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Discussion Starter #1
Ok, so the CPL858 is chugging along in the crew cab, and has been doing very well. One thing it does, tho, is under full boost, the turbo starts making a 'chattering' sound. Is this normal, or an indication of something else? It almost sounds like it's trying to make more boost than it can handle, so it's 'chuffing' out the intake. I know, not a technical description...

I can easily recreate the sound by rowing through the gears, and getting on it in 4th or 5th once boost builds. With my 31" tires and 4.10 rear end, I can't load is up enough in the lower gears... =)
 

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yep your surgin, my 6bt used to do it. There are some who like that sound and think its cool BUT its not cool at all. Its hard on the turbo. How much boost are you pushin..........?
 

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Discussion Starter #4
I don't know, I see a boost gauge in my future, along with a pyro...
 

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Basically you're trying to get more pressure from the turbo than I can sustain at low flow rates. The pressure builds to an unsustainable level then blows backwards through the turbo.

The fixes are reduce boost (who wants to do that?), fit a compressor with smaller trim (bigger difference between intake diameter and overall diameter) or fit compound turbos.
 

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A little light chuffing is normal and won't hurt the turbo. Mine does it all the time and is just loud enough to be noticed, but not more than that.

If you can hear heavy chuffing that is an issue to be concerned about.
 

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Are you using the stock H1C turbo?
 

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Sounds like surge to me and it can grenade your turbo. Is this a larger compressor that stock? If it is and has a very tight turbine housing, then you could be overturning the compressor for the air needs of the engine. "Hybreds" that are not a good match can do this. It is not something that is normal for a well matched system. Some hot diesels do this due to turbos designed to run at high RPM and boost levels, but it is not a good idea to run one that is doing it all the time such as every time you let off the go pedal to shift. While it may sound kindof cool, it could bite you in the end.
 

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Are you using the stock H1C turbo?
It is a stock H1C from a '92 or '93 Dodge 6BT Cummins

It will only chuff a little when REALLY loading it, like up a big hill.
 

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Discussion Starter #10
It's the stocker for the 4bt, as far as I know, it came straight out of a p30 chassis bread truck. It doesn't make any abnormal sounds when I let off, only when I'm loading it up (getting on the go pedal in 4th or 5th, up a hill).
 

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FYI I have no more than 3 hours of run time on my HY35, and the constant barking has already started to show up as a loose shaft.. :( Brian went through about 4 turbos with as little as a hundred miles on one because of such a bad surge problem....
 

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This thread makes me wonder about believing that “a bigger turbo is a better turbo” (without getting too outrageous). I don’t know much about performance increases with turbos, nor have I been able to figure out a compressor map yet. I was wondering if someone on this forum can choose a turbo setup that is “theoretically” correct for me. On my CPL 0858, I would like to keep the H1C and go with a 16 cm2 turbine housing. It seems to be the proper size for limiting exhaust restriction. What size compressor wheel would allow (with the proper fuel at an appropriate EGT) about 25 PSI boost? Once this has been determined, can the spool-up rate be judged? Can it be determined from the compressor map of this setup whether there will be a possibility of turbo bark problems? If it is possible, this might be a good power/economy/efficiency combination. What do you think?
 

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My 00' F250 Powerstroke would chatter a bit.... only on a long pull uphill, did it hurt it? I dunno, traded for my 02' Excursion..... it dosen't chatter at all. Problem solved :). -wingnut13
 

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Do you guys with the surge problem have the waste gate disabled? I'm putting an HY35 on my build but now ya got me worried. I guess limiting the boost with the waste gate should solve it at the expense of power.
 

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Bigger is certainly not always better. It has to be the proper balance. However, I like your idea of the larger turbine housing. So many people get caught up wanting the diesel turbo to spool like a race car. If you go a little larger it will lag a little bit, but it will be much less likely to over boost at low RPM causing surge and will also help with lower EGT and drive pressure. My 6BT has a 19cm housing and it is not that bad. It is a little slow to respond, but once rolling it spools very quickly. I have not towed a big load yet, but just the weight of the truck spins it hard in every gear but first. I think it will work nice while towing. With the full manual shift auto, I can punish the turbo and I have never had any chatter.

This thread makes me wonder about believing that “a bigger turbo is a better turbo” (without getting too outrageous). I don’t know much about performance increases with turbos, nor have I been able to figure out a compressor map yet. I was wondering if someone on this forum can choose a turbo setup that is “theoretically” correct for me. On my CPL 0858, I would like to keep the H1C and go with a 16 cm2 turbine housing. It seems to be the proper size for limiting exhaust restriction. What size compressor wheel would allow (with the proper fuel at an appropriate EGT) about 25 PSI boost? Once this has been determined, can the spool-up rate be judged? Can it be determined from the compressor map of this setup whether there will be a possibility of turbo bark problems? If it is possible, this might be a good power/economy/efficiency combination. What do you think?
 

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Discussion Starter #16
Looks like my 'chatter' had killed the turbo, she's got axial and radial play, and lots of white smoke at idle (oil getting past the seal), and LOTS of black smoke under load. This is a 'chevy' engine, so I'll guess it's a 16cm housing. What are my options to eliminate the surging while keeping the egt's low?
 

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I really wonder about all this............we have a Hyster 70 at work with a 6CT 8.3 liter with a Holset H1E turbo. This thing has the original engine....the hour meter is stuck on 5892 and has been that way for at least 10 years, so I am thinking it has about 8-10 thousand hours on it. All original (most of that time is spent idling all day long)

It chuffs HORRIBLY when letting off slightly to part throttle from full throttle. Turbo is still fine.

Now, the 4BT SHAKES BAD. Way worse than a 6 cylinder Cummins....could the vibrations be wiping out turbos early?
 

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Discussion Starter #18 (Edited)
That's not the action that I was experiencing. What mine was doing was at partial throttle, the turbo was boosting normally. At full load (go pedal to the floor), in 4th or 5th gear, after the turbo spooled up and the exhaust cleaned up, when the engine is putting out the most heat and velocity, the turbo couldn't keep up. It would make the chattering sound as long as I could keep load on the engine, up to it defueling at the govenor, when the sound would go away. Definitely sounded like it was building boost to an unsustainable level, backflowing, and building again, 5-10 times a second. Maybe chattering is the wrong word...
 

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It would make the chattering sound as long as I could keep load on the engine,
That is also what my 4BT is doing.
I haven't checked wheel play in the turbo lately.
 
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