Engine/Transmission (1994 - 1998) Too much turbo bark

[Berrigan]

We hear the bark in the HVAC trade alot on centrifugal chillers. Same noise for the same reason. The turbo on the chiller pushes refrigerant to the high pressure side. When the difference between the low side and high side of the turbo is too great the refrigerant gas goes backwards through the blades for a second or so. The turbo does not actually begin to turn backwards. What you hear is the gas (or air in the trucks case) going backwards thru the turbo blades. In the trucks case when the right foot pulls back exhaust gases slow, turbo slows, and now the turbo outlet on the air side is being asked to hold back 30 or more pounds of compressed air that the intake valves are not letting into the engine very fast. The slowing turbo cant hold back the air because it has slowed and lost some of its pumping capacity. The air takes the path of least resistance and makes noise doing so. I dont think it will hurt the turbo if it happened once in a while, but if its doing it alot it is putting loads on the turbo that cant be good for it.



Every bombing thing we do has the potential to make the bark worse. Auto trans trucks wont do it as much cause there is no boost drop between gears. Anyone with a stick should ease out of the throttle between gears to give the engine a chance to gobble up that high pressure air before it tries to blow the turbo south.



Just my humble opinion

 

[Ben Rumson]

Re: Bark Bark Bark!

Originally posted by R. ebel

To lesson the amount of turbo barking remove your silencer ring.



Thanks for the tip. I'll give it a try this next week or so. Plan on putting 1500 - 2000 miles on her over the next two weeks... Good place to test it.



PS I'll be thinking about the rest of you when I'm at 1/4 throttle crusing down the interstate with 10 psi boost here and there for 6 hours straight.



MAN, I love this truck when it's up to temp and hummin' along!!!!

 

[Wirenut]

I don't know anything about that "whooshing" sound, but I definitely know the bark. It is a "braap" sound. It happens alot in 4th or 5th gear when I'm gettin into it and realize the clutch is starting to slip real bad and let off immediately. That's sure to bark it every time. It defintely has nothing to do with the wastegate cause I don't have one.

 

[turboduck]

Originally posted by DBCooper

Thanks for all of the replies. I could hear it bark before the BHAF, but it just seems way too easy now. This whole thing didn't really concern me much, but I thought I would bring it up to see if I was missing something. I try to let up slowly, but with our wonderful drivers on this side of the mountains sometimes it's not possible. We don't have bad traffic, we have LAME drivers. Anyhow, I have heard both ways that barking the turbo is or isn't bad for it. I tend to believe, as Bill said, that it can ruin your day. The physics just don't add up to no problems with stopping something from over 100,000 rpms to nothing and back up. That's if it doesn't reverse when all the air goes out the in pipe.

Paul, jumping out of a 727 over western Washington wasn't what I had planned and most of the money went into the Columbia when I lost my grip, so I need to keep my trusty '98 for a couple more years.

Note to the FBI, it's a JOKE, so quit calling me!!!

Dan

You are showing your age a lot of tdr member's weren't even born

when hijacking 727 and lowering rear steps and jumping was in

when was that 1970??

 

[Deezul1]

Mine sure sounds more like a bark than a whoosh, and as the boost #s went up the louder the Braap. Its easy to avoid by learning to lift your foot a split second slower at high boost and it doesnt take much to lessen it quit a bit and it will trash your turbo if it happens enough. I believe with the BHAF you can hear it better as you can also hear the turbo whistle better plus its flowing more air now also.

 

[illflem]

Think DB Cooper was in 1971. Hard to imagine that in '71 there were no metal detectors, airport searches and credit cards were uncommon.

 

[Air Bulldog]

I build the Air Bulldog hood and I have noticed that on trucks that have turbo bark my hoods will expand and contract very rapidly right where the hood meets my air box, so there must be a lot of air coming back from the turbo. My own truck is an auto it will do it every time if I hit the throttle hard then get off completely.