Engine/Transmission (1998.5 - 2002) Turbo bark on PDR HX40-16 question

[fj40charles]

Just installed PDR HX40 with 16 cm housing. I've got an adjustable boost elbow and I'm still in the process of tweaking it until I can get it to build boost pressure up to 38 PSI with Comp box on 5x5. The turbo is great. It pulls like a bat our of he!! when it starts to spool up.



I've noticed that I can get it to bark very easily with my 6 speed between shifts when I let off the throttle abruptly after pushing 25 PSI of boost. I'm having to learn how to keep my foot in the throttle or not to let off the throttle so quickly.



I'd like to the know if you're experiencing the same amount of barking. I'm concerned because because I don't want to damage the turbo until I can "learn" to drive with this one. I can't ever remember ever making my HX35 bark.



Thanks in advance,

Charles

 

[fj40charles]

This post really belongs in the products and accessories forum.

 

[TPlasek]

My HX35 with 3" strait pipe barks every time I shift above 2200 RPM's. It is very noticable. I figured it was the turbo blades stalling when the air stopped flowing across them.



Is this correct??? Does it harm the turbo in anyway???

 

[fj40charles]

Hey Tim,



Are you still going to Poteau this weekend? Anyone else beside you and Scott Havis? It is going to be lots of fun.



Charles

 

[TPlasek]

Oh YEAH!!! I am ready to hit the rocks. Scott is leaving on Thr night and I am leaving noon on Friday. I am very eager to test out my 112" wheelbase jeep.



I'll try to keep up with the cruisers...

 

[fj40charles]

"Try to keep up with the Cruisers" with your 44" tires and 112" wheelbase. ;-)



Man, that wheelbase is soooooo long. I can't wait.



I'll be driving with my little bitty 36" tires.



Charles

 

[drawson]

I have barked my too many times doing the same thing you are talking about but by far the worse bark was running up a hill towing w/ cruise on and have some dink pull out in front of me and kicking the cruise off with the brake peddle.

 

[Devildog]

You may want to call Piers and see what he has to say, Let us know.

 

[fj40charles]

I talked to Al at PDR and he said to check to see if there is a turbo silencer ring installed. He said there was a batch of new HX40's that was not machined for the silencer ring. I'll have to wait until I get home to check. Also, Al said the turbo should not be barking at only 25 PSI.



I'm interested to know if anyone else is experiencing the same problem.

 

[TPlasek]

So, is you HX40 supposed to have a silencer ring or not. Does the ring keep it from barking??? What diffference does it make if it barks or not? Other then the LOUD noise at shift points, I don't see how it could be bad for the turbo. I do see how it could be bad for boost. Isn't it just the way the air moves over the turbo blades causing them to stall? I know aicraft fan-jet engines will do the same "bark" if they experience a stong crosswind on takeoff do to the fan blades stalling.

 

[csutton7]

barking is usually not good for turbos---it shortens their life span---chris

 

[TPlasek]

I guess I ask too many questions. The thing I would like to know, is WHAT causes the turbo to bark. I expressed my theory on it but if someone who actually knows would explain it, I would appreciate it much.

 

[fj40charles]

It is the sudden difference in pressure. As you let your foot off the throttle after heavy boost, the boost pressure will want to back out real quickly. This causes the turbo to want to stop and start to reverse directions real quickly. The turbines and/or the turbo shaft will flex. Do a search on "turbo bark" and you'll see lots of posts relating to this.



I looked at my turbo this morning and it has a silencer ring. Still trying to figure it out. .



Charles

 

[drawson]

Or is it caused by the sudden lose of the hot exhaust gases driving the exhaust side?

 

[csutton7]

silencer ring has nothing to do with barking---it just reduces the whine of the turbo, because the air flows more freely--chris

 

[fj40charles]

Al at PDR asked me to remove the silencer ring and see if the barks gets worse or not. He said there are variations in the compressor housing. I'll take some pics with the silencer ring on and off and get the serial number of the housing and email them to PDR and see what happens.

 

[fj40charles]

Believe it or not, removing the silencer ring did the trick. I can get it up to 30 PSI of boost without any turbo barking. I guess the silencer ring prevented the air from flow back freely. I have not gotten the turbo past 30 PSI. This weekend, I'll be towing about 8,000 lbs and should be able to get near 40 PSI.



Piers Diesel is Great. Great customer service and wonderful tech support... ...



Charles



disclaimer: not affliated with any vendor.

 

[csutton7]

I'll eat my words--I would've never thought the silencer ring would have anything to do with barking--the things you learn on this site never cease to amaze me---good job to AL and you, Charles... chris