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12-02-2022, 02:24 PM

#16

RockyMtn96XJ

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Join Date: Aug 2019

Location: Littleton, CO

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Year: '96

Model: Cherokee (XJ)

Engine: 4.0 HO

Quote:

Originally Posted by Randy Bobani

The Jeep engine is port injected and the combustion chamber features a swirl inducing ridge on the plug side. This ridge will atomize fuel even if you blast it in with a fire hose. Multi-hole injectors were introduced to atomize fuel in OHC engines where inducing swirl is impossible. They are also required for 4 valve chambers where the injector is positioned directly in the center of the chamber. AFR being the same, Injector flow rate being the same, there will be zero difference in performance between a Jeep engine with OE injectors v the Chinese 4 or 12 hole injectors.

Dang thats some good info there........... I was wondering what that "ridge" was going into the chamber. I was thinking to myself "what an inefficient piece of crap design this is, let's just interrupt the flow of perfectly good 36-hole atomized fuel so it collects here and then is just rolls off the edge of the ridge and into the cylinder as intake air moves across it and blasts it into the chamber." No wonder there is almost zero improvement when putting in 4-hole injectors.

Now we are going to have people start asking "can I shave off the ridge so my 4-hole injectors work better? I'm trying to hit 18 seconds in the 1/4 mile so I need all the help I can get...."
Seriously though.... what if. Atomized fuel directly into the chamber (ridge removed) vs. atomized fuel thats been re-collected on an obstruction and is then just allowed to flow into the chamber as physics allows it. OBVIOUSLY concentrated and no longer atomized.
Im not talking about a 10hp improvement, but I'm sure acceleration could see an improvement across the board. Maybe even a MPG increase if its effective enough... 1-2 MPG, not miraculously achieving 25 MPG.
This is just hypothetical since I wont be grinding on my motor............. Hahaha...

BTW it took 2 complete sets of china crap injectors for me to get 6 good ones. At least they didnt argue with me and just sent 6 more injectors no questions asked.

Last edited by RockyMtn96XJ; 12-02-2022 at 02:32 PM.

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12-02-2022, 03:02 PM

#17

cruiser54

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Join Date: Aug 2011

Location: Prescott, Az

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Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by vroomvroom

Thanks for advising, I'll keep that in mind. Does he also offer pigtails for injector connections. Mine are all brittle and are somewhat broken. They are hanging on for now but will need to be replaced. At least for my piece of mind.

Yes.

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vroomvroom (12-06-2022)

12-02-2022, 07:52 PM

#18

lawsoncl

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Join Date: Dec 2017

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Year: 1989

Model: Comanche (MJ)

Engine: 4.0

The refurbished 4-hole Bosch I installed were a huge improvement, only because the old ones were weeping gas out of the rusty bodies. Maybe a slightly better idle over the 30-year old originals, but otherwise no real change in mileage or power.

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12-03-2022, 06:44 AM

#19

Ralph77

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Join Date: Oct 2015

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Year: 2000

Model: Cherokee (XJ)

Quote:

Originally Posted by lawsoncl

When I did mine I noticed a better idle and the butt dyno said she responded a little better.
But that too was about it.
Somebody once said a long time ago and I kinda agree with it that it is not the 4 hole injectors that are causing any improvement you see.
It is just the fact that you have fresh clean injectors in there that don't have 200K on them.
LOL.