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New DAP 100HP SAC 7x9 injectors

01_Cummins_4x4
01_Cummins_4x4
in Diesel Auto Power

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Posted
  • Staff

I just got my replacement injector yesterday since one of them from the original 6 was causing a severe miss at idle, like the pop off pressure wasn't set right.

 

I put the injector in my 01 Dodge Ram 2500 Cummins HO 6 speed 4x4 that I bought 12/5/2020, and it doesn't miss now, but it lopes like it has a cam in it. Unbeknownst to me as this is my 1st HO Cummins (my two previous were '99 Ram 2500 Cummins with a 47RE trans and SO VP44 pumps. I just found out that my Industrial Injection VP pump that is on my pickup when I bought it, is the HO pump. Apparently since the HO pump is a low volume/ high pressure pump, it can't provide enough fuel to feed the 100 HP injectors, hence the idle not being as smooth as normal. I removed them last night and installed my stock Bosch injectors and it runs smooth like it did before I installed the 100 HP injectors.

 

Since I only put 10 miles on the injectors, can I send them back and exchange them for 75 HP SAC injectors?

 

Thanks,

 

Doug

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  • Owner

I would send those 100 HP injectors back for pop testing under warranty. I know a lot of injector builder have set there pop pressure lower 300 to 305 bar (4,351 to 4,423 PSI) to increase the fuel flow. Myself I went the other direction. I'm running 7 x 0.010 popped at 320 bar (4,641 PSI). It does make a difference in MPG and longevity because the bottom limit 293 bar (4,250 PSI).

The ho pump is not causing the issue.  Ho's are plenty fine with 100's

  • Owner

I've seen another member pull his injectors after 28k miles and they fell to 280 bar. He sent the injectors back to re-popped to 315 bar IIRC. Might talk to @pepsi71ocean he could tell you more.

Call them up.  You might have just got a bum injector. It happens.

 

  • Author
  • Staff

I already sent one new injector back and just installed the replacement in it, and it acts like there's a rv camshaft in the motor. It ran great going down the road for a few miles, just noticed the lopey idle.

 

I took the 100 HP injectors out and put my stock HO injectors back in, and the motor runs smooth like normal again.

  • Author
  • Staff
6 hours ago, Me78569 said:

The ho pump is not causing the issue.  Ho's are plenty fine with 100's

What is the pop off pressure of the HO pump vs the SO pump?

  • Author
  • Staff

I talked with Brayden at DAP a little bit ago. He sent me a RMA to send the injectors back to test their pop off pressure. 

 

He said DAP sets their 100 HP SAC injectors at 312 Bar. Their 75 HP SAC injectors are set to 308-310 Bar. He looked it up on their system and said they show stock injectors at 307 Bar. 

 

 

  • Owner

Hence why I did a custom 7 x 0.010 popped to 320 bar. Will admit I had studder and idle issues on SACs vs VCO injectors. My current are VCOs.

  • Author
  • Staff

DAP won't take the injectors back and exchange them for 75 HP injectors for me, but they will test the pop-off pressure on them under warranty.

 

Should I have them set the BAR on them to a certain pop off pressure since I have the HO pump? I'm new to understanding the pop-off pressure aspect of the pump and injectors.

dont make any decisions until they test them for you.   For %99 of the guys out there stock pop is fine.  

  • Owner

Remember the pop pressure only controls the starting point of injection at what pressure. Both HO and SO pump can reach upwards above 18,000 PSI.

 

Like my injectors being raised in pop helped for efficiency and longevity but it makes the timing late so ive got to add more timing on the Quadzilla.

  • 2 weeks later...
  • Author
  • Staff

Lenny at DAP told me that two of the new injectors were only at 302-303 bar. They reworked all of them so that they are at 312-313 bar now. 

  • Author
  • Staff
1 hour ago, Mopar1973Man said:

Should work better.

I got them installed after installing new cab lights last Saturday night. The injectors work great now.

  • 8 months later...

Nowcwhat about SAC compared to VCO

 

SAC slightly more smoke more performance orientated compared to vco.

 

Im probably going to replace my 7×009 sac with sac 7x010 150 or 175 wichever DAP sends.

 

I've got over 100k on my 009s and its time

That topic needs its own thread.. SAC vs VCO is a semi debated topic in the diesel performance world.. 

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