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Newell Gurus
Classic turbo boost - Printable Version

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Classic turbo boost - Tf175 - 03-07-2021

Just checking to see what 8v92TA owners are seeing for turbo boost . My dash gauge indicates 9 psi max . Coach by itself,  accelerating up a grade . Same boost when accelerating from 60 mph to 80 , slight grade . Still pulling at 80 , but rpm around 2400 , so I backed off .
I have read numbers on the Web from 10 to 25 psi . Dash gauge indicates about 3 psi low when compared to another gauge I use in the shop,  so maybe I have 12psi . 
Just replaced both pipes from manifolds to turbo , no soot evident after test drive just now . 60 degrees , elevation about 400 ft , give or take. All new fuel filters . 
BTW,  no exhaust smoke , usual indicator of low boost /turbo issue .
Thanks ,
Chris


RE: Classic turbo boost - kyleb - 03-07-2021

Mine indicates a max of 20 psi.

Is your air filter good?

Are you getting full throttle travel at the engine?


RE: Classic turbo boost - Johnnyboy - 03-07-2021

Definitely seems low, I believe when I had mine I was 15-18 PSI, the higher the RPM the higher the boost.


RE: Classic turbo boost - Guy - 03-07-2021

Our "classic" boost instrumentation is notoriously inaccurate, more of a suggestion than an indication ,but...... a 35 year old 15 or 20 ton rv in the shape of a brick  "80 mph on an incline" and still pulling. What was your pyrometer reading at 80 mph and 2400 rpm ?  Seems like it might be running just fine. To quote a famous guru, "just my two cents".


RE: Classic turbo boost - Tf175 - 03-08-2021

Replies appreciated! 
Air filter looks good,  under 8k miles . Throttle moves to max , at least in static test . 
Pyrometer was 600 at 80 mph , 2400 rpm .
Appeared as slight grade . Max boost at lower rpm under load . 
I want all available power for pulling trailer , also concerned about possibility that turbo could be losing vane material , particularly on intake side . 
Suspect fuel rack adjustment needs attention as there is exhaust temp imbalance between banks at idle .
Thanks , Chris

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RE: Classic turbo boost - Little - 03-10-2021

Ours shows about 20 lb boost at 1900 rpm under full load. 1500 ft elevation, pulling a 16000 lb stacker trailer. Thats the highest I recall. I don't know how accurate the gauge is. The pyro never gets near 1000. The tiny plastic pipe that from turbo to gauge is near 50 ft long so I don't put much faith in accuracy. If your throttle is opening full your exhaust temps should br much higher if you have a turbo issue. I know they do fail but I have never seen one of these turbos come apart except where engine parts try to escape thru the turbo.The oil seals seem to fail first. YMMV Mark


RE: Classic turbo boost - Tf175 - 05-24-2021

A bit of boost update .
Using a regulator and new 30# gauge, connect to 1/8 vinyl tube at engine , thereby testing tubing , connections,  dash gauge . Test :
New gauge :10 #  , dash 5#
New gauge : 20# , dash  10 # 
Dash gauge ( combo w/Pyro )
 is a 0 to 20 psi instrument. 
One could assume (we all know what that means ) that 9 to 10 psi indicated while driving could actually be 18 to 20 psi . As the coach came with the 20 psi boost gauge it would seem that was intended to cover expected boost .
I have 100 ft of tubing , plan on a lash up to see what boost looks like on new gauge while driving . 
Thanks for inputs !
Chris


RE: Classic turbo boost - Tf175 - 05-24-2021

Recent Bus Grease Monkey video involved a Wanderlodge with 8V92 DDEC , down on power and low boost .
They replaced several items including injectors and turbo. DDEC diagnostics showed 23 psi on test drive after repairs .
Perhaps the 'Lodge had a higher HP rating , ours is 475 hp per valve cover sticker . I inspected intake side of turbo , looks good , spins freely , no axial play . Haven't removed pipe to look at exhaust side .
Replaced the air filter gauge , air filter looks good , new gauge should verify .
Chris


RE: Classic turbo boost - Tf175 - 06-05-2021

    Turbo saga continues. 
Ran 5/32 tubing from engine intake forward to the new 30# gauge . Test drive . Saw max boost of 17/18 psi on new gauge , dash reading 9 or 10 . So I'm thinking the boost levels are on par with other mechanical 8V92s .
Now I check the new Filter Minder and find it at 20 inches , almost max . Air filter looks good,  but must be time for replacement. 
Chris


RE: Classic turbo boost - Fulltiming - 06-05-2021

Might try resetting the Filter Minder first. If it comes back to the previous level after driving the coach, then it will be time for a new filter.