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Possible valve float?


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Truck runs great but when I go WOT it just feels like it runs out of power on the top end. I have the wastegate at ~40Psi and drive pressure will hit ~55-60psi at WOT. Truck just kind of dulls out at anything 80+mph. Is this symptoms of valve float? Truck does have stock springs in it and I know I’m already ordering some new ones since it needs them anyways just hadn’t gotten around to it yet. I have 3.54 gears so I’m not reving the truck out as I only see roughly 2000rpm while going 70 in od 

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7 hours ago, Bullet said:

I wouldn't think so...sounds like it's just defueling at a certain rpm.  I run up to 60psi boost and rev to 3500+ and I haven't had any float issues with stock springs and rods. 

It shouldn’t be defueling is the thing. All defuel permaters on the quad are turned off. And I shouldn’t be out of injector as my turbos only a 67mm with a small backhousing, could my turbo be choking it out on the top end? 

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Drive pressure could be fixed by porting the wastegate port from about 5/8" to 15/16"  It will almost double the from w from the wastegate and reduce drive pressure closer to a 1.2:1.0 Boost (48psi drive, 40psi boost).  There is lost energy overcoming all that back pressure.

 

Our new 103# spring will be ready to go beginning of next week.  Matched specs with our new computerized spring dyno.

 

Remember that these trucks move a lot of air and are not very aerodynamic.  Drag soaks up a lot of HP.  I guessd on some of these but 60MPH is 50HP, and 100HP is 188HP.

 

 

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