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Max boost for att

bigdaddyinacaddy

bigdaddyinacaddy

Obsessed
Messages
120
Reaction score
2
Location
Jena, LA
Just wondering what other's results are. I still haven't got a retune so I'm running a gl4 designed for the gm-4. I was coming back from town last night and gave her a slow roll in to 85-90mph and the boost creeped over 22 psi. So I tried to recreate it with the camera out and the boost actually jumped when shifting to 25 psi and held 22 steady. I was just wondering if anyone had got this much boost out of one of these. It won't let me post the video through tapatalk app so I'm gonna post to YouTube then post the link for you guys.
 
I don't have a drive pressure gauge but egt's never got over 1000 (sorry you can't see the numbers in the video, but it's right at the 1000 notch). Not saying they won't go above that, I've had it wrapped up to 1300 before but it was ~20° outside last night so I think that kept it running cool.
 
I do not recall seeing over 15 with Heath's tune that adjusts for the ATT; ~1100F was common for WOT.

Am dropping in a P-400 along with a new tune and if I remember, in a month or two when I finally get the Burb back, will post updates.

IIRC, Chevypoor got those type of numbers.
 
You win! :thumbsup:
I get about 18 PSI peak sustained boost and have gone to 1550 EGT. -1.5 TDCO. Different precups and outside temps may be affecting the results.
 
WW, I just noticed you bought a D word w/ a C word in it. Now that chassis and engine can get test by a true professional weak link finder!
 
Lol I win lol woooo
Jay, I may not get a retune this thing pulls hard and sounds wicked over 20psi
Ww, 1550 is scary high man but yes Arizona temps and n/a precups are to blame for that for sure. And you bought a d word with a c in it?? Noooooooooo lol
Tax time is comin boys I'm not sure if I wanna invest in the new or old! Or both lol
 
Yes, I did a Cummins conversion the 'easy' way. Truck it is wrapped in was 'free' but the engine and trans were expensive. :firedevil: I may have to try a spool valve equipped ATT on it's small looking turbo...

Already found coolant per UOA in the manual transmission. Seriously :WTF:
 
So you got a oil analysis and there was coolant in the manual trans?? Wtf is right lol I bought a duramax 2 months ago and loaded it down with 96 joints of 2 3/8 tubing (~20k#) on a 3 axle gooseneck and found out the PO had abused the Allison, it slips under a real heavy load
 
Lol yea wish I could afford it. Speaking of, what are your opinions on just sealing off the bigger of the scrolls for a weekend putt around backroads truck? Would it have the same effect?
 
Just thought that I would add that I plan on making the truck look very similar to this soon, so mpg are out the window. Just wondering if there would be any other ill effects from totally sealing off the bigger of the scrolls. ImageUploadedByTapatalk1389160336.508861.jpg
Planned on adding a 8" single center- offset miter cut stack to the bed. May snorkel it as well, something ran up the passenger side windshield to the roof lol hope I never need that but just in case ;-)
 
Shoot . . . If you are going to go into that territory, might as well go ahead and stack it. :coal:

And from what I am reading in other threads, might want to reconsider whether to get an ATT tune ;)
 
Being a mud truck you will want to keep the upper rpm flow from both scrolls. W/ 4.56's you shouldn't want for power.

Source Unknown
 
Not bashing the ATT but why would you buy one to block off one of the scrolls to make power on a mudder truck etc? Why not buy another turbo that will do the job without blocking or a diverter valve?
 
Well you can block one off with a diverter valve and have it open at a preset psi. A mechanical VGT of sorts. As has been discussed before. Quick spool up and top end power
 
Yea I planned on lifting it ~9" and runnin 40's so I would have to drop the gears to 4.56 or maybe even a 5.13.
Actually the cost of a straight axle, springs and all the brackets is about the same as a good full 6" diff drop lift, but the straight axle would be a lot more durable and allow me to get a lot more lift. I am torn between a few options. 1. Keep the np241 transfer case and use 77-79 ford Dana 60 axles or 2. Shorten the output shaft on my transmission, use a 4-6bolt pattern adapter and use a np208 transfer case with a 32 spline input shaft. This way I can use 73-87 gm axles with a passenger side drop as pictured above. Also can't decide whether I wanna keep the 4l80e or get a nv4500.
I have owned 2 lifted gm trucks in the past and I can honestly tell you firsthand that the ifs is not made for bigger tires. It may can be beefed up somewhat but why spend $2500 for a ifs lift (6") and then put a ugly body lift on it just to clear 38's. Rambling lol
I just thought the sealing of the scroll would have the same effect as a diverter valve in the quick spooling area. I'm not really worried about boost at cruise or anything like that. It wouldn't be too terribly restrictive at higher rpms would it? Like damaging restrictive? I'm not planning on being up there for too long. I wouldn't need to be if the boost would just come 500rpm sooner. I figured it would just boost more and come on sooner that's all. But I have contemplated swapping to a hx40 just for the sound and low rpm boost.
Me and a buddy were ridin to a wildlife refuge about 15 miles from here and ran up on this. ImageUploadedByTapatalk1389224027.432175.jpg
Warwagon, does that look like your truck? Lol
 
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