Attention Turbo Gurus: Need HX35 Advice

[DEZLPWR]

With my DDII's and Plug-N-Power, I am pegging my 35psi Autometer boost gauge when I put my foot in the throttle.



EGT's are not a problem. I can't seem to get above 1100 no matter what...



My questions are:



1. How much boost will my stock HX35 take before blowing up?



2. What boost psi range is most efficient (most power)?



I'll try dialing in my PS boost elbow to the best range based on your suggestions. At 35psi+ it seems strong as ever. I am going to try 32psi or so and see how that is for now.



Man, I love the power of my combo! Stock clutch is holding ok so far..... Gotta love that too!



Bombs away & thanks,



Steve

 

[TxDieselKid]

I think you should....

It sounds to me like you need to step up to a Pier's turbo, and send me that worn out HX-35.



1. ) Your running at the higher end of the 35's range. I think it is good up to around 45 psi, but after that your flirting with a BOMB, and not the kind that make you go fast.



2. ) I think it's good range is from around 12psi to 30 psi. This is just ballbark guessing that I'm doing.



AJB

 

[Stefan Kondolay]

I ran my hx35 at over 40psi for about 6 months with know problems. If I were you I would run your turbo till she blows and then get one of a PDR turbo. You'll love it I know I do. What do you got to loose.

 

[drawson]

I have been seeing up to 45 PSI out of mine now for about 3 months no problems at all but this is way outside the map for these baby turbos

 

[MikeR]

Keep your stock turbo. It's still good for a little more psi. For a year I ran my HX35 with 44psi and I had no problems with it or my EGT's. I think that 50psi is the blowing point.



I think your mods should be able to produce 36psi.

 

[Strick-9]

I ran my stock HX-35 at 45-48 psi for quite a while.



There's no reason to do that though. It doesn't produce more power or lower EGTs over about 32-35 psi.



The turbo is so inefficient above that level that although you have more boost it is very hot and the oxygen content isn't better than 32-35 psi.



On the exhaust side, you are creating a LOT of backpressure on the engine to drive the turbo up to 45+ psi. This excess backpressure robs the engine of horsepower.



Lower your peak boost until your EGTs are as high as you feel comfortable or your smoke output on the top end increases drastically.



It's been said many times before, you only need enough boost to burn the fuel, any more is just a waste and causes excess stress on both the turbo and the engine as well as robbing horsepower.



-Chris

 

[Archive]

(I just lost my original note because my internet connection tends to drop at some very inopportune moments so I'm typing very fast... . for me anyway... . )



Quickly,



Our turbos do not have an engineered "set point" at which they will catastrophically fail. The turbine wheel/housing and the compressor wheel/housing combination the engineers select are a compromise, and will vary from engine rating to rating. (CPL's)



There are a myriad of factors that will influence the operational service life of the turbo. I will single out only one in regards to our BOMBed engines and that would be imbalance within our rotating assemblies.



FACT: The turbine wheel & shaft and the compressor wheel are NOT "perfectly" balanced by Holset before the turbo is assembled. They ARE balanced to the point that the remaining imbalance is below the manufacturing threshold that the engineers have dictated. There is always a level of imbalance present, even when the rotating assembly is considered "balanced" and ready for installation.



My point is this, they all leave the factory within specs, some just leave with a lower level of inherit imbalance than the others. I don't know where my turbo would fall within that group, so I surely don't know where yours would either. I won't even go into the areas of heat soak, lubrication, foreign material, operating clearances. (bearing/shaft,pinwheel/housing) ECT... ... .



If you DO push your stock turbo to the point of destruction, rest assured that hot metal will be sent careening off into your aftercooler. Hopefully none of it OR the lube oil will make it thru to the engine.



I limit my stock turbo boost at 32psi. untill I can upgrade the turbo. IMO, the factory residual imbalance plus any operational factors that have further impacted the current level of imbalance are what will ultimately dictate how long a turbo will last at elevated boost pressures. (RPM's)



BTW. I would venture the opinion that a PDR modified turbo is balanced well below the factory specs. (If you're from Iraq that means it's MUCH BETTER than stock. )

 

[Diesel Freak]

TopFuel... . well said!