.0:1 for street use right? whereas a N/A is 13:1. I will be using a standalone engine management (something that doesn't seem to popular in the jeep community), hence the Megasquirt. I won't have any issues with running rich, i'd have to go with a extremely large injector to run into issues where the MS 12x12 windows are not good enough.. And i have no intentions of running the injector over 80% duty cycle. Think about it, a turbo 2.5L will most likely put out more power then your average 4.0... with 2 less cyclinders, do you really think i wont need larger injectors.

So for the next question, anyone know what the stock fuel pump can flow? or if it can even handle bumping up the fuel pressure?

[midnightcwby]

Larger, higher flow injector equates to shorter required duty cycle to move the same amount of fuel... right?!

If this is right, then sure you'd want larger, higher flow injectors for your turbo application if your running the Mega Squirt management computer.

I'm going to use a Mega Squirt V3 fuel only setup too.  I'm kind of swamped with my move and all, but I'm expecting an increase in my disposable income after I get a few paychecks from Intel.  This will help 'fuel' my Mega Squirt fuel only project.  

I was wondering about swapping in 4.0l injectors in my early '95 YJ too.  What year injectors from a 4.0l do I need to look for?

[Jeffy]

I believe 4.0L's used the same one, unlike the 2.5L.  The 2.5L changed when the TJ was near completion.  Many parts were fitted on the 95's to see how well they worked in the rear world.  The main difference with injectors though, is the plug used.

[wrangler387]

Midnight, you got it right.

Injector plugs are the main differences typically, but the're are side and top feed, and they differ in heights sometimes too. I'm goign to be putting 450cc dsm injectors onto the jeep once i get megasquirt rolling, i just really don't want to spend (and also don't have the money to spend) 200 bucks for an adjustable FPR. I'm alittle worried about how low the fuel pressure is, because i'm sure the damn spray pattern from the injectors is going to be horrible. I'd like to build my MS board this weekend, but EASTER LOL has me tied up, so i'm hoping the following weekend. I can't wait for school to be over so i'll have time to work on the jeep. I'm hoping i'll have enough time to build my own header/turbo manifold.