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Anybody running 12 hole injectors?


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I plan on doing the injector upgrade very soon and was going to use the Bosch 746 4-hole injectors. Ran across some info where some people have gone to the Bosch 12 hole injectors over their existing 4 hole injector upgrade for even better atomization. Most reported smoother running and more responsive acceleration, a couple noted minor increase in MPGs. Price is @$40 more I believe. Curious if anybody has installed these and general opinions considering "more is not always better". Flow rate is 24/lb on the 12 hole units.  

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I replaced my 1 holes with 12 holes injectors from ksuspension https://www.ksuspensionfab.com/store/p22/New%2FRemanufactured%3A_12_Port_Upgraded_Injectors.html So far the injectors have been good, I can confirm that the engine does run smoother at idle and has increased thottle response from me driving the truck  around my neighborhood. I can't confirm improve mpg with them since I haven't drove my truck much since I am restoring/modify my truck right now. Heads up when you install the new injectors your engine may run rough for about 15 minutes while the Ecm learns the new injectors. Hope this helps.

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44 minutes ago, Pete M said:

improved running over... what?  the brand new 4-holes they were running?  or the 30 year old 1-holes they were running? 

They had already replaced stock 1 holes with 4 hole units and were happy with them, but then recently went to the newer 12 hole units. They both seemed to feel the idle and throttle response improved again, much like it had when going from 1 to 4 hole. Others reported additional MPG gains............

 

Limey, after more research, apparently stock flow rate is 23.2/lb which is interesting considering that I had planned on the 746's based on many discussions here. 746's come to find out are rated at 20.2/lb. Also have seen a lot of info on people running 703's (23/lb) on Renix 4.0's because they have the same EV1 connectors. 99+ guys seem to mostly run 784's (24.4/lb), they have the EV6 connectors. 

 

I just want to make sure when I purchase "new" units, I've got the best ones suited for my stock Renix 4.0L and only have to swap them once. 

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1 hour ago, jeeppapa said:

Really good info here guys. I’m going to upgrade my 88 Comanche and the 01 Cherokee. Squeeze as much mileage as possible.


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Search 746 injectors here and you'll have plenty to read LOL. The more and more I read the 746s are definitely the recommended units for your 88 Renix, and 784s are well received for your 01 XJ. Saw plenty of negative comments on the 703s. Your XJ might be a good candidate for the 12 hole units (0280 156 161). 

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It all depends at what pressure the injector is rated for. A 24lb injector at 43 psi would be about 21.7lb @39 PSI. If it is rated at 39 psi then it would choke a Renix.  Stock renix injectors are 21lb @39psi.  If your injectors are 23.2lb @49psi they would be around 18.4lb at 39 psi which is a bit small. If they are 23.2lb @43psi then they would be dead on 21lb which is perfect for a Renix. a lot of Bosch injectors are rated at 43 psi. I suspect these are too.

 

To calculate flow you need to do the following calculation:-

 

(New PSI/Original PSi) x Original Flow. So a 24lb @43PSI injector flowing at 39 psi would be (39/43)*24= 21.7.

 

Most early HO stroker guys use 24lb/39 PSI Mustang 4 hole injectors. Which on the 39 PSI HO rail gives you enough flow for the bigger combustion chamber. (96 onwards had 49 psi rails so 30lb Ford injectors are needed.

 

Knowing the PSI the flow is rated at is critical in making a correct decision.

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4 minutes ago, Gubachoo said:

 

Are they cleaned units from programbo or used ones from somewhere? I might be interested. 

i bought them new and used them on my 4.0 for nearly a year.  I've not done anything to them besided remove them, put them in a ziplock and place them on a shelf.

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You can also look at the yellow Ford injectors (556) they are available in both plug styles.

 

Cheap and readily available (4 hole)

 

I have run them in both my 2.5 and many 4.0's and am very happy with them......

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Picking up a set of 746s from coolwind57. Looking forward to installing them when the weather is consistently warm. I've also got a bored TB from Mean Lemons to install and was going to replace the IAC, TPS, O2 sensor and do Cruiser's CPS mod too. Oh, and I have a 90 ECU to swap out also. If I was a patient man I'd do these step by step and see how each improved (hopefully) how the truck runs. But I'm not sure I'll be able to do that......get 'r done. :brows:

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1 hour ago, WahooSteeler said:

Picking up a set of 746s from coolwind57. Looking forward to installing them when the weather is consistently warm. I've also got a bored TB from Mean Lemons to install and was going to replace the IAC, TPS, O2 sensor and do Cruiser's CPS mod too. Oh, and I have a 90 ECU to swap out also. If I was a patient man I'd do these step by step and see how each improved (hopefully) how the truck runs. But I'm not sure I'll be able to do that......get 'r done. :brows:

 

i got the bored Renix TB from Mean Lemons too.  One of my all-time favorite mods.  Made a big difference on up-hill power!

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On February 28, 2019 at 3:15 PM, WahooSteeler said:

Picking up a set of 746s from coolwind57. Looking forward to installing them when the weather is consistently warm. I've also got a bored TB from Mean Lemons to install and was going to replace the IAC, TPS, O2 sensor and do Cruiser's CPS mod too. Oh, and I have a 90 ECU to swap out also. If I was a patient man I'd do these step by step and see how each improved (hopefully) how the truck runs. But I'm not sure I'll be able to do that......get 'r done. :brows:

 

Patience, grasshopper:laugh:

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I did the O2 sensor first. Mine was game over, it didn't ever go to closed loop. Drove like a 30 year old truck after that. Then I did the 746 injectors or the PCM next not sure. The PCM seemed to help the idle, it seemed smoother. The injectors make a very noticeable difference. They are awesome! Drove better than ever. Then I did the bored throttle body from Meanlemons. That is a game changer IMHO. Truck runs like a scalded dog. Now to see what indexing the distributor and new wires will do. 

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15 hours ago, JMO413 said:

I did the O2 sensor first. Mine was game over, it didn't ever go to closed loop. Drove like a 30 year old truck after that. Then I did the 746 injectors or the PCM next not sure. The PCM seemed to help the idle, it seemed smoother. The injectors make a very noticeable difference. They are awesome! Drove better than ever. Then I did the bored throttle body from Meanlemons. That is a game changer IMHO. Truck runs like a scalded dog. Now to see what indexing the distributor and new wires will do. 

 

careful, at this rate of improvement you may end up with a self driving truck. :D  or maybe a flying truck?  topfuel dragster?  something epic for sure.  :comanche:

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4 hours ago, Pete M said:

 

careful, at this rate of improvement you may end up with a self driving truck. :D  or maybe a flying truck?  topfuel dragster?  something epic for sure.  :comanche:

Just shooting for a reliable fun to drive truck that everyone stares at. So far I have achieved the goal! There aren't many Comanches in southeast Iowa.

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