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205/100's and a 68 setup ?'s

10K views 13 replies 10 participants last post by  SCjake  
#1 ·
Hey guys, Im running 205/100cc injectors form Holders diesel and a 68mm KC turbo. Been running this setup for a few months now and Matt from gearhead and I have been tweaking my tuning. The weird thing is Im only making 29psi of boost. Doesn't matter if its on my reduced fuel file or a full fuel. Even made a tune where he closed the vanes off as much as he felt comfortable doing and still only 29psi. I have checked for boost/exhaust leaks and there are none. All stock boots have been replaced. The only thing I can think of is that I am dropping below 45psi on fuel at wot. Could that be causing the injectors to not provide enough fuel to spool over 29psi? Im kind of at a loss on what to look for or do, besides get a better fuel pump set up obviously. Even though its drops pressure and only builds 29psi it still runs like a scalded dog and pulls like a train. Smoke isn't terrible after it spools but I think it could be cleaned up just a little more. What do yall think?
 
#3 · (Edited)
more boost isn't always your friend... If it runs good and cleans up the 205's descent, id lever B. more boost might clean it up a little better but with the added BP you might not gain you any performance. IMO

Edit: provided you have no leaks...
 
#4 ·
This is true and I had thought about that myself. It just seemed a little low to me. My stock turbo was pushing 35-36psi. Like you said though more boost isn't always the best.
 
#5 ·
my stg 2 never pushed as much boost as my stocker did until i went to bigger injectors, but it defiantly moved more air.

I think the reason it makes more is because the tuning opens the veins wide open but with all the heat and flow its getting the BP still climbs and builds boost. hope that makes sense...
 
#6 ·
Check the basics first... boost leaks, exhaust leaks, bad sensors, etc
Also get an actual boost gauge. The stock MAP/Boost sensor does not read very well past 28-33psi.


I am having similar issues... and have had some customers have similar issues.


Some guys make 35-50psi all day, others struggle to make more than 30psi.


The most important thing to know is what is EBP/Back pressure doing? Mine won't go past 30psi... so it has something to do with tuning limiting the vane position. Many people don't know this but there is no "boost desired" when dealing with tuning these 6.0 powerstroke trucks. You get boost from desiring different parameters. Mainly EBP. EBP will always be equal to or higher than boost.
 
#7 ·
Charlie is right, if you're still using livewire or edge any obd2 port to read boost off the factory sensor that's probably part of your problem. Hook a mechanical gauge up for both boost and back pressure. Also, dropping below 45 psi won't do your injectors any favors. I'm in the process of finishing my ad150 install, feeding the stock pump for now, (Got a fuelab to put on it) might be enough for me, but I've only got 75% nozzles, not 100's like the OP. I've spoke with a few people who've run some type of lift pump before their stock pump, and it was enough to maintain fuel pressure, others with the same 205/75 injectors still had fuel pressure drop even with a lift pump. I'll report back hopefully next day or two and let you know if I hold fuel pressure.

Also, I noticed that my boost would peak at 29 with some tunes, 33 with other tunes going off stock sensor/obd2...with a real boost gauge, I realized all the tunes were 35+ psi. Hope that made sense.
 
#8 ·
Yeah I have been taking my readings from the obd2 port from a Dashdaq, guess its time for some actual gauges lol. And from what I have looked over and tested for leaks, everything is tight. I have actually completely forgot to take a look at my ebp reading. If I were to get an actual gauge for ebp would I just get a boost gauge and tap into the exhaust manifold?

And yeah let me know Gearhead2012, I would like to know. I've been leaning towards and A1000 or a fuel lab with some fleet guard/cat/wix/etc filter bases and filters.
 
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#10 ·
Well, got the ad150 finished last night. It holds pressure a lot better....at least as best I can tell, my rear driveshaft is out right now, I'm having a one piece aliminum made, so it was kinda sketchy, actually...it was really sketchy going WOT in front wheel drive only, but it doesn't drop as bad. Before on just the stock pump, a moderate Wot pull, 5 seconds or so, it would drop to less than 35 psi. Now with the ad150 feeding the stock pump 55 psi was the lowest I saw.

To the OP, I got a good deal on a fuelab 41402, it'll provide plenty of fuel for you in 'reduced' mode...or lots of guys run the aeromotive A1000 pump. Got a buddy who runs it with 350/100's as a single, he holds fuel pressure just fine, actually his regulator is set almost all the way out, meaning the pump isn't breakin a sweat lol. I'm just running two pumps for redundancy on the street. There's only a few things I hate worse than trying to fix something on the side of the road.
 
#11 ·
I'm running 205/100s and a Barder 68 and can hit 40-45psi all day long. That is on a mechanical gauge though. Like stated above, I bet that is your issue.
 
#13 ·
Look at my sig for my setup.
My Max boost reading is also 33psi to date.
 
#14 ·
My stock map sensor will only read 29psi boost through the obdll port with tsd and gear head tunes. However my isspro gauge is reading 52psi boost, I'd guarantee 100% that's why your seeing such low numbers. But also, your on stock pump with BIG injectors. Which means higher egts and more.smoke because fuel pressure is down and your getting poor atomization. Get a second lift pump or an a1000/fuel lab 41402 and your truck will love it. Low fuel pressure leads to injector failure.