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  #1  
Old October 14th, 2019, 08:52
98xjclassicmc 98xjclassicmc is offline
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What fuel injectors should I buy for an upgrade on my 98 4.0?

Just wondering what fuel injectors are worth the cost for an upgrade on my 1998 Classic 4.0? Is a 12 hole better than a 4 hole?
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  #2  
Old October 14th, 2019, 09:00
RCP Phx RCP Phx is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

The 12 hole's are "snake oil" but I've had excellent results with the 4 hole injectors from these guys. I've got several sets from them.
https://precisionautoinjectors.com/c...jeep-injectors
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  #3  
Old October 14th, 2019, 10:38
lawsoncl lawsoncl is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

Most of the cheap 12-hole injectors are chinese knock-offs of questionable quality.
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  #4  
Old October 14th, 2019, 13:07
98xjclassicmc 98xjclassicmc is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

Yea I'm definitely going with Bosch for sure. Ksuspension I heard is a good retailer too with a lifetime warranty. I just didnt know if 12 was really worth it or if 4 is just as good if not better in regards to Bosch brand
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  #5  
Old October 14th, 2019, 13:58
RCP Phx RCP Phx is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

K fab doesn't have a very good rep on naxja.
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  #6  
Old October 14th, 2019, 14:47
lawsoncl lawsoncl is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

Quote:
Originally Posted by RCP Phx View Post
K fab doesn't have a very good rep on naxja.

Yes, multiple people have claimed they're selling the chinese fake-bosch injectors.


JHC7399 over on CherokeeForum.com sells refurbished, flow matched 4-hole Bosch for a good price. Lots of people reporting good luck with those (myself included)
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  #7  
Old October 14th, 2019, 15:23
98xjclassicmc 98xjclassicmc is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

Oh wow ok didnt know that. Thanks for the feedback on these
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  #8  
Old October 14th, 2019, 21:54
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cruiser54 cruiser54 is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

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Originally Posted by lawsoncl View Post
Yes, multiple people have claimed they're selling the chinese fake-bosch injectors.


JHC7399 over on CherokeeForum.com sells refurbished, flow matched 4-hole Bosch for a good price. Lots of people reporting good luck with those (myself included)

Me too. For a few 4.0s and a 5.2 in my grand Cherokee.
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  #9  
Old October 15th, 2019, 01:04
ijeeep ijeeep is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

If both 4 hole and 12 hole injectors flow 24 Lbs/hr then all things considered your XJ is not going to run faster or jump higher because...24 Lb/hr it's what they flow. That said 12 hole injectors make sense. More smaller holes = more finer spray= easier and more complete combustion.
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  #10  
Old October 15th, 2019, 06:31
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cruiser54 cruiser54 is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

Quote:
Originally Posted by ijeeep View Post
If both 4 hole and 12 hole injectors flow 24 Lbs/hr then all things considered your XJ is not going to run faster or jump higher because...24 Lb/hr it's what they flow. That said 12 hole injectors make sense. More smaller holes = more finer spray= easier and more complete combustion.
12 hole do make sense, except it seems they're all chinese crap.

4 hole refurbished Bosch are still the best choice.
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Old October 15th, 2019, 08:32
RCP Phx RCP Phx is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

Quote:
Originally Posted by ijeeep View Post
If both 4 hole and 12 hole injectors flow 24 Lbs/hr then all things considered your XJ is not going to run faster or jump higher because...24 Lb/hr it's what they flow. That said 12 hole injectors make sense. More smaller holes = more finer spray= easier and more complete combustion.
If it was only that simple! 12 hole injectors will be easier to foul internally/externally.

Example comparing "x" flow rate injectors(not real numbers)"

1 hole injector- (1) 25 micron hole
4 hole injector- (4) 5 micron holes
12 hole injector- (12) 1 micron holes
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  #12  
Old October 15th, 2019, 15:31
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kastein kastein is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

Quote:
Originally Posted by RCP Phx View Post
If it was only that simple! 12 hole injectors will be easier to foul internally/externally.

Example comparing "x" flow rate injectors(not real numbers)"

1 hole injector- (1) 25 micron hole
4 hole injector- (4) 5 micron holes
12 hole injector- (12) 1 micron holes
I agree, though yeah those hole sizes do not scale relative to each other. (it'd be 1x 25 micron, 4x 12.5 micron, 12x 3.6 micron)

Another issue with the 12 hole ones beside all the things already mentioned is that many of the ones being sold are actually intended for 3 or 4 valve cylinder heads. They have 6 holes facing one side and 6 facing the other and spray two separate cones of atomized fuel that on the engine they are intended for would aim down each intake port, but on our intake/head basically point at the port walls. Not exactly helpful.

I personally have never had any problems with stock injectors with hundreds of thousands of miles and thousands of miles of E10 gas through them, so I have not bothered with this "upgrade". It's especially hard when it's difficult for the layperson to differentiate between actual legit Bosch (or other respected aftermarket) manufactured injectors and counterfeit garbage that's being churned out in China and sold as legitimate.
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  #13  
Old October 15th, 2019, 17:46
country2 country2 is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

Quote:
Originally Posted by RCP Phx View Post
The 12 hole's are "snake oil" but I've had excellent results with the 4 hole injectors from these guys. I've got several sets from them.
https://precisionautoinjectors.com/c...jeep-injectors



I went fron the stock 1 hole injectors on my 2000 to 12 hole Bosch injectors and right off the bat I noticed a good improvement in throttle response, smoother idle and somewhat better gas mileage to work in back twice gas needle did not move as far as before but has not been a tank yet.
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  #14  
Old October 15th, 2019, 21:06
ijeeep ijeeep is offline
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Re: What fuel injectors should I buy for an upgrade on my 98 4.0?

Quote:
Originally Posted by cruiser54 View Post
12 hole do make sense, except it seems they're all chinese crap.

4 hole refurbished Bosch are still the best choice.
If your worried there's plenty Bosch OEM Ford 12 hole injectors in the wrecking yards.
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