Is your haze this bad with big injectors? VIDEO INSIDE

Gasoline Sucks

Gasoline Sucks

slow 12v
Joined
Sep 21, 2010
Messages
967
I have 042 cut dvs and 5x16 SAC injectors since I'm planning on a twins build soon. My problem is the haze/smoke from 0-10,12psi under very light throttle. I have an in cab pre-boost adjustment and a 180 pump gov spring in the AFC to try to keep fuel down. Even if I adjust the pre-boost all the way out to where theres not enough fuel to spool in first gear it still hazes bad. I'm tryin a set of stock dvs to see if it cleans up but I just want to make sure my timing didnt slip or something I'm missing. I tow a lot and im sick of cleaning soot off customers boats :bang

thanks for any info

FF8FA61F-FB5E-49AD-AAFC-4C9AEDD4672D-17530-000008DE4897E363_zpscfcba126.mp4 video by hondacr8288 - Photobucket
 
Works for me?

Try this one

[ame="http://s408.photobucket.com/albums/pp163/hondacr8288/?action=view&current=FF8FA61F-FB5E-49AD-AAFC-4C9AEDD4672D-17530-000008DE4897E363_zpscfcba126.mp4"]FF8FA61F-FB5E-49AD-AAFC-4C9AEDD4672D-17530-000008DE4897E363_zpscfcba126.mp4 video by hondacr8288 - Photobucket[/ame]



[ame="http://s408.photobucket.com/albums/pp163/hondacr8288/?action=view&current=FF8FA61F-FB5E-49AD-AAFC-4C9AEDD4672D-17530-000008DE4897E363_zpscfcba126.mp4"]FF8FA61F-FB5E-49AD-AAFC-4C9AEDD4672D-17530-000008DE4897E363_zpscfcba126.mp4 video by hondacr8288 - Photobucket[/ame]
 
Yea well if you had to tune yours with a screw driver, a spring and a wrench........ ;)

If i turn it down it will not spool and is a total turd.

Im going to try a lighter afc spring and use a needle valve to regulate pressure to the afc. Maybe it will require less pre-boost fuel.
 
video worked for me, and mine hazed about that much with the 5x20's maybe a little less
 
Mine hazes alot less than that with Westons comps, 7x.013's and a 950cc pump. I'd go back to 181's.
 
My truck might smoke that much at WOT and I tune it with a screwdriver just like you. The 6x16 sacs I had were dirty like your injectors. Swapped to a smaller injector and its really clean now.
 
Mine hazes about that much with the 042s and 5x.017s. Im planning on 181s when i get home. Same deal, cant tighten up the afc enough without killing power.

Sent from my ADR6350 using Tapatalk 2
 
That is quite dirty. Even my previous 5x20s were not that dirty. Two things that have worked for me in my experience in solving this issue: 1) delivery valves (the mushroom style seat works better whether 131s or other 7mm delivery valves); and 2) going from a 145 degree injector to a 155 degree injector. Now, I will say I have never tried a 145 degree sac 5x16 only a 145 degree vco 5x16 so it is possible the angle is not responsible for the reduction in smoke but my gut feeling says the angle is what reduced my smoke. The 5x20s were 145 degree sac but obviously much larger so that comparison is less valid in my estimation.

Now that I think of it nearly ever time i've increased timing part throttle smoke went down as well.
 
Last edited:
The problem with these trucks is you cant move enough air to completely burn the fuel you need to get a reasonable amount of take-off power.. without making a pile of smoke.
Ive tried a few different injectors around the +75hp area and the cleanest was the 7x.010 155*. But the top end power sucked with those. Might be related to fuel jet mass and penetration. Currently using 370 marine injectors with very low timing.
The only thing I can think of that would fix this is a supercharger over turbo combo like crazy carl is doing. I intend to get one of these setups at some point and Ill post all the info I can about efficiency / smoke for you guys. Gotta be a way to have your cake and eat it too with these old 12v.
Newer trucks have electronics and variable turbos that give them a big advantage in this area. I still think the 12v is easier to work on and more reliable in the long run.
 
Last edited:
Two things I have read that I thought might cause my issue.

1. Different dvs result in different timing, some dvs cause you to loose some timing and higher pop injectors casue you to loose timing. If thats true and im only at 17* if my injector pop retards timing a bit plus the dvs robbing some timing I could be back to stock timing.

2. I have read the SAC is known to be dirty due to the tip design? Figured its not helping. Im going to try smaller dvs and a timing bump ~2-3+ degrees. Hopefully it helps. I dont think my TIGHT converter is helping either. Stalls around 12-1300 rpm but i can make 10 psi by 16-1700rpm.
 
The 6.7L engine was the first Cummins engine in an on-road application to use a sac type nozzle, and at the time is was the most stringently regulated emissions engine Cummins had produced. So if this can be achieved with a micro-blind sac nozzle, I feel it may be a bit unfair to make an assumption that the nozzle design is the root cause of what you are seeing.

Each truck reacts differently to additional fuel/timing and cone angle alterations, you need to find what works best for your setup, this is often a bit of a pain, but part of the deal.
 
Last edited:
I messed with injector pop a little. Went as low as 260, as high as 300. Lowered the smoke and power with higher pop-off. I dont think the extra pressure does much, the shortening of the injection event is probably what does all that.

I think low stall speed plays into the smoke too. lower RPM means lower intake velocities.
 
You must log in or register to reply here.
Back
Top