I should have left my truck at the 500hp level. Never ahd a single issue with it. Ever since I started the quest for 600+, I have had nothing but problems.
Anyway, here is the new one....

Towed this weekend for the first time with the Flux 1.8s. It maybe injectors or it could be the turbo going bad - haven't checked for shaft paly yet. I don't know much about drive pressures and how they relate and affect boost - maybe someone could fill me in on the basics - but, I think I have a drive pressure problem.
When towing up a highway with the cruise set at 60mph, on inclines the boost would start to rise and around 15psi the turbo would start to sputter and bark and the boost needle was fluxuating drastically. It is just like bark from letting out of the throttle, but mind you this is under throttle. It would do it until about 25psi. Anything over 25psi it was fine. I could force it into 3rd gear and the rpms and boost would come up and it was fine. I could pull the hill at 70mph and it barely did it - due to the fact that boost was higher trying to maintain speed. This was with only the injectors and turbo. I tried various levels of the Juice. Level 2 would still do it but not as bad but would lug really bad and smoke like crazy. Level 5 wouldn't do it vary bad at all but would lug and smoke like crazy and then pull through to higher boost. I haven't been happy with the combination of the injectors and turbo since I got it back because it smokes like crazy until the turbo lights - which is normally at about 15psi. I know there are guys out there towing with 100hp injectors. What do you guys think is going on?

 

I have 3 flows with a 66 never had a problem but i have a 6spd??? Mine will smoke really bad until the rpm's come up also the only time I have heard a surge is when I was going about 40 mph and shifted to 6th with my horse trailer on.

 

That my friend is surge...drive around it...always tow above 2k...you will get better mileage too!

You have too much fuel and and no RPMS to eat the boost...your turbo wants to make...but can't...and stalls...surges.

 

seems like it is harder to control with an auto?

 

Also..make sure your electronics don't fuel too hard/fast on low boost while towing...

I have my "tow" settings in the past...a little softer on the bottom than my "race" settings.

 

That's just it. There is no driving around what it is doing. The only way to accomplish that is running in 3rd gear and it gets horrible mileage then. By the way, I have always gotten the best mileage keeping it under 2k. As soon as it breaks 2k it falls like a rock - loaded or empty.

So is the surge from the injectors being too large then? Before the injectors I could run the Juice on any power setting - including off - with no issues.

 

I'm not sure what the wheel sizes and housing sizes are on the A3k. If I went to a compound set up with a 62 or a stocker as the top, would that solve my problem or would it be worse because the big brother would be kicking in too soon?

 

I would not think the A3k would cause this... should be an equivalent to a 62/14 or close. If you went to a compound-- let me qualify this as a new "twins" owner and just learning a lot myself so don't consider this gospel and wait for someone like Nathan to chime in-- the stocker will allow you to spool faster but really limit you on top end. You WILL tow better for sure. If you go to a 62/14 on top... it will give you great top end and high hp but I think way too laggy for towing. Even ATS on their compounds, which are really aggressive BTW, use a A2K and A5K. A big brother would not kick in too soon and is maybe way too much turbo for towing. I do think that for good towing, flux 1.8 may be too much... maybe 1.5 tops... but I am not an expert there either, let Don M answer that one. I know I am going with flux 1's with mine. Personally--JMO-- I think you have a bad match of components for towing. Dragging-- great!

 

I can tow great with Flux 3.3's...and a 64/13 doing most of the work. Get a few miles on the set up and you will be able to figure it out. It took me 2,000miles before things started to feel right again with my new set up.

You may have a hole in your "towing speeds". With my A5k before...I had to be 70 mph or less in 3rd or 80 or more in 4th. Now...I have maybe a 5 mph "hole" around 70...

I think "smaller" twins would work for you...but I can't believe you can't make that turbo work right now. Turn the Juices low end fueling down to 1 and the MP-8 almost off when towing...then play with the high end Juice settings till you find a "smooth" fuel curve you can control with your foot.

 

That is the only thing I didn't try. Turning the low boost fooling down and running the Juice on high settings. I still think it will smoke a lot, because even with the Juice off it smokes a lot under low boost conditions. But I will certainly give it a shot.
I notice you have a TC switch and controller. Do you do anything with that set up while towing to manage things better?
What I don't want to have to do is what you stated above. Under 70mph be forced to run in 3rd gear. I like it when I put it in OD and left it alone no matter what. If it needed to pull a hill the boost would come up and it never shifted down and didn't smoke so bad I couldn't see the camper. Do you think twins would re-achieve those results?

 

I keep my converter locked almost all the time...unless I am stuck in a low rpm situation. It is impossible to cram 500 hp plus of fuel through out motors at 1200-1900 rpms IMHO with a load behind...

Unloaded...the truck will accerelate quickly enough to allow the air to catch up...but with a load it will not...and bam...surge, smoke, heat! I have surged my A5k so hard once that it locked the tires up with a HUGE trailer behind me.

You may have to rethink your electronics and try somethign else...to get more adjustibility or a different fuelign curve to work with the "bigger" sticks. Yours are not THAT big...but maybe too big for the fuel delivery of the Juice.

I get better mileage at constant cruise at 80 than at 70. My boost is 7-8 and 800 on the pryo at 70 and 1950 rpms and 11-13 and 700 at 80 at 2200 rpms. I think that the turbos are just on the MAP better above 2k in my set up. The A5k was happy above 2k too. I towed 25k plus several times...1000 mile plus trips and was happy at 80...just not at 70 or 75.

The more modded the trucks are...the more particular thy become to some degree...