OK, if I have my TST PM on anything above level 1 setting, and I lift off the throttle, the turbo barks. Funny thing is the first time I heard this, several months ago, it scared the $hit out of me. I thought the turbo blew up or something, or the "oh mighty turbo" blew the bolts out where it connected to the exhaust. Now, back to the barking (no pun intended), so is it pretty much if you lift off the throttle you'll get a bark? Do you just lift off the throttle easy, or push in the clutch, or...what? Is the reason for the bark in regard to high boost pressure? Will this damage the turbo? What is the highest PSI people has seen on the PDR HX-40, is it in the 40's?

 

Usually if you are not towing a large load the 40 is pretty easy to control. Just slowly ease up on the throttle and that generally cures it. The stalling or barking is kinda tough on the turbo. Many folks think the compressor wheel actually spins backwards but it is just loosings its grip on the air it is compressing in most cases. Kinda like loosing traction. Bad compressor stall, surge, whatever can actually turn the compressor wheel in reverse, but it generally only happens on gassers when they backfire, it aint pretty either.<br><br><br>The 40 is best kept around 40PSi. Its off the map anyway at anything higher than that and it can shorten its life span going further. Even the newer compressors from Holset dont like anything past 40psi for long term use.<br><br>Don~<br>

 

Put a muzzle on that dog..... uhhh I mean slowly let off on the throttle vs. abruptly.

 

It's like taking a little pinwheel that is spinning at about 144000 rpm's loaded and trying to blow air backwards through it. That squeal or &quot;Bark&quot; as everyone calls it is the force of the compressed air in the intake mainfold and associated piping coming back out of the intake manifold and associated piping backwards through the compressor side of the turbo to the low pressure or suction side. (hope that made sense) While I have never heard of anyone blowing up a turbo doing it, I try to avoid it usually by leaving off the hammer a little slower to let the cylinders take the pressure and not stuff it back through the turbo. I can't imagine it is doing the turbo bearings and seals any good.<br><br>

 

I have done everything I could to find out if turbo barking is as bad as everyone says. I called lots of people who build and deal with Holset turbos and even researched Holsets web site. NOT ONE said that it is bad and some didnt even know what I was talking about!!! Holset even says not a problem. I would think that with such a problem that people who build turbos would know somthing about &quot;barking&quot;?

 

Thanks for the replies. It looks like everything is inline with what I was thinking. I didn't know if some company had some special part that would take the bite out of the bark. <br><br>I've seen the turbo kickout about 45 psi when pulling a trailer up an incline before the PM3 retarded the fuel as a result of high EGTs. Usually I try to keep it under 40 and adjust the PM3 accordingly.<br><br>Thanks again, and keep it between the ditches...

 

I would be very careful about hitting 45 psi of boost...that will shorten the life of an HX-40 FAST. <br><br>I am guessing your turbo is not wastegated? If it is...set it at 38-40. The PDR turbo is definately better then a stock 40 but I think Piers likes to see the max boost lower then your peaks.