low boost at highway speeds

tbauer03

tbauer03

TRBOBOX
truck seems to being doing fine but at highway speeds if i ease it into WOT it will only develope 5lbs of boost. When i am in other gears and wot it doesnt have any trouble making 15-20lbs. Whats the deal? is it the converter or something? the turbo is a stealth 70 and i got a 28k 9/11 converter, 422 cam, vortec heads. any thoughts here?
 
tbauer03

tbauer03

TRBOBOX
Re: low boost at highway speeds

just took it down the highway and played around with it. At around 70mph 2,000 RPM's if i punch it it does not down shift and will just spool 5lbs but slowly increases. I am guessing the fact that it does not downshift is my problem bc when i just shifted it down manually it spooled up
 
sy538

sy538

New member
Re: low boost at highway speeds

There probably is not enough exhaust at 2000 rpm to spool that turbo. Any time you are in 4th gear and under 95-100 mph it should shift down at wot. Even if it doesn’t shift down, I think a 2800 stall converter should let your engine spin to 2800 rpm whenever you step on it. Do you have a torque converter lock up switch? Have you adjusted your TV cable?
 
nightdiver

nightdiver

Active member
Re: low boost at highway speeds

This is transmission related. Fix the downshift problem and youre fine.
Got any mods in the tranny ?
 
tbauer03

tbauer03

TRBOBOX
Re: low boost at highway speeds

yeah it was rebuilt about a year ago with stronger parts i will give the shop a call who built it and see if they will fix it.
 
nightdiver

nightdiver

Active member
Re: low boost at highway speeds

Is this your original 4l60 ? Looks like the VB springs and valves are not the right one
 
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