I got a question for you guys. Ever since I had the trans rebuilt if i am getting into the pedal pretty good and the converter locks up the turbo will flutter or bark because the L/U drops the RPM so much. Is there a way to stop this? yes I know get my foot out of it....will a bigger turbo stop this from happening? Are my 370's, 4K springs and the "real" converter all to blame? Is it do to the Goerend converter being a little loose for the auto to spool up? I told Dave I was looking for 500-600hp and it's my DD and i would sled pull and drag race a few times a year. I suppose a BOV would take care of the issue as I would ratehr add one that kill a turbo from barking it.

 

How many rpm's does it drop when at wot lock up? From your singnature, i say your about ready for a bigger turbo.

 

I am ready for a bigger turbo.....no doubt about....Once I have some things paid off my goal is an HX/Ht3B compound set-up. I might go with a true HX-40 for a single then throw the HT3b under it....if I can find a deal on one. As far as the RPM drop. I should pay attention to that more but I would say it's a good 500 or so. If a BOV is the answer what size would I need and where is best to install it? Before or after the I/C?

 

are you loosing boost when it locks ups or gaining boost?

 

The gauge flutters IIRC when it happens but i am not 100% positive..... I'd have to watch the gauge closer and make it happen again.

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This doesn't happen on a daily basis as i drive pretty easily but when I go to pass someone on a two lane road and it drops out of L/U and spools then then I level off on the go pedal and the L/U engages it pulls the R's down and then I get the flutter. Maybe it's more of a compressor surge than a bark? I know what the bark is from but can someone explain compressor surge to me then?

 

mabey it waste gate acting up

 

I talked to a couple more guys and it's from the L/U on the converter. They have the same issue. It's a part throttle thing as well. If you are really hammering on it the RPM drop isn't as much and the boost pressure has somewhere to go. The cheapest way for me to stop it is to put in a TTC switch and lock the converter when i go to pass....Oh yeah. I have a 300-500 RPM drop when the converter locks depending on how much I am on the skinny pedal.

 

Sorry to bump a thread this old, but I've been doing searches and reading for days and this is the closest I've gotten to my issue. I'm getting what I think is this noise as well, but only when the TC locks (shifts into 4th?) at or near WOT, like an uphill entrance ramp to the highway, or accelerating with a heavy trailer, or both. Mainly pulling a trailer. It never happens when I lift, only when I keep it pretty much pegged while it shifts.

When it shifts/locks up, it goes from @2500rpm to like, 15-1600; and boost goes from 25psi+ to @10. The needle bounces hard once or twice between the two when it "barks", before settling around ten (and all my power goes away until I've accelerated back up to a decent RPM). It's almost as if there should have been another gear between 3-4 in this trans, but that's another issue entirely. Anyway:

I've put well over 100,000 miles on this truck, as far as I know it's always barked like this. At every service I check the turbo for shaft play, and there is a barely discernible amount, but that too has always been there and it doesn't seem to be getting worse. That said, I don't want it to. It sounds seriously messed up when it happens, and I've thought for years that what I needed was a BOV, but all the reading I could find here about them on automatics is either negative or inconclusive... never mind that the search here leaves a bit to be desired, especially if what you're looking for is most commonly typed with three letters.
So what is the final deal with BOV's? Would it make this problem go away? I'm getting sick of people asking WTF is wrong with my truck every time it barks, and lifting between shifts with an automatic is ridiculous, especially when I'm trying to merge a trailer on the highway and need every second of acceleration I can get out of this rig. I would buy a BOV in a heartbeat if it would solve this.

 

it will not solve your problem dont buy one. the only time i ever bark turboes is when i get off of boost very quickly. is it doing anything else any leaks? something else has to the culprite? you shouldnt drop 25psi when shifting into OD. a few lbs yes but not like you are discribing. and OD is the gear on the pretty stock trucks that makes you feel like your driving a rocket (compared to the other gears) perplexing...

 

No leaks. It doesn't drop 25psi, it drops from 25psi @ 2500rpm to about 10psi @ 1500rpm. My boost pressure is, and always has been, directly related to rpm and I don't think this is unusual. Yes, when the TC locks it does feel stronger, but not when you're trying to get five tons of trailer up to highway speeds with a stock truck. There's nothing rocket about that situation, and it isn't going to accelerate out of 1500rpm with less than half your boost available when you're pulling that kind of weight behind you. An empty truck with no trailer, that's a whole other story and it takes almost no time to recover from the shift into OD, but even then the dramatic drop in rpm causes the turbo to make a noise like it's about to puke it's guts for a second if I'm at WOT when it shifts into OD. Not as bad as when I'm doing the same thing towing a load, but still noticeable. The only way to avoid it is to lift off the throttle the instant it shifts into overdrive, giving the boost a chance to drop before the rpms do.